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Purpose: To describe corneal disorders in patients with systemic parasitic disease., Methods: Cross-sectional study consisted of ophthalmologic examinations, peripheral blood tests and skin biopsies in 496 subjects (395 Indians and 101 non-indians) from the upper Negro River, Brazilian Amazon., Results: Mansonella ozzardi was detected in the blood of 140 (28.23%) subjects. Seventy-six (55.07%) of them also presented multiple nummular opaque superficial lesions in the cornea. None of the examined patients presented onchocercal-related skin lesions or positive skin biopsies for filaria., Conclusion: There was a significant association between mansonelliasis and keratitis.

The long-term effect of a single oral dose of 150 microg/kg of body weight of ivermectin on Mansonella streptocerca microfilariae was studied in western Uganda. Before treatment, the geometric mean microfilaria density (mf) in 93 infected persons was 2.4 mf/mg of skin (range, 0.1-42.6). One year after treatment, 43 persons (46%) were microfilaria-negative, and the geometric mean in the remaining persons dropped significantly, to 0.7 mf/mg (range, 0.1-6.9). Thus, ivermectin is highly effective against M. streptocerca, and a single dose leads to a sustained suppression of microfilariae in skin. In Africa, ivermectin is used for mass treatment to control Onchocerca volvulus and Wuchereria bancrofti. Because these filarial parasites are often coendemic with M. streptocerca, the treated population may receive the additional benefit of suppression of M. streptocerca microfilariae.

To differentiate the skin-dwelling filariae Mansonella streptocerca and Onchocerca volvulus, a nested polymerase chain reaction (PCR) assay was developed from small amounts of parasite material present in skin biopsies. One nonspecific and one specific pair of primers were used to amplify the 5S rDNA spacer region of M. streptocerca. Biopsies with different microfilaria densities obtained from 104 Ugandans living in an area endemic for M. streptocerca were tested using both the nested PCR assay and standard parasitologic assessment of microfilariae. All 82 samples from microfilaria carriers were positive when tested using the nested PCR assay. In addition, M. streptocerca DNA could be detected in 16 samples thought to be microfilaria negative. Furthermore, six days following ivermectin treatment, M. streptocerca DNA was found in 12 of 14 microfilaria-negative biopsies. Control skin samples from patients infected with O. volvulus were all negative in the nested PCR assay. This assay improves the diagnosis of M. streptocerca and will facilitate further epidemiologic studies.

We studied the short-term effects of a single dose of 150 micrograms/kg body weight ivermectin on Mansonella streptocerca in an area endemic for streptocerciasis, but not for onchocerciasis, in western Uganda. Six and 12 days after treatment no microfilaria (mf) were found in the skin of 53 out of 96 mf carriers living in 3 villages, and the geometric means of the mf densities of remaining mf carriers were only 33-40% of pretreatment levels. This reduction of mf density was highly significant (P < 0.0001). Immunohistological examination of skin biopsies showed degenerated and disintegrating mf surrounded by activated eosinophils (positive for activated cationic protein), macrophages, and neutrophils (positive for myeloperoxidase and defensin) on day 6 after treatment. Remarkable was the invasion of young, L1 protein-positive macrophages and the release of neutrophil defensin as signs of acute inflammation. We conclude that ivermectin has a strong microfilaricidal activity against M. streptocerca. Common adverse effects were increased pruritus and acute papular dermatitis in 45% of 86 mf carriers on day 6 after treatment. No serious adverse side-effects were noticed in about 700 treated persons.

The prevalence of filariae in wild raccoons trapped in southeast Georgia was determined. Examination of blood samples revealed that 74 of 113 raccoons (66%) trapped in 6 southeastern Georgia counties were infected. Seventy-three of these raccoons (65%) were infected with Mansonella llewellyni and this parasite was observed in raccoons from every location examined. Dirofilaria tenuis was found in 22 raccoons (20%) and was observed in only 3 of the 6 counties surveyed. An adult specimen of Acanthocheilonema procyonis was found in the subcutaneous tissues of 1 of 5 necropsied raccoons. This is the first record of filariae in raccoons from Georgia. In addition, Dirofilaria-like larvae were found in Aedes taeniorhyncus mosquitoes collected in Liberty County.

