The waterborne diseases include viruses, bacteria and protozoa. BACTERIAL diseases are common to most countries; differences tend to be in the form of additional types of bacteria and a higher incidence in wastewaters in developing or tropical countries. Those bacteria sufficiently prevalent to be of concern in developed nations are Samonella, enterpathogenic Escherichia coli, Shigella, and Yersinia; and to a lesser extent Legionella and Leptospira. Samonella and E. coli are always found in sewage and sludge. Salmonella is present in domestic animals; only Salmonella typhi (typhoid) lives in man only. Shigellae (dysentery) is essentially exclusively a human disease. Vibrio cholerae (cholera) survives in water for only a short time; epidemics associated with contaminated drinking water show recent contamination. Shigellosis is the second most common enteric bacterial infection observed in the U.S.A. In 1976, the incidence rate for shigellosis was 6 per 100,000; salmonellosis at 11 per 100,000. LEGIONELLA has been isolated from the water in the cooling towers of air conditioning units in association with disease outbreaks, suggesting that disease in man results from exposure to aerosols containing the organism. Wastewater-exposed workers and the neighbors of treatment plants have not shown that exposure posed a risk of infection. SALMONELLA: The Cincinnati-Chicago-Memphis study showed higher levels in wastewater workers; especially among inexperienced workers in Memphis. YERSINIA: A study of sewage workers in Manitoba did not reveal a wastewaterexposure effect. BACTERIAL ENDOTOXINS: Toxins released from the cell walls of gramnegative bacteria after their death can produce fever and chesttightness in exposed individuals. This appears to be a problem during sludge heat-treatment operations for sludge drying, at land application sites, and at composting operations. Individuals exposed to