Laboratory vector studies on six mosquito and one tick species with chikungunya virus.

The tick Ornithodoros savignyi and the mosquitoes Culex horridus, Culex quinquefasciatus, Aedes fulgens, Ae. furcifer and Mansonia africana were tested for infection rates and ability to transmit chikungunya virus. O. savignyi and Cx quinquefasciatus did not become infected and Cx quinquefasciatus failed to transmit the virus between vervet monkeys, Cercopithecus aethiops. Only one of 17 Cx horridus feeding on a blood-virus mixture became infected which included infection of the salivary glands. Ae. fulgens had a high infection rate and transmitted the virus between Mystromys albicaudatus rodents. Ae. furcifer and Ma. africana both transmitted virus between vervet monkeys: the 50% infection threshold and the transmission rate were less than 4.5 logs and 25% respectively for Ae. furcifer and c. 5.5 logs and 29% for Ma. africana. In a further test, Ae. furcifer transmitted virus from a monkey to hamsters at a transmission rate of 32%. Attempts to demonstrate transovarial transmission of the virus in Ae. aegypti and Ae. furcifer were unsuccessful. It is concluded that Ae. furcifer is fitted for its suspected role as epidemic vector and that Ma. africana could also act as an important epidemic vector in southern Africa.