Seroprevalence of Tularemia in Wild Bears and Hares in Japan

Abstract

Tularemia is a zoonotic disease caused by Francisella tularensis. The distribution of the pathogen in Japan has not been studied well. In this study, seroprevalence of tularemia among wild black bears and hares in Japan was determined. Blood samples collected from 431 Japanese black bears (Ursus thibetanus japonicus) and 293 Japanese hares (Lepus brachurus) between 1998 and 2009 were examined for antibodies against F. tularensis by micro-agglutination test (MA) or enzyme-linked immunosorbent assay. By subsequent confirmatory tests using western blot (WB) and indirect immunofluorescence assay (IFA), eight sera from Japanese black bears were definitely shown to be seropositive. All of these eight bears were residents of the northeastern part of main-island of Japan, where human tularemia had been reported. On the other hand, no seropositive Japanese hares were found. These results suggest that Japanese black bears can serve as sentinel for tularemia surveillance and may help understand the distribution of F. tularensis throughout the country. This is the first report on detection of antibody to F. tularensis in black bears of Japan.

Serosurveillance forFrancisella tularensisAmong Wild Animals in Japan Using a Newly Developed Competitive Enzyme-Linked Immunosorbent Assay

“…The remaining 45 samples were collected in tubes and processed using standard protocols to obtain sera. These 45 sera samples did not show positive agglutination in the MA test (Hotta et al 2012).…”

“…The blood samples from the Japanese black bears (Ursus thibetanus japonicus) and Japanese hares (Lepus brachyurus angustidens) were the same as those used in our previous study (Hotta et al 2012). Sera or plasma samples from 150 Japanese black bears were obtained from six prefectures (Iwate, Fukushima, Ibaraki, Nagano, Gifu, andHyogo) between 2002 and2007, and 21 of these were identified as MA-positive ( ‡ 1:10) in our previous study (Hotta et al 2012).…”

“…However, in Asia, the ecology of tularemia is not well understood because of a paucity of surveillance studies. In Japan, Japanese black bears have been reported as a candidate sentinel species for tularemia (Hotta et al 2012); however, there have been no other studies aiming to elucidate the distribution of F. tularensis among various wild animals.…”

“…Most serosurveillance studies that have been conducted to determine the distribution of F. tularensis in the wild have been based on the detection of serum antibodies (Al Dahouk et al 2005, Hotta et al 2012, Kuehn et al 2013). The microagglutination (MA) test is the most commonly used method for tularemia screening across multiple animal species.…”

“…In the present study, we used this novel cELISA to examine the seroprevalence of tularemia among wild animals in Japan. We tested not only wild hares and bears (Hotta et al 2012) but also rodents, birds, raccoon dogs, monkeys, foxes, and masked palm civets located in an area in which human tularemia is known to be endemic.…”