Possible windborne spread to western Turkey of bluetongue virus in 1977 and of Akabane virus in 1979.

An outbreak of bluetongue in sheep started in the Menderes valley, Aydin Province, Western Turkey, in October 1977. The severity of the disease indicated that it had not been there before but had been introduced into the area. Analysis showed that, while it was possible for the virus to have been brought into the area by movement of infected animals, there was also a period of south-easterly winds which could have carried infected midges from Cyprus, where bluetongue was present.

Possible origin of the bluetongue epidemic in Cyprus, August 1977.

Possible origins of an epidemic of bluetongue in Cyprus in August 1977 have been analysed. First outbreaks occurred simultaneously in the south-east of the Famagusta district and on the north coast of the Kyrenia district respectively. Although the epidemic was due to type 4, which had been responsible for the previous outbreak in 1969, no evidence of persistance of virus could be found.

Possible windborne spread of bluetongue to Portugal, June-July 1956.

The possible sources for the epidemic of bluetongue in Portugal at the beginning of July 1956 were examined. Introduction through authorized importation of domestic or wild ruminants was not feasible, since no cattle, sheep or goats were imported and the wild ruminants were confined to Lisbon Zoo, which was too far from the initial outbreaks. Weather maps were examined to see if the wind could have carried infected Culicoides midges from North Africa.

Possible spread of African horse sickness on the wind.

Analyses of outbreaks of African horse sickness showed that movement of infected Culicoides midges on the wind was most likely responsible for the spread of the disease over the sea from Morocco to Spain in 1966, from Turkey to Cyprus in 1960, and from Senegal to the Cape Verde Islands in 1943. The pattern of spread of the epidemic in the Middle East in 1960 could have been laid down by the infected midges carried on spells of south-east winds, and analyses of outbreaks in Algeria in 1965 and India in 1960 also suggested windborne spread of the disease. Each spread occurred when the presence of virus, host and vector coincided either with a spell of winds unusual for a particular time of year (Spain, Cyprus, Cape Verde Islands and Algeria) or with a series of disturbances usual at that time of the year (Middle East and India).