Rates of infection in, and transmission of, African horse-sickness virus by Aedes aegypti mosquitoes.

This research study investigates the rate at which Aedes aegypti mosquitoes can get infected with, and transmit, the African horse sickness virus (AHSV). The findings suggest that this type of mosquito is unlikely to be a successful carrier of AHSV.

Methodology

• The researchers used two main means to infect the Aedes aegypti mosquitoes: through ingestion of blood that contained the virus, and through direct inoculation of the virus into the mosquitoes.
• In the first method, the mosquitoes were fed with blood that had a virus concentration gradient of 5.8 to 6.5 log10 MLD50/0.02 ml.
• In the second method, the mosquitoes were directly inoculated with the virus intrathoracically, that is, directly into the thorax region of the mosquitoes.

Infection Rates

• The infection rates among the mosquitoes varied greatly based on the method of infection.
• Those that ingested blood with the virus had an extremely low infection rate of less than 3%.
• Conversely, mosquitoes that were directly inoculated with the virus had much higher infection rates.

Transmission Experiment

• The researchers then conducted experiments to assess the ability of the infected mosquitoes to transmit the virus.
• The mosquitoes were urged to feed on embryonated hen eggs, but they failed to pass on the virus through their bites.
• Furthermore, when these inoculated mosquitoes were allowed to engorge themselves with uninfected blood through a chick skin membrane, the virus could not be detected in either the membrane or the blood.

Conclusions

• The study concluded that Aedes aegypti mosquitoes are unlikely to be effective vectors for the transmission of the African Horse Sickness Virus.
• This is largely due to their low infection rates when they ingest the virus and their inability to transmit the virus even when they have high infection rates.