Why is Zika virus so rarely detected during outbreaks and how can detection be improved?

Diawo Diallo, Mawlouth Diallo

Even during outbreaks, detection of Zika virus (ZIKV; genus Flavivirus, family Flaviviridae) in its mosquito vectors is surprisingly uncommon. Here we explore the reason for this apparent paradox and suggest strategies for improving the efficacy of ZIKV detection. There are several likely explanations for the rarity of ZIKV detection in field-collected mosquitoes during outbreaks, including the lag between the period when people are clinically ill and the initiation of entomological investigations, the prompt spraying of houses of identified cases, the difficulty of identifying some of the households of ZIKV infected cases, and the low efficiency of the sampling methods currently available. Thus, timely entomological investigation of suspected cases before the intervention of the vector control squad would enhance ZIKV detection from mosquitoes. For this to happen, administrative, financial and logistical issues must be solved before the beginning of outbreaks, and routine entomological surveillance must be conducted in foci of ZIKV amplification. Improving ZIKV detection during outbreaks is of paramount importance because identification of the mosquito species and population involved as vector in a given outbreak is a key element to a comprehensive and effective vector control strategy.