Prevalence and level of antibodies to the circumsporozoite protein of human malaria parasites in five states of the Amazon region of Brazil

Abstract

The aim of this study was to determine the prevalence of malaria infection and antibodies against the repetitive epitopes of the circumsporozoite (CS) proteins of Plasmodium falciparum, P. malariae, P. vivax VK210, P. vivax VK247, and P. vivax-like in individuals living in the states of Rondônia, Pará, Mato Grosso, Amazonas, and Acre. Active malaria transmission was occurring in all studied sites, except in Acre. P. falciparum was the predominant species in Pará and Rondônia and P. vivax in Mato Grosso. Infection by P. malariae was low but this Plasmodium species was detected in Rondônia (3.5%), Mato Grosso (2.5%), and Pará (0.8%). High prevalence and levels of serological reactivity against the CS repeat peptides of P. falciparum were detected in Rondônia (93%) and Pará (85%). Sera containing antibodies against the CS repeat of P. malariae occurred more frequently in Rondônia (79%), Pará (76%), and Amazonas (68%). Antibodies against the repeat epitope of the standard CS protein of P. vivax VK210, P. vivax VK247, and P. vivax-like were more frequent in Rondônia, Pará, and Mato Grosso. The high frequency of reactions to P. malariae in most of the areas suggests that the infection by this Plasmodium species has been underestimated in Brazil. Key words: Plasmodium -infection -Amazon region -BrazilMalaria remains as a serious health problem in the Amazon Basin of Brazil and approximately 99% of some 600,000 cases notified annually occur in this region (Ministério da Saúde 2003, Coura et al. 2006. Malaria is heterogeneously distributed in the nine states of the Legal Amazon and the number of annual cases fluctuates, increasing in some states where gold mining activities take place, massive migration occurs, and new settlements projects are implemented. However, the states of Pará, Amazonas, and Rondônia are always among the major malaria-endemic regions. Based on microscopic examination from the records of the Brazilian Ministry of Health, P. falciparum and P. vivax are the most prevalent Plasmodium. The reported prevalence of P. malariae is very low (< 1%). In the last 15 years the number of P. vivax has increased and presently accounts for 78% of all malaria cases reported in the country. Besides the classic P. vivax VK210, two species-specific circumsporozoite (CS) protein variants P. vivax VK247 (Rosenberg et al. 1989) and P. vivax-like (Qari et al. 1993, 1994 were described. The human P. vivax-like parasite has a CS repeat which corresponds to the simian parasite P. simiovale. Otherwise the identity of these parasites is not clear, since a line of the human isolates has not yet been obtained and the clinical manifestation of these infections is unknown.Antibodies to sporozoites represent a serological transmission indicator and have been used in epidemiological studies to estimate the level of malaria in endemic areas. It is well known that individuals living in malaria endemic areas exposed to sporozoite infections develop antibodies directly to the repetitive epitopes of the CS protein. The prevalence and le...

Epidemiological profile of malaria in the state of Tocantins, Brazil, from 2003 to 2008

“…In Brazil, the most frequent species that cause infection in humans are: P. vivax, which accounted for 83.7% of registered cases, P. falciparum, by 16.3% and P. malariae (rarely observed) 26 . However, studies conducted by ARRUDA et al 2 revealed a discrepancy between the prevalence of antibodies against P. malariae and the malaria cases officially reported. According to the authors, the low incidence of reports on this species is due to the thick smear method, the official technique for the diagnosis of malaria in Brazil, which does not allow the evaluation of morphological difference of erythrocytes infected with P. vivax and P. malariae, and this can lead to a misidentification of the species, underestimating the true incidence of the latter.…”

Analysis of lymphocytes in patients with Plasmodium vivax malaria and its relation to the annexin-A1 and IL-10

“…In 2011, only 263,323 cases were reported [1]. In other Brazilian regions, the transmission risk is low or nonexistent [2]. In Mato Grosso, the disease is predominantly focal.…”

Situação epidemiológica da malária no Estado do Tocantins, Brasil, a partir da emancipação política e administrativa, 1989 a 2009

“…4,5 Já, a baixa frequência do P. malariae registrada nos sistemas de informação requer acompanhamento mais detalhado pelos diversos setores envolvidos no processo: estudos publicados relevam que a semelhança do P. malariae com o P. vivax pode provocar equívoco na identificação. O método de visualização adotado no Brasil, da microscopia da gota espessa de sangue, capaz de detectar densidades baixas de parasitos, 4 tem sido questionado por Arruda e colaboradores 24 em suas pesquisas na Amazônia Legal: esses autores destacaram uma diferença entre a prevalência de anticorpos contra P. malariae e os casos notificados oficialmente, e comentam que a técnica oficial, recomendada pelo Ministério da Saúde como padrão-ouro para detecção e identificação de parasitos da malária, não permite avaliar a diferença morfológica das hemáceas infectadas por P. vivax e P. malariae, podendo levar a uma identificação incerta da espécie e a um cálculo equivocado de incidência.…”