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We compared the impact of three rounds of annual and five rounds of semiannual mass drug administration (MDA) with albendazole plus ivermectin on helminthic infections in Liberia. Repeated annual cross-sectional community surveys were conducted between 2013 and 2019 in individuals of 5 years and older. Primary outcome was the change of infection prevalence estimates from baseline to month 36 (12 months after the last treatment). After three rounds of annual MDA, Wuchereria bancrofti circulating filarial antigen (CFA) and microfilaria (Mf) prevalence estimates decreased from 19.7% to 4.3% and from 8.6% to 0%, respectively; after semiannual MDA, CFA and Mf prevalences decreased from 37.8% to 16.8% and 17.9% to 1%, respectively. Mixed effects logistic regression models indicated that the odds of having Mf decreased by 97% (P < 0.001) at month 36 (similar odds for annual and semiannual MDA zones). A parallel analysis showed that the odds of CFA were reduced by 83% and 69% at 36 months in the annual and semiannual treatment zones, respectively (P < 0.001). Onchocerca volvulus Mf prevalence decreased slightly after multiple MDA rounds in both treatment zones. Reductions in hookworm and Trichuris trichiura prevalences and intensities were slightly greater in the annual treatment zone. Ascaris lumbricoides prevalence rates were relatively unchanged, although infection intensities decreased sharply throughout. Results show that annual and semiannual MDA were equally effective for reducing LF and soil-transmitted helminth infection parameters over a 3-year period, and reductions recorded at month 36 were sustained by routine annual MDA through month 72.

Schistosomiasis is a parasitic infection highly prevalent in Central Africa where it is co-endemic with many other parasitic infections, including soil-transmitted helminths (STHs). For its optimal control, there is a need of descriptive epidemiological data for each endemic region. The objective of the present study was to determine the epidemiological situation around schistosomiasis in Lambaréné, Gabon. A cross-sectional study was conducted among schoolchildren. One urine sample per day was collected on three consecutive days for the diagnosis of schistosomiasis using a urine filtration technique. One stool sample was collected for the detection of Schistosoma spp. and STH spp. eggs using the Kato-Katz technique, and for larvae, using the coproculture technique. A total of 614 schoolchildren were included in the analysis. The overall prevalence of schistosomiasis and STH infections was 26% (159/614) and 15% (70/473), respectively. Human-freshwater contact was the main risk factor for schistosomiasis in the area (relative risk (RR) = 2.96 [2.20-4.00], P < 0.001). Hematuria (RR = 5.53 [4.30-7.10], P < 0.001) and proteinuria (RR = 2.12 [1.63-2.75], P < 0.001) as well as infection with Trichuris trichiura (RR = 1.86 [1.33-2.61], P = 0.002) and Ascaris lumbricoides (RR = 1.96 [1.19-3.21], P = 0.039) were associated with an increased risk of schistosomiasis. Trichuris trichiura was the highest prevalent STH species in the area. Our study reports a moderate prevalence for schistosomiasis with human-water contact as the main risk factor, whereas the prevalence of STH infections appears to be low. Our results stress the need for the implementation of WHO recommendations for schistosomiasis control.

The Awa indigenous people of Ecuador live in remote areas and were included in health programs only recently. The first screening for parasitic infections in the Awa communities was implemented in the context of community epidemiology. During the site visits in each community, the health-care staff collected the samples for stool microscopy and serology for Strongyloides. A total of 705 individuals consented for the study, representing 40% of the Awa population living in the targeted communities; 184 (26%) participants supplied a stool sample. Giardia intestinalis was found in about 11% of samples. Prevalence of Ascaris lumbricoides and Trichuris trichiura was 54.9% and 36.9%, respectively. No hookworm eggs were found. In addition, Strongyloides stercoralis larvae were found in eight individuals (4.3%), whereas serology was positive in 22.7% of the individuals tested. The community-based approach resulted in an impressive participation. There was a high prevalence of parasites associated with relevant morbidity.

Children in the Peruvian Amazon Basin are at risk of soil-transmitted helminths (STH) infections. This study aimed to determine the prevalence of STH infection in children from a rural Amazonian community of Peru and to elucidate epidemiological risk factors associated with its perpetuation while on a school-based deworming program with mebendazole. Stool samples of children aged 2–14 years and their mothers were analyzed through direct smear analysis, Kato–Katz, spontaneous sedimentation in tube, Baermann’s method, and agar plate culture. A questionnaire was administered to collect epidemiological information of interest. Among 124 children, 25.8% had one or more STH. Individual prevalence rates were as follows: Ascaris lumbricoides, 16.1%; Strongyloides stercoralis, 10.5%; hookworm, 1.6%; and Trichuris trichiura, (1.6%). The prevalence of common STH (A. lumbricoides, T. trichiura, and hookworm) was higher among children aged 2–5 years than older children (31.6% versus 12.8%; P = 0.01). In terms of sanitation deficits, walking barefoot was significantly associated with STH infection (OR = 3.28; CI 95% = 1.11–12.07). Furthermore, STH-infected children more frequently had a mother who was concomitantly infected by STH than the non-STH–infected counterpart (36.4% versus 14.1%, P = 0.02). In conclusion, STH infection is highly prevalent in children from this Amazonian community despite routine deworming. Institutional health policies may include hygiene and sanitation improvements and screening/deworming of mothers to limit the dissemination of STH. Further studies are needed to address the social and epidemiological mechanics perpetuating these infections.

Stool samples from 122 children from urban slum (n = 72) and rural (n = 50) areas were analyzed using multi-parallel real-time qPCR to determine the prevalence of intestinal parasites from two communities in Colombia. Findings indicated a prevalence of 86.1% Blastocystis spp., 62.5% Giardia intestinalis, 19.4% Cryptosporidium spp., 19.4% Ascaris lumbricoides, and 5.6% Trichuris trichiura in an urban slum; and 76% Blastocystis spp., 68% Giardia intestinalis, 20% Entamoeba histolytica, 50% Ascaris lumbricoides, 46% Trichuris trichiura and 2% Strongyloides stercoralis in rural areas. Polyparasitism was higher in rural (58%) compared to urban (25%) areas (p = 0.001). Trichuris trichiura burden was higher in the rural area (p = 0.002). Over 40% of helminth infections in rural areas had a heavy parasite burden by WHO classification. Over half of urban and rural children were infected with Giardia intestinalis and Blastocystis spp. Our data provides accurate epidemiologic surveillance for public health interventions.

The aim of this study was to determine for the first time the prevalence of enteroparasites in preschool children originating from the seven departments of the Pacific region in Nicaragua. One stool sample of each of 1,217 children, from 6 months to 5 years of age, was collected and personal data were recorded on delivery of the container. Samples fixed in 10% formalin were processed by a formol-acetate concentration and a modified Ziehl–Neelsen technique. The overall prevalence of enteroparasite infections was 68.2% with a total of at least 20 species. Blastocystis hominis (45.5%), Giardia intestinalis (31.7%), Trichuris trichiura (8.2%), and Ascaris lumbricoides (5.2%) were the most prevalent protozoa and helminth species in the total study as well as in all departments. Protozoan prevalence presented a statistically significant difference by gender (male: 69.6%; female: 46.7%; P < 0.001), and males presented a higher T. trichiura infection rate than females (male: 9.9%; female 6.4%; P < 0.035). Protozoan prevalence increased with age with a statistically significant difference (P < 0.001). Helminths were always more prevalent in urban areas (P < 0.0002). Protozoan infections result statistically higher than helminth infections so that water-based transmission could be suspected. Based on the differences with respect to species and parasite prevalence between the seven departments in the Pacific region of Nicaragua, the exploration of local factors associated with the transmission of enteroparasites should also be considered to reduce infection.

