National Health Laboratories, Islamabad, Pakistan, Center for Disease Control, Public Health Service, U.S. Department of Health, Education, and Welfare, Yale Arbovirus Research Unit, Yale University School of Medicine, Department of Epidemiology and Public Health, Atlanta, Georgia 30333
This paper describes the clinical, epidemiological, and laboratory investigations undertaken to isolate and identify the etiological agent of a nosocomial cluster of hemorrhagic fever cases due to Crimean hemorrhagic fever (CHF)-Congo virus. Since this virus is usually transmitted by ticks it was surprising that the index case, in a nomadic shepherd, occurred during the winter season when ticks are relatively inactive. These are the first cases of CHF-Congo virus found in humans in Pakistan. Investigations on other biological properties, particularly strain differences and virulence, are being continued at the Islamabad laboratory.