Significance of vertical transmission of arboviruses in mosquito-borne disease epidemiology.

Mosquito-borne diseases (MBDs) are increasingly prevalent due to the resultant impact of global change with significant health and economic impacts worldwide. Dengue virus (DENV), chikungunya virus (CHIKV), Zika virus (ZIKV), yellow fever virus (YFV), Japanese encephalitis (JEV), and West Nile virus (WNV) transmitted by Aedes and Culex species have been identified as arboviruses of public health interest. The vertical transmission (VT) refers to the process where infected mosquitoes transmit viruses to their offspring; this has been often overlooked in MBD epidemiology. We conducted a systematic review to evaluate the role of VT in the occurrence, prevalence, and spread of MBDs, focusing on study types, mosquito species, and virus genera. In total, 73 studies from 2005 to 2024 relating to VT in the mosquito population were reviewed. Findings revealed the occurrence of VT across multiple mosquito species in natural and experimental settings, with significant variation in VT rates depending on vector species, virus genus, and study location. Aedes aegypti, Aedes albopictus, Aedes vexans, Culex pipiens, Culex tarsalis, and Culex quinquefasciatus were identified as mosquito species that support VT, while pathogens identified to be transmitted vertically were DENV, ZIKV, WNV, CHIKV, YFV, Sindbis virus (SINV), Ross River virus (RRV), and Mayaro virus (MAYV). VT rates were reported as minimum, and infection rate (MIR) varied across species, study type and location. Also, a high VT rate may precede a mosquito-borne disease outbreak. These findings indicate that VT, though often overlooked, contributes to the dynamics of MBD transmission and could influence disease outbreaks and endemism, especially under changing climatic conditions, highlighting the need for incorporating VT in mathematical models, experimental studies, and control strategies to understand dynamics of MBDs, given its potential role in sustaining arbovirus transmission and influencing outbreak dynamics.