Trichuris trichiura is a soil-transmitted helminth infecting human populations globally. Human cases caused by Trichuris suis and Trichuris vulpis have also been reported. Molecular identifications of Trichuris species infecting human populations in Lao PDR and Myanmar are lacking. Here, we explored molecular data obtained from Trichuris eggs recovered from human fecal samples from these countries and compared these with new and existing data from Thailand. Nuclear ribosomal DNA (18S and ITS2) sequences were amplified from Trichuris eggs and sequenced. Forty-one samples showed 99–100% similarity in their 18S sequences to published sequences of T. trichiura and one sample showed 99% similarity to a sequence of T. suis. Similarly, 41 samples showed 92–100% similarity in their ITS2 sequences to published sequences of T. trichiura and one sample showed 94–97% similarity to sequences of T. suis. This study is the first molecular confirmation of human infection with T. suis in northeast Thailand and the first molecular confirmation of the species of Trichuris infecting humans in Lao PDR and Myanmar.

Soil-transmitted helminths, or parasitic intestinal worms, are among the most prevalent and geographically widespread parasitic infections in the world. Accurate diagnosis and quantification of helminth infection are critical for informing and assessing deworming interventions. The Kato–Katz thick smear technique, the most widely used laboratory method to quantitatively assess infection prevalence and infection intensity of helminths, has often been compared with other methods. Only a few small-scale studies, however, have considered ways to improve its diagnostic sensitivity. This study, conducted among 4,985 school-age children in an area of rural China with moderate prevalence of helminth infection, examines the effect on diagnostic sensitivity of the Kato–Katz technique when two fecal samples collected over consecutive days are examined and compared with a single sample. A secondary aim was to consider cost-effectiveness by calculating an estimate of the marginal costs of obtaining an additional fecal sample. Our findings show that analysis of an additional fecal sample led to increases of 23%, 26%, and 100% for Ascaris lumbricoides, Trichuris trichiura, and hookworm prevalence, respectively. The cost of collecting a second fecal sample for our study population was approximately USD4.60 per fecal sample. Overall, the findings suggest that investing 31% more capital in fecal sample collection prevents an underestimation of prevalence by about 21%, and hence improves the diagnostic sensitivity of the Kato–Katz method. Especially in areas with light-intensity infections of soil-transmitted helminths and limited public health resources, more accurate epidemiological surveillance using multiple fecal samples will critically inform decisions regarding infection control and prevention.

Historically, the diagnosis of soil-transmitted helminths (STHs) (e.g., Strongyloides stercoralis, Trichuris trichiura, Ancylostoma duodenale, Necator americanus, and Ascaris lumbricoides) has relied on often-insensitive microscopy techniques. Over the past several years, there has been an effort to use molecular diagnostics, particularly quantitative polymerase chain reaction (qPCR), to detect intestinal pathogens. While some platforms have been approved by regulatory bodies (e.g., Food and Drug Administration) to detect intestinal bacteria, viruses, and protozoa, there are no approved tests currently available for STH. Although studies comparing qPCR to microscopy methods for STH are imperfect, due in large part to a lack of a sufficient gold standard, they do show a significant increase in sensitivity and specificity of qPCR compared with microscopic techniques. These studies, as well as the advantages and disadvantages of using qPCR for STH diagnosis, are discussed. Guidelines for those designing future studies utilizing qPCR are proposed for optimizing results, as is the proposition for using standardized molecular diagnostics routinely for STH in clinical laboratories and for field-based studies when possible.

A cross-sectional study was conducted to provide comprehensive data on the patterns and associated risk factors of soil-transmitted helminth (STH) infections among five Orang Asli subgroups in Peninsular Malaysia. The overall prevalence of STH infections was 59.9% (95% confidence interval [CI] = 56.1–63.7%). Trichuris trichiura (54.3%; 95% CI = 50.4–58.2%) was the predominant species followed by Ascaris lumbricoides (26.7%; 95% CI = 23.3–30.1%) and hookworm (9.1%; 95% CI = 6.9–11.3%). This study showed diversity for STH infections by subgroup with poverty and personal sanitary behavior as important risk factors for infection. Risk profile analyses indicating that Orang Kuala subgroup who has a generally well-developed infrastructure and better quality of life had a low rate of infection. There is a need for poverty reduction and promotion of deworming programs along with mass scale campaigns to create awareness about health and hygiene to reduce STH infections.

We evaluated the Newton Nm1, a commercially available handheld light microscope and compared it with conventional light microscopy for the diagnosis of soil-transmitted helminth infections. A total of 91 Kato-Katz thick smears were examined by experienced microscopists and helminth eggs were counted and expressed as eggs per gram of stool (EPG). Mean egg counts were significantly higher with the conventional light microscope (5,190 EPG versus 2,386 EPG for Ascaris lumbricoides; 826 versus 456 for Trichuris trichiura; both P < 0.05). Using regression coefficients and accounting for intensity of infection, we found that the agreement between the two devices was excellent for both species (κ = 0.90, 95% confidence interval = 0.82–0.99 for A. lumbricoides and κ = 0.96, 95% CI = 0.91–1.00 for T. trichiura). The Newton Nm1 microscope may be a useful tool for the detection and quantification of soil-transmitted helminth infection in clinical, epidemiologic, and public health settings.

Epidemiologic studies of co-infection with tuberculosis (TB) and intestinal parasites in humans have not been extensively investigated in China. A cross-section study was conducted in a rural county of Henan Province, China. Pulmonary TB (PTB) case-patients receiving treatment for infection with Mycobacterium tuberculosis and healthy controls matched for geographic area, age, and sex were surveyed by using questionnaires. Fecal and blood specimens were collected for detection of intestinal parasites, routine blood examination, and infection with human immunodeficiency virus. The chi-square test was used for univariate analysis and multivariate logistic regression models were used to adjust for potential confounding factors. A total of 369 persons with PTB and 366 healthy controls were included; all participants were negative for human immunodeficiency virus. The overall prevalence of intestinal parasites in persons with PTB was 14.9%, including intestinal protozoa (7.9%) and helminthes (7.6%). The infection spectrum of intestinal parasites was Entamoeba spp. (1.4%), Blastocystis hominis (6.2%), Trichomonas hominis (0.3%), Clonorchis sinensis (0.3%), Ascaris lumbricoides (0.5%), Trichuris trichiura (2.2%), and hookworm (4.6%). The prevalence of intestinal parasites showed no significant difference between persons with PTB and healthy controls after adjusting for potential confounding factors. There was no factor that affected infection rates for intestinal parasites between the two groups. Infection with intestinal parasites of persons with PTB was associated with female sex (adjusted odds ratio [AOR] = 2.05, 95% confidence interval [CI] = 1.01–4.17), body mass index ≤ 19 (AOR = 3.02, 95% CI = 1.47–6.20), and anemia (AOR = 2.43, 95% CI = 1.17–5.03). Infection of healthy controls was only associated with an annual labor time in farmlands > 2 months (AOR = 4.50, 95% CI = 2.03–10.00). In addition, there was no significant trend between rates of infection with intestinal parasites and duration of receiving treatment for infection with M. tuberculosis in persons with PTB. The prevalence of intestinal parasites was not higher in persons with PTB, and there was no evidence that PTB increased susceptibility to intestinal parasites in this study. However, for patients with PTB, women and patients with comorbidities were more likely to be infected with intestinal parasites.

