Human external ophthalmomyiasis occurring in Barbados.

Human infection with the sheep nasal botfly Oestrus ovis occurs sporadically. In most cases, there is a history of a strike in the eye by the adult fly. Human O. ovis has been reported rarely from the Americas. We report the first case of O. ovis infection in the Caribbean region, which occurred in an urban area of Barbados. The patient responded to removal of the larvae from the conjunctiva and symptomatic treatment.

Human external ophthalmomyiasis occurring in Barbados

Human infection with the sheep nasal botfly Oestrus ovis occurs sporadically. In most cases, there is a history of a strike in the eye by the adult fly. Human O. ovis has been reported rarely from the Americas. We report the first case of O. ovis infection in the Caribbean region, which occurred in an urban area of Barbados. The patient responded to removal of the larvae from the conjunctiva and symptomatic treatment

Fatal autochthonous eosinophilic meningitis in a Jamaican child caused by Angiostrongylus cantonensis.

A fatal case of infection with Angiostrongylus cantonensis is reported in a 14-month-old Jamaican boy. Although infection with Angiostrongylus was not considered initially, sections of multiple worms were observed in the brain and lungs at autopsy and confirmed the infection. This is the first reported fatality due to this infection in the Western Hemisphere, and follows shortly after an outbreak of eosinophilic meningitis among a group of travelers to Jamaica. The source of infection in this case could not be determined.

Report of ezootic Angiostronglyus cantonesis from Jamaica [ABSTRACT]

OBJECTIVE: To study the status of infection with Angiostrongylus cantonensis in wild rats and snails in Jamaica following an outbreak of eosinophilic meningitis amongst tourists. METHODS: One hundred and thirty-one Rattus rattus and 94 R norvegicus were collected, mainly from the eastern portion of Jamaica. The animals were dissected and the heart and pulmonary arteries explored to reveal A cantonensis. Similarly, several species of land snails were collected. A portion of the head/foot was excised, fragmented and placed in separate dishes of digestion fluid (0.01 percent pepsin in 0.7 percent v/v aqeous HCI). Dishes were examined for nematode larvae 4-5 hours and 24 hours post-digestion. A microscopical comparison of larvae with museum specimens confirmed identification. RESULTS: Overall, significantly more R rattus (42.7 percent) than R morvegicus (21.3 percent) were infected (x2=11.28;p<0.0001). Considering only those parishes where 15 or more rats were collected (Hanover, Manchester, St.James, St. Elizabeth, Kingston and St.Andrew, and Portland) the prevalence of rodent infections ranged from 6 to 59 percent. Of three snails and one slug species collected, only Thelidomus asper harboured A cantonensis larvae. This snail was collected from Manchester where the highest prevalence of rodent infections also occurred. CONCLUSIONS: The findings indicate that A cantonensis is present in rats and snails in Jamaica. In the context of reports (1996, 2000) of eosinophilic meningitis on the island, we recommend that public health officials, clinical parasitologists and travel medicine practitioners consider A cantonensis as a causative agent of eosinophilic meningitis in residents and travellers to Jamaica. (AU)

Survey for Cyclospora cayetanensis in domestic animals in an endemic area in Haiti.

From January 1997 through July 1998, we examined stool samples from 327 domestic animals, including pigs, cattle, horses, goats, dogs, cats, guinea pigs, chicken, ducks, turkeys, and pigeons in Leogane, Haiti, for the presence of Cyclospora cayetanensis infection. No coccidian oocysts morphologically compatible with C. cayetanensis were detected in any of the animal samples, despite their living in, or near, households with infected individuals. These results suggest that domestic animals are not reservoir hosts for C. cayetanensis and that in this endemic area, humans are the only natural host for this parasite.

Cyclospora cayetanensis infections in Haiti: a common occurrence in the absence of watery diarrhea.

Stool samples from a population-based cohort of mothers and children living in Leogane, Haiti were tested for Cyclospora cayetanensis from January 1997 through January 1998. Data on gastrointestinal symptoms were also collected. During the winter months of January to March, the infection was detected in 15-20% of the persons sampled. Most infections did not appear to be causing diarrhea and most infected persons had few oocysts detectable in concentrates of stool. The infection appears to have marked seasonality, with highest rates during the driest and coolest time of the year. It may be that in this tropical setting, high summer temperature is the critical environmental factor that influences the seasonality of infection. This study demonstrates that Cyclospora infections in Haiti are common in the general population.

