Seroconversion for west Nile and St. Louis encephalitis viruses among sentinel horses in Colombia

Abstract

We prospectively sampled flavivirus-naïve horses in northern Colombia to detect West Nile virus (WNV) and St. Louis encephalitis virus (SLEV) seroconversion events, which would indicate the current circulation of these viruses. Overall, 331 (34.1%) of the 971 horses screened were positive for past infection with flaviviruses upon initial sampling in July 2006. During the 12-month study from July 2006-June 2007, 33 WNV seroconversions and 14 SLEV seroconversions were detected, most of which occurred in the department of Bolivar. The seroconversion rates of horses in Bolivar for the period of March-June 2007 reached 12.4% for WNV and 6.7% for SLEV. These results comprise the first serologic evidence of SLEV circulation in Colombia. None of the horses sampled developed symptoms of encephalitis within three years of initial sampling. Using seroconversions in sentinel horses, we demonstrated an active circulation of WNV and SLEV in northern Colombia, particularly in the department of Bolivar. The absence of WNV-attributed equine or human disease in Colombia and elsewhere in the Caribbean Basin remains a topic of debate and speculation

Serological detection of West Nile virus in horses and chicken from Pantanal, Brazil

“…The rate of detection of WNV seroprevalence (8%) among the horses in our study is similar to the values reported for horses in other studies within South America, such as Colombia with a prevalence of 9% (Mattar et al 2005) and 5% (Mattar et al 2011), Venezuela 4% (Bosch (Tauro et al 2012).…”

The Global Ecology and Epidemiology of West Nile Virus

“…The first detection of WNV in South America was in an autumn 2004 epidemiological survey of horses which had not been vaccinated against WNV or traveled outside of Córdoba and Sucre in the Caribbean region of Colombia [ 304 , 305 ].…”

West Nile Virus Ecology in a Tropical Ecosystem in Guatemala

“…In addition to Guatemala and Puerto Rico, transmission was detected in northern Colombia. 12 The widespread activity suggests a possible climatologic basis for the virus activity. The assessment of rainfall and temperature factors in Puerto Barrios supported previous findings from temperate locations that WNV transmission is associated with high temperature and low rainfall.…”

“…2,3 Culex mosquitoes and passerine birds appeared to be responsible for WNV amplification in Puerto Rico in 2007. 4,5 By 2007, serologic evidence for WNV circulation in free-ranging birds and/or horses was reported in numerous tropical locations around the rim of the Caribbean Basin, including Mexico, [6][7][8] Guatemala, 9,10 Costa Rica, 11 Colombia, 12 Venezuela, 13 Guadaloupe, 14 Puerto Rico, 15 Dominican Republic, 16,17 Haiti, 18 Jamaica, 19 and Cuba. 15 Ecological parameters of WNV transmission have yet to be clearly defined in tropical ecosystems typical of the Caribbean Basin countries.…”