In the course of investigating suspected cases of viral haemorrhagic
fever in South Africa patients were encountered who had been bitten by ticks, but who lacked evidence of
infection with Crimean-Congo haemorrhagic
fever (CCHF) virus or non-viral tick-borne agents. Cattle sera were tested by enzyme-linked immunoassay to determine whether tick-borne viruses other than CCHF occur in the country. The prevalence of antibody in cattle sera was 905/2116 (42.8%) for CCHF virus, 70/1358 (5.2%) for Dugbe, 21/1358 (1.5%) for
louping ill, 6/450 (1.3%) for West Nile, 7/1358 (0.5%) for
Nairobi sheep disease, 3/625 (0.5%) for Kadam and 2/450 (0.4%) for Chenuda. No reactions were recorded with Hazara, Bahig, Bhanja, Thogoto and Dhori viruses. The CCHF findings confirmed previous observations that the virus is widely prevalent within the distribution range of ticks of the genus Hyalomma, while antibody activity to Dugbe
antigen was detected only within the distribution range of the tick Amblyomma hebraeum. Cross-reactivity for the nairoviruses, Hazara,
Nairobi sheep disease and Dugbe, was detected in serum samples from 3/72 human patients with confirmed CCHF
infection, and serum from 1/162 other patients reacted monospecifically with Dugbe
antigen. The latter patient suffered from febrile illness with prolonged
thrombocytopenia.