Chiggers (Acariformes: Arachnida) a vectors of scrub typhus and its reservoir in northern Thailand

Abstract

          The survey of Chiggers ( Acariformes: Arachnida) was carried out in six upper northern provinces of Thailand, Mae Hong Son, Lumphun, Lunpang, Chiang Rai, Payao and Chiang Mai during January to September 2004 and 2005. The study aims to know the genus of the chiggers, habitat of rodents and its antibody against Rickettsias. Each study sites at least 20 Rodent traps were placed and chigger were isolated from rodent ears. Furthermore rodent and chigger were identified following the given specific keys. Five rodents were collected in 2004 with relatively low in percent trap success of 1.50 and only two species of rodents were collected, Bandicota sarilei (80%) and Bandicota indica (20%). However 26 rodents were trapped with percent trap success had increased to 5.36 in 2005. Of these they were identified as Bandicota indica (39%), Rattus exulans(23%), R. surifer (15%), R. berdmorei (15%), Bandicota savilei ( 4%), Mus caroli (4%) respectively. The habitat of rodent is varies, for example, paddy field, grove, foot hill, forest with slow running stream and under field crop etc. Immuno-Fluorescence Assay of rodent blood found non specific sera with Rickettsia spp. Where as chiggers were identified as genus Heas/ipia sp.and Gahrliepia sp. which is not specific- vector of scrub typhus in Thailand.