An outbreak of Congo-Crimean haemorrhagic fever (CCHF), an indigenous virus infection of South Africa, was last identified in 1996.

Four workers at an ostrich abattoir in Oudtshoorn became ill in October 1996 and one subsequently died with extensive gastrointestinal bleeding. Some nine days later a further 12 patients were admitted to Tygerberg Hospital, 11 and the virus was isolated from one patient. A further seven patients at Oudtshoorn Hospital had high levels of specific CCHF antibodies.

CCHF, that has long been recognised in Asia, came to international attention after a disease outbreak in the Crimean peninsula in 1944 and 1945. The causative agent was later recognised to be identical to the Congo virus, isolated in Zaire.

Many wild and domestic animals act as reservoirs for the virus, including cattle, sheep, goats, and hares. Ixodid (hard) ticks act both as a reservoir and vector for CCHF virus.

Ground-feeding birds may disseminate infected vectors. Twenty-seven species of ticks are known to harbor the CCHF virus.

CCHF is endemic in eastern Europe, particularly in the Soviet Union. However, it may occur in other parts of Europe, especially around the Mediterranean. CCHF has been recognised in northwest China, Central Asia, and the Indian subcontinent and may occur in the Middle East and throughout much of Africa.

Humans become infected by being bitten by ticks or by crushing ticks, often while working with domestic animals or livestock. Contact with blood, secretions, or excretions of infected animals or humans may also transmit infection.

In areas with endemic CCHF, the disease may occur most often in the spring or summer.

Available evidence, including recently unpublished experiences, suggests that blood and other body fluids are highly infectious, but simple precautions, such as barrier nursing, effectively prevent secondary transmission.

The incubation period for CCHF is about 2-9 days.

Initial symptoms are nonspecific and sometimes occur suddenly. They include fever, headache, muscle and joint pain, abdominal pain, and vomiting.

Sore throat, conjunctivitis, jaundice, photophobia, and various sensory and mood alterations may develop. A rash is common and bleeding from needle-puncture sites may occur with hemorrhage from multiple other sources.

The case-fatality rate has been estimated to range from 15% to 70%.

For more information visit these sites: Centres for Disease Control and Prevention (Atlanta, US) and   National Institute for Virology (University of the Witwatersrand)