Longitudinal Studies of Japanese Encephalitis Virus Infection in Vector Mosquitoes in Kurnool District, Andhra Pradesh, South India

Abstract

A 4-yr (2002-2006) entomological study was carried out in Kurnool district, Andhra Pradesh state, south India, to identify the mosquito vectors of Japanese encephalitis virus (family Flaviviridae, genus Flavivirus, JEV). In total, 37,139 female mosquitoes belonging five genera and 18 species resting on vegetation were collected in villages and periurban areas at dusk. Mosquito species composition and pattern of JEV infection in mosquitoes varied in periurban and rural areas. In periurban area, Culex gelidus Theobald was abundant, making up 49.7% of total catch followed by Culex tritaeniorhynchus Giles (44.5%). In rural area, Cx. tritaeniorhynchus was predominant, making up 78.9% of total catch followed by Culex quinquefasciatus Say (10.8%), Anopheles subpictus Grassi (7.1%), and Cx. gelidus (1.1%). In light trap collections, Cx. gelidus and Cx. tritaeniorhynchus predominated in periurban and rural areas, respectively. Of 50,145 mosquitoes screened JEV isolations were made only from Cx. gelidus and Cx. tritaeniorhynchus. Based on high abundance and frequent JEV isolation, Cx. tritaeniorhynchus was found to be the principal vector in both areas, whereas Cx. gelidus plays a secondary vector role in periurban areas only.

Emerging infectious diseases

“…However, in both Sri Lanka, and India this pattern appears to have changed with the disease now spreading to rural areas as well 25 . Although vector densities are generally much higher in urban areas when compared to rural areas, vector densities in rural areas are now seen to be quite high 10,26 . Therefore, the potential 'threat' of major dengue outbreaks in rural areas is present.…”

“…The rise in the incidence of dengue infections in the rural areas further adds to this threat 9,10 . Therefore, unless vector densities are reduced, dengue infections may overtake other infectious diseases as the number one killer in many countries in South Asia.…”

Prevalence of japanese encephalitis and its modulation by weather variables

“…The blood samples were collected from the school children (6 to 10 years old) through finger prick method. The sera of school children were examined by haemagglutination inhibition (HI) test following protocol of Clarke and Casals (Arunachalam et al, 2009) for identifying the flavivirus antibodies (JE/West Nile/Dengue).…”

“…Mosquitoes were sampled from identified villages at bimonthly Mutheneni et al 53 intervals during 2001 to 2006 and identified to species level (Arunachalam et al, 2009 …”

“…Subsequently, JE epidemic have been reported in as many as 25 states/union territories of India (Kabilan et al, 2004). Recently in Uttar Pradesh, Bihar, and Andhra Pradesh, JE has emerged as a perennial public health problem (Arunachalam et al, 2009). An epidemic of JEV was reported in 2005 in Gorakhpur, Uttar Pradesh, India.…”