We conducted a cluster-randomized trial to assess the impact of a school-based water treatment, hygiene, and sanitation program on reducing infection with soil-transmitted helminths (STHs) after school-based deworming. We assessed infection with STHs at baseline and then at two follow-up rounds 8 and 10 months after deworming. Forty government primary schools in Nyanza Province, Kenya were randomly selected and assigned to intervention or control arms. The intervention reduced reinfection prevalence (odds ratio [OR] 0.56, 95% confidence interval [CI] 0.31-1.00) and egg count (rate ratio [RR] 0.34, CI 0.15-0.75) of Ascaris lumbricoides. We found no evidence of significant intervention effects on the overall prevalence and intensity of Trichuris trichiura, hookworm, or Schistosoma mansoni reinfection. Provision of school-based sanitation, water quality, and hygiene improvements may reduce reinfection of STHs after school-based deworming, but the magnitude of the effects may be sex- and helminth species-specific.

Post-treatment soil-transmitted helminth re-infection patterns were studied as part of a randomized controlled trial among school-aged children from an ethnic minority group in Yunnan province, People's Republic of China. Children with a soil-transmitted helminth infection (N = 194) were randomly assigned to triple-dose albendazole or placebo and their infection status monitored over a 6-month period using the Kato-Katz and Baermann techniques. Baseline prevalence of Trichuris trichiura, Ascaris lumbricoides, hookworm, and Strongyloides stercoralis were 94.5%, 93.3%, 61.3%, and 3.1%, respectively, with more than half of the participants harboring triple-species infections. For the intervention group (N = 99), the 1-month post-treatment cure rates were 96.7%, 91.5%, and 19.6% for hookworm, A. lumbricoides, and T. trichiura, respectively. Egg reduction rates were above 88% for all three species. Rapid re-infection with A. lumbricoides was observed: the prevalence 4 and 6 months post-treatment was 75.8% and 83.8%, respectively. Re-infection with hookworm and T. trichiura was considerably slower.

We created a mobile phone microscope and assessed its accuracy for the diagnosis of soil-transmitted helminths compared with conventional microscopy. Mobile phone microscopy has a sensitivity of 69.4% for detecting any helminth egg and sensitivities of 81.0%, 54.4%, and 14.3% for the diagnosis of Ascaris lumbricoides, Trichuris trichiura and hookworm respectively.

Results of studies on the associations of maternal helminth infection and malaria-helminth co-infection on birth outcomes have been mixed. A group of 696 pregnant women from the Kwale district in Kenya were recruited and tested for malaria and helminth infection at delivery. Birthweight was documented for 664 infants. A total of 42.7% of the mothers were infected with Plasmodium falciparum, 30.6% with Schistosoma haematobium, 36.2% with filariasis, 31.5% with hookworm, and 5.9% with Trichuris trichiura; co-infection was present in 46.7%. Low birthweight (LBW) (weight < 2,500 grams) was present in 15.4% of the offspring, and 8.3% had a weight z-score ≤ 2 SD below the World Health Organization mean. Only gravida, age, and locale had a significant association with LBW. The high prevalence of maternal infection coupled with a higher than expected percentage of LBW highlight a need for further investigation of the association of maternal co-infection with LBW.

We conducted a community cross-sectional survey of soil-transmitted helminthiasis in humans and dogs in four provinces in northern Laos. We collected and tested human and dog fecal samples and analyzed results against sociodemographic data. The prevalence of Ascaris lumbricoides, Trichuris trichiura, hookworm, and Strongyloides stercoralis was 26.1% (95% confidence interval [CI] = 23.7-28.4%), 41.5% (95% CI = 38.8-44.1%), 46.3% (95% CI = 43.3-49.0%), and 8.9% (95% CI = 7.4-10.4%), respectively. We observed strong heterogeneity for helminthiasis by ethnicity, province, and wealth status, which coincided with a risk profile demonstrating that Mon-Khmer persons and the poorest households are highly vulnerable. Necator americanus was the dominant hookworm species infecting humans and Ancylostoma ceylanicum was the only Ancylostoma species detected. Hookworm prevalence in village dogs was 94%, and the dominant species was A. ceylanicum. Necator americanus was also detected in dogs. It appears that dogs have a role in human hookworm transmission and warrant further investigation.

Soil-transmitted helminth (STH) infections, and schistosomiasis and other trematodiases often have a high prevalence in developing countries. Here, we present updated information on the prevalence of these parasites in the Lao People's Democratic Republic (Lao PDR) in 2012, arising from the annual national helminthiasis survey. Fecal specimens were collected from 8,610 inhabitants of 12 provinces and one municipality (Bokeo, Houaphan, Luang Namtha, Luang Prabang, Oudomxay, and Phongsaly Provinces from northern Lao PDR; Bolikhamxay and Xieng Khouang Provinces and Vientiane Municipality from the central part of the country; and Attapeu, Champasak, Saravan, and Sekong Provinces from southern Lao PDR). The overall prevalence of three major STHs, Ascaris lumbricoides, Trichuris trichiura, and hookworms (Necator americanus and Ancylostoma duodenale) were 11.6%, 8.5%, and 25.0%, respectively. Prevalence of Schistosoma mekongi infection was 0.1%, and of miscellaneous trematodiases (including opisthorchiasis) was 14.0%. Clearly, the nationwide parasite control project is still necessary to reduce morbidity caused by helminthic diseases.

Helminth control programs have been implemented in Zanzibar for over a decade. In June/July 2007, approximately 6 months after the last school-based anthelmintic treatment, a cross-sectional survey was carried out in two schools, and results were compared with data obtained in the same schools in 1994. Multiple stool samples collected from 368 school children were subjected to the Kato-Katz, Koga agar plate, and Baermann methods. The prevalence of Trichuris trichiura, hookworm, Ascaris lumbricoides, and Strongyloides stercoralis was 46.6%, 21.6%, 16.9%, and 10.2%, respectively. Infection intensities were generally low. Compared with 1994, the prevalence of S. stercoralis, hookworm, A. lumbricoides, and T. trichiura decreased by 81.0%, 80.5%, 70.6%, and 48.6%, respectively. Infection intensities decreased by > 95% for all helminth species studied. Our study confirms that preventive chemotherapy successfully reduces the level and intensity of helminth infections. To consolidate achievements made, additional control measures such as health education and environmental sanitation are needed.

