Analysis on Dengue Vector Density Survey in Kaohsiung and Pingtung Areas of Southern Taiwan, 2004-2008

Yen-Chang Tuan

2009 Vol.25 NO.7

Correspondence Author： Yen-Chang Tuan

Abstract：

This study collected the dengue mosquito survey data obtained in 1346 villages of 71 townships/districts/cities in Kaohsiung and Pingtung areas during 2004-2008 and performed the analysis of correlation between the weekly occurred dengue cases and various vector indexes, as well as other analysis relevant to mosquito breeding source.
Based on the surveys conducted during the last five years, the A. aegypti was not found only in Maulin Township in Kaohsiung City and County and in 15% of townships/cities in Pingtung County but A. albopictus was found in all villages in Kaohsiung and Pingtung areas. Although the geographical distribution of A. albopictus was wider than that of A. aegypti in Kaohsiung and Pingtung areas, the distribution of A. aegypti in densely populated Kaohsiung City was wider than that of A. albopictus. Moreover, the number of villages where only A. aegypti was found in Kaohsiung City appeared to be an increasing trend, which was not found in Kaohsiung and Pingtung Counties. The item of others, such as drainage ditch, water tower, and canvas for shelter use, unclassified type of breeding source, represented the largest part of mosquito breeding source, and, then, in the descending order, water bucket, follower vase, plant saucer, pottery pot, discarded tire, polystyrene box and plate, plastic basket, empty can, cup, refrigerator saucer, and flooded basement. The fact that the unclassified mosquito breeding source reached as high as 33% suggests the necessity of redefining the classification for the type of breeding source. A correlation between Adult A. aegypti Index and annual dengue incidence was identified in all villages of Kaohsiung and Pingtung areas in the recent five years, and their correlation coefficients were higher than those between Adult A. albopictus Index and dengue incidence. In addition, a correlation was also identified between the weekly occurred dengue cases and Adult A. aegypti Index, but no correlation was found between dengue cases and Adult A. albopictus Index. Analysis of the performance among governments of Kaohsiung and Pingtung County (City) on density survey revealed that Kaohsiung City has completed the largest number of villages, 42,497; Pingtung County has completed the highest number of households, 3,067,830; Pingtung County has identified the largest number of water-holding containers, 2,835,610; and Pingtung County has removed the largest number of breeding containers, 162,828. In addition, the highest ratio, 4:6, of water-holding containers found indoor versus outdoor occurred in Kaohsiung City, and the ratio of breeding containers found indoor versus outdoor fell between 1:9 and 2:8 in Kaohsiung and Pingtung areas.
Keywords: dengue fever, Aedes aegypti, Aedes albopictus, mosquito breeding source, geographical mosquito distribution