The effect of Schistosoma mansoni infection on child morbidity in the State in Bahia, Brazil: II — Analysis at the individual level

The present investigation was carried out on a sample of 840 children (5 to 16 years old) from ten small towns of the State of Bahia in northeastern Brazil. The objetive was to study, by using a cross sectional methodology, the evolution of schistosomiasis morbidity (hepatic and splenic enlargement) in children, and the role of the intensity of S. mansoni infection in this process. The children were analised in three age groups (5 to 8, to 12 and 13 to 16 years old) and classified as uninfected, mildly infected, moderately infected and heavily infected according to the number of eggs in the stool. In children aged 5 to 8 years, increasing egg counts were not associated with increasing frequencies of hepatic or splenic enlargement. In the 9 to 12 years old group and association was observed with the prevalence of hepatic enlargement, but not with the prevalence of spleen enlargement. In the oldest group, 13 to 16 years old, an association was observed with the prevalence of enlargement of both organs. It was evident that in this population schistosomiasis morbidity develops in the early period of life as a gradual process starting with liver enlargement and followed by spleen enlargement some years later. It was found that the intensity of infection has a fundamental role in this process, although there is a latent period of some years before clinical splenomegaly appears in moderate-heavily infected children. The Authors suggest that the prevalence of splenomegaly in the 13 to 16 years old group is a good measure of the community level of schistosomiasis morbidity and could be used to measure the impact of control programs.

Serologic studies on the behaviour of influenza virus type A in persons of greater São Paulo during 1976, 1978 and 1979

Sera of persons of different age groups collected in 1976, 1978 and 1979 were tested for the presence of HI antibodies against various strains of the H3N2 and H1N1 subtypes of influenza virus. The occurrence of infection by H3N2 subtype was recorded during the 1976-1978 period but in 1979, circulation of this subtype of virus was limited. The prevalence of antibody against A/São Paulo/1/78 (H1N1) was significantly higher than that of antibody to A/USSB/90/77 (HIND in 1978. However in 1979 the predominant strain was A/USSR/90/77 (HIND. Persons under 20 years of age were the most affected by H1N1 subtype. Antibodies to H1N1 subtype were detected in sera of individuals older than 20 years in 1976, before the re-emergence of this strain. Serological results indicate that infections by H3N2 subtype in 1978 occurred in 65.4% of young children (0-4 year group). About 47.0% of children from the 0-4 year group had antibodies to H1N1 subtype in 1979. Antibodies to swine influenza virus were detected in 60% of 60+ year old people.

Water-contact patterns and schistosoma mansoni infection in a rural community in northeast Brazil

We evaluated the influence of water-related human activities, contaminative behaviour, house location, education and socio-economic status on endemic Schistosoma mansoni infection. The study was conducted in a hilry non-irrigated area of rural northeast Brazil amongst a defined population of subsistence farmers, of whom 93% were infected by age 20. The area was mapped, water bodies were surveyed, and a detailed questionnaire was performed on each household. Infection was assessed by duplicate stool examinations using the sensitive Bell technique to quantify egg excretion. For each household, and index of intensity of infection was computed by grouping individual log-transformed egg counts as an age-sex adjusted Z score. Few households had a sanitary installation or a domestic water supply. However, neither water-contact nor contaminative behavior were indiscriminate. The people made considerable effort to defaecate far from a water source, to obtain household drinking water from the cleanest source, and to bathe only at certain sites where privacy is assured. Land ownership and literacy correlated poorly with the household index of intensity of infection. The key influence on infection status was the relative location of the house and snail-free or snail colonized water sources. In this area, a safe domestic water supply is the critical input needed to achieve definitive control of endemic Schistosomiasis.

Comparative study of the biological behaviour in hamster of two isolates of leishmania characterized respectively as L. major-like and L. donovani

Hamster inoculated intraperitoneally with 1 x 10(7) parasites of L. donovani and L. major-like of the New World were studied in groups of 15, 30, 60 and 90 days of infection. The parasite load and density showed progressive increase with the evolution of the infection and was higher in the L. donovani groups than in the L. major-like groups. The L. major-like groups showed parasite density higher in the spleen than in the liver and was similar in both organs in L. donovani groups. The histopathology showed a diffuse marked hyperplasia and hypertrophy of the reticuloendothelial system with high parasitism in the L. donovani groups while there was focal involvement of these organs in L. major-like groups, forming nodules of macrophages that were scantly parasitised. The biological behaviour could be useful in the preliminary studies of Leishmania strain in regional laboratories and understanding the histopathology of lesions caused by different leishmania species.

