Vector competence of three Venezuelan mosquitoes (Diptera: Culicidae) for an epizootic IC strain of Venezuelan equine encephalitis virus.

This study explores the capability of three mosquito types from Venezuela to carry and spread Venezuelan equine encephalitis (VEE) virus, with findings indicating that the mosquito species Aedes taeniorhynchus is particularly effective in transmitting the disease.

Understanding the Research Objective

• This research aimed to investigate the “vector competence” of three mosquito species from northwestern Venezuela for the Venezuelan equine encephalitis (VEE) virus strain that caused an outbreak in 1995.
• Vector competence refers to the ability of a species to both acquire an infection and then transmit the pathogen to a new host.
• The three mosquito species examined were Aedes taeniorhynchus, Culex declarator, and Mansonia titillans.

Methodology and Critical Findings

• Research experiments involved infesting these mosquito types with the VEE virus and observing rates of infection and subsequent dissemination to see their potential as virus spreaders.
• Among the three species, Aedes taeniorhynchus showed the highest susceptibility to infection, with a 94% rate of infection and 89% developing a disseminated infection, ie the spreading of the virus within the mosquito.
• Culex declarator showed minimal vector competence with only one individual from 28 infected (about 4%), and this one did not develop a disseminated infection.
• Mansonia titillans, on the other hand, was moderately susceptible, with 3 of 8 infected (38%) and 25% of these developing a disseminated infection.

Role of Aedes taeniorhynchus in the 1995 Outbreak

• The study further confirmed the high competence of Aedes taeniorhynchus through an additional experiment where virus-exposed mosquitoes were allowed to feed on susceptible hamsters, with successful transmission of the virus observed.
• The conclusion from these results is that Aedes taeniorhynchus would have been an important vector during the 1995 VEE outbreak in Columbia and Venezuela, given its high rate of infection and the ability to efficiently transmit the VEE virus.

Implications of the Research

• This research provides valuable information about vector competence relevant to the control of VEE and understanding of its transmission dynamics.
• Knowing which vector species are particularly competent can help inform strategies to manage and prevent future outbreaks of the disease.