Air streams and the introduction of animal diseases borne on Culicoides (Diptera, Ceratopogonidae) into Israel.

The role of air streams and climatic conditions in the transport of biting midges (Culicoides spp.), the vectors of bluetongue and Akabane viruses, is known from other parts of the world. Knowledge of such climatic systems may enable predictions to be made on the occurrence of these diseases and may also assist in drawing up vaccination and control programmes. In this study, data on temperature, relative humidity, wind speed and direction have been analysed for the years 1964, 1966, 1969 and 1988, at altitudes of 0.5 km, 1 km and 1.5 km. The authors examine the relationship between these parameters and outbreaks of bluetongue and Akabane. The results show that outbreaks of bluetongue and most seroconversions did not occur before the season of the Persian trough air-stream system. This was despite the fact that the vector C. imicola was present in March and April, i.e. before this air-stream system began. Circumstantial evidence to indicate the introduction of infected midges by wind is stronger than the evidence against such an introduction. In addition, the amount of precipitation in the spring seasons of 1968 to 1986 could not be positively correlated to the number of bluetongue outbreaks. These results indicate that cooperation among the countries in the region of the Persian trough air system could provide an early warning system against wind-borne infected vectors. An outbreak of bluetongue in one country would be a warning to the next country along this route.