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Hookworm and threadworm infections are major public health problems in developing countries. A cross sectional study comprising 843 participants (346 males and 497 females) was conducted in three populations: i) Thai residents (TR) of Ubon Ratchathani Province, Thailand; ii) Laotian immigrant workers (LI) in the same province; and iii) Laotian residents (LR) in Champasak Province, Lao PDR. Participants were interviewed based on a structured questionnaire regarding their health status. Stool samples from participants and 300 samples from domestic animals (277 dogs and 23 cats) living in the participants households were collected and examined for parasitic infection using a formalin-ether concentration and a Harada-Mori filter paper culture techniques. Approximately one-third of TR and LI populations and domestic animals in Thailand were positive for parasitic infections, while almost half of LR population and domestic animals were positive. We confirmed by PCR and DNA sequencing a case of Ancylostoma ceylanicum infection in a Thai man. We also observed infections of other parasites, such as Taenia spp and Opisthorchis viverrini. Multivariate analysis indicated that risk factors for hookworm infection were population group and walking barefoot. Factors associated with threadworm infection were population group, adult male, lack of previous antiparasitic treatment and of knowledge of parasitic infection, and failure to wash hands after contact with domestic animals. Our results highlight the high prevalence of both hookworm and threadworm infections especially among LI population and domestic animals in both countries. Our findings emphasize the need for public health intervention to control the spread of parasitic infections in Thailand and Lao PDR.

We studied the prevalence and risk factors for pinworm infection in children attending the kindergarten of Thammasat University, Pathum Thani, Thailand, using the Scotch-tape technique. Slides were examined by a standard light microscope; 20% of negative slides were reexamined for quality control. Symptoms and risk factor data were collected using a structured questionnaire. Three hundred thirty children age 3 to 6 years old were sampled (males=159). Sixty-five (19.7%) had symptoms consistent with pinworm infection. No pinworm eggs were detected. Most parents (73%) had a good socioeconomic status and 64% were university graduates. Pinworm infection may be uncommon in urban Thailand.

In this study, adult patients were treated with praziquantel to expel intestinal flukes. Unexpectedly, dozens of adult Enterobius vermicularis worms with disfigured morphology, which had not been detected on fecal examination using Kat's modified thick-smear technique, were expelled from 6 of 33 patients.

In Thailand, Mae Hong Son Province is highly endemic for malaria. Knowing this, the local Health Department has introduced a program to educate local residents about the risk factors, in particular the dangers and symptoms of malaria. This study was conducted to evaluate these efforts, by determining the number of malaria infections in a segment of the population, and also by testing for enterobiasis among a group of its children. Two villages in Mae Hong Son Province were chosen for this purpose with a combined population of about 300. Of these, 195 were screened for malaria. Two subjects were diagnosed positive for malaria by microscopy. One of these two villages was chosen to screen for Enterobius vermicularis infection in children as well. Out of 69 stool samples, five (7%) showed infection with E. vermicularis: three with a low number of eggs (1-50), and two with a high number of eggs (>100). Compared with infection rates in similar studies, the results of this study indicate that the Health Department's efforts are meeting with relative success. The low prevalence of infection indicates that the villagers are using the information they have received to help combat infection.

Parasite life-history traits reflect past environmental and host selective pressure that act to produce strategies that maximize successful transmission. Pooled human pinworm eggs were pretreated with 0.9% NaCl, acid digestive enzyme, and alkaline solutions (pH 9.0) and then incubated in 0.9% NaCl at room temperature and 37 degrees C both with and without 5% CO2. Eggs pretreated with both acid and base had the same hatching pattern, which was markedly different to that of the untreated eggs. At room temperature (RT), hatching of the pretreated eggs occurred on the first day and reached its peak rate (>90%) on day 3; at 37 degrees C hatching occurred on the second day and was more than 80% by day 5. Hatching of the untreated eggs was evident on day 2 at RT and between days 3-5 at 37 degrees C although in smaller numbers (<20%). The CO2 did not affect the hatching of larvae. The larvae could survive after hatching in 0.9% NaCl for 2 and 4 days at 37 degrees C and 25 degrees C, respectively. The present investigation gives a different information that human pinworm ova can hatch into larvae with or without exposure to acid digestive enzyme or alkaline solutions.

