Seasonal activity and hosts of the vectors of Crimean-Congo haemorrhagic fever in South Africa.

The seasonal activity and hosts of two species of Hyalomma, H. marginatum rufipes and H. truncatum, were studied in a Crimean-Congo haemorrhagic fever (CCHF) zone near Bloemhof in the western Transvaal. The study was conducted at the S.A. Lombard Nature Reserve, where a child had died from this disease. It was found that adults of the two species are very common during summer while the immature stages were active during winter and also demonstrated a second peak of activity in November. H. marginatum rufipes adults fed mainly on eland and zebra, while H. truncatum preferred black wildebeest, springbok and blesbok as hosts. Immature specimens of H. truncatum fed on hares and rodents and those of H. marginatum rufipes on hares, rodents and guinea-fowl. It appears that the immature stages pick up the virus from hares and other small mammals, but it is the adult ticks who transfer the virus to man. The epidemiology of tick-borne CCHF is discussed.