Epidemic non-A non-B hepatitis in urban Karachi, Pakistan

An outbreak of icteric non-A non-B (NANB) hepatitis occurred in a residential community of urban Karachi, Pakistan, from August 1986 through October 1986. Of the 114 cases reported from this community during the 1986 calendar year, a clustering of 85 cases was seen during the above period. Twenty-seven percent of 226 households and 9% of 1,250 individuals were affected. Five persons were hospitalized and 1 death occurred in a young pregnant woman. Cases occurred predominantly in the less than or equal to 29-year-old age group (72%), with a male:female ratio of 1.8:1. Thirty-four cases occurred singly within households, while in 28 households multiple cases were seen. Analysis of the epidemic curve and intervals of onset of multiple cases within households suggested prolonged common source exposure rather than secondary person-to-person transmission. No single water source was implicated but a contaminated municipal supply was presumed. Information collected from several other communities and from a university hepatitis reference laboratory suggested that the outbreak was part of a larger urban epidemic of NANB hepatitis. Based upon this investigation and data from recently published reports, it is concluded that NANB hepatitis is endemic in Pakistan.