Occurrence of arbovirus infections in two riverine populations in the municipality of Humaitá, Amazonas, Brazil

Jaqueline Carvalho de Oliveira Silva ^1,2, Igor Rodrigo Ferreira Siqueira ², Leormando Fortunato Dornelas ¹

⁰Fundação Oswaldo Cruz, Programa de Pós-Graduação Stricto Sensu em Biologia da Interação Patógeno Hospedeiro, Manaus, AM, Brasil.

Revista Da Sociedade Brasileira De Medicina Tropical +

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March 27, 2024

View abstract on PubMed

Summary

Dengue virus IgG antibodies were highly prevalent in Amazonian riverside populations, indicating past exposure. The study found no evidence of local arbovirus vectors, suggesting infections were acquired elsewhere.

Area Of Science

Epidemiology
Virology
Public Health

Background

Riverine communities in the Amazon are vulnerable to arbovirus infections due to their proximity to urbanized areas and reliance on river travel.
Emerging arboviruses like dengue, Zika, and chikungunya require robust epidemiological surveillance in Brazil.
This study focuses on riverside populations in the Brazilian Amazon, a region with significant arbovirus transmission potential.

Purpose Of The Study

To determine the seroprevalence of IgG and IgM antibodies against dengue, Zika, and chikungunya viruses in a riverside population.
To conduct molecular analysis for detecting viral RNA of dengue, Zika, chikungunya, Oropouche, and Mayaro viruses in human serum samples.
To identify local mosquito vectors and assess their role in arbovirus transmission within these communities.

Main Methods

A cross-sectional study was conducted in the Humaitá municipality, Brazilian Amazon, involving over 80% of the local riverside population.
Human serum samples (n=205) were analyzed for IgG and IgM antibodies against specific arboviruses and for viral RNA.
Entomological samples were collected to identify mosquito species and potential arbovirus vectors present in the study area.

Main Results

High prevalence of IgG antibodies against dengue virus (85/205 individuals) was detected, indicating widespread prior exposure.
No molecular evidence of Zika, chikungunya, dengue, Oropouche, or Mayaro virus RNA was found in human serum samples.
Entomological surveys identified numerous Diptera, with *Mansonia* as the most common genus, but notably excluded *Aedes aegypti* and *Aedes albopictus*.

Conclusions

The high prevalence of dengue IgG antibodies suggests significant past exposure to the virus in the studied riverside population.
The absence of key arbovirus vectors (*Aedes aegypti*, *Aedes albopictus*) in the sampled areas supports the conclusion that infections likely originated outside these communities.
Findings highlight the importance of considering external transmission sources for arboviruses in remote populations.