Factors influencing the abundance of Japanese encephalitis vectors in ricefields in India – I. Abiotic

Sunish, I. P.; Reuben, R

doi:10.1046/j.0269-283x.2001.00324.x

Cited by 74 publications

(45 citation statements)

References 12 publications

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“…In addition, mixed pixels containing water (low NDVI) and vegetation have lower NDVI than pure vegetation pixels containing no water or mosquito habitat. Finally, previous studies have shown initial planting and tillering rice stages to have the highest immature abundance and decreasing larval abundance with increasing rice height (Mutero et al, 2000;Sunish and Ruben, 2001;Jacob et al, 2007). Increased rice height is thought to decrease larval abundance by blocking oviposition and reducing the temperature of the water by blocking sunlight.…”

Section: Discussionmentioning

confidence: 99%

Modeling the distribution of Culex tritaeniorhynchus to predict Japanese encephalitis distribution in the Republic of Korea

et al. 2010

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Abstract. Over 35,000 cases of Japanese encephalitis (JE) are reported worldwide each year. Culex tritaeniorhynchus is the primary vector of the JE virus, while wading birds are natural reservoirs and swine amplifying hosts. As part of a JE risk analysis, the ecological niche modeling programme, Maxent, was used to develop a predictive model for the distribution of Cx. tritaeniorhynchus in the Republic of Korea, using mosquito collection data, temperature, precipitation, elevation, land cover and the normalized difference vegetation index (NDVI). The resulting probability maps from the model were consistent with the known environmental limitations of the mosquito with low probabilities predicted for forest covered mountains. July minimum temperature and land cover were the most important variables in the model. Elevation, summer NDVI (July-September), precipitation in July, summer minimum temperature (May-August) and maximum temperature for fall and winter months also contributed to the model. Comparison of the Cx. tritaeniorhynchus model to the distribution of JE cases in the Republic of Korea from 2001 to 2009 showed that cases among a highly vaccinated Korean population were located in high-probability areas for Cx. tritaeniorhynchus. No recent JE cases were reported from the eastern coastline, where higher probabilities of mosquitoes were predicted, but where only small numbers of pigs are raised. The geographical distribution of reported JE cases corresponded closely with the predicted high-probability areas for Cx. tritaeniorhynchus, making the map a useful tool for health risk analysis that could be used for planning preventive public health measures.

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Section: Discussionmentioning

confidence: 99%

Modeling the distribution of Culex tritaeniorhynchus to predict Japanese encephalitis distribution in the Republic of Korea

et al. 2010

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“…Japanese encephalitis Transmission cycle of Japanese encephalitis (JE) is confined to rice field prone areas (Sunish and Reuben 2001) (Fig. 3) and involves pigs and birds as amplifier hosts.…”

Section: The Logic Of Impact Of Global Warming On Vbdsmentioning

confidence: 99%

Climate change and threat of vector-borne diseases in India: are we prepared?

Dhiman

Pahwa

Dhillon³

et al. 2010

Parasitol Res

141

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It is unequivocal that climate change is happening and is likely to expand the geographical distribution of several vector-borne diseases, including malaria and dengue etc. to higher altitudes and latitudes. India is endemic for six major vector-borne diseases (VBD) namely malaria, dengue, chikungunya, filariasis, Japanese encephalitis and visceral leishmaniasis. Over the years, there has been reduction in the incidence of almost all the diseases except chikungunya which has re-emerged since 2005. The upcoming issue of climate change has surfaced as a new threat and challenge for ongoing efforts to contain vector-borne diseases. There is greater awareness about the potential impacts of climate change on VBDs in India and research institutions and national authorities have initiated actions to assess the impacts. Studies undertaken in India on malaria in the context of climate change impact reveal that transmission windows in Punjab, Haryana, Jammu and Kashmir and north-eastern states are likely to extend temporally by 2-3 months and in Orissa, Andhra Pradesh and Tamil Nadu there may be reduction in transmission windows. Using PRECIS model (driven by HadRM2) at the resolution of 50 x 50 Km for daily temperature and relative humidity for year 2050, it was found that Orissa, West Bengal and southern parts of Assam will still remain malarious and transmission windows will open up in Himachal Pradesh and north-eastern states etc. Impact of climate change on dengue also reveals increase in transmission with 2 C rise in temperature in northern India. Re-emergence of kala-azar in northern parts of India and reappearance of chikungunya mainly in southern states of India has also been discussed. The possible need to address the threat and efforts made in India have also been highlighted. The paper concludes with a positive lead that with better preparedness threat of climate change on vector-borne diseases may be negated.

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“…JEV has a complex life cycle involving domestic pigs and specific type of mosquito, i.e., C. tritaeniorhynchus, which lives in rural rice-growing and pig-farming regions. Transmission cycle of JE is confined to rice field prone areas (Sunish and Reuben 2001) and involves pigs and birds as amplifier hosts. The adult mosquitoes are active at night, with peak of activities 1 h after dark.…”

Section: Introductionmentioning

confidence: 99%

Larvicidal, repellent, and ovicidal activity of marine actinobacteria extracts against Culex tritaeniorhynchus and Culex gelidus

et al. 2010

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The purpose of the present study was to assess the effect of crude extracts of marine actinobacteria on larvicidal, repellent, and ovicidal activities against Culex tritaeniorhynchus and Culex gelidus (Diptera: Culicidae). The early fourth instar larvae of C. tritaeniorhynchus and C. gelidus, reared in the laboratory, were used for larvicidal, ovicidal, and repellent assay with crude extracts of actinobacteria. Saccharomonospora spp. (LK-1), Streptomyces roseiscleroticus (LK-2), and Streptomyces gedanensis (LK-3) were identified as potential biocide producers. Based on the antimicrobial activity, three strains were chosen for larvicidal activity. The marine actinobacterial extracts showed moderate to high larvicidal effects after 24 h of exposure at 1,000 ppm and the highest larval mortality was found in extract of LK-3 (LC(50) = 108.08 ppm and LC(90) = 609.15 ppm) against the larvae of C. gelidus and (LC(50) = 146.24 ppm and LC(90) = 762.69 ppm) against the larvae of C. tritaeniorhynchus. Complete protections for 240 min were found in crude extract of LK-2 and LK-3 at 1,000 ppm, against mosquito bites of C. tritaeniorhynchus and C. gelidus, respectively. After 24-h treatment, mean percent hatchability of the ovicidal activity was observed. The percent hatchability was inversely proportional to the concentration of extract and directly proportional to the eggs. Crude extracts of LK-1 and LK-3 showed no hatchability at 1,000 ppm against C. tritaeniorhynchus and C. gelidus, respectively. This is an ideal ecofriendly approach for the control of Japanese encephalitis vectors, C. tritaeniorhynchus and C. gelidus.

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Factors influencing the abundance of Japanese encephalitis vectors in ricefields in India – I. Abiotic

Cited by 74 publications

References 12 publications

Modeling the distribution of Culex tritaeniorhynchus to predict Japanese encephalitis distribution in the Republic of Korea

Modeling the distribution of Culex tritaeniorhynchus to predict Japanese encephalitis distribution in the Republic of Korea

Climate change and threat of vector-borne diseases in India: are we prepared?

Larvicidal, repellent, and ovicidal activity of marine actinobacteria extracts against Culex tritaeniorhynchus and Culex gelidus

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