Risk groups and control measures for Crimean-Congo hemorrhagic fever

Abstract

As with many vector-borne, zoonotic diseases, the ecology of the pathogen- reservoir-vector cycle predisposes certain individuals to infection with Crimean- Congo hemorrhagic fever virus (CCHFV). Hence, there are several groups of individuals who are considered to be at risk of contracting Crimean-Congo hemorrhagic fever (CCHF), specifically, people from endemic areas who are susceptible to tick bite, particularly from Hyalomma spp. ticks. These include individuals who work outdoors, particularly those who work with large domestic animals. This fact was exemplified during a recent CCHF outbreak in Turkey where 90% of the infected patients were farmers [1]. Although CCHFV has been isolated from numerous species of ticks (see Chapter 12), those of the Hyalomma genus are considered the primary vector in CCHF enzootic and endemic areas. The distribution of CCHFV coincides precisely with the distribution of Hyalomma ticks [6]; therefore, there appears to be little or no risk in areas outside the known distribution of these ticks. Exposures such as crushing-infected ticks and butchering-infected animals have also been a frequent source of CCHFV infection. Other groups who are at risk include those caring for CCHF patients. In fact, the risk of nosocomial infection in health-care workers is well documented and can be extremely high. This can be exemplified by a nosocomial outbreak that occurred at Tygerberg Hospital in South Africa where 33% of the medical staff who had contact with CCHF patients through accidental needle sticks developed CCHF and another 8.7% contracted disease by other contacts with the patients' blood [14]. Nosocomial infections with CCHFV will be discussed in greater detail in Chapter 21. In addition to health-care workers who care for CCHF patients, laboratory workers, and researchers working directly with the virus in the laboratory, or with infected vectors and/or animals, are at a higher risk of infection.