Intestinal multiparasitism, the accuracy of different diagnostic techniques, and the influence of sampling effort were studied among 215 individuals in a Bulang village, Yunnan province, People's Republic of China. Behavioral, demographic, and socioeconomic data were obtained by questionnaire. Multiple stool specimens were examined by the Kato-Katz, Koga agar plate, Baermann, and ether-concentration methods. Eight helminth and 7 protozoa species were diagnosed. The prevalence of each of the 3 main soil-transmitted helminths (Ascaris lumbricoides, hookworm, and Trichuris trichiura) exceeded 85%. Blastocystis hominis was the most prevalent intestinal protozoan (20.0%). Over 80% of the individuals harbored 3 or more intestinal parasites concurrently. The infection intensities were predominantly light for hookworm and T. trichiura but moderate for A. lumbricoides. Examination of 3 instead of 1 stool specimen increased the sensitivity of helminth diagnosis, most notably for hookworm. Intestinal multiparasitism is rampant in this rural part of Yunnan province and calls for control measures.

To determine the role of moderate- and low-intensity infections with Schistosoma mansoni and intestinal helminths (hookworm, Trichuris trichiura, Ascaris lumbricoides) on the prevalence of anemia and their relationship to iron consumption, a cross-section of 1,709 children in rural Brazil was studied. All participants were selected for infection with one or multiple helminthic parasites, and demographic, anthropometric, and dietary intake were surveyed. The prevalence and intensity were as follows: hookworm infection, 15.7% and 8.6 eggs/g; T. trichiura, 74.8% and 190.5 eggs/g; A. lumbricoides, 63% and 1,905.5 eggs/g; S. mansoni, 44.5% and 60.3 eggs/g. There was no increase in odds ratio for anemia with any combination of intestinal helminths without S. mansoni infection. By logistic regression, the odds ratio for having anemia when infected with S. mansoni and two intestinal helminths was 1.7 (95% CI, 1.1-2.5) and for S. mansoni and three intestinal helminths was 2.4 (95% CI, 1.2-4.6) compared with children with a single parasite species. Children with an adequate intake of iron had no increased odds of anemia independent of the combination of parasite infections.

The objective of this study was to examine the independent effect of infection with each of four helminths (Ascaris lumbricoides, Schistosoma japonicum, Necator americanus, and Trichuris trichiura) on cognitive function after adjusting for the potential confounders nutritional status, socioeconomic status (SES), hemoglobin, sex, and the presence of other helminthes. This cross-sectional study was carried out in a rural village in Leyte, The Philippines in 319 children 7–18 years old. Three stools were collected and read in duplicate by the Kato Katz method. Infection intensity was defined by World Health Organization criteria. Cognitive tests were culturally adapted and translated. Learning and memory cognitive domains were each defined by three subscales of the Wide Range Assessment of Memory and Learning, which had an inter-rater reliability ≥ 0.92 and test-retest reliabilities ranging from 0.61 to 0.89. A household SES questionnaire was administered. A logistic regression model was used to quantify the association between performance in different cognitive domains (learning, memory, verbal fluency, and the Philippine Non-Verbal Intelligence Test) and helminth infections. After adjusting for age, sex, nutritional status, hemoglobin, and SES, S. japonicum infection was associated with poor performance on tests of learning (odds ratio [OR] = 3.04, 95% confidence interval [CI] = 1.1–6.9), A. lumbricoides infection was associated with poor performance on tests of memory (OR = 2.2, 95% CI = 1.04–4.7), and T. trichiura infection was associated with poor performance on tests of verbal fluency (OR = 4.5, 95% CI = 1.04–30). Helminth infection was associated with lower performance in three of the four cognitive domains examined in this study. These relationships remained after rigorous control for other helminths and important confounding covariates.

Schistosoma japonicum has been related to anemia, but the mechanisms mediating this relationship remain unresolved. The primary objective of this study was to assess the role of occult blood loss in mediating S. japonicum-associated anemia after adjusting for age, sex, socioeconomic status (SES), and other helminth infections. The secondary objective was to identify intensity categories of risk for occult blood loss for Trichuris and hookworm after adjustment for the presence of other helminth infections. The role of occult blood loss in mediating S. japonicum-associated anemia was studied cross-sectionally in 729 individuals 8-30 years old in Leyte, The Philippines. Three stool specimens were examined in duplicate for helminth eggs. Hemoglobin, fecal occult blood loss, and anemia were measured and related to the presence and intensity of helminths. Multivariate models were made to adjust for confounding by other helminths and SES. In multivariate models, hemoglobin significantly decreased with increasing infection intensity of S. japonicum, hookworm, and T. trichuria (P < 0.0031, P < 0.0001, and P < 0.0001, respectively). Individuals with higher intensities S. japonicum and T. trichuria were significantly more likely to be fecal occult positive (odds ratio [OR] = 3.54; P = 0.008 and OR = 2.68; P = 0.013, respectively), although this was not true for individuals with hookworm. Additionally, individuals with higher intensities of S. japonicum, hookworm, and T. trichuria were all more likely to be anemic (OR = 3.7, P = 0.0002; OR = 5.3, P = 0.0003; and OR = 1.6, P = 0.021, respectively). It is likely that occult blood loss plays a role only at heavier intensity S. japonicum infections and some other mechanism, such as anemia of inflammation, may be contributing to anemia.

This study analyzed the prevalence of intestinal parasitoses diagnosed shortly after arrival in the United States among African refugees before and after implementation of an overseas program of empirical treatment with albendazole. Variables included results of microscopy of a single stool specimen, age, sex, ethnicity, departure origin, and receipt of albendazole. Of 1,254 refugees, 56% had intestinal parasites. Fourteen percent had helminths, and 2% had multiple helminths. In addition, 52% had protozoans with 25% having multiple protozoans. The most common pathogens were Giardia lamblia (14%) and Trichuris trichiura (9%). Overall, refugees who arrived in Massachusetts after implementation of the treatment program were less likely to have any parasites (odds ratio [OR] = 0.61, 95% confidence interval [CI] = 0.47-0.78) and helminths (OR = 0.15, 95% CI = 0.09-0.24) than refugees who arrived previously. These more recently arrived refugees were also less likely to have hookworm (OR = 0.03, 95% CI = 0.00-0.29), Trichuris (OR = 0.05, 95% CI = 0.02-0.13), Ascaris (OR = 0.07, 95% CI = 0.01-0.58), and Entamoeba histolytica (OR = 0.47, 95% CI = 0.26-0.86). Empirically treating refugees prior to departure for the United States appears to have resulted in decreases in intestinal helminths and possibly some protozoans among African refugees tested shortly after arrival in this country.