Malária humana: padronização e optimização de testes sorológicos para diagnóstico individual e inquéritos soroepidemiológicos

O teste de imunofluorescência indireta (IFI) é considerado teste de referência na soroiogia da malária. Neste trabalho procuramos optimizar o teste empregando P. falciparum obtido de sangue humano e de cultura e P. vivax obtido de sangue de paciente como antígenos, para pesquisa de anticorpos IgG e IgM. Das variáveis técnicas estudadas melhores resultados foram obtidos quando os soros foram diluidos ern PBS contendo 1% de Tween 80 e as lâminas contendo a suspensão antigênica foram estabilizadas em dessecadores ou fixadas com acetona. Foi também padronizado o teste imunoenzimático ELISA com antigenos de P. falciparum obtidos em cultura. O estudo comparativo com o teste de imunofluorescência indireta para pesquisa de anticorpos IgG mostrou: a) nos pacientes primo infectados por P. falciparum a sensibilidade para ambos os testes foi de 71%; b) nos pacientes primo infectados pelo P. vivax a sensibilidade foi de 40% para ambos os testes; c) nos pacientes não primo infectados e com malária atual pelo P. falciparum a sensibilidade para ambos os testes foi de 100%; d) nos pacientes não primo infectados e com malária atual pelo P. vivax a sensibilidade foi de 85% para o teste ELISA e de 92% para a IFI; e) nos pacientes com malária mista a sensibilidade para ambos os testes foi de 100%. A especificidade da IFI foi de 100% e do teste ELISA 95% nos casos de indivíduos não maláricos. Os resultados obtidos sugerem ser o teste ELISA, uma boa alternativa para o teste de IFI, para a pesquisa de anticorpos IgG anti P. falciparum, na soroiogia da malária.

Aggregatory behaviour of platelets incubated with subcellular fractions of normal and chagasic human syncytiotrophoblast

The surface of human syncytiotrophoblast does not induce maternal blood platelet aggregation even though it is not an endothelium. It can be surmised that as occurs in endothelial injury the subcellular components of the syncytiotrophoblast may have pro-or antiaggregatory activity. During congenital Chagas' disease which is associated to trophoblast lesions, platelets may play a role in the development of T. cruzi-induced placentitis. In the present work the aggregatory behaviour of normal human blood platelets was recorded after their challenging with subcellular fractions of syncytiotrophoblast isolated from normal and chagasic women. Nuclear, Mitochondrial, Microsomal and Supernatant fractions isolated from normal and chagasic syncytiotrophoblast failed to induce per se any aggregatory reaction on platelets. When samples of platelet-rich plasma (PRP) were preincubated with normal and chagasic nuclear fractions and then stimulated with collagen at threshold level (CT-PRP) an inhibition of the aggregatory response was observed. Treatment of CT-PRP with normal and chagasic mitochondrial fractions induced inhibition of platelet aggregation whereas only chagasic fraction reduced latency time. Microsornal fraction from normal placentas showed no significant effects on platelet aggregation. It is concluded that subcellular fractions of normal human syncytiotrophoblast do not exhibit any effect on platelet aggregation, whereas those subcellular fractions enriched in intracellular membrane components isolated from chagasic placentas inhibit platelet aggregation.

Bancroftian filariasis in two urban areas of Recife, Brasil: the role of individual risk factors

Bancroftian filariasis is spreading in towns of endemic areas as in Recife, northeastern Brazil, where it is a major public health problem. This paper deals with the prevalence of microfilaraemia and filarial disease in two urban areas of Recife, studying their association with individual characteristics and variables related to the exposure to the vectors. The parasitologic survey was performed through a "door-to-door" census and microfilaraemia was examined by the thick-drop technique using 45µl of peripheral blood collected between 20:00 and 24:00 o' clock. 2,863 individuals aged between 5 and 65 years were interviewed and submitted to clinical examination. Males aged between 15 and 44 years old presented the greatest risk of being microfilaraemic. Microfilaraemia was also significantly associated with no use of bednet to sleep. The risk of being microfilaraemic was greater among those who had lived in the studied areas for more than 5 years. The overall disease prevalence was 6.3%. Males presented the greatest risk of developing acute disease. The risk of developing chronic manifestations was also greater among males and increased with age. We found no association between time of residence, bednet use, microfilaraemia and acute and chronic disease. We may conclude that in endemic areas there are subgroups of individuals who has a higher risk of being microfilariae carriers due to different behaviours in relation to vector contact.