Gastrointestinal Illness at Sewickley, Pa.

On Aug. 25, 1975, the Allegheny County Health Dept. (ACHD) received information from a physician in Sewickley, Pa., indicating an unusual frequency of occurrence of gastrointestinal illness in the Sewickley area. On the same day, ACHD notified the Pittsburgh Regional Office of the Pennsylvania Dept. of Envir. Resources (DER) of the outbreak, and suggested that it might be associated with drinking water. On Aug. 27, the Center for Disease Control (CDC), Atlanta, Ga., was notified regarding the outbreak. CDC was requested by ACHD to conduct an epidemiological investigation. The EPA was invited to participate in conducting an investigation of the watersupply system. Sewickley is located in southwestern Pennsylvania in Allegheny County, on the northern bank of the Ohio River. It is approximately 12 mi west of the city of Pittsburgh. Surveillance over water-supply systems in Pennsylvania is the responsibility of DER. The regional office in Pittsburgh maintains surveillance activities over water supplies in nine southwestern Pennsylvania counties, including Allegheny County. On Aug. 27, the regional office was notified of EPA's intention to assist CDC in conducting an investigation and was requested to provide background information about the water-supply system. Since DER had begun its investigation of the system on Aug. 24, the agencies agreed to pursue a joint evaluation of the system to determine if events associated with the operation of the watersupply system were connected with the disease outbreak. The joint EPA-DER evaluation began on Aug. 28.