Exposure variables in bancroftian filariasis in the Nile Delta.

To demonstrate focality of filariasis within endemic rural areas and to define exposure variables which may influence this phenomenon, the population of an agrarian endemic village, of 12,500 individuals, in the Nile Delta of Egypt was censused. A sequential sample of individuals residing in every fifth house was tested for microfilaremia (239 households with 8.6 +/- 3.5 individuals per household (HHD). Three areas of the village were tested simultaneously and a questionnaire was filled out for each sampled HHD with special emphasis given to the entomological and environmental factors that might affect filarial infection. One area (area A) had a higher intensity of larvae and biting adults of the main filarial vector, Culex pipiens, than the other two areas (areas B and C). Of the 1488 persons who agreed to be tested in the three areas 181 (12.2%) were microfilaremic. Microfilaremia prevalences were the same in males and females and microfilariae were present in all age groups. Filarial infection was most prevalent in area "A" (1.16 +/- 0.14 infected people per HHD) than in area "B" (0.44 +/- 0.11) or "C" (0.72 +/- 0.10) (ANOVA; p = 0.0003). several possible predictor variables were analyzed by logistic regression with the presence of infection as the response variable. Among individuals residing around the main Cx. pipiens development sites, those living in houses facing vacant land are exposed to more mosquito bites and had a greater chance of having filarial infection (relative risk [RR] = 1.5; logistic regression, P = 0.0089). People residing in large households had a reduced chance of having filarial infection (RR = 0.87; logistic regression, p = 0.0015). These data show that the distribution of microfilaremic individuals is uneven within the study village and suggest that small HHD and houses that bordered open areas containing mosquito development sites are potential risk factors for acquiring filarial infection.

Estimates of Egyptian culcine longevity in nature altered by fluctuations in biting population density.

Estimates of vectorial capacity (VC) depend upon longevity of mosquito field populations, and expected longevity is estimated from the parity rate of the population. Seasonal variation in parity rates confound estimates of longevity which may not reflect actual population survival but are induced by changes in the rate of emergence of female mosquitoes. By comparing parity rates and biting activity in natural population of 2 Culicine mosquitoes, Culex pipiens and Cx. antennatus, we found that parity rate was low in the beginning of the season and high at the end. Parity rate appeared least affected during the weeks with maximal daily biting activity. We conclude that estimates of VC are most accurately determined for the two vector species studied when mosquito biting activity is maximal.

Survival estimates for adult Culex pipiens in the Nile Delta.

In an endemic area for Wuchereria bancrofti filariasis in the Nile Delta, survival of adult female Culex pipiens was estimated by parity rate, mosquito infection and infectivity rates. Infection rates and 4th instar larval populations, as well as infection and parity rates, were linearly correlated. Infectivity correlated only with parity rates. These associations corresponded to parallel changes in ambient temperature. Although survival calculated from parity rates measured longevity of both infected and non-infected Cx. pipiens, survival based on infection and infectivity was a more reliable indicator for parasite transmission.

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 discovery and preliminary characterization of a novel trypanosomatid parasite from Rattus norvegicus and stray dogs from Alexandria, Egypt.

A survey of rodents and dogs was carried out in Alexandria and its environs to see if an animal reservoir was associated with an outbreak of infantile kala-azar in this area. Three rodent species, Rattus rattus, Rattus norvegicus and Mus musculus, were commonly trapped and examined. A flagellate parasite was isolated from the spleens of two R. norvegicus. It was typed serologically by excreted factor serotyping and enzymologically by thick starch electrophoresis of four of its enzymes: GPI, G6PD, 6PGD and PGM. The same type of parasite was also isolated from two stray dogs from the same vicinity. This flagellate was quite distinct from Leishmania donovani, Leishmania major and Leishmania tropica, the three common Old World species of Leishmania; but its exact identity remains uncertain. It could be a new leishmanial entity or a flagellate parasite of another genus.

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.

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.

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 1 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 1 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.

Natural infections of Leishmania major in domestic dogs from Alexandria, Egypt.

Two leishmanial isolates from dogs from Alexandria, Egypt, were typed serologically and biochemically as Leishmania major. This is the second time that L. major has been shown to occur in dogs. The significance of these findings as a misleading phenomenon in relation to the relatively recent outbreak of infantile kala-azar in the area of Alexandria is discussed.

Sand fly fever-Naples infection in Egypt.

Two Egyptian male patients with sand fly fever-Naples virus infection are presented. The virus was isolated from one patient while both patients had diagnostic rises in indirect fluorescent antibody titers to the virus. The viral isolate, SFN 85055, grows to much higher titers and plaques more efficiently than the prototype sand fly fever-Naples virus and should facilitate work with this virus.

Serologic and immunologic studies in patients with AIDS in North America and Africa. The potential role of infectious agents as cofactors in human immunodeficiency virus infection.

