In December 1994, the primary health care center (PHCC) of Ashwag village in Saudi Arabia (population 2446) reported 13 cases of hepatitis A, but had reported zero cases for more than one year. Twelve cases had onset in the three weeks following the heavy rains that interfered with the delivery of water by truck from the bin Iyada well.
Methodology
We defined an outbreak associated case of hepatitis A as an Ashwag resident with jaundice and fever from November, 1994 to February, 1995. We chose the closest seven houses to each house with an outbreak associated hepatitis A case, and tested family members for anti HAV IgM and IgG. We compared the water supply of the cases' houses to the water supply in the houses with one or more susceptible persons (without anti HAV).
Results
In the three weeks following the flood, 12 children developed hepatitis A. The attack rate was highest in the 1-4 years age group [21.5/1000]. Areas of Ashwag where the water truck continued supplying the houses with water from Bin Iyada well after the flood had a higher attack rate [7.1/1000] than the other areas. Households with cases were more likely to use Bin Iyada as well as the main drinking water source (OR undefined, P =0.0006) or as the alternative source (OR undefined, P =0.04) than households with susceptible members. The Bin Iyada well was located on the bank of the wadi (intermittent watercourse). It was not sealed and the holding tank was uncovered. The well and holding tank were twice covered with flood water. Interviews indicated that 75% of households had disposal sanitary sewage, and members of the other 25 % used the wadi for defecation.
Conclusion
A common source waterborne outbreak of hepatitis A resulted from surface water flooding a community well and holding tank and poor environmental sanitation. The investigation of this outbreak showed that in rural areas the spread of waterborne diseases would be contained with attention to safe water supplies and sanitary sewage disposal.