In a cross-sectional epidemiological and clinical study of human filariasis, 630 individuals were examined for Onchocerca volvulus, Wuchereria bancrofti and Mansonella perstans infections in five communities in the Kaiyamba Chiefdom, Moyamba District, Sierra Leone. The overall prevalence of O. volvulus infection in males 144(39.1%) and females 94(35.9%) was not significantly different and the sex prevalence rate between communities was also not significant (G = 3, d.f. = 4, P > 0.05). Prevalence of O. volvulus was significantly lower (G = 42.331, d.f. = 5, P < 0.001) in the 5-9 age group (13.3%) compared to the 40-49 age group (61.9%). Sixty-four (10.2%) and 38(6.0%) of individuals examined were positive for W. bancrofti and M. perstans infections respectively and prevalence of both infections in the five communities was not significant. Mixed infections with the all three filaria parasites were recorded in 10(3.2%) of the individuals. One hundred and sixty-four (71.3%) clinical cases due to W. bancrofti were inflammatory in nature; 36.5% were chronic, of which, 26.6% were hydroceles and 9.4% involved elephantiasis of both the scrotum and the lower legs. All 19(3.0%) of M. perstans-related clinical cases were inflammatory. Ninety-three(63.3%) of O. volvulus positive individuals that presented symptoms were inflammatory in nature, 14(9.5%) had ocular symptoms and 57(38.8%) had subcutaneous nodules. These data indicate that infections due to O. volvulus, W. bancrofti and M. perstans may be of public health importance in Sierra Leone.

Parasitic infection as the only or concomitant cause of infertility in Caucasian women is rare. A parasitic infection may also present itself quite unexpectedly as a coincidental finding as shown with this case report. Moving microfilariae of Mansonella perstans were found in the aspirated follicular fluid of a patient who underwent in-vitro fertilization (IVF) with embryo transfer because of tubal pathology due to Chlamydia trachomatis. The patient also appeared to have a Schistosoma infection. To our knowledge, the presence of parasites in follicular fluid has never been reported before. We expect that infertility physicians may be confronted with parasitic infections more often, not only in patients originating from tropical countries but also in Western women as a result of a tendency to travel more frequently to exotic and (sub)tropical countries.

The prevalence of the apathogenic filaria Mansonella perstans was studied in four parishes in western Uganda as part of an onchocerciasis control programme to avoid futile treatment. Blood samples from 1543 persons aged over 14 years from 19 villages were examined for the presence of microfilariae using a modified Knott method. The prevalence of microfilaraemic persons ranged between the parishes from 39% (95% CI 35.9-42.0%) to 81% (95% CI 76.2-84.8%). With exception of single microfilariae of Onchocerca volvulus no other filaria species was detected. Onchocerciasis mass treatment campaigns did not reduce the prevalence of M. perstans infection, since 6-12 months after treatment with a single dose of 150 micrograms/kg ivermectin the prevalence in 124 persons was about the same as before treatment. The QBC-fluorescence technique was employed for the detection of microfilariae in samples from outpatients of the government hospital in Fort Portal: in 16% of 120 children and 24% of 369 adults microfilariae of M. perstans were detected.

Two aetiological studies on filariasis were conducted from January to June, 1993. In the first study, 690 blood samples clinically diagnosed of filariasis were examined. In the other, 150 blood samples and 150 skin snips collected from the same group of eye clinic Patients clinically diagnosed of filariasis were investigated. Of the 690 subjects, 108 (15.64%) had filariasis with M. perstans and Loa loa accounting for 98.15 and 1.85% of positive cases respectively. Among the eye clinic patients, 16% had M. perstans while O. volvulus was seen in 4% of patients. There was no concurrent infection with these two agents. A statistically significant association existed in the frequency of M. perstans in the different ages treated (p > 0.01) while non existed by sex (p > 0.01). The possible involvement of M. perstans in ocular filariasis and its treatment are discussed.

