Yellow fever infection after recent convalescence from chikungunya fever: report of a fatal case

An epidemic of chikungunya fever occurred in Luanda, Angola, at the end of 1970, being followed by, and partly concurrent with, an epidemic of yellow fever. In March 1971, a 16-year-old white boy, who had chikungunya fever 3 weeks before, was admitted to hospital with yellow fever. He had a severe illness ending in death on the 8th day. Serum taken on admission yielded YF virus designated as strain 47FA; it is essentially identical to YF (Asibi strain) virus. This serum had HI antibody only to CHIK virus, of 11 arbovirus antigens tested. A positive CF test for CHIK antibody in this serum confirmed the earlier infection with CHIK virus. The authors speculate that persons convalescent from chikungunya fever may be less resistant to infection with YF virus.