Asymptomatic Plasmodium vivax carriers in Thai and Foreigners living in Tak Province, Thailand

Abstract

Asymptomatic Plasmodium vivax carriers and antibodies specific to P. vivax were studied among Thais and foreigners living in Thasongyang and Maesot districts, Tak province. 449 and 403 blood samples were from Thasongyang and Maesot Districts, respectively. Five from 449 Thasongyand samples were malaria positive. Of these, 3 were positive for P. falciparum and 2 were P. vivax malaria. There was no malaria positive among samples from Maesot. Low parasitaemia asymptomatic carriers were difficult to be detected by microscopy. In this study antibodies against P. vivax were also detected by Enzyme Linked Immunosorbent Assay (ELISA). Serum samples were diluted to 1:100. one hundred and twenty five samples from Thasongyang were positive of which 37 and 88 samples had antibodies to P. vivax and non-P. vivax, respectively. Serum samples from Thasongyang district had significantly (p = 0.001) higher number of positive for P. vivax antibodies than those collected from Maesot district. Serum collected from Maesot district had significantly (p = 0.014) higher number of positive for P. vivax than non-P. vivax antibodies. In contrary, there was no statistically different in the presence of antibodies to P. vivax and non-P. vivax among Thais and foreigners living in Thasongyang and Maesot districts.