The prevalence and microfilarial density of Loa loa and Mansonella perstans filariasis have been determined in three successive surveys in one village in the dense rainforest of Southern Cameroon. The prevalence of L. loa microfilaraemia was 30.9% with a geometric mean density of 81.4 microfilariae/30 microliter blood. There was no difference between men and women. The prevalence increased with age from 14.5% at 0-9 years to 52.9% at 40-49 years, whereafter it stablized. The microfilarial density increased until the age of 30-39 years. The highest densities have been found around noon, although the difference was not significant. The prevalence of M. perstans microfilaraemia was 26.6% with a median density of 2.0 microfilariae/30 microliter blood. Both prevalence and density were increasing with age and were higher for men than for women. The time of day that the blood sample was taken had no influence on the microfilarial density of M. perstans.

Twenty-five of 30 patas monkeys (Erythrocebus patas) inoculated with varying numbers (35 to 135) of third-stage larvae of Mansonella ozzardi developed patent infections in an average of 163 days. There was no correlation between the size of the inoculum and the length of the prepatent period. Ten of the monkeys were monitored thereafter by regular blood examination for extended periods of time in order to characterize the onset, course and duration of patency. Typically, with the onset of patency, microfilaremias increased steadily, peaking at about 20 weeks and then decreased slowly stabilizing at low levels for up to 48 weeks. Thereafter microfilariae disappeared from the blood and occasionally reappeared in scanty numbers. Laparotomies and followup studies indicated that the spleen was involved in the suppression of peripheral microfilaremia as had been observed earlier in patas monkeys infected with Loa loa. In ten monkeys splenectomized after the initial "wave" of microfilaremia, it was observed that (a) 30% of the animals remained amicrofilaremic, (b) another 30% reestablished patent infections but microfilaremias were lower than presplenectomy levels, and (c) in the remaining 40%, levels of microfilaremia equaled or exceeded pre-splenectomy levels. Patent infections persisted for up to 212 weeks. One monkey splenectomized prior to inoculation with 87 larvae developed a patent infection with microfilaremia which persisted for 156 weeks. Three monkeys with low and high levels of microfilaremia bled at four hour intervals over a 28 hour period showed no evidence of periodicity in the microfilaria.(ABSTRACT TRUNCATED AT 250 WORDS)

Infections with Mansonella perstans are common in certain parts of Africa and South America. There is no standard treatment at present. We evaluated the effect of albendazole on microfilaremia in ten consecutive patients. No decrease in microfilarial counts could be demonstrated after a median follow-up period of 45 days. Albendazole was not shown to be useful for treatment of Mansonella perstans filariasis.

Over 100 million persons suffer from diseases caused by filariae infestation, and one billion are at risk. A simple isolation method for both analytical and preparative separation is presented. Based on the simplest field-flow fractionation technique, the gravitational one, effective isolation of microfilariae is achieved. Microfilariae are eluted in the void volume of the channel without pollution by red blood cells. The red blood cell elution peak shows a total absence of microfilariae, as demonstrated after fraction collection and microscopic investigation. The elution mode of microfilariae and red blood cells appears to be a steric one, as confirmed by a reinjection experiment. The simplicity, low cost and the relatively short time required for this separation (10 min) indicate that gravitational field-flow fractionation could become a new separation tool for screening of microfilariae. With both live and dead microfilariae, the high recovery (66-80%) allows preparative fractionation for diagnostic purposes or fundamental research.

This report summarizes the findings of the 17 published studies involving humans who have been experimentally infected with filarial parasites. Over the past 60 years, 45 individuals have been deliberately infected with Wuchereria bancrofti, Brugia malayi, Brugia pahangi, Loa loa, Mansonella perstans, Mansonella ozzardi, and/or Onchocerca volvulus. The findings from these experimental infections of humans have helped define microfilarial survival and periodicity within human hosts, the prepatent period for the causative agents of lymphatic filariasis, etiologic agents for particular clinical syndromes, immunologic and hematologic consequences of filarial infection, and the role of chemotherapeutic agents in the prevention and treatment of filarial infections.

