Serological evidence of Eastern equine encephalitis circulation in equids in Pará state, Brazil.

Josynélia Do Socorro Da Silva Sena Nunes Nunes,Bruno De Cássio Veloso De Barros,Helder Henrique Costa Pinheiro,Ricardo José De Paula Sousa Guimarães,Jannifer Oliveira Chiang,Ana Cecília Ribeiro Cruz,Milene Silveira Ferreira,Lívia Medeiros Neves Casseb,Wilgner Duarte Magalhães Reis,Pedro Fernando Da Costa Vasconcelos

doi:10.29374/2527-2179.bjvm001720

Abstract

Serum samples from 89 equids were analyzed (75 horses, 9 donkeys, and 5 mules) from the municipality of Viseu, Pará state, Brazil. Samples were collected in November 2014 and August 2015. The antibody prevalence against the following alphaviruses was estimated: Eastern equine encephalitis virus, Western equine encephalitis virus, Mucambo virus, and Mayaro virus. Seroprevalence was determined by the hemagglutination inhibition (HI) technique. Sera that exhibited HI antibodies with heterotypic reactions for the analyzed viruses were subjected to the 90% plaque reduction neutralization test (PRNT90). The HI prevalence of monotypic reactions to EEEV was 7.9%, and that of WEEV was 1.1%, as confirmed by PRNT90. Viral isolation attempts were negative for all tested blood samples. Our results suggest the circulation of equine encephalitis complex viruses. Future studies should evaluate the possible involvement of arthropod hosts and residents in the viral transmission in the study area.

Highlights

Eastern equine encephalitis virus (EEEV) is an arthropod-borne virus belonging to the genus Alphavirus, family Togaviridae (Chen et al, 2018)
The present study aimed to investigate the prevalence of antibodies against four arboviruses belonging to the genus Alphavirus in equids in Viseu, a municipality in the eastern region of Pará state located at the border with the state of Maranhão, in which there have been no serological studies on Alphavirus circulation in equids
Of the 89 serum samples analyzed by the hemagglutination inhibition (HI) test, 13/89 (14.6%) showed heterotypic reactions (HRs) to all four viruses (EEEV, Western equine encephalitis virus (WEEV), Mucambo virus (MUCV), and Mayaro virus (MAYV)), and in 6/89 (6.7%) sera, a monotypic reaction (MR) to EEEV was detected

Summary

Introduction

Eastern equine encephalitis virus (EEEV) is an arthropod-borne virus (arbovirus) belonging to the genus Alphavirus, family Togaviridae (Chen et al, 2018). EEEV was first isolated in 1933 from horse brain tissue obtained after an outbreak in New Jersey and Virginia, United States (TenBroeck & Merrill, 1933). EEEV is enzootic in North America along the Atlantic and Gulf Coasts up to Texas, the Caribbean, and Central America. EEEV are enzootic along the north and east coasts of South America and the Amazon River basin (Causey et al, 1962).

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