Title:	Cross-sectional study defines difference in malaria morbidity in two Yanomami communities on Amazonian boundary between Brazil and Venezuela
Authors:	Tosta, Carlos Eduardo Morgado, Anastácio Coura, José Rodrigues Marcano, Teodardo José
Assunto::	Malária Imunidade Indígenas Yanomami Amazônia
Issue Date:	2004
Citation:	TOSTA, Carlos Eduardo et al. Cross-sectional study defines difference in malaria morbidity in two Yanomami communities on Amazonian boundary between Brazil and Venezuela. Memórias do Instituto Oswaldo Cruz , v. 99, n. 4, 2004. Disponível em: <http://www.scielo.br/pdf/mioc/v99n4/v99n4a05.pdf>. Acesso em: 26 out. 2010. doi: 10.1590/S0074-02762004000400005.
Abstract:	It is well established that immunity to malaria is short-lived and is maintained by the continuous contact with the parasite. We now show that the stable transmission of malaria in Yanomami Amerindian communities maintains a degree of immunity in the exposed population capable to reduce prevalence and morbidity of malaria. We examined 508 Yanomami Amerindians living along Orinoco (407) and Mucajaí (101) rivers, on the Venezuelan and Brazilian Amazon region, respectively. At Orinoco villages, malaria was hyperendemic and presented stable transmission, while at Mucajaí villages it was mesoendemic and showed unstable transmission. The frequency of Plasmodium vivax and P. falciparum was roughly comparable in Venezuelan and Brazilian communities. Malaria presented different profiles at Orinoco and Mucajaí villages. In the former communities, malaria showed a lower prevalence (16% x 40.6%), particularly among those over 10 years old (5.2% x 34.8%), a higher frequency of asymptomatic cases (38.5% x 4.9%), and a lower frequency of cases of severe malaria (9.2% x 36.5%). Orinoco villagers also showed a higher reactivity of the immune system, measured by the frequency of splenomegaly (72.4% x 29.7%) and by the splenic index (71.4% over level 1 x 28.6), and higher prevalence (91.1% x 72.1%) and mean titer (1243 x 62) of antiplasmodial IgG antibodies, as well as a higher prevalence (77.4% x 24.7%) and mean titer (120 x 35) of antiplasmodial IgM antibodies. Our findings show that in isolated Yanomami communities the stability of malaria transmission, and the consequent continuous activation of the immune system of the exposed population, leads to the reduction of malaria prevalence and morbidity.
metadata.dc.description.unidade:	Faculdade de Medicina (FMD)
DOI:	https://dx.doi.org/10.1590/S0074-02762004000400005
Appears in Collections:	Artigos publicados em periódicos e afins

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