West Nile seroprevalence study in Bolivian horses, 2011.

The research article discusses a study conducted in Bolivia in 2011, where horse sera were examined to check for antibodies against the West Nile Virus (WNV). The results showed a high percentage of positive responses, indicating that WNV was circulating among the horse populations in Bolivia.

Study Design and Methodology

• The study was a seroepidemiological one, meaning it related to the patterns, causes, and effects of health and disease conditions in defined equine populations.
• Samples of horse serum were collected from various regions across Bolivia.
• These samples were analysed using a commercially available WNV competitive enzyme-linked immunosorbent assay (C-ELISA), a common tool for detecting antibodies in serum.
• Of the C-ELISA-positive sera, 66 were additionally evaluated using the WNV plaque reduction neutralization test (PRNT), virus neutralization (VN), and an immunoglobulin M (IgM)-WNV ELISA.
• The aim of these further tests was to eliminate false-positive results, and to examine whether the horses had recently been infected with WNV.

Findings

• 59.4% of the sera tested had a positive response to the WNV C-ELISA.
• However, no WNV IgM was found in the 66 C-ELISA-positive samples that underwent additional testing.
• Neutralizing antibodies were discovered in 21 and 18 samples by the PRNT and VN tests, respectively. These proteins, produced by the immune system, can neutralize the biological effect of the virus.

Conclusions

• The researchers concluded that a significant proportion of the Bolivian horses in the study showed serological reactions to viruses in the Japanese encephalitis antigenic complex (JEAC), which included the WNV.
• WNV, accounted for 31.8% of these reactions, indicating that the virus was in circulation among the horse populations in Bolivia at the time of the study.