Honduras has at least five-times more human immunodeficiency virus (HIV)-infected individuals than any other country in Central America. The relationship between HIV status and the presence of intestinal parasites in this part of the world is unknown. This study presents the results from a prospective, comparative study for the presence of parasites in 52 HIV-positive and 48 HIV-negative persons in San Pedro Sula, Honduras. Infection with HIV was determined by microagglutination and confirmed by Western blot analysis. Parasites were detected in stools using formalin-ether concentration, and Kinyoun and trichrome staining. Age, sex, and clinical state of HIV infection were recorded for each study participant. Our results indicate that Cryptosporidium parvum and Strongyloides stercoralis, which are intracellular or live in the mucosa, were found exclusively in persons infected with HIV. In comparison, the prevalence of the extracellular parasites Giardia lamblia, Ascaris lumbricoides, and Trichuris trichiura was significantly higher (P < 0.05) in persons who were HIV-negative. Trichuris worms are in contact with the gut epithelium and less so with the mucosa, whereas Strongyloides lives within the gut mucosa. It is possible that changes in the gut epithelium due to HIV infection do not affect the mucosa and therefore would not affect Strongyloides. We conclude that infection with HIV may selectively deter the establishment of certain intestinal parasites. This may be due to the fact that HIV-induced enteropathy does not favor the establishment of extracellular parasites. Intracellular and mucosal dwelling organisms, however, may benefit from pathologic changes and reduced local immune responses induced by the virus, which, in turn, may lead to higher prevalence among HIV-infected individuals.

A randomized trial carried out in rural Zanzibar comparing a single dose of 200 micrograms/kg of ivermectin and 400 mg/day for three days of albendazole for treatment of strongyloidiasis and other intestinal nematodes is described. In 301 children with Strongyloides stercoralis infection, treatment with ivermectin or albendazole resulted in cure rates of 83% and 45%, respectively. While both drugs were very effective against Ascaris lumbricoides, Trichuris trichiura was cured only in 11% (ivermectin) and 43% (albendazole) of the subjects, although the mean eggload was reduced by 59% and 92%, respectively. Ivermectin was ineffective against hookworms, while albendazole resulted in a cure rate of 98%. No severe side effects were recorded and mild side effects were of transient nature for both treatments. Therefore, ivermectin provides a safe and a highly effective single dose treatment for S. stercoralis and A. lumbricoides, while it is not an alternative for the treatment of T. trichiura and hookworm infections.

To document patterns of intestinal parasitism in the United States, we analyzed results of 216,275 stool specimens examined by the state diagnostic laboratories in 1987; parasites were found in 20.0%. Percentages were highest for protozoans: Giardia lamblia (7.2%), Entamoeba coli and Endolimax nana (4.2% each), Blastocystis hominis (2.6%), and Entamoeba histolytica (0.9%). The most commonly identified helminths were nematodes: hookworm (1.5%), Trichuris trichiura (1.2%), and Ascaris lumbricoides (0.8%). Identifications of G. lamblia increased broadly from the 4.0% average found in 1979, with 40 states reporting increases and seven reporting decreases. Seasonally, Giardia identifications increased in the summer and fall, especially in the Midwest. Nine states reported hookworms in more than 2% of specimens; none were states with indigenous transmission. We analyzed similar, but abbreviated, data for 1991; parasites were found in 19.7% of the 178,786 specimens and Giardia was found in 5.6%. States reporting percentages of Giardia identification in the highest quartile for both 1987 and 1991 were located in the Midwest or in the Northwest. Cryptosporidium was identified in both the 1987 and 1991 surveys; it had not been identified in a previous survey. For each year, Cryptosporidium was reported from 25 states across the country (for both years in 17 states). We conclude that intestinal parasitism should not be overlooked as a cause of gastrointestinal illness in the United States and that the prevalence of Giardia may be increasing.

Ivermectin is a safe, effective, and relatively well-tolerated drug for the treatment of human onchocerciasis. However, due to side effects of the drug, large-scale ivermectin distribution without medical supervision is not recommended. The mechanisms involved in the pathogenesis of ivermectin-induced adverse reactions are not yet known. Since onchocerciasis patients are likely to have concurrent parasitic infections, we investigated whether side effects that occur after ivermectin treatment could be related to the presence of parasite eggs and cysts in stool samples prior to treatment. One hundred twenty-nine onchocerciasis patients were treated with a single dose of ivermectin (150 micrograms/kg) and side effects were graded according to the classification of Greene and others. Stool samples were collected before and three days after treatment. A high percentage (80.5%) of the patients reported adverse effects (57% mild, 14.1% moderate, and 9.4% severe reactions). Most (95.1%) of the patients had one or more concurrent parasitic infections. No relationship could be found between the occurrence and extent of side effects and the severity of concurrent intestinal parasitic infections. However, side effects were significantly correlated with pretreatment microfilarial counts. Ivermectin treatment did not induce significant short-term changes in Trichuris trichiura or Schistosoma mansoni egg counts. However, a significant reduction in Ascaris lumbricoides egg counts and Entamoeba coli cyst loads was observed; a cure rate of 46% for cysts was reached. In contrast, hookworm egg production increased after ivermectin treatment. Further studies are required to verify ivermectin-induced changes in cyst and hookworm loads as well as the significance of these findings.

Use of sewage or wastewater in agriculture is becoming increasingly common as a result of a global water scarcity. Intestinal nematode infections have been identified as the main health risk associated with this practice. To protect consumer and farmer health, the World Health Organization (WHO) has established an intestinal nematode water quality standard. However, because of a lack of well-designed studies, the validity of this guideline is questioned. This report presents the findings of a study on the risk of intestinal nematode infections in farming families occupationally exposed to untreated and partially treated wastewater in Hyderabad, India. The study found an increased risk of hookworm (odds ratio [OR] 3.5, 95% confidence interval [CI] = 2.2-5.5), Ascaris lumbricoides (OR = 5.3, 95% CI = 2.0-14), and Trichuris trichiura (OR = 5.6, 95% CI = 1.8-18) infection when untreated wastewater (150 intestinal nematode ova/liter) was used for crop production. Use of partially treated wastewater (28 intestinal nematode ova/liter) was only associated with an increased risk (OR = 3.2, 95% CI = 1.2-8.6) of A. lumbricoides infection. The findings of the study suggest that the current WHO intestinal nematode guideline of 1 ova/liter is sufficient to protect farmer health.

This study compared five methods for detecting the eggs of the human parasitic geohelminths Ascaris, Trichuris, and hookworm in infant stool, and describes the epidemiology of infection in infants from a parasite-endemic area. A total of 424 infants 5-11 months old were enrolled from three villages on Pemba Island, Zanzibar. Methods used included the Kato-Katz technique, formol ethyl acetate sedimentation, modified formol ethyl acetate sedimentation, modified Wisconsin floatation, and simple gravity sedimentation. Of methods used alone, Wisconsin floatation and simple gravity sedimentation each provided the highest sensitivity for detecting eggs of these three geohelminths (89.6%). Of methods used in combination, the Kato-Katz technique/simple gravity sedimentation and Wisconsin floatation/simple gravity sedimentation each provided the highest sensitivity (99.0%). Prevalence of geohelminth infection was 26.5%. Between five and nine months of age the mean prevalence was 9.4%, while at 10 and 11 months of age the mean prevalence was 43.4%. Village prevalence varied from 3.6% to 43.8%. Infant geohelminth infection can occur at a high prevalence, and what method is best depends on research specifics.