Serologic and immunologic studies were performed in 38 African and 60 US patients with acquired immunodeficiency syndrome (AIDS), 100 African and 100 US heterosexual men and women, and 100 US homosexual men to examine the potential role of infectious agents in human immunodeficiency virus (HIV) infection. There were no significant differences in the prevalence of antibodies to cytomegalovirus, Epstein-Barr virus, hepatitis A and B viruses, herpes simplex virus, syphilis, and toxoplasmosis among the African and US patients with AIDS, African heterosexual controls, and US homosexual men. However, these four groups all demonstrated a significantly greater prevalence of antibodies to each of these infectious agents compared with US heterosexual men. Immunologic studies demonstrated a significant elevation of activated lymphocytes (HLA-DR and T3 positive) and immune complexes in both AIDS populations and African heterosexual and US homosexual populations, compared with the US heterosexual population. These data demonstrate that the immune systems of African heterosexuals, similar to those of US homosexual men, are in a chronically activated state associated with chronic viral and parasitic antigenic exposure, which may cause them to be particularly susceptible to HIV infection or disease progression.

Arboviral causes of non-specific fever and myalgia in a fever hospital patient population in Cairo, Egypt.

Fever and myalgia are non-specific clinical manifestations of illness which commonly occur in patients with arboviral disease. In Egypt, such illness is often mis-diagnosed as "influenza". To determine arboviral aetiology in patients admitted with fever and myalgia, acute and convalescent sera samples were obtained from 55 patients admitted with these clinical manifestations to the Imbaba Fever Hospital, Giza, Egypt, during October and November 1984. Based on viral isolation, and a comparison of acute and convalescent sera, 4 patients (7%) had acute arboviral infections. Haemagglutination inhibition and indirect immunofluorescence tests showed that one had West Nile virus (WNV) infection, 2 had sandfly fever virus-Naples (SFN), and 1 had sandfly fever virus-Sicilian (SFS) infection. SFN was isolated from the acute serum sample of 1 of the 2 patients with SFN infection.

Serological tests for detecting Rift Valley fever viral antibodies in sheep from the Nile Delta.

To determine the accuracy of serological methods in detecting Rift Valley fever (RVF) viral antibodies, we examined serum samples obtained from 418 sheep in the Nile Delta by using five tests. The plaque reduction neutralization test (PRNT) was considered the standard serological method against which the four other tests were compared. Twenty-four serum samples had RVF viral antibodies detected by PRNT. Hemagglutination inhibition and enzyme-linked immunosorbent assay antibodies to RVF virus were also present in the same 24 serum samples. Indirect immunofluorescence was less sensitive in comparison with PRNT, and complement fixation was the least sensitive. These results extend observations made with laboratory animals to a large field-collected group of Egyptian sheep.

A possible route for the introduction of Rift Valley fever virus into Egypt during 1977.

Rift Valley fever (RVF), which was enzootic in Sudan in 1976 and epidemic in Egypt in 1977-78, may have been introduced into Egypt from Sudan via sheep transported along Lake Nasser. A hypothesis is presented which describes sheep transport from holding areas in north-central Sudan, where RVF was epizootic, to live animal markets in southern Egypt. Travel time from north-central Sudan to the Aswan area was less than 5 days, approximating the incubation period of RVF virus in sheep. Reintroduction of RVF or other diseases from Sudan into Egypt will be facilitated by the construction of new roads linking the two countries.

Rift Valley fever surveillance in mobile sheep flocks in the Nile Delta.

Rift Valley fever (RVF) surveillance was carried out in the Nile Delta by monitoring mobile and stationary sheep flocks for antibodies to RVF virus. Sheep are known to be susceptible to RVF virus infection and experienced severe morbidity in 1977 and 1978 when RVF was epidemic in Egypt. Four hundred six sheep in 32 flocks were surveyed during 1984. Twenty-four sheep from 7 flocks had antibodies to RVF virus detected by hemagglutination inhibition and plaque reduction neutralization tests. Antibodies were found primarily in sheep greater than 3 years of age, although 1- and 2-year-old sheep were included in the sample. No seroconversion was observed among 177 seronegative sheep that were bled successively for a period of 10 months. These results indicate that epizootic RVF was probably not present in the Nile Delta during 1984.

Rodenticide-induced signs simulating Rift Valley fever in sheep and goats in Egypt.

Epidemic Rift Valley fever is generally recognised when a higher than expected frequency of abortions and haemorrhages occurs in sheep and other livestock. Other infectious agents can cause similar clinical signs. In Egypt, an outbreak of abortions and haemorrhages in sheep and goats in 1982 was traced to intoxication with the rodenticide brodifacoum. The epidemic lasted for three weeks and resulted in 120 deaths. The end of the epidemic coincided with a heavy rainstorm. This outbreak demonstrates the need for the strict control of the use of rodenticides and widens the differential diagnosis of epidemic abortion in sheep and goats.

Cardiac pathology in schistosomal cor pulmonale correlated with chest roentgenographs; a case report.

Case report of a 31-year-old male patient from Puerto Rico. Authors report chronic schistosomal cor pulmonale in which the roentgenographic appearance of the heart is correlated with the pathological description of marked dilatation and hypertrophy of the pulmonary conus and infra-conal area. This case report demonstrates the extent of conal dilatation which can be visualized on chest X-ray.