Longitudinal analysis of the development of filarial infection and antifilarial immunity in a cohort of Haitian children.

Longitudinal studies are being conducted in Leogane, Haiti to investigate the relationship between acquisition of filarial infection and development of antifilarial immunity as well as the impact of maternal infection on this relationship. Children (0-24 months of age) residing in Leogane were enrolled and were examined periodically to monitor parasitologic status and to collect serum for antigen and antifilarial antibody determinations. To examine the development of filarial antigenemia and antifilarial antibody responses in this cohort, serum samples were selected from a cross section of the population at two (n = 82) and four years of age (n = 76). Antigen prevalence increased from 6% among two-year-olds to more than 30% among four-year-olds, but in only one four-year-old child were microfilaria detected in a 20-microl smear. The proportion of antigen-positive children born to antigen-positive mothers was higher than the proportion of antigen-positive children born to antigen-negative mothers (9.8% versus 0% for two-year-olds; P = 0.15; and 39.6% versus 22.7% for four-year-olds; P = 0.18). Antifilarial IgG4 levels were significantly higher among antigen-positive children at both two and four years of age (P < 0.001). In analyses of paired samples, antifilarial IgG4 responses increased significantly more among children who acquired infection by four years of age than among children who remained antigen negative, whereas antifilarial IgG1 and IgG2 responses changed equally for antigen-positive and -negative children. Antifilarial antibody levels were not influenced by maternal infection status, but were significantly influenced by age, antigen status, and the neighborhood within the community. These results provide evidence that children acquire infection early in life and suggest that antifilarial antibody responses may peak in early childhood.

First reported outbreak of abdominal angiostrongyliasis.

Human abdominal angiostrongyliasis is a potentially fatal disease caused by Angiostrongylus costaricensis, a nematode found in the Americas. During the period of December 1994 through August 1995, an outbreak of this disease occurred in Guatemala. We identified 22 cases of abdominal angiostrongyliasis and conducted a matched case-control study to identify risk factors for illness. The median age of the 18 cases enrolled in the study was 37 years (range, 9-68 years), and 11 (61.1%) were male. Consumption of the following six raw food items was associated with angiostrongyliasis: mint (odds ratio [OR], 6.9; 95% confidence interval [CI], 1.5-66.0), shrimp (OR, infinite; 95% CI, 1.4 to infinite), and four kinds of ceviche that reportedly contained raw mint (OR for consumption of mint or ceviche that contained mint, 7.0; 95% CI, 1.0-315). We conclude that raw mint was the likely vehicle of infection for this outbreak. To our knowledge, this is the first reported outbreak of abdominal angiostrongyliasis and the first time that a specific food item has been epidemiologically linked to the disease.

An increase in hookworm infection temporally associated with ecologic change.

This report describes a significant increase in the prevalence of hookworm infection in an area of Haiti where intestinal parasites are common, but hookworm has not been common. Changing environmental conditions, specifically deforestation and subsequent silting of a local river, have caused periodic flooding with deposition of a layer of sandy loam topsoil and increased soil moisture. We speculate that these conditions, conducive to transmission of the infection, have allowed hookworm to reemerge as an important human pathogen.

Th1-like antifilarial immune responses predominate in antigen-negative persons.

To characterize immune responses associated with the putatively immune state in bancroftian filariasis (that is, both microfilaria and antigen free), humoral and cellular responses were compared among antigen- and microfilaria-negative, antigen-positive and microfilaria-negative, and microfilaria-positive individuals. Antifilarial isotype levels were measured by enzyme-linked immunosorbent assay. Peripheral blood mononuclear cell responses were measured by proliferation, by bioassay for interleukin-2 (IL-2) and IL-10, and by reverse transcription-PCR for IL-4, IL-5, and gamma interferon. The absence of circulating filarial antigen was associated with Th1-like responses, including significantly higher proliferative (P < 0.001) and IL-2 (P = 0.008) responses and a higher prevalence of gamma interferon (0.02 < P < 0.1) responses. Significantly elevated antifilarial immunoglobulin G4 (IgG4) levels (P = 0.0035) were associated with antigenemia, whereas microfilaremia was associated with significantly decreased antifilarial IgG2 levels (P = 0.0014). IL-4 mRNA levels were not significantly different among the three groups; however, there was a subpopulation of microfilaremic individuals who did not make detectable levels of IL-4 mRNA and who produced low antifilarial IgG4 levels compared with those of individuals who had detectable levels of IL-4 mRNA. IL-5 mRNA levels also were not significantly different among groups; however, more microfilaremic individuals produced IL-5 mRNA in response to adult filarial antigens, and total parasite-specific IL-4 and IL-5 mRNA levels were significantly correlated (P = 0.05). Although longitudinal data are not currently available, the elevated Th1-like responses in antigen- and microfilaria-negative individuals are consistent with the hypothesis that these responses contribute to protection in putatively immune individuals.

