Prevalence of Antibodies to Japanese Encephalitis Virus among Inhabitants in Java Island, Indonesia, with a Small Pig Population

Eiji Konishi*, Yohei Sakai, Yoko Kitai, AND Atsushi Yamanaka

Department of International Health, Kobe University Graduate School of Health Sciences, Kobe, Japan; Department of Microbiology and Infectious Diseases, Kobe University Graduate School of Medicine, Kobe, Japan; International Center for Medical Research and Treatment, Kobe University School of Medicine, Kobe, Japan; Indonesia-Japan Collaborative Research Center for Emerging and Re-emerging Infectious Diseases, Institute of Tropical Disease, Airlangga University, Surabaya, Indonesia

Japanese encephalitis virus (JEV) is maintained through a transmission cycle between amplifier swine and vector mosquitoes in a peridomestic environment. Thus, studies on natural JEV activities in an environment with a small size of pig population have been limited. Here, we surveyed antibodies against JEV in inhabitants of Jakarta and Surabaya located in Java Island (Indonesia), which has a small swine population. Overall, 2.2% of 1,211 sera collected in Jakarta and 1.8% of 1,751 sera collected in Surabaya had neutralizing antibody titers of 1:160 (90% plaque reduction). All the samples with titers of 1:160 against JEV were also examined for neutralizing antibodies against each of four dengue viruses to confirm that JEV antibody prevalences obtained in the present survey were not attributable to serologic cross-reactivities among flaviviruses distributed in Java. These results indicated that people in Java Island are exposed to natural JEV infections despite a small swine population.
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Received May 19, 2008. Accepted for publication February 2, 2009.
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Acknowledgments: We thank Dr. Pudjiatmoko of the Indonesian Embassy in Tokyo, Japan and Mr. Kris Cahyo Mulyatno of Institute of Tropical Disease, Airlangga University, Indonesia for their assistance in collecting information about sizes of human and pig populations in Indonesia.
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Financial support: This work was supported in part by a grant-in-aid through the Program of Founding Research Centers for Emerging and Reemerging Infectious Diseases, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, and through Research on Emerging and Re-emerging Infectious Diseases, the Ministry of Health and Welfare of Japan.
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* Address correspondence to Eiji Konishi, Department of International Health, Kobe University Graduate School of Health Sciences, 7-10-2, Tomogaoka, Suma-ku, Kobe 654-0412, Japan. E-mail: ekon@kobe-u.ac.jp
Authors’ addresses: Eiji Konishi, Yohei Sakai, and Yoko Kitai, Department of International Health, Kobe University Graduate School of Health Sciences, 7-10-2, Tomogaoka, Suma-ku, Kobe 654-0412, Japan, Tel/Fax: 81-78-796-4594, E-mails: ekon@kobe-u.ac.jp, sakatom2002@yahoo.co.jp, and sunbaby_spring5nw9@yahoo.co.jp. Atsushi Yamanaka, Indonesia-Japan Collaborative Research Center for Emerging and Re-emerging Infectious Diseases, Institute of Tropical Disease, Airlangga University, Kampus C, UNAIR, Jl. Mulyorejo, Surabaya 60115, Indonesia, Tel/Fax: 62-31-599-2445, E-mail: paradios99@yahoo.co.jp.

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Source:

Am. J. Trop. Med. Hyg., 80(5), 2009, pp. 856-861