Dear Sir: We write to comment on the article by Humphries and others1 recently published in the American Journal of Tropical Medicine and Hygiene: in our opinion, the study is well conducted, however, we respectfully disagree with the conclusions and in particular with the claim made by the authors about the failure of albendazole treatment of hookworms. We summarize here the reasons of our disagreement: Humphries and others base the claim for albendazole failure in treating hookworm infection on the analysis of cure rate (CR) results that they measured at 61%; however, in the case of infections caused by hookworm and other soil-transmitted helminths (STHs), the CR is not a good indicator of drug efficacy because it is influenced by the intensity of infection at baseline and by the sensitivity of the parasitological method used to recover eggs from stool.2 As a result, it is very difficult to compare CRs obtained in different settings and reach meaningful conclusions about differences in drug efficacy. Our opinion is that drug efficacy in STH infections should be assessed with a more apt indicator, namely the egg reduction rate (ERR). The data presented by Humphries and others show an ERR of over 80% and this corresponds to the normal range of efficacy of albendazole against this parasite,3 as correctly reported by the authors. We would also like to stress the fact that the main objective of preventive chemotherapy against hookworm and other STH infections (those by Ascaris lumbricoides and Trichuris trichiura) is not to achieve cure of infected individuals, but rather to significantly reduce the number of worms harbored by such individuals4; this is because the average observed reduction (that can be measured by counting the number of eggs passed out in feces) is sufficient to cause the parallel decrease: • of transmission (because of the reduced number of eggs contaminating the environment)5; and • of morbidity (because the few surviving worms—that cannot replicate in the human host—cause less harm to the human host).6 As an additional comment, we would also like to express our concern about the method used by the authors to assess drug quality (i.e., in vitro anthelminthic activity), because this method has never been validated for albendazole that is insoluble in water; in addition, in our experience, the key factors in determining the quality of drugs used against STH are the tablet dissolution and disintegration times, and none of them was tested by the authors. Finally, we strongly disagree with the authors' statement that “mebendazole and pyrantel are not any longer recommended for the treatment of hookworm infection”; again, the studies on which the authors formulate their conclusion are based on the evaluation of the cure rate,7,8 and therefore, for the reasons mentioned previously, not conclusive. As a matter of fact, the World Health Organization (WHO) continues to include mebendazole and pyrantel in the list of recommended drugs for the treatment of STH infections. The WHO is seriously concerned about unjustified claims of drug resistance made on the basis of incorrect interpretations of parasitological results and on the poor understanding of the STH biology and control strategies. These claims create uncertainty among the managers of control programs about the efficacy of the control measures to be implemented and undermine the scaling up of STH control activities. As a consequence, a working group reporting to the WHO Strategic and Technical Advisory Group on Neglected Tropical Diseases (NTD) was established with the aim of developing a Standard Operating Procedure to be implemented whenever a control manager suspects a reduction of the drug activity (report available at http://www.who.int/neglected_diseases/NTD_STAG_Report_2011.pdf). Although we hope that this much needed tool will be available before the end of the year, we take this opportunity to invite AJTMH and other scientific journals to carefully assess the grounds on which claims of drug failure are based should similar papers be submitted for publication.

The purpose of this study was to evaluate the efficacy and the tolerance of nitazoxanide in children as a single broad-spectrum antiparasitic agent in the treatment of mixed parasite infections with both intestinal protozoa and helminths. Two hundred seventy-two children (age range = 2-14 years) participated in this study. We systematically surveyed every household head using questionnaires designed to obtain information about household socioeconomic status and hygiene. Parasitic infections were confirmed by three stool examinations using direct smear, Ferreira concentration, and cold acid-fast Kinyoun staining methods. One hundred twenty-one (44%) children tested positive for protozoa such as Giardia lamblia (18%), Entamoeba histolytica/E. dispar (10%), Blastocystis hominis (7%), Cryptosporidium parvum (4%), and Cyclospora cayetanensis (3%), and helminths such as Hymenolepis nana (10%), Trichuris trichiura (6%), and Ascaris lumbricoides (6%). There were also two cases of infection with Enterobius vermicularis. After a complete physical examination was performed, 121 patients received treatment with nitazoxanide. Overall, 84% of the protozoa and 95% of the helminths were completely eliminated from the patients. Nitazoxanide was very well tolerated, with no serious adverse effects reported.

As early as 1 day following the administration of mebendazole to 14 patients for the treatment of Trichuris trichiura infections, the eggs of this worm were observed to be abnormal in size, shape and color. Some of the morphological changes are: increased size, the presence of a membrane, distorted configuration by elongation, distorted shape of the polar plugs, abnormal number of polar plugs, decrease in size, and abnormal yolk material which is refractive to bile staining and development to the larval stage. Some abnormal eggs with normal-appearing yolk material developed to motile larvae.

The isolated Lake Lindu Valley of Central Sulawesi is the only reported Indonesian focus of oriental schistosomiasis. In April 1972 a parasitological survey involving over 1,400 people was conducted in the valley's four villages. Schistosoma japonicum infections were detected in 37.9% of all Lindu people by direct and formalin-ether concentration examinations of stools: 57.1% in Anca, 42.4% in Tomado, 30.0% in Langko, and 11.7% in Puroo. Peak prevalences of schistosomiasis were reached in the second decade of life and remained high thereafter among both male and female populations. Prevalences of other helminthic parasites are reported as follows: Hymenolepsis diminuta

Children with severe Trichuris trichiura infection pose significant social, clinical, and therapeutic problems in Malaysia. Thirty such children were investigated, and mebendazole was found to be safe and effective in the treatment of severe trichuriasis but it had to be given for a longer period than currently recommended. A poor correlation was found between egg load and worm burden in these children. Direct visualization of the rectal and colonic mucosa was the most reliable method of assessing severity in untreated cases, and response to treatment. The eggs of Trichuris that had been exposed to mebendazole were morphologically altered and not viable when incubated. This may be of considerable epidemiological importance.

The efficacy of oxantel pamoate (1, 4, 5, 6-tetrahydro-2-[trans-3-hydroxystyryl]-1-methyl pyrimidine pamoate) was evaluated in 25 children with severe Trichuris infection. The presence of chronic dysentery and sigmoidoscopic demonstration of whipworms in the intestinal mucosa were the criteria for inclusion in the trial. Most of these patients had severe anemia, rectal prolapse, digital clubbing, hypoproteinemia, and growth retardation. There were a high incidence of concomitant parasitism with other intestinal helminths and with Entamoeba histolytica and Giardia lamblia. Sigmoidoscopic grading of Trichuris load and egg count in the feces were carried out prior to treatment and 2 days after each course of oxantel therapy. Oxantel was administered at a dose of 10 mg/kg body weight twice daily for a 3-day course. Satisfactory response, as judged by relief of dysentery and absence of whipworms from the mucosa at sigmoidoscopy, was achieved in 17 patients after the first course and in the remaining 8 patients after a second course of oxantel. The drug was well tolerated and no side effects were noted during or after treatment. It is concluded that oxantel is a safe and effective anthelmintic for severe clinical trichuriasis.