A survey of knowledge, attitudes, and perceptions (KAPs) of lymphatic filariasis, elephantiasis, and hydrocele among residents in an endemic area in Haiti.

To assess knowledge, attitudes, and perceptions about bancroftian filariasis, 104 residents of an endemic area in Haiti were interviewed. Questions focused on 1) whether people understood the relationship between infection and disease, 2) recognition of the role that mosquitoes play in transmission, 3) perceived importance of hydrocele and elephantiasis in relation to other recognized diseases, and 4) the willingness of the community to participate in a control program. Fewer than 50% of residents had heard of filariasis and only 6% of those surveyed knew that it was transmitted by mosquitoes. In contrast, all persons knew of the clinical conditions of hydrocele and elephantiasis. Hydrocele was thought to be caused by trauma (60%) or trapped gas (30%); elephantiasis by walking bare foot on soil or water (37%) or by use of ceremonial powder that had been sprinkled on the ground (23%). Of 76 respondents, 53% and 38% thought that hydrocele could be treated through surgery or a drug, respectively, whereas 86 respondents, 85% and 15% believed that either surgery or a drug could be used to treat elephantiasis. In this context, persons were not referring to a specific drug; rather, they believed a drug existed (possibly in some other country) that could cure these conditions. Hydrocele and elephantiasis ranked second to acquired immunodeficiency syndrome as perceived health problems, most likely because residents believed treatment for conditions such as malaria, intestinal worms, anemia, and diarrhea was easily obtained. Responses were influenced by age, sex, and symptoms, but none of these effects were statistically significant except that persons with hydrocele or elephantiasis were more likely to have sought treatment than persons without these conditions (P = 0.0006). The survey results indicate that awareness of the causes of disease, the relationship between infection and disease, and goals of treatment must be heightened through community-based education campaigns to increase the possibility of acceptance and support of control programs.

Age-specific prevalence of antigenemia in a Wuchereria bancrofti-exposed population.

Antigen detection assays serve as a useful adjunct to blood examinations for studies of filariasis, in terms of the diagnostic and epidemiologic information provided. We examined the utility of the Og4C3 antigen detection enzyme-linked immunosorbent assay for field studies and analyzed the distribution of Wuchereria bancrofti antigenemia in a Haitian population. Using serum samples collected following venipuncture, antigenemia levels were correlated with microfilaremia (P < 0.001). The microfilariae had a pronounced nocturnal periodicity while the sensitivity of the antigen assay was the same whether serum samples were collected during the day or at night. To determine whether the Og4C3 assay could be used in conjunction with fingerprick blood examinations, nocturnal blood surveys were conducted. Of 419 persons surveyed, 207 (49.4%) were antigen-positive with the Og4C3 assay. Serum specimens from all 121 microfilaremic individuals were antigen positive (100% sensitivity). The age prevalence of antigenemia increased from 24.5% for 1-5-year-old children to 70% for persons greater than 50 years of age. These results demonstrate that the Og4C3 assay is a sensitive tool for the detection of infection and raise questions about the expression of protective immunity in populations exposed to infection.

Trypanosomes and microfilariae in feral owl and squirrel monkeys maintained in research colonies.

