Epidemiological Studies on Japanese Encephalitis in Kyoto City Area, Japan I. Evidence for Decrease of Vector Mosquitoes

Maeda, Osamu; Takenokuma, Kunihachi; Karoji, Yoshiaki; Matsuyama, Yukichi

doi:10.7883/yoken1952.31.27

Cited by 12 publications

(5 citation statements)

References 4 publications

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“…Cx. tritaeniorhynchus is highly susceptible to viral infection; studies suggest that over 30% become infected after feeding on a viremic pig [20]. Mosquito populations are dependent on environmental and seasonal factors for their propagation.…”

Section: Introductionmentioning

confidence: 99%

The relationship between mosquito abundance and rice field density in the Republic of Korea

et al. 2010

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BackgroundJapanese encephalitis virus (JEV), the causative agent of Japanese encephalitis (JE), is endemic to the Republic of Korea (ROK) where unvaccinated United States (U.S.) military Service members, civilians and family members are stationed. The primary vector of the JEV in the ROK is Culex tritaeniorhynchus. The ecological relationship between Culex spp. and rice fields has been studied extensively; rice fields have been shown to increase the prevalence of Cx. tritaeniorhynchus. This research was conducted to determine if the quantification of rice field land cover surrounding U.S. military installations in the ROK should be used as a parameter in a larger risk model that predicts the abundance of Cx. tritaeniorhynchus populations.Mosquito data from the U.S. Forces Korea (USFK) mosquito surveillance program were used in this project. The average number of female Cx. tritaeniorhynchus collected per trap night for the months of August and September, 2002-2008, was calculated. Rice fields were manually digitized inside 1.5 km buffer zones surrounding U.S. military installations on high-resolution satellite images, and the proportion of rice fields was calculated for each buffer zone.ResultsMosquito data collected from seventeen sample sites were analyzed for an association with the proportion of rice field land cover. Results demonstrated that the linear relationship between the proportion of rice fields and mosquito abundance was statistically significant (R2 = 0.62, r = .79, F = 22.72, p < 0.001).ConclusionsThe analysis presented shows a statistically significant linear relationship between the two parameters, proportion of rice field land cover and log10 of the average number of Cx. tritaeniorhynchus collected per trap night. The findings confirm that agricultural land cover should be included in future studies to develop JE risk prediction models for non-indigenous personnel living at military installations in the ROK.

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Section: Introductionmentioning

confidence: 99%

The relationship between mosquito abundance and rice field density in the Republic of Korea

et al. 2010

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“…The population obtained from the model without diapause re‐increased rapidly in autumn, i.e., when the temperature became cooler, allowing the population to grow after its decrease during the high summer temperature (Figure a). However, in nature, the population decrease is observed in temperate regions [ Maeda et al ., ; Tsuda and Hayashi , ]. By incorporating the effect of diapause into the model, the population increase during autumn is suppressed because some active adults shift to the diapause state, and thus, the model output becomes consistent with the population trends observed in the field (Figure ).…”

Section: Discussionmentioning

confidence: 83%

“…GeoHealth 10.1002/2017GH000054 summer temperature (Figure 3a). However, in nature, the population decrease is observed in temperate regions [Maeda et al, 1978;Tsuda and Hayashi, 2014]. By incorporating the effect of diapause into the model, the population increase during autumn is suppressed because some active adults shift to the diapause state, and thus, the model output becomes consistent with the population trends observed in the field (Figure 2).…”

Section: 1002/2017gh000054mentioning

confidence: 78%

Population of the temperate mosquito, Culex pipiens, decreases in response to habitat climatological changes in future

2017

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Predictions of the temporal distribution of vector mosquitoes are an important issue for human health because the response of mosquito populations to climate change could have implications for the risk of vector‐borne diseases. To elucidate the effects of climate change on mosquito populations inhabiting temperate regions, we developed a Physiology‐based Climate‐driven Mosquito Population model for temperate regions. For accurately reproducing the temporal patterns observed in mosquito populations, the key factors were identified by implementing the combinations of factors into the model. We focused on three factors: the effect of diapause, the positive effect of rainfall on larval carrying capacity, and the negative effect of rainfall as the washout mortality on aquatic stages. For each model, parameters were calibrated using weekly observation data of a Culex pipiens adult population collected in Tokyo, Japan. Based on its likelihood value, the model incorporating diapause, constant carrying capacity, and washout mortality was the best to replicate the observed data. By using the selected model and applying global climate model data, our results indicated that the mosquito population would decrease and adults’ active season would be shortened under future climate conditions. We found that incorporating the washout effect in the model settings or not caused a difference in the temporal patterns in the projected mosquito populations. This suggested that water resources in mosquito habitats in temperate regions should be considered for predicting the risk of vector‐borne diseases in such regions.

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“…(1) Improvement in sanitation and changes in methods of rice farming have led to a decline in vectors [3] .…”

Section: Discussionmentioning

confidence: 99%

Japanese Encephalitis in a 7‐Month‐Old Japanese Boy

Tamada

Kasai

Hara

et al. 1990

Pediatrics International

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A 7‐month‐old Japanese boy was diagnosed as having meningo‐encephalitis with anterior horn cell damage. The complement fixation (CF) and hemagglutination inhibition (HI) tests showed increased antibody titers against Japanese encephalitis (JE) virus, but HI antibody in the mother's serum was not increased. It appears that the lack of JE‐antibodies from the mother may have resulted in increased JE viral infectivity in the patient. A decrease in the incidence of antibodies against various viruses in women of childbearing age may lead to increased rates of severe viral infection in infants.

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Epidemiological Studies on Japanese Encephalitis in Kyoto City Area, Japan I. Evidence for Decrease of Vector Mosquitoes

Cited by 12 publications

References 4 publications

The relationship between mosquito abundance and rice field density in the Republic of Korea

The relationship between mosquito abundance and rice field density in the Republic of Korea

Population of the temperate mosquito, Culex pipiens, decreases in response to habitat climatological changes in future

Japanese Encephalitis in a 7‐Month‐Old Japanese Boy

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