Vector Competence of Aedes aegypti Populations from Entebbe, Uganda, for Zika Virus

We evaluated the vector competence of three strains of Aedes aegypti formosus from Entebbe, Uganda, for Zika virus (ZIKV). The aim was to find out if these strains were competent or incompetent vectors for ZIKV, to explain the lack of ZIKV outbreaks in the city of Entebbe. We observed transmission rates ranging from 33% to 78%; however, these rates were not statistically significantly different, suggesting that there were no real differences among the strains. Nonetheless, this showed that populations of Ae. aegypti formosus in Entebbe are competent vectors for ZIKV. The reason why there is no detectable transmission of ZIKV to humans in Entebbe is currently unknown. The lack of detectable transmission despite Ae. aegypti formosus competence for ZIKV suggests that other parameters, such as preference for nonhuman blood, may be limiting its ability to serve as a vector.