Do some conditions contribute to the reemergence of the Venezuelan equine encephalitis virus in the Colombian Alta Guajira?

Abstract

Introduction: In the last 18 years, epizootics of Venezuelan equine encephalitis have not occurred in places with historic epidemic register (1925-1995) in the Guajira Peninsula, Colombia.

Objective: To assess if the Guajira Peninsula, Colombia, still maintains the epidemiological conditions for Venezuelan equine encephalitis virus reemergence.

Materials and methods: Research was carried out in places affected by the 1995 epidemic. We evaluated: 1) abundance and seasonal variation of vector mosquito populations; 2) availability of mammals that are potential amplifiers of the virus, and 3) knowledge among the community about the disease and its vectors.

Results: Most of the 16 mosquito species were found during the rainy season. Aedes taeniorhynchus and Psorophora confinnis showed direct relation with rainfall and temperature. In contrast, the dominant species, Deinocerites atlanticus, was always present in the collections, regardless of climatic conditions. No IgG antibodies were found in humans younger than 17 years old, goats or bovine sera. One third of those interviewed remembered the last epidemic and had basic understanding of the disease. Only 20% of the families were owners of equines, and 8% was informed of the importance of equine vaccination.
Conclusions: Some epidemiological conditions that eventually could help epizootic Venezuelan equine encephalitis virus reemergence are maintained. However, an abrupt decrease in the number of susceptible equines was found in the area. Apparently, this new condition has not allowed the virus reemergence and is the biggest observed change.