We studied the growth of primary schoolchildren with hookworm (87%), T. trichiura (97%), and A. lumbricoides (49%) who received a single 400 mg dose of albendazole or an identical placebo. Children were allocated at random to placebo (PL, n = 72) or albendazole (A, n = 78) groups, treated, and re-examined 6 months later. The A group gained significantly more than the PL group in weight (1.3 kg), percent weight for age (4.5% age points), percent height for age (0.5% age points), percent weight for height (4.3% age points), percent arm circumference (2.9% age points), and in triceps and subscapular skinfold thicknesses (1.2 mm). The PL group showed significant decreases between exams in percent weight for age, percent height for age, percent weight for height, percent arm circumference for age, and skinfold thicknesses for age. The A group had highly significant increases (P less than 0.0002) in all of these parameters except height for age. From Exam 1 to 2, the A group exhibited decreases (P less than 0.0002) in geometric means eggs per gram of feces (epg): for hookworm, means = 1,183 epg at Exam 1 vs. 136 epg at Exam 2 (67% egg reduction); for T. trichiura, means = 2,857 epg at Exam 1 vs. 1,061 epg at Exam 2 (28% egg reduction); and for A. lumbricoides, means = 86 epg at Exam 1 vs. 2 epg at Exam 2 (91% egg reduction). The PL group had a borderline increase in geometric means hookworm egg count, no significant change in T. trichiura egg count, and a small but significant decrease in A. lumbricoides egg count. Decreases in intensities of all infections were significant predictors of growth improvement. Hookworm egg count entered the equations for all 6 measurements, and A. lumbricoides and T. trichiura entered 4/6 equations. Single dose treatment with albendazole, despite continual exposure to infection, can permit improved growth rates in areas where intestinal helminths and protein-energy malnutrition are highly prevalent.

Summary 1. A group of 1139 individuals on two sugar properties on the south coast of the Dominican Republic have been surveyed to determine the prevalence of intestinal parasitic infections. 2. The percentage prevalence of the most common pathogenic parasites are: Hookworm 59.2%; Trichuris trichiura 58.9%; Endamoeba histolytica 34.2%; and Ascaris lumbricoides 20.1%. 3. Clinical amebiasis is not common among the indigenous population and no instance of hepatitis or amebic abscess of the liver has been encountered. 4. Clinical hookworm disease is not common in this portion of the Dominican Republic despite widespread infection of the population investigated. 5. Differences in prevalence of the most common parasites observed between the two Bateys and the cane field villages are probably to be attributed to local population densities, local rainfall and soil conditions, and varying availability and use of latrines.

Summary Thiabendazole was administered orally in a suspension to 163 adults and children and found to be very effective against Ancylostoma duodenale, Ascaris lumbricoides, Necator americanus and Strongyloides stercoralis and slightly effective against Trichuris trichiura. Five treatment regimens were used and evaluated. A dosage of 25 to about 30 mg of thiabendazole per kg of body weight twice daily for 3 days was very effective and well tolerated. This was substantiated by the results obtained in a double-blind placebocontrolled study. Side effects were few with this regimen. With all treatment regimens side effects were transitory and not severe.

Fecal blood loss measured with Cyanomet-hemoglobin method was estimated in 9 children with various degrees of infection with Trichuris trichiura. The children ranged in age from 3-14 years. Stools were examined several times to rule out other parasitic infections. The eggs of only 1 other parasite Ascaris were found in 4 children. The red cell count packed red cell volume and hemoglobin were determined every 3-4 days. Serum iron and iron binding capacity were determined also. 6 of the 9 children had anemia with hemoglobin ranging from 4-11.2 g/100 ml of blood. The study children were passing in the stool from 1-14 million Trichuris eggs per day--4-118.7 thousand eggs per gram of feces. Expressing infection in terms of grams of feces gives only a very rough measure of burden since stools were watery in 6 cases. This means of expression was used because diarrhea is the most common symptom of the disease. Fecal blood loss ranged from 0.8-8.6 ml per day depending roughly on the degree of infection. It was reduced markedly after treatment except in case 3. This child expelled only 11 parasites and continued to pass over 1 million eggs daily. A high correlation was found between the net fecal blood loss and net number of eggs per day. There was no correlation between the fecal blood loss and the number of eggs per gram of feces because of the variable consistency of the feces. According to these results about 0.005 ml of blood is lost per day per each Trichuris which is 6-10 times less than from Necator americanus and 30-50 times less than from Ancylostoma duodenale. The amount of fecal blood loss per day per million eggs ranges from 0.21-1.58 ml with a mean of 0.78 ml. Approximately 0.25 ml of blood is lost per each 1000 eggs per gram of feces. It was estimated that infections of over 800 parasites producing over 5 million eggs daily induce anemia in children.

Summary Dithiazanine iodide and tetrachloroethylene, alone and in various combinations, were tested for anthelmintic effect in an institutionalized population, both after single regimens and after dosing at regular intervals for an extended period. The results of the study are based on a total of 1,974 treatment regimens in 197 patients. The use of single treatments of dithiasanine alone was effective against Trichuris trichiura but showed little or no effect on hookworm infections. Tetrachloroethylene alone in low dosages had a slight effect on hookworm and none on T. trichiura. Combining the two drugs did not improve the effectiveness against T. trichiura, but apparently did slightly improve the effect on hookworm. Giving repeated dosages of the drugs at weekly, monthly, or quarterly intervals did not markedly improve the anthelmintic effect over the single use of similar regimens. Transmission of T. trichiura continued in all treatment groups, and in none was there any complete elimination of helminths. The data conclusively demonstrated a reduced effectiveness of dithiasanine when used for repeated treatment of T. trichiura in the same patient. Reasons for this lesser effectiveness are not apparent. Dithiasanine, while removing most of the T. trichiura when used as an initial treatment, did not clear the parasite from the groups treated nor eliminate its transmission when repeated dosages were given over an extended period. Addition of small amounts of tetrachloroethylene to the regimens improved the effect against hookworm but not against T. trichiura. Nine of 14 Ascaris lumbricoides infections were eliminated. No effect on two Hymenolepis nana infections were seen.

Summary Phthalofyne (3-methyl-1-pentyn-3-yl acid phthalate), a synthetic chemical compound demonstrated to have trichuricidal activity against both Trichuris vulpis and Trichuris trichiura, was given to 10 healthy young Filipino males harboring Trichuris trichiura. Of 7 cases who received 100 to 125 mg./kg. by mouth, alone or in combination with the same dose given by enema, 4 had rather minimal complaints of nausea and/or vomiting and none received significant therapeutic benefit. The highest oral dose, 175 mg./kg. given to a single patient, produced considerable nausea and apparently complete regurgitation of gastric contents and no therapeutic benefit, suggesting that effective single oral doses would not be easily retained. The phthalofyne enemas, containing respectively 200 mg./kg. and 450 mg./kg. of the drug, and given one week apart to a single patient, produced no side effects and no significant therapeutic effect. The simultaneous administration of 145 mg./kg. by mouth and 450 mg./kg. by enema resulted in moderately severe toxic effects including generalized malaise, nausea and vomiting, conjunctivitis, keratitis, and impaired auditory and visual acuity, all of which subsided within one to several days. In the one case so treated, Trichuris eggs were absent from the stools during a period of several days after therapy, though eggs were found in 1 of 3 stool specimens examined 6 weeks after therapy.