For the first time, a parasitologic survey has been carried out in the Niefang District (continental area of equatorial Guinea) within a sample of 829 people aged of more than 10 years. Parasitologic incidence was 27.1 p.c. for Loa-Loa and 66.3 p.c. for Mansonella perstans. Significant differences were noted in the prevalence and in the mean density of microfilariae of both species according to the altitude of the villages surveyed.

Microfilariae were found in blood samples of a 32 year-old-student from Guinea-Bissau (Africa). Based on parasite morphology as well as some other features the microfilariae were identified as Mansonella perstans. The course of infection was asymptomatic (except for slight urticarial skin lesions). The microfilariae disappeared from peripheral blood after mebendazole treatment (200 mg daily for 1 month).

A study of Mansonella perstans filariasis conducted in the Chaillu mountains, Southern Congo, showed that 108 of 134 Pygmies (80.6%) and 79 of 302 Bantus (26.2%) presented with microfilaraemia. The mean microfilarial densities were also significantly higher in the Pygmies (1213 ml-1 of blood) than in the Bantus (136 ml-1). Ninety eight per cent of the Culicoides taken which had bitten man in the daytime were C. grahamii, and 0.8% of these were infected with filarial larvae. Two other species of Culicoides (C. kumbaensis and C. rutshuruensis) might also play a role in the transmission of M. perstans.

Studying nycthemeral microfilarial density in eight carriers of Mansonella ozzardi, Nathan et al. concluded that there is an absence of periodicity in M. ozzardi in Trinidad. Re-examination of the results obtained shows evidence of crypto-periodicity. Two of the eight patients showed highly significant periodicity but the biorhythms appear to be almost out of phase, the respective peaks being at 18.00 hours and 02.00 hours. The six other patients showed no obvious periodicity; the calculated acrophases (peak hours), instead of being randomly spaced, regrouped with the preceding ones: late afternoon in two subjects and in the second half of the night for the other four. It is concluded that the apparent non-periodicity is due to the co-existence of two periodic forms, but these are markedly out of phase.

Microfilariae of Mansonella ozzardi, concentrated from human blood, frozen with a cryoprotectant chemical, and stored at liquid or vapor-phase liquid nitrogen temperatures were motile when thawed after 2.5 years of preservation.

We describe a rapid, efficient method for purifying Loa loa microfilariae from blood that does not affect their longterm motility. It is based on the separation of microfilariae on a performed discontinuous Percoll gradient, followed by filtration on cellulose ester membranes. The parasite population, after isolation, is close to 100% pure, 100% viable and remains motile for at least 20 days. Recovery from original blood samples is typically around 90%. The method, because of its simplicity and minimal material requirements, could be used with up to 210 ml of blood. It also allows the isolation of Mansonella perstans microfilariae.

Morphological studies of stained Mansonella streptocerca microfilariae from the skin of man and chimpanzees in West Africa revealed that the tail is bifid rather than blunt. This feature may be useful in characterization of related species.

One hundred and twelve inhabitants of an area endemic for M. ozzardi received 20 cmm capillary blood samples by finger prick before and 30 minutes after the ingestion of 100 mg of diethylcarbamazine citrate. No significant variations in microfilaremia were detected. Thus, a provocative dose of DEC would not appear to be helpful in sampling for mansonellosis in Haiti.

The prevalence of Mansonella ozzardi in the Comisaría del Vaupés of eastern Colombia was investigated as part of an extensive study of human filariasis in Colombia. Three hundred and forty-seven individuals from various parts of Vaupés were examined. The overall infection rate for M. ozzardi was 49%, but the distribution of the parasite was not uniform throughout the Comisaría. Microfilariae were found in both venous blood samples and ski biopsies of infected individuals. The rate of infection was 55% for males and 42% for females, and infection ratenerally low, with 88% of the positive films having less than 50 microfilariae.

