Increased Adult Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae) Abundance in a Dengue Transmission Hotspot, Compared to a Coldspot, within Kaohsiung City, Taiwan

Abstract

The assumption that vector abundance differences might drive spatial and temporal heterogeneities in vector-borne disease transmission is common, though data supporting it is scarce. Here, we present data from two common mosquito species Aedes aegypti (Linnaeus) and Culex quinquefasciatus Say, biweekly sampled as adults, from March 2016 through December 2017, with BG-sentinel traps in two neighboring districts of Kaohsiung City (KC), Taiwan. One district has historically been a dengue transmission hotspot (Sanmin), and the other a coldspot (Nanzih). We collected a total 41,027 mosquitoes, and we found that average mosquito abundance (mean ± S.D.) was higher in Sanmin (Ae. aegypti: 9.03 ± 1.46; Cx. quinquefasciatus: 142.57 ± 14.38) than Nanzih (Ae. aegypti: 6.21 ± 0.47; Cx. quinquefasciatus: 63.37 ± 8.71) during the study period. In both districts, Ae. aegypti and Cx. quinquefasciatus population dynamics were sensitive to changes in temperature, the most platykurtic environmental variable at KC during the study period, a pattern predicted by Schmalhausen’s law, which states that organisms are more sensitive to small changes in environmental variables whose average value is more uncertain than its extremes. Our results also suggest that differences in Ae. aegypti abundance might be responsible for spatial differences in dengue transmission at KC. Our comparative approach, where we also observed a significant increment in the abundance of Cx. quinquefasciatus in the dengue transmission hotspot, suggests this area might be more likely to experience outbreaks of other vector borne diseases and should become a primary focus for vector surveillance and control.

Impact of Climate Variability and Abundance of Mosquitoes on Dengue Transmission in Central Vietnam

“…In countries where dengue is endemic, mosquito activity was monitored for vector control interventions and to evaluate the effectiveness of control methods. Studies conducted in Taiwan indicated that mosquito abundance was a predictor of the dengue transmission risk [67] and that mosquito indices and climatic variables were early warning factors [68]. Herein, we found a positive association between container index and dengue transmission, suggesting that the mosquito population plays an important role in dengue fever transmission in central Vietnam.…”

The effect of resource limitation on the temperature-dependence of mosquito population fitness

“…The global public health burden of some vector-borne diseases has increased substantially in recent decades [1, 2]. The geographical distribution and abundance of vectors is strongly linked to transmission patterns of these diseases [3, 4]. There is growing concern that climate and land-use change, coupled with rapid globalization, may result in shifts in both the distributions of vector species and the diseases they transmit [5].…”

Real-time dengue forecast for outbreak alerts in Southern Taiwan

“…Kaohsiung was selected as the study area due to an abnormally increased incidence of dengue fever in 2014 and 2015 including 15,008 cases in Kaohsiung in 2014 and 19,710 cases in Kaohsiung in 2015. This is significantly higher than baseline, which encompassed approximately 300–2,000 cases annually in the preceding years, 2005–2013 [ 14 , 21 – 25 ].…”

“…The relationship between temperature and mosquito activity has been reported in many published papers [ 21 , 25 , 27 – 30 ], motivating us to establish the mosquito biting rate function. The biting rate (BR) is a function of temperature and is used instead of temperature to explore the relationship with dengue case number.…”