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Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/122724
Infection of Anopheles aquasalis from symptomatic and asymptomatic Plasmodium vivax infections in Manaus, western Brazilian Amazon
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BACKGROUND: Asymptomatic individuals are one of the major
challenges for malaria elimination programs in endemic areas. In
the absence of clinical symptoms and with a lower parasite
density they constitute silent reservoirs considered important
for maintaining transmission of human malaria. Studies from
Brazil have shown that infected individuals may carry these
parasites for long periods. RESULTS: Patients were selected from
three periurban endemic areas of the city of Manaus, in the
western Brazilian Amazon. Symptomatic and asymptomatic patients
with positive thick blood smear and quantitative real-time PCR
(qPCR) positive for Plasmodium vivax were invited to participate
in the study. A standardised pvs25 gene amplification by qPCR
was used for P. vivax gametocytes detection. Anopheles aquasalis
were fed using membrane feeding assays (MFA) containing blood
from malaria patients. Parasitemia of 42 symptomatic and 25
asymptomatic individuals was determined by microscopic
examination of blood smears and qPCR. Parasitemia density and
gametocyte density were assessed as determinants of infection
rates and oocysts densities. A strong correlation between
gametocyte densities (microscopy and molecular techniques) and
mosquito infectivity (P < 0.001) and oocysts median numbers
(P < 0.05) was found in both groups. The ability to infect
mosquitoes was higher in the symptomatic group (41%), but
infectivity in the asymptomatic group was also seen (1.42%).
CONCLUSIONS: Although their infectivity to mosquitoes is
relatively low, given the high prevalence of P. vivax
asymptomatic carriers they are likely to play and important role
in malaria transmission in the city of Manaus. The role of
asymptomatic infections therefore needs to be considered in
future malaria elimination programs in Brazil.
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MARTINS CAMPOS, Keillen M., et al. Infection of Anopheles aquasalis from symptomatic and
asymptomatic Plasmodium vivax infections in Manaus, western
Brazilian Amazon. Parasites & Vectors. 2018. Vol. 11, num. 288. ISSN 1756-3305. [consulted: 12 of August of 2026]. Available at: https://hdl.handle.net/2445/122724