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A Hepatitis A Outbreak from Untreated Drinking Water in a Rural Saudi Arabian Town.


An unusual increase of hepatitis A cases from Afif district, Riyadh Region was identified through surveillance in February 1997. We proceeded to Afif to estimate the extent of the outbreak and to identify its source and mode of transmission.


We defined a hepatitis A case as onset of jaundice between January 1 and April 30, 1997, in a resident of Afif district. We interviewed affected families about contact with and food exposures common to other families with hepatitis A. We compared the water source of 19 families with one or more cases to 41 control-families without a case selected from the same neighborhoods of Afif town.


We detected 72 outbreak-associated cases of hepatitis A including 47 in Afif town (attack rate [AR] = 18.5/10,000), 17 from rural villages (AR = 14.5/10,000) and 8 from neighboring districts. Over two weeks, hepatitis A cases increased from a base line of under one case per month to 14 cases and averaged 4 cases per week for the next 10 weeks. The 5-14 year-old age group had the highest AR (43/10000). Interviews revealed no common exposure of affected families to other hepatitis A or common meals or eating places. Afif water was trucked in from up to 250 kilometers away and sold directly from trucks or through 10 commercial stations which sold both treated (filtered and chlorinated) and untreated water. All 19 case-families used untreated drinking water compared to 24(58%) control-families (p <0.01, Fisher's exact test). Seven (37%) case-families bought untreated water directly from trucks compared to only 2 (5 %) control-families (p< 0.01, Fisher's exact test) and 3 (16%) bought water from trucks originating from a well in a neighboring district (Qassim) compared to none of the control-families (p < 0.05, Fisher's exact test). This well had been declared unfit for human consumption by the Qassim authorities after several hepatitis A cases had occurred in a nearby village. Hepatitis A was not associated with any one water station in Afif and the original water source for many stations included this suspect well. However station records were insufficient to verify the actual sources during the outbreak.


A common source outbreak of hepatitis A in Afif was transmitted through untreated drinking water, probably originating in a contaminated well in a neighboring region. Similar untreated water supplies are present in other areas of Saudi Arabia and represent a continuing threat to the public health.