Experimental transmission of Quaranfil virus by Argas (Persicargas) arboreus ticks from rookeries of the cattle egret, Bubulcus i. ibis L., indicated a high vector potential of this species. Widespread infection beyond the digestive tract of the tick usually occurred by and after 44 days of extrinsic incubation.
A. (P.) persicus, the fowl tick, could be experimentally infected with Quaranfil virus and retained the virus for up to 120 days. However, transmission to chicks was accomplished only by mass feeding, indicating that this species is a poor vector. Since the virus was detected in only 1 of 25 coxal fluid samples, poor spread of virus beyond the digestive tract is suggested. Mechancial transmission through regurgitation of partly digested blood retaining some active virus might have accounted for the transmissions noted.
Transstadial transmission of Quaranfil virus was obtained with both tick species. The failure to demonstrate transovarial transmission of Quaranfil virus in A. (P.) arboreus, the natural vector, indicates that a vertebrate host is necessary for perpetuation of this virus.
Genetically controlled differences in susceptibility to Quaranfil virus account for the high vector efficiency of A. (P.) arboreus and the low efficiency of the closely related A. (P.) persicus. Ecological factors appear to be of secondary importance in the virus-tick relationships. These studies demonstrate the need for meticulous taxonomic investigations to accompany research on vector efficiency, pathogen transmission, and arthropods in relation to the epidemiology of disease.