Microfilariae of Mansonella ozzardi were seen in specimens of skin taken by biopsy from 4 of 6 subjects previously shown to be positive for microfilariae in the blood. While most of the microfilariae were confined to small blood vessels in the papillary and superficial reticular dermis, some were in perivascular spaces and a few were noted in the dermal interstitium. There was no microscopic evidence that the minimal cutaneous disease seen could be directly attributed to the microfilariae.

The densities of microfilariae of Mansonella ozzardi in different regions of the body of infected individuals were studied. The density in venous blood closely approximated to that found in finger capillaries, but was significantly lower than the densities in capillaries of the scapular region and buttocks. A possible explanation for this concentration of microfilariae is the lack of glomi in these two sites, which consequently have a lower flow of blood than areas where glomi occur and where microfilarial densities are lower. No relationship was found between blood and skin densities in the buttocks and scapular region, probably due to the inadequacy of the skin snip method used for the detection of this species of filaria. It was concluded that the most acceptable detection method for M. ozzardi remains the sampling of finger capillary blood. It could not be decided, due to the paucity of data, whether any relationship exists between skin microfilarial densities and the biting sites of the vectors.

Patients harbouring Loa loa and/or Mansonella perstans infections, or presenting typical filarial symptomatology, were treated with mebendazole, a drug shown to be efficient in other parasitoses. Of the patients who took the drug during 21 days and provided regular blood samples, 84% showed a significant decrease in their L. loa microfilaraemia and 100% in their M. perstans microfilaraemia, with a concomitant improvement in the clinical manifestations and no side reaction to drug administration. Additionally, the long-lasting effect of the drug (up to day 200 in some cases) may suggest a positive action on the adult worm. Mebendazole may consequently be regarded as a safer alternative to diethylcarbamazine for the treatment of these two parasitoses.

Sera from individuals in an area of Haiti endemic for Mansonella ozzardi were analyzed for reactivity to antigens of Brugia pahangi, Dirofilaria immitis, Mansonella llewellyni or Ascaris lumbricoides using either an enzyme-linked immunosorbent assay or an indirect immunofluorescent antibody test. IgM and IgG reactivity to all antigens was observed with sera from both microfilaremic and amicrofilaremic individuals when compared to reactivity of sera from individuals from nonendemic areas. Antibody reactivity to B. pahangi was greater than that to other antigens. IgG reactivity of sera from endemic patients to filarial antigens was consistently greater than that of IgM. Antibody reactivity was not correlated with age or microfilarial density.

The study was undertaken to determine primates were susceptible to infection with Caribbean and/or Amazon strains of Mansonella ozzardi of man. Twenty-three animals including three chimpanzees, four squirrel monkeys, one capuchin, five rhesus and 10 patas monkeys each received, by subcutaneous or intraperitoneal injection, 25-170 infective larvae of M. ozzardi harvested either from infected Culicoides furens collected in Haiti or Simulium sp. (sanguineum complex) collected in the Colombian Amazon and transported to our laboratories in Louisiana. Patent infections were obtained in seven of 10 patas monkeys but not in any other species of primates. The prepatent period ranged in duration from 149-186 days with a mean of 168 days. All of the patas monkeys developed modest microfilaremias that persisted for as long as 1 year, the duration of our observations. Adult worms were obtained at necropsy from three of four patas monkeys. The worms were recovered from soakings of the carcass and skin rather than from the abdominal cavity and mesenteries. However, their precise habitat was not determined.

