# Seroprevalence of Rift Valley and Crimean-Congo Hemorrhagic Fever Viruses, Benin, 2022–2023

## TL;DR

A study in Benin found low antibody prevalence for two viral diseases but highlights issues with serologic tests in malaria-endemic areas.

## Contribution

The study identifies potential false positives in serologic testing due to cross-reactivity with malaria antibodies in endemic regions.

## Key findings

- No patients tested positive for Rift Valley or Crimean-Congo hemorrhagic fever viruses via PCR.
- 1.1% and 0.3% of patients had IgG antibodies for Rift Valley and Crimean-Congo viruses, respectively.
- Malaria antibodies may cause false positives in serologic tests due to cross-reactivity with viral antigens.

## Abstract

We screened 650 febrile patients from Benin for Rift Valley fever and Crimean-Congo hemorrhagic fever viruses during 2022–2023. None were positive by reverse transcription PCR; 1.1% and 0.3%, respectively, had virus-specific IgG. False-positive results from malaria-associated antibodies likely reacting with histidine-tagged viral antigens mandate careful validation of serologic tests in malaria-endemic regions.