[Virus exchange between feeding ticks in the absence of viremia in a vertebrate host (distant transmission)]

Abstract

The data obtained with tick-borne encephalitis virus did not confirm the conclusion made by L. D. Jones et al. (1987, 1989) on the possibility of distant virus transmission from infected to non-infected ticks feeding at some distance on the host unable to produce suprathreshold viremia level and on the role of saliva gland substrate as the enhancer of the process. The property discovered by L. D. Jones et al. may be intrinsic not to all arboviruses but only to Orthomyxoviridae with which they worked. Therefore, we don't see any reasons for a complete revision of WHO definition of arboviruses. However, the possibility of arbovirus exchange during joint feeding of ticks of different sexes and species on aviremic animals has been confirmed. In these cases due to sexual and other pheromones and virus release with saliva during blood-sucking Flaviviridae and Orthomyxoviridae virus exchange is possible between infected and non-infected ticks: tick-borne encephalitis virus is exchanged in 33-100% of cases between sexes and in up to 30% of cases between species, while Orthomyxoviridae virus is exchanged in 54-88% of cases between male and female individuals of the same species.