West Nile virus host-vector-pathogen interactions in a colonial raptor.

Area of Science:

• Veterinary Entomology
• Arbovirology
• Avian Ecology

Background:

• Avian hosts play varied roles in West Nile virus (WNV) transmission dynamics.
• Identifying key avian taxa is crucial for understanding WNV epidemics.
• This study investigates the contribution of red-footed falcons to WNV circulation.

Purpose of the Study:

• To evaluate the role of red-footed falcons in WNV circulation.
• To analyze host-vector, vector-virus, and host-virus interactions simultaneously.
• To assess the WNV host competence of red-footed falcons.

Main Methods:

• Mosquitoes were trapped in red-footed falcon nest-boxes using a specialized method.
• WNV presence in mosquitoes was determined by RT-PCR.
• WNV seroprevalence in nestlings was assessed using ELISA.
• Antibody titers were analyzed in relation to nestling age and hatching order.

Main Results:

• A novel method efficiently trapped mosquitoes in nest-boxes, correlating with host attraction.
• Culex pipiens and Culex modestus showed decreased blood-feeding success on older nestlings (14+ days).
• WNV was detected in 4.2% of mosquitoes, while 25.4% of nestlings were seropositive.
• Younger and earlier-hatched nestlings exhibited higher WNV antibody levels.

Conclusions:

• Red-footed falcons are exposed to local WNV, with higher risk for younger nestlings.
• Lack of viremia and high seroprevalence suggest short viremic periods or maternal antibody transfer.
• Maternal immunity may protect nestlings despite short antibody half-life.
• Red-footed falcons demonstrate low WNV host competence and are unlikely WNV reservoirs.