Plasmodium Vivax: Transmission-Blocking Immunity in a Malaria-Endemic Area of Colombia

Abstract

Plasmodium vivax transmission-blocking activity was assessed in sera from acutely infected patients from a malaria-endemic area in Colombia. We measured reduction in the number of oocysts that developed in the midguts of Anopheles albimanus mosquitoes artificially fed with blood from these patients. Of 88 mosquito batches that developed infections when parasites were mixed with normal AB human serum, one-third (36.4%) showed full transmission-blocking activity (>or= 90% inhibition) when mixed with autologous sera, 29.6% showed partial activity (50-89%), 17.0% did not block transmission (0-50%), and 17% did not enhance transmission. Transmission-blocking activity correlated with antibody titer by an immunofluorescent antibody test and decreased with the serial dilution of the sera. This activity disappeared at a 1:4 dilution in most sera tested. Afro-Colombian individuals showed lower activity than other ethnic groups and febrile patients produced stronger inhibition than those without fever.

Characterization of Plasmodium vivax Transmission-Blocking Activity in Low to Moderate Malaria Transmission Settings of the Colombian Pacific Coast

“…In this study, and in the former one, 14 similar percentages of sera (35% high and 32% intermediate level, respectively) from P. vivax acutely infected individuals showed TB activity (≥ 50% inhibition). In the present study we had the opportunity to determine the difference of TB activity in infected 14 and non-infected individuals from the same region.…”

“…In this study, and in the former one, 14 similar percentages of sera (35% high and 32% intermediate level, respectively) from P. vivax acutely infected individuals showed TB activity (≥ 50% inhibition). In the present study we had the opportunity to determine the difference of TB activity in infected 14 and non-infected individuals from the same region. In contrast to the high prevalence of TB activity found in acutely infected individuals, only 6.8% and 9.1% of sera from non-infected volunteers maintained similar levels of TB activity (high and intermediate levels, > 50%) ( Table 1 ).…”

“…10,12 In this community, infected individuals also presented significantly higher specific anti-P. vivax antibodies (24%, ≥ 1:3,200) 14 than non-infected volunteers (20.6% up to 1:1,600). The fact that parasite exposure triggers an efficient antibody boosting highlights the contribution of antiparasite immune response to produce TB.…”

“…9 In lowto-moderate malaria P. vivax transmissions setting of Latin America, only two studies have been reported, one in Mexico and another in Colombia. 14,15 Both studies indicated high TB activity in infected individuals at the time of malaria diagnosis, but neither addressed the question about duration.…”

Plasmodium vivax Sporozoite Production in Anopheles albimanus Mosquitoes for Vaccine Clinical Trials

“…albimanus mosquito colonies in both endemic and non-endemic sites of Colombia. [9][10][11] This mosquito species is widely distributed in the American continent, ranging from southern regions of Mexico to northern Peru. 12,13 This mosquito species has been found naturally infected by both P. vivax and P. falciparum and is considered a primary malaria vector in Latin America.…”