A group of 358 owl and squirrel monkeys imported from Colombia, Peru, and Bolivia for the U.S. Agency for International Development Malaria Vaccine Development Program was examined for trypanosomes and microfilariae. Trypanosoma rangeli, isolated by hemoculture from Aotus nancymai, Saimiri b. boliviensis, and S. b. peruviensis, accounted for 76.6% of all trypanosome infections. Trypanosoma cruzi was isolated from 25 of 194 S. b. boliviensis, including two mixed infections with T. rangeli. Identifications of trypanosomes were confirmed by blinded tests with a panel of five rRNA probes on a subsample of cultures identified morphologically. Although no trypanosomes were isolated from Aotus vociferans or A. lemurinus griseimembra, positive serologic responses to T. cruzi were observed by indirect immunofluorescence assay in all species of monkeys examined and ranged from 42.1% among S. b. peruviensis to 92.3% among A. vociferans. Among T. rangeli-infected monkeys, 43.7% were seronegative for T. cruzi. No microfilariae were found in S. b. boliviensis or A. l. griseimembra. Mansonella barbascalensis and Dipetalonema caudispina were observed in A. vociferans, M. panamensis in A. nancymai, and M. saimiri and D. caudispina in S. b. peruviensis. Such naturally occurring infections in imported animal models are potential sources of accidental transmission to animal handlers and uninfected laboratory animals and can introduce confounding variables into otherwise well-planned and well-executed studies.

Transplacental transmission of Wuchereria bancrofti in Haitian women.

To document the occurrence of transplacental transmission of microfilariae and to determine how frequently it occurred, umbilical cord blood samples and placental tissues were collected from 22 microfilaria-positive women in an area with endemic Wuchereria bancrofti. Microfilaria (mf) counts in the women ranged from 1 to 3,820 mf/ml. Microfilariae were detected in 2 placenta samples and a single cord blood sample. The positive cord blood sample and 1 of the positive placenta samples came from the same woman; no microfilariae were found in a finger prick sample taken from the infant 3 wk after delivery. Our results suggest that microfilariae cross the placenta in less than 10% of pregnancies of microfilaria-positive mothers. Furthermore, the microfilaria count of the mother does not seem to influence directly whether microfilariae are present in the placental blood pool. Although actual transfer of microfilariae to the fetus may occur infrequently, exposure to parasite antigens occurs with much greater frequency. The effect of in utero exposure to either microfilariae or parasite antigens may render newborns tolerant and explain why children born to infected mothers are almost 3 times more likely to become infected than are children born to uninfected women.

Strianema venezuelensis gen. et sp. n. (Filarioidea: Onchocercidae) from Venezuelan armadillos (Dasypus spp.).

A new filaria, Strianema venezuelensis gen. et sp. n., is described from armadillos in Venezuela. The adults inhabit the subcutaneous tissues and the microfilariae are found in the skin and occasionally the blood. The adults, which are of small size (males 9.6 to 13.8 mm in length by 57 to 63 microns in diameter, females 18.3 to 26.3 mm in length by 95 to 120 microns in diameter), have a distinctly striated cuticle. This filaria resembles most closely the genus Cercopithifilaria, from which it can be distinguished by the absence of a buccal capsule or pre-esophageal ring, and 11 to 13 pair of caudal papillae, three or four pair of which are separated as a group anterior to the cloaca. The species, S. venezuelensis, can be distinguished from the three other species of filariae described from armadillos by the undivided esophagus, number and distribution of caudal papillae in the male, size and shape of the spicules, and the distinctive microfilaria. The microfilaria, which averages 280 microns in length, has a unique, slender, almost filamentous tail.

Albendazole in the treatment of onchocerciasis: double-blind clinical trial in Venezuela.

A double-blind clinical trial was conducted in Monagas State, Venezuela to assess the tolerance and efficacy of albendazole in the therapy of Onchocerca volvulus infection. Forty-nine patients (26 treated and 23 controls) received a 10-day course of albendazole (400 mg/day) or a placebo. Consistent with the excellent tolerance observed, albendazole did not kill microfilariae. However, analysis of changes in microfilarial densities (mf/mg of skin) over one year showed that albendazole was active against O. volvulus, presumably by interfering with embryogenesis. The nature, degree, and duration of this effect remain to be determined.

Bancroftian filariasis: long-term effects of treatment with diethylcarbamazine in a Haitian population.

Two groups of Wuchereria bancrofti-infected Haitians who had undergone treatment with diethylcarbamazine (DEC) were followed for up to five years after treatment to document the long-term effects of treatment on adult worms and microfilariae and on the recurrence of infection. One group of 69 persons who had received 12 daily treatments had a significant decrease in microfilaria levels until year 4, when a small number of individuals experienced a resurgence of this parasite stage in the peripheral blood. In a second group of 57 persons who had been treated weekly for 12 consecutive weeks, there was a greater reduction in the microfilaria levels following treatment, and for the full four years of followup, these levels remained more depressed than those of the group that received daily treatment. Our results indicate that DEC kills or permanently sterilizes adult W. bancrofti. Furthermore, these results demonstrate conclusively that in Haiti, the use of DEC provides long-term benefits to treated persons, even though they continue to reside in an area with endemic filariasis.

