Korean haemorrhagic fever in staff in an animal laboratory

In March, 1975, and January, 1978, there were outbreaks of Korean haemorrhagic fever (K.H.F.) among staff in the animal laboratory of the clinical research building of Tohoku University hospital. 13 doctors and 1 veterinarian had K.H.F., and all except 1 had a mild but typical clinical course. K.H.F. antibody titres were significantly raised in all 14 patients. 12 other doctors working in the same room had no symptoms and no K.H.F. antibody. K.H.F. antibody was also detected in 3 animal technicians who had not been ill, but who had worked in the same room. Antibody was not detected in any of the 4 technicians who worked in different animal rooms in another building. Epidemiological studies suggest that laboratory rats were the source of the infection. High titres of K.H.F. antibody were most common in rats reared in the animal laboratory associated with the outbreak.