Prevalence and level of antibodies to the circumsporozoite proteins of human malaria parasites, including a variant of Plasmodium vivax, in the population of two epidemiologically distinct areas in the state of Acre, Brazil

Abstract

A seroepidemiological study of the prevalence of antibodies against the repeating epitopes of circumsporozoite (CS) proteins of human malaria parasites was conducted in 2 different areas in the state of Acre, Brazil in 1987 and 1990. In 1987 antibodies against the CS protein of the VK 247 variant Plasmodium vivax as well as antibodies against the CS proteins of P. falciparum and the classic P. vivax were found at relatively high rates in the 2 areas, but significant microepidemiological differences were observed. In 1990, when large scale migration in Amazonia had ceased and control measures were applied in the study areas, the malaria endemicity decreased, as determined by the declining prevalence of anti-sporozoite antibodies against all Plasmodium species, and the small number of individuals with positive blood smears. Antibodies against sporozoites of the variant P. vivax did not cross-react with the CS proteins of the classic P. vivax, nor with antibodies against sporozoites of P. falciparum and P. malariae. Sera containing antibodies against the CS protein of P. malariae were found at a very low frequency, and only in 1987. The anti-CS protein antibody response to all Plasmodium species was age-related.

Assessing the incidence of infection with Plasmodium falciparum among international travelers.

“…Therefore, the data are probably biased towards disease and are unlikely to be representative for average German travelers to malarious areas. However, considering the previously demonstrated low sensitivity of the ELISA used in this investigation, [8][9][10] at least one-third of all infected persons appear to remain undetected by this test. No specimen derived from the malaria-negative control group of 342 volunteers was positive for CS antibodies.…”

“…[4][5][6][7] Seroconversion rates of 60% to P. vivax-specific CS antibodies have been found in patients with P. vivax malaria for the first time. 8,9 Sensitivity and specificity of an available ELISA system (Sclavo Diagnostici, Sienna, Italy) have been evaluated in nonimmune patients after one episode of malaria infection. 10 While the sensitivity was found to be rather low (55.8%) during a period of 8-90 days after onset of symptoms, its specificity was 100%.…”

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

“…A retrospective study showed that the P. vivax VK247 and P. vivaxlike were present in indigenous populations since 1987 (Arruda et al 1998). Antibodies to these variants were also detected in other regions of the Brazilian Amazon; in the states of Acre (Kremsner et al 1992, Branquinho et al 1993, Marelli et al 1997, Machado et al 2000. More recently antibodies to the CS repeats of these two variants were also detected in areas of very low endemicity in the states of Espírito Santo (Arruda, unpublished observations) and São Paulo (Curado et al 1997).…”

Phase I Safety and Immunogenicity Trial of Plasmodium vivax CS Derived Long Synthetic Peptides Adjuvanted with Montanide ISA 720 or Montanide ISA 51

“…Importantly, even low LSP vaccine doses were enough to induce sero-conversion in 95% of the volunteers and sera from 86% of the participants recognized the native protein in sporozoites. Although IFAT titers may appear low, the high seroconversion is encouraging because in field conditions only a limited number of the individuals continuously exposed to P. vivax recognize sporozoites, 51,52 even if they are continuously exposed to the complete mass of parasite proteins. Interestingly, similar antibody titers were indicated in a previous trial 53 to induce significant in vitro sporozoites invasion inhibition.…”