Dogs as Sentinels for Human Infection with JEV | CDC EID

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Volume 16, Number 7–July 2010
Dispatch
Dogs as Sentinels for Human Infection with Japanese Encephalitis Virus
Hiroshi Shimoda, Yoshito Ohno, Masami Mochizuki, Hiroyuki Iwata, Masaru Okuda, and Ken Maeda
Author affiliations: Yamaguchi University, Yoshida, Yamaguchi, Japan (H. Shimoda, Y. Ohno, H. Iwata, M. Okuda, K. Maeda); and Kyoritsu Seiyaku Corporation, Kudankita, Chiyoda-ku, Tokyo, Japan (M. Mochizuki)

Suggested citation for this article

Abstract
Because serosurveys of Japanese encephalitis virus (JEV) among wild animals and pigs may not accurately reflect risk for humans in urban/residential areas, we examined seroprevalence among dogs and cats. We found that JEV-infected mosquitoes have spread throughout Japan and that dogs, but not cats, might be good sentinels for monitoring JEV infection in urban/residential areas.
Japanese encephalitis virus (JEV), a common cause of serious acute encephalitis in humans, is primarily transmitted by Culex tritaeniorhynchus mosquitoes and is widely endemic to Southeast Asia and the Western Pacific region (1). Annual incidence of Japanese encephalitis (JE) is ≈50,000 cases,with 10,000 deaths (2). In Japan during the 1950s, several thousand JE cases occurred each year. However, as a result of a JEV vaccination program, isolation of pig farms, and reduction of mosquitoes, the number of JE cases in Japan has decreased markedly, to <10 cases per year since 1992 (3). In 2005, the strong recommendation for JE vaccination was halted because of a severe vaccine-associated side effect in 1 person; however, since 2009, a newly developed JE vaccine has been available and vaccination has been resumed.

Annual serosurveys for JEV antibodies in pigs, the main amplifiers of JEV, tend to show high seropositivity in western Japan (3). Our previous study of JEV in wild animals in the Kinki district also showed high seroprevalence: 83% among wild boars and 59% among raccoons (4). These data indicate that JEV remains endemic to Japan.

However, serosurveys of wild animals and pigs may not accurately reflect risk for humans because these animals remain separate from human populations and thus may not indicate the prevalence of JEV in urban/residential areas of Japan. Therefore, additional monitoring of the risk for JEV infection in humans in these areas, in addition to annual surveillance of pigs, is needed. To determine seroprevalence in family-owned dogs and cats, which share living space with humans, we conducted serosurveys of JEV in these species.

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Suggested Citation for this Article
Shimoda H, Ohno Y, Mochizuki M, Iwata H, Okuda M, Maeda K. Dogs as sentinels for human infection with Japanese encephalitis virus. Emerg Infect Dis [serial on the Internet]. 2010 Jul [date cited]. http://www.cdc.gov/EID/content/16/7/1137.htm

DOI: 10.3201/eid1607.091757