S. El Said

Persistence of human leishmanial antibodies in an endemic area of visceral leishmaniasis in El Agamy, Egypt

In an endemic area of visceral leishmaniasis (VL), individuals with leishmanial antibodies that reacted in the radioimmunoassay (RIA) were retested to determine duration of leishmanial antibody retention. One fourth of adults retained antibodies for at least 10 months. At least 2/3 of asymptomatic children retained leishmanial antibodies for 5 to 7 months after detection. 2/3 of children treated for VL retained leishmanial antibodies for 5 to 7 months after treatment, while 1/3 retained antibodies for over a year. These data modify conclusions that can be drawn from a single serosurvey. Since leishmanial RIA antibodies can persist in humans for at least two transmission seasons, incidence estimates require serial serosurveys.

The epidemiology of human visceral leishmaniasis in El Agamy (Alexandria Governorate), Egypt: serosurvey and case/control study.

In Alexandria Governorate, Egypt, 27 cases of visceral leishmaniasis (VL) were detected from 1982-1985 through active and passive case detection. Twenty-two were located in El Agamy, a resort town of 50,000 residents located 15 km west of the City of Alexandria. To describe the disease focus, eight areas of 100-200 households in El Agamy were mapped and censused. All individuals were examined clinically, and blood was obtained by finger stick to measure leishmanial antibodies by radioimmune assay. Two case/control studies were carried out in the mapped areas. In one study, case households were more often found near open garbage containers than were control households. In a second case/control study, houses with cases of VL or seropositive individuals were found more likely to face open areas. These results demonstrate that characteristics of houses which could increase exposure to reservoir hosts can be associated with VL or leishmanial seropositivity. This suggests that control programmes should improve garbage disposal and should focus on houses located in peripheral areas of the community.

Dot-ELISA, a potential immunoassay for the detection of Plasmodium falciparum antibodies

The dot enzyme-linked immunosorbent assay (dot-ELISA) was compared to the indirect immunofluorescent assay (IIFA) and radioimmunoassay (RIA) for the detection of malaria antibodies. Of 281 sera tested by dot-ELISA, 220 were from Ethiopia, 11 from the Sudan, and 50 from Egypt. A close correlation between the dot-ELISA and RIA results was observed in 92% of the 220 Ethiopian cases. Of the remainder, 6% gave positive RIA and negative dot-ELISA results, and 2% gave positive dot-ELISA and negative RIA results. Antibody titres determined by dot-ELISA and RIA were positively correlated in 10 of the 11 Sudanese cases tested by direct microscopical examination. The eleventh case was positive by dot-ELISA at 1:1000 dilution, but negative by RIA and direct examination. With the 50 Egyptian sera, the dot-ELISA results showed close correspondence to the IIFA results, but the dot-ELISA was 20-40 fold more sensitive than the IIFA. To test specificity, 62 samples from patients with 11 different diseases and conditions were examined by dot-ELISA. No malaria antibodies were detected in any of these or in sera from healthy controls. Dot-ELISA is a potentially useful method for sero-epidemiological studies of malaria.

Human cutaneous leishmaniasis in two communities in eastern Sinai, Egypt.

Cutaneous leishmaniasis (CL) (L. major) has been documented in soldiers of the Multinational Force in the Sinai as well as in visitors to the area. However, little is known about the prevalence of this disease in the local populations. We identified 2 villages in northeastern Sinai near the infected camps of the Multinational Force and, in a population-based study, measured the prevalence of CL.Populations studied included residents in 2 towns as well as a Bedouin family living on the village periphery. Leishmanial parasites were identified from smears taken from cutaneous lesions. Three of 90 residents in I village and 3 of 8 Bedouins had CL. None of 43 residents examined in the second town had CL. Two of 6 individuals had multiple lesions, and at least I had recurring ulcers. Five of the 6 affected individuals were males and the 6 represented all age groups. The 6 infected individuals came from 3 families. Infected individuals had traveled outside of the village more frequently than uninfected individuals, suggesting that transmission was more common outside of residential areas.

Immunosuppressive medication associated with leishmanial antibodies in adults residing in an endemic focus of infantile visceral leishmaniasis—a case/control study

In a focus of infantile visceral leishmaniasis in Al Agamy (Alexandria), Egypt, adults were found by radioimmune assay to have leishmanial antibodies. This finding was unexpected, and an explanation was sought. Seropositive adults and age- and sex-matched seronegative controls were interviewed to ascertain possible predisposing risk factors. Ten of 16 seropositive individuals were taking corticosteroids compared to one of 22 seronegative individuals (P = 0.0002). Two seropositive individuals (one woman and one man) were taking phenylbutazone, and two women were taking female sex hormones. The association between immunosuppressive medication and leishmanial seropositivity suggests that acquired changes in host population immunocompetence may significantly alter age-specific seroprevalence of leishmanial antibodies.