Zika vector transmission risk in temperate Australia: a vector competence study

Area of Science:

• Medical Entomology
• Virology
• Infectious Diseases

Background:

• Zika virus (ZIKV) is a significant emerging pathogen responsible for recent global outbreaks.
• Australia's temperate climate zone and the potential invasion of Aedes albopictus necessitate an assessment of local mosquito vector competence.

Purpose of the Study:

• To evaluate the susceptibility and transmission capability of five Australian mosquito species against Zika virus.
• To assess the role of Aedes albopictus as a potential invasive vector in Australia.

Main Methods:

• Mosquitoes were orally infected with a Cambodian Zika virus strain via membrane feeding.
• Quantitative PCR (qPCR) was used to assess virus infection and dissemination in mosquito tissues.
• Saliva was tested for Zika virus presence using cell culture (Vero cells) and TCID50 assays.

Main Results:

• Culex species were unable to transmit Zika virus. Aedes aegypti served as a positive control, showing high infection and transmission rates.
• Local Aedes species (Ae. notoscriptus, Ae. camptorhynchus) showed low dissemination despite midgut infection. Ae. albopictus demonstrated efficient vector competence.
• Wolbachia prevalence was high in Cx quinquefasciatus and Australian Ae. albopictus populations.

Conclusions:

• Local Aedes species pose a low risk for widespread Zika epidemics in southern Australia.
• The invasive Ae. albopictus is an efficient vector and represents a significant threat if established in mainland Australia.
• Further studies on temperature's impact on ZIKV replication in mosquitoes are crucial for comprehensive risk assessment.