Summary During 1953 a single fecal sample from each of over 10,000 Puerto Rican school children was examined for helminth eggs, especially those of S. mansoni. The following average percentage rates of infection were found: S. mansoni, 10.0; hookworm (Necator and Ancylostoma), 17.1; Trichuris trichiura, 92.6; Ascaris lumbricoides, 20.3; and Strongyloides stercoralis, 0.4. The incidence of S. mansoni in boys and girls was 12.5 and 8.1 per cent, respectively. This difference was significant at odds greater than 99:1. A high degree of correlation (r = 0.89) was found between the age of the boys and their rate of S. mansoni infection, while with the girls, these factors were not correlated (r = 0.38). In general, the abundance of the snail vector (Australorbis glabratus) was related directly to the incidence of human schistosomiasis. There was little or no agreement between S. mansoni infection rates in snails and those in human beings at a given time in a particular locality. The epidemiological aspects of these findings are discussed in the light of results obtained from a study of human beings, snails and S. mansoni infections in three stream communities and from other studies in selected regions in Puerto Rico.

Summary Data are presented on a heretofore unstudied, rather isolated village in southeast Taiwan. It was found that the prevalence of hookworm was significantly lower among the aborigines in the area than it is among the people on the western plains of Taiwan. Ascaris lumbricoides, Trichuris trichiura and hookworm rates indicated no unusual relationship with respect to sex or age. Comparison by ethnic groups did not indicate any significant differences between Taiwanese and aborigines in the infection rates of A. lumbricoides, T. trichiura, or hookworm. Hymenolepis nana was found in aborigines only. Intestinal parasites were found in 82% of 87 aborigines and 85% of 52 Taiwanese.

Summary Study of the intestinal parasites of residents of Ward Siloe, Cali, Colombia, constituted an integral part of the preventive health services in the Family Care Program, Department of Preventive Medicine and Public Health, University of Valle. Altogether 233 families were included in the parasitologic survey. Eighty-eight percent (1227 persons) of families 1–106 provided an average of three stools per person, while 1052 persons of families 107–233 contributed about 2 stools per person during a somewhat shorter time. Stool specimens were examined six days a week by standard direct and zinc sulfate concentration technics for all parasite objects. Record cards were kept of the stage and number of each species diagnosed, and were filed by patient's name, age, sex, family number and relationship of patient to the head of the family. Special study was made of the six common potentially pathogenic parasites (Entamoeba histolytica, Giardia lamblia, Ascaris lumbricoides, Trichuris trichiura, Necator americanus and Strongyloides stercoralis). Rates of infection were calculated for each of these parasites by Areas (I–IV), by age groups, on the basis of persons found infected and of positive stools, and by consecutive trimesters over a four-year period. Less frequent pathogens diagnosed included: Balantidium coli, Isospora belli and I. hominis, Taenia saginata, Hymenolepis nana and H. diminuta. Examination of the feces of dogs, mice, rats and cockroaches showed that, although there were indications that parasite objects of human origin had often been ingested by these animals, there was no suggestive evidence that they had contributed to the prevalence of human intestinal parasitoses. Exposure within the home environments in Siloe favors repeated infection, beginning during the first months of life and continuing until old age. Lack of a clean domestic water supply, filthy latrines and no facilities for garbage disposal provide unusually favorable opportunity for continued reexposure to infection in Ward Siloe, Cali.

Summary 1. Trichuris trichiura is not a harmless parasite but frequently gives rise to severe or even fatal disease. 2. We find in the literature no specific treatment. 3. Chenopodium does not remove this parastie. 4. Leche de Higueron offers a safe and hopeful means of treating this disease. 5. This juice possesses a slight vermicidal action on ascaris and ankylostoma. 6. In this series of cases, this treatment caused the passage of trichuris in 57 per cent of cases.

Summary One hundred thirty-two ambulatory patients, harboring 284 intestinal worm infections, were treated with thiabendazole. Dosage and administration of the drug were varied in four different groups studied. Best results were obtained against Strongyloides stercoralis, Ascaris lumbricoides and hookworms. Effectiveness was very weak for Trichuris trichiura, and no effect was found in Taenia solium or T. saginata infections. From one-third to one-half of the patients showed manifestations of intolerance, usually transient and not severe. A review of the publications on clinical trials up to September 1964 is presented.

Summary and Conclusions Estimations of efficiency of the formalin-ether sedimentation concentration procedure for the detection of ten common intestinal parasites have been determined from an analysis of data obtained in multiple-stool examination series. Approximately 1,000 residents of four, rural, Japanese villages were examined in two five-stool series and findings were analyzed by the maximum-likelihood method of Sawitz and Karpinos. Mean estimates of efficiency for the detection of protozoan cysts were comparable to those computed by other investigators for the ZnSO4 centrifugation-flotation technic. These estimates, in per cent, for the formalin-ether procedure were 60.2 for Entamoeba histolytica; 75.1 for E. coli; 60.4 for Endolimax nana; 55.7 for Iodamoeba butschlii; and 44.5 for Giardia lamblia. Corresponding figures for helminths were: 91.9 for Ascaris lumbricoides; 92.2 for Trichuris trichiura; 78.9 for hookworm; 41.1 for Trichostrongylus sp.; and 47.6 for Schistosoma japonicum. The efficiency of the formalin-ether procedure for the detection of some organisms, especially protozoan cysts, was observed to vary and, in some instances, the differences were probably significant. These variations are assumed to be due to a combination of factors including technical error, limitations of the analytical method and the examination procedure itself, possible biologic characteristics of the organisms that might affect their detection, and normal fluctuations in the mean infection intensity in the different population groups. Re-examination of about one-half of the people within 60 days after the initial examination series permitted a better estimate of the reliability of the technic. The number of additional infections detected in the second examination series was about equal in all instances to the number of cases present in the first series, but absent in the second. The rate of misses for E. histolytica was no greater than the rate for more easily recognized forms. On the basis of the latter data, it was estimated that examination of five separate stools by the formalin-ether technic will detect about 97 per cent of amebiasis cases in a population. Similar data were also obtained for the other nine parasites.

One hundred fifteen patients with light to severe infections of Trichuris trichiura were treated with mebendazole. A double blind study was designed with test subjects receiving placebos, and 2, 3 and 4 days of active medication, 100 mg twice daily. Extensive blood and urine analyses before, during, and 8 days after initial treatment showed no significant changes due to the administration of mebendazole. Patients tolerated the drug well and no toxic side effects were observed. Egg count comparisons on stools collected before and after treatment indicated cure rates of 53.3%, 64.3% and 66.7% for patients on the 2, 3 and 4 day regimens respectively, after 42 days. In the patients not cleared of their worm burdens, an 87.3% to 96.1% egg reduction was observed.