Mansonella ozzardi is redescribed from adult worms collected from the subcutaneous tissues of patas monkeys (Erythrocebus patas) infected with a Haitian strain of the filaria. The worms are small and very slender; females measure about 49 mm in length by 0.15 mm in diameter and males, 26 by 0.07 mm. Haitian (Caribbean) and Colombian (Amazon) forms of the filaria are morphologically identical, as are their microfilariae. Mansonella is most closely related to Tetrapetalonema. Based on taxonomic priority the latter becomes a synonym of Mansonella. As a consequence, T. perstans and T. streptocerca of man in Africa are designated as M. perstans (Manson, 1891) n. comb. and M. streptocerca (Macfie and Corson, 1922) n. comb. Further, M. ozzardi is most closely related to the species M. llewellyni (Price, 1962) n. comb., a parasite of the raccoon, and M. interstitium (Price, 1962) n. comb. found in squirrels, both in North America.

A day blood smear survey for Mansonella ozzardi in the north coast communities of Trinidad recorded a prevalence of 4.8% in 4,488 persons examined. Prevalence rates were highest in the four western-most communities, where the vector, Culicoides phlebotomus, is a severe nuisance problem. Prevalence rates increased with age and were higher in males than in females. Mean microfilaria densities were low in both sexes up to 50 years of age but in older males the density increased with age. Wuchereria bancrofti infections were detected in five of the ten communities surveyed.

The prevalence of Loa loa and Mansonella perstans filariasis has been determined in 6 rural villages in eastern Gabon. Between 18.9 and 27.2% of people carry L. loa microfilariae with an overall microfilarial rate of 25.1%. The microfilarial rate for M. perstans was more variable, between 33.3 and 62.2% (average 49.1%). No significant difference was seen in the microfilarial rate with age over 15 years for either parasite, but men were infected more frequently than women. Anti-L. loa antibody titres were measured, using a homologous microfilarial antigen in ELISA. Taking the parasitological and immunological evaluations together, only 10% of the sample population appear to be free of these filarial infections. L. loa and M. perstans microfilaraemia and corresponding serology were also investigated twice in 150 people at a one-year interval. 99.1% of the cases who had no circulating L. loa microfilaria in March 1984 still did not show any 12 months later. Similarly, 97.1% of the untreated, microfilaraemic cases still harboured this parasite a year later. The same was not observed for M. perstans, since microfilariae appeared or disappeared in 26.7% of the cases. This suggests different dynamics for the two filarial infections. Variation in individual anti-L. loa antibody titres was low. The possibility of a genetic influence on the expression of loiasis is discussed.

Between January 1981 and March 1982, a filariasis survey was conducted among 668 Haitian immigrants and 155 Southeast Asian refugees residing in Florida, U.S.A. Microfilariae were detected only in Haitians, with 6.7% positive for Wuchereria bancrofti and 1.3% positive for Mansonella ozzardi. The majority of individuals with bancroftian filariasis came from five coastal urban areas including Port-au-Prince, Duvalierville, Gonaïves, Leógane and Cap-Haitien. No unequivocal signs of bancroftian filariasis or mansonellosis were seen. Membrane feeding of several species and strains of laboratory-reared mosquitoes on blood from a volunteer microfilaremic with W. bancrofti showed that Aedes aegypti and A. taeniorhynchus, but not Culex quinquefasciatus, were susceptible to infection with the Haitian strain of W. bancrofti. Culicoides furens, a known vector of M. ozzardi in Haiti and present in Florida, was not tested. Further studies are needed to determine the competence of Florida vectors for transmitting W. bancrofti and M. ozzardi to the indigenous human population.

Night and day blood surveys for filariasis were conducted among inhabitants of Bori Local Government Area in the Niger Delta area of Nigeria between October 1983 and July 1984. Of the 1674 persons examined 47.0% had microfilaraemia. The infections were due to Mansonella perstans only. The prevalence of the infection was higher among males (51.8%) than among females (42.4%), and increased with age in both sexes. Eight persons were found with elephantoid scrotums and all had microfilariae of M. perstans.

Eight patients from Uganda, Sudan, Nigeria, and Zaire presented with swelling of the eyelids, proptosis, or conjunctival granulomas. In 5 patients the cause was Mansonella perstans; in 1, it was a Wuchereria bancrofti-like worm; and in 2, an unidentifiable worm. The morphologic features and histopathologic changes in the conjunctiva and periorbital fat are described and illustrated.