A study of enterobiasis and its correlation with various factors that could potentially influence the rate of infection was conducted among 3,621 primary school children (five to ten years old), drawn from sixteen schools in Bang Khun Thian District, Bangkok. Diagnosis was by the transparent tape swab technique, which was used to recover Enterobius vermicularis eggs from the perianal region. The transparent tape swabs were then placed on slides for examination by light microscopy. The average rate of infection for the group was 21.57%. No statistically significant differences were found between the male and female children. The younger children had a higher rate of infection. Subjects from schools located in industrial and metropolitan areas showed slightly higher rates of infection than those from agricultural areas. Data from the questionnaires in the study indicated that factors such as parental socio-economic status (occupational, income and education) and the children's personal hygiene contributed to the varying rates of infection.

We surveyed Karen hilltribe villages in the Mae Chaem District of Chiang Mai Province between April and May 2001. Two hundred and forty-nine pre-school children were selected by stratified sampling from 10 villages and were examined for Enterobius vermicularis eggs by the Scotch tape perianal examination technique. One hundred and thirteen (53 boys and 60 girls) were found to have E. vermicularis eggs, giving an overall infection rate of 45.38%. We were able to determine that E. vermicularis infection is prevalent among the children of these hilltribe villages.

A prevalence survey of Enterobius vermicularis in primary school students aged 6-10 years in Bang Plee district, Samut Prakarn Province, Thailand was undertaken from January to March 2000. There were 783 subjects, 395 males and 388 females. Diagnosis was done by transparent tape swab technique. It revealed that 1) worms were found in 38.82% of the students, 2) there was a correlation between prevalence of parasite infection and student sex and age and 3) family socio-economic background (income and occupation) had no relationship with the prevalence of the enterobiasis (p < 0.05).

A cross sectional survey of Enterobius vermicularis was carried out in 808 children in the Bangkok metropolis and nearby provinces. This was accomplished in a mobile health clinic from Huachiew Chalermprakiet University provided for communities in the areas during April 1999 to May 2000. Children 5-10 years of age were investigated for infestation of Enterobius vermicularis. Diagnosis was done by means of the transparent tape swab technique to recover eggs in the perianal region for examination under a light microscope. The average infection rate in children was 21.91%. The highest infection rate (38.59%) was found in Ang Thong Province, while the lowest one (11.66%) was found in Chonburi Province. The rate of infection seemed to relate to household environmental factors. The infection rate was significantly higher (p<0.05) in agricultural areas and areas farthest from urban Bangkok. Industrial and urban areas had the lower rates of infection. There was no significant difference (p>0.05) in the incidence of infection between males and females.

A prospective observational study was conducted in a male orphanage to find out the prevalence of enterobiasis and its incidence after blanket chemotherapy using mebendazole. We found that the prevalence of enterobiasis was 28.9%. The incidence density of enterobiasis after blanket chemotherapy was 379.82 per 1,000 person-years which was quite high. We suggest that blanket chemotherapy should be repeated at every 6 months interval to control enterobiasis in orphanages.

The infection rate and relationship of enterobiasis with socio-economic status were determined in children aged 1-8 years, living in a rural area in Malaysia. Of the 178 subjects 40.4% were infected with Enterobius vermicularis. The distribution of enterobiasis among these children were analyzed in relation to age groups and sex. The rate of infection was significantly higher in older children (5-7 years). The association of enterobiasis with other factors studied such as number of persons per house, household income per months and mother's employment status were not significant. The sensitivity of three successive days anal swabs compared to a single swab was found to be statistically significant.