Long-term persistence of Chikungunya virus neutralizing antibodies in human populations of North Eastern Thailand.

Background: Chikungunya virus (CHIKV) outbreak recurrences in Thailand are unpredictable and separated by unexplained and often long silent epidemiological periods that can last for several years. These silent periods could be explained in part by the fact that infection with one CHIKV strain confers lasting natural immunity, even against other CHIKV strains. In this study we evaluated the persistence of CHIKV-specific neutralizing antibodies in the population of Chumpae District, Khon Kaen Province, nineteen years after a CHIKV outbreak occurred in the same area in 1991.

Dengue, Japanese encephalitis and Chikungunya virus antibody prevalence among captive monkey (Macaca nemestrina) colonies of Northern Thailand.

The potential of macaque Macaca nemestrina leonina in Thailand to be infected by endemic arboviruses was assessed. The prevalence of antibodies of three arboviruses actively circulating in Thailand was determined by Plaque Reduction Neutralization assay procedures using samples from captive colonies in Northern Thailand. Out of 38 macaques, 9 (24%) presented reacting antibodies against dengue virus, 5 (13%) against Japanese encephalitis virus, and 4 (10%) against Chikungunya virus.

Elevated Japanese encephalitis virus activity monitored by domestic sentinel piglets in Thailand.

Twenty-nine domestic piglets from pig farms located in three provinces of Thailand between 2003 and 2004 were used as sentinel animals for Japanese encephalitis virus (JEV) circulation. Piglets were used as sentinel to underline, on one hand, the role of domestic pigs as JEV amplifying host and, on another hand, to point out the interest of using sentinel animals for Japanese encephalitis surveillance. JEV activity was demonstrated through i/ antibody detection using a specific ELISA test for the identification of Immunoglobulins of class M and G, ii/ virus isolation on cell culture, after experimental mosquito inoculation for virus amplification.