LEPTOSPIRA SPP. SEROPREVALENCE OF CO-INFECTION WITH OPISTHORCHIS VIVERRINI INFECTION IN NORTHEAST, THAILAND

Leptospirosis caused by Leptospira species bacteria is an emerging infectious zoonotic disease with high morbidity and mortality in both tropical and subtropical regions. In Thailand, leptospirosis is endemic in the Northeastern region, where carcinogenic liver fluke, Opisthorchis viverrini (Ov), infection is also highly endemic. Here, we report the effects of Ov infection on seroprevalence of Leptospira infection at the community level. Sera were collected from asymptomatic Ov-positive and negative people from Khon Kaen and Kalasin Provinces in Northeast Thailand. Anti-Leptospira IgM antibody detection using immunochromatography test (ICT) kits showed overall seropositivity against L. interrogans of 265 ( 59.2%) out of 448 samples. Leptospira seroprevalence rate in the Ov-positive group was comparable with that in the Ov-negative group without a statistical difference, although the Leptospira seropositive rate of males was significantly higher than that of females. When 265 ICT- kit seropositive samples were examined for serovars using the Microscopic Agglutination Test (MAT), 24 sera were MAT -positive and 31 serovars were identified due to multiple serovar infection in some individuals. Among 2 MAT- positive sera, 18 were in the Ov-positive group and 6 were Ov-negative group. The most predominant serovar in this study was Australis (32%) followed by Shermani (26%), Cynopteri (23%) while the detection rates of other serovars, Icterohaemorrhagiae, Autumnalis, Grippotyposa, and Pomona, were <10%. Among 31 serovars detected, 23 were in the Ov-positive group and 8 were in the Ov-negative group. These results indicate that Ov infection might modulate the susceptibility/immunoreactivity of humans to different serovars of Leptospira.