SUMMARYA study was carried out in the area of influence of the Porto Primavera Hydroelectric Power Station, in western São Paulo State, to investigate ecological and epidemiological aspects of malaria in the area and monitor the profile of the anopheline populations following the environmental changes brought about by the construction of the lake. Mosquitoes captured were analyzed by standardized indicator species analysis (ISA) before and during different flooding phases (253 m and 257 m elevations). The local human population was studied by means of parasitological (thin/thick blood smears), molecular (PCR) and serological tests. Serological tests consisted of Enzyme Linked Immunosorbent Assay (ELISA) with synthetic peptides of the circumsporozoite protein (CSP) from classic Plasmodium vivax, P. vivax variants (VK247 and "vivax-like"), P. malariae and P. falciparum and Indirect Immunofluorescence Assay (IFA) with asexual forms of P. vivax, P. malariae and P. falciparum. The results of the entomological survey indicated that, although the Anopheles darlingi population increased after the flooding, the population density remained very low. No malaria, parasite infection or DNA was detected in the inhabitants of the study area. However, there was a low frequency of antibodies against asexual forms and a significant prevalence of antibodies against P. vivax, P. vivax variants, P. falciparum and P. malariae; the presence of these antibodies may result from recent or less recent contact with human or simian Plasmodium (a parallel study in the same area revealed the existence of a sylvatic cycle). Nevertheless, these results suggest that, as in other places where malaria is present and potential vectors circulate, the local epidemiological conditions observed could potentially support the transmission of malaria in Porto Primavera Lake if infected individuals are introduced in sufficient numbers. Further studies are required to elucidate the phenomena described in this paper.
SUMMARYYellow fever (YF) is an acute viral infectious disease transmitted by mosquitoes which occurs in two distinct epidemiological cycles: sylvatic and urban. In the sylvatic cycle, the virus is maintained by monkey's infection and transovarian transmission in vectors. Surveillance of non-human primates is required for the detection of viral circulation during epizootics, and for the identification of unaffected or transition areas. An ELISA (enzyme-linked immunosorbent assay) was standardized for estimation of the prevalence of IgG antibodies against yellow fever virus in monkey sera (Alouatta caraya) from the reservoir area of Porto Primavera Hydroelectric Plant, in the state of São Paulo, Brazil. A total of 570 monkey sera samples were tested and none was reactive to antibodies against yellow fever virus. The results corroborate the epidemiology of yellow fever in the area. Even though it is considered a transition area, there were no reports to date of epizootics or yellow fever outbreaks in humans. Also, entomological investigations did not detect the presence of vectors of this arbovirus infection. ELISA proved to be fast, sensitive, an adequate assay, and an instrument for active search in the epidemiological surveillance of yellow fever allowing the implementation of prevention actions, even before the occurrence of epizootics.
LIMA MA. Circulation of yellow fever virus antibodies in a simian population in the Porto Primavera Hydroelectric Plant region, in São Paulo. [Master's Degree Dissertation -College of Public Health -USP). 2006Introduction -Yellow fever (YF) is an infectious viral disease transmitted by mosquitoes. The YF virus maintains itself in two basic cycles: an urban, manmosquito-type cycle and a wild cycle, in which the virus is maintained through the infection of monkeys and transovarian transmission in mosquitoes. Thus, active surveillance of non-human primate populations is required to detect yellow fever virus circulation while it is still epizootic and to determine, through the presence of antibodies, possible virus circulation in regions that are considered either exempt of or transitional for the disease. Objectivestandardize the ELISA (Enzyme Linked Immunosorbent Assay) to check the prevalence of IgG-class antibodies against the YF virus in the sera of monkeys (Alouatta caraya) that inhabit the Porto Primavera Hydroelectric Plant reservoir region, in São Paulo. Results -The ELISA test was standardized using a commercial anti-monkey conjugate to test samples collected from 570 monkeys. None of the tested samples were reactive to the presence of YF virus antibodies. Conclusions -The results are coherent with the YF epidemiology in the region. Even though it is considered a transition area, thus far no YF epizootic occurrence or outbreak among the human population has been reported in the area and entomological investigations have not pointed to the presence of YF vectors there. The test revealed to be very sensitive, fast, and useful for the disease's epidemiological surveillance. Besides the viral circulation in the reservoirs, it is necessary an entomological surveillance on the vectors to take measures of prevention, as vaccination.
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