Risk factors for Japanese encephalitis: a case-control study

Abstract

Japanese encephalitis (JE) has been found to be endemic in Bali, Indonesia. A case-control study was conducted to identify factors associated with JE infection. All 94 serologically confirmed JE cases (cases) and 163 cases of encephalitis or aseptic meningitis without JE (controls) identified in Bali during 2001-2004 were included in the study. Potential risk factors were surveyed at hospital admission. Univariate analyses revealed the following factors to be associated with JE: older age, referral from sub-district health centre or private hospital, playing outdoors after dinner, use of mosquito repellent or spraying, proximity of the residence to rice fields, and pig ownership by the family or next-door neighbours. Multivariate analysis identified proximity to rice fields (OR 2.93, 95% CI 1.57-5.45), pig ownership (OR 2.24, 95% CI 1.17-4.26), and older age (OR 1.21, 95% CI 1.09-1.33) as being independently associated with the risk of JE. Because rice cultivation and pig rearing are essential to the economy of Bali, JE immunization is the best intervention for prevention of JE in Bali.

Use of Insecticide-Treated Nets Among Pig Owners Living in Japanese Encephalitis Endemic Areas of Northern Myanmar

“…The literature indicated that pigs play a central role in the transmission of both the Japanese encephalitis virus and cysticercosis [18]. Expansion of the JE virusendemic area depends on irrigated rice farming and pig rearing [3]. A higher proportion of rice planting could, therefore, predict a higher risk of JE [19].…”

“…Humans are incidental or dead-end hosts because they usually do not develop a level or duration of viremia sufficient to infect mosquitoes. Culex tritaeniorhynchus, the major mosquito vector, breeds by laying eggs in rice fields, and the pig is considered the most common amplifying host of the JE virus [3]. An estimated 67,900 JE cases typically occur annually, of which only 10% are reported to the World Health Organization [4].…”

“…An estimated 67,900 JE cases typically occur annually, of which only 10% are reported to the World Health Organization [4]. Transmission mainly occurs in rural agricultural areas, often associated with rice cultivation and flood irrigation [2,3,5].…”

Vector Control of Zoonotic Arbovirus Disease in Indonesia

“…Beberapa faktor penentu kejadian penyakit JE di Indonesia karena interaksi induk semang dengan vektor (Liu et al 2010). Penyebaran virus JE sangat tergantung oleh beberapa faktor, antara lain binatang perantara seperti babi, kera, burung dan vektor (nyamuk).…”

“…Berdasarkan laporan hasil surveilans berbasis rumah sakit di enam provinsi pada tahun 2005-2006, disimpulkan bahwa JE telah endemis di Indonesia dengan persentase positif antibodi terhadap JE antara 1,8 hingga 17,9% (Ompusunggu et al 2008). Pulau Bali merupakan salah satu daerah endemis JE, terutama di musim hujan (Kari et al 2006;Liu et al 2010). Kasus JE pada manusia di Indonesia telah ditemukan di 17 provinsi hingga tahun 2006.…”