Date Published: February 6, 2015
Publisher: Public Library of Science
Author(s): B. Katherine Poole-Smith, Ryan R. Hemme, Mark Delorey, Gilberto Felix, Andrea L. Gonzalez, Manuel Amador, Elizabeth A. Hunsperger, Roberto Barrera, Michael J Turell. http://doi.org/10.1371/journal.pntd.0003462
Abstract: BackgroundAedes mediovittatus mosquitoes are found throughout the Greater Antilles in the Caribbean and often share the same larval habitats with Ae. Aegypti, the primary vector for dengue virus (DENV). Implementation of vector control measures to control dengue that specifically target Ae. Aegypti may not control DENV transmission in Puerto Rico (PR). Even if Ae. Aegypti is eliminated or DENV refractory mosquitoes are released, DENV transmission may not cease when other competent mosquito species like Ae. Mediovittatus are present. To compare vector competence of Ae. Mediovittatus and Ae. Aegypti mosquitoes, we studied relative infection and transmission rates for all four DENV serotypes.MethodsTo compare the vector competence of Ae. Mediovittatus and Ae. Aegypti, mosquitoes were exposed to DENV 1–4 per os at viral titers of 5–6 logs plaque-forming unit (pfu) equivalents. At 14 days post infectious bloodmeal, viral RNA was extracted and tested by qRT-PCR to determine infection and transmission rates. Infection and transmission rates were analyzed with a generalized linear model assuming a binomial distribution.ResultsAe. Aegypti had significantly higher DENV-4 infection and transmission rates than Ae. mediovittatus.ConclusionsThis study determined that Ae. Mediovittatus is a competent DENV vector. Therefore dengue prevention programs in PR and the Caribbean should consider both Ae. Mediovittatus and Ae. Aegypti mosquitoes in their vector control programs.
Partial Text: Dengue virus (DENV, Family Flaviridae, Genus Flavivirus) is most commonly transmitted to humans by the bite of an infected Aedes aegypti mosquito. Worldwide, Ae. aegypti and Aedes albopictus are the main vectors for DENV transmission, however Ae.albopictus has not been found in Puerto Rico (PR). The most common container Aedes mosquito species in PR are Ae. aegypti and the Caribbean treehole mosquito, Aedes mediovittatus. Ae. mediovittatus mosquitoes inhabit both natural water-holding containers in cooler, shady forested areas and artificial containers in low density housing and rural areas while Ae. aegypti mosquitoes are more abundant in areas of high density urban housing [1–3]. Despite the apparent habitat differences between the two mosquito species, vector control personnel in Cuba reported Ae. mediovittatus larvae exploiting the same artificial aquatic habitats normally occupied by Ae. aegypti mosquitoes after an intensive Ae. aegypti elimination campaign . Since Ae. mediovittatus mosquitoes inhabit peridomestic containers and feed on potentially DENV-infected humans, they may be potential secondary DENV vectors in PR and the Caribbean .
This study concluded that Ae. mediovittatus mosquitoes are equally competent vectors for DENV-1, DENV-2, and DENV-3 when compared to Ae. aegypti . However, Ae. aegypti mosquitoes were more susceptible to DENV-4 infection than Ae. mediovittatus. This is the first study that compared the competence of Ae. mediovittatus and Ae. aegypti mosquitoes for all four DENV serotypes. A previous study by Gubler et al. also compared both species, however due to differences in methodology including: a higher incubation temperature (30°C) and a different titration method (mosquito infectious dose 50), we cannot directly compare the results between the two studies. Since these are the only studies that have compared locally collected Ae. mediovittatus and Ae. aegypti mosquitoes, we compared the overall conclusions between the two studies; Gubler concluded that Ae. mediovittatus was more susceptible to infection with DENV-1 and DENV-2 than Ae. aegypti . In contrast, the infection rates in our study were not significantly different between mosquito species, except for DENV-4.