Antifilarial cellular responses detected in a Haitian pediatric population by use of a microblastogenesis assay.

Previous reports have demonstrated age-related shifts in antifilarial humoral immune responses in 6- to 10-year-old Haitian children; the responses consisted of elevated parasite-specific IgG2 and IgG3 in amicrofilaremic children and elevated IgG4 in microfilaremic children. In this study, the cell-mediated immune responses to soluble adult and microfilarial extracts of Brugia pahangi, determined by use of a microblastogenesis assay, were examined. Capillary blood samples were collected by finger prick from 176 Haitian children in an area with endemic Wuchereria bancrofti. Antigen-specific cellular responsiveness varied as a function of infection status but not age or sex; amicrofilaremic children had significantly greater responses to adult antigens than did microfilaremic children. Significant responses were detected in children less than 2 years of age; thus, correlations observed between filarial antigen-specific responses and infection status are established early in life.

Guatemalan human onchocerciasis. II. Evidence for IgG3 involvement in acquired immunity to Onchocerca volvulus and identification of possible immune-associated antigens.

Ag-specific isotypic differences in immune response to Onchocerca volvulus Ag were assessed for 778 long term residents of endemic Guatemalan areas by quantitative ELISA with 5-min incubation steps and immunoblot. The study population was separated into five groups based on clinical status: N+F+, N+F-, N-F+, N-F-H+, and N-F-H-, where N = O. volvulus adults (nodule), F = microfiladermia, and H = history of O. volvulus infection. A subset of 44 individuals with high exposure to onchocerciasis from the N-F-H- group were critically evaluated and designated as "putatively immune." IgG1 reactivity to O. volvulus Ag was elevated in the majority of infected persons, but not in putatively immune individuals. Specific IgG3 levels, however, were equally elevated in all groups. The majority of N+F- persons also had elevated IgG1 levels, but they were lower than those found in F+ persons. IgG3 reactivities to a group of antigens at 20 kDa (GP20) were seen in many uninfected persons and some N+F- persons. In contrast, most F+ persons, react to this Ag with IgG1 and not IgG3. A mangabey inoculated with the infectious larval stage of O. volvulus (L3), but showed no signs of infection, began to recognize GP20 at 2 wk postinoculation. Early recognition of GP20 was possibly elicited by the larval stage. Purified nodule Ag from N+F+ individuals contained GP20, however, identical nodule Ag prepared from N+F- individuals did not. These data suggest that GP20 Ag may be common to both uterine microfilaria and the infectious larval stages. The fact that GP20 is predominantly recognized by IgG3 in putatively immune persons and some N+F- persons suggests that this increased IgG3 activity may be important in acquired immunity to onchocerciasis.

Guatemalan human onchocerciasis. I. Systematic analysis of patient populations, nodular antigens, and specific isotypic reactions.

The population from five Guatemalan plantations in areas endemic for onchocerciasis was surveyed, and 1032 individuals were recruited to participate in our study. From physical examination, past clinical history (5 to 8 yr), laboratory evidence and sample availability, a group of 778 long term residents with confirmed disease status were selected for detailed examination. We were able to identify 268 long term residents of endemic areas who had never been infected, 44 of these are from hyper- and mesoendemic areas. The 44 uninfected individuals from the hyper- and mesoendemic areas, because of their considerable exposure to this disease, were classified as "putatively immune." Intact nodules containing adult worms of Onchocerca volvulus were homogenized in the presence of protease inhibitors and fractionated into particulate and aqueous isotonic soluble antigens. Systematic analysis of these Ag fractions showed considerable amounts of Ig, presumably associated with Ag in the form of immune complexes. Individual specific antibody reactions from all 778 patients to nodule Ag were examined. Reactions to O. volvulus antigens by antibodies from patients with confirmed parasitic infections were almost exclusively restricted to IgG1 and IgG4 isotypes. Antigenic activity appeared to be primarily associated with low molecular mass (14 to 29 kDa) components. Some competitive blocking of antibody activities of other isotypes by IgG1 was observed, most notable was that of IgG3 and IgA. IgG4 and IgM activities were not significantly blocked.