West Nile Virus in the State of Ceará, Northeast Brazil

Abstract

In June 2019, a horse with neurological disorder was diagnosed with West Nile virus (WNV) in Boa Viagem, a municipality in the state of Ceará, northeast Brazil. A multi-institutional task force coordinated by the Brazilian Ministry of Health was deployed to the area for case investigation. A total of 513 biological samples from 78 humans, 157 domestic animals and 278 free-ranging wild birds, as well as 853 adult mosquitoes of 22 species were tested for WNV by highly specific serological and/or molecular tests. No active circulation of WNV was detected in vertebrates or mosquitoes by molecular methods. Previous exposure to WNV was confirmed by seroconversion in domestic birds and by the detection of specific neutralizing antibodies in 44% (11/25) of equids, 20.9% (14/67) of domestic birds, 4.7% (13/278) of free-ranging wild birds, 2.6% (2/78) of humans, and 1.5% (1/65) of small ruminants. Results indicate that not only equines but also humans and different species of domestic animals and wild birds were locally exposed to WNV. The detection of neutralizing antibodies for WNV in free-ranging individuals of abundant passerine species suggests that birds commonly found in the region may have been involved as amplifying hosts in local transmission cycles of WNV.

An Overview of Neglected Orthobunyaviruses in Brazil

“…Three other enzootic arboviruses of increasing importance in Brazil are the Mayaro virus (MAYV, Togaviridae ), West Nile virus (WNV, Flaviviridae ) and Oropouche orthobunyavirus (OROV, Peribunyaviridae ) [ 24 , 25 , 26 , 27 , 28 , 29 ]. MAYV is an alphavirus involved in epidemics of fever and arthritis in Brazil.…”

“…WNV, which is involved in epidemic and epizooties of neurological disorder in North America and Europe, has been increasingly detected in Brazil. WNV was first detected in western Brazil in 2011, and since then it has been detected in several regions of the country [ 27 , 28 , 29 ].…”

“…In São Paulo, southeast Brazil, the TCMV was isolated from a pool of Anopheles cruzii, and from a febrile patient during the Rocio virus epidemic in a rural area of a coastal county influenced by the Atlantic Forest biome ( Figure 2 ) [ 78 ]. Recently, hemagglutination-inhibition antibodies were found in small ruminants and equids from northeastern Brazil, suggesting that TCMV may circulate in several biomes in Brazil [ 28 ]. Anopheles species are considered the main vectors of Anopheles A serogroup viruses.…”

“…Among the equines with monotypic reactions for MAGV, three animals were two years old at the moment of the venipuncture in 2009, suggesting that MAGV circulated in equines of the region between 2007 and September 2009 [ 30 ]. Additionally, hemagglutination-inhibition antibodies for MAGV were detected in small ruminants and equids by HI from northeastern Brazil [ 28 ]. Together, these findings suggest enzootic circulation of MAGV in different regions of Brazil.…”

“…In a serosurvey conducted in the western Brazil between 2009 and 2011, all 375 equines, 232 sheep and 66 caimans tested were seronegative for CARV [ 30 ]. Recently though, hemagglutination-inhibition antibodies for CARV were detected in rural human populations and from several samples from small ruminants and equids by HI from the Northeast Region of Brazil, suggesting that CARV might be more widespread in Brazil than originally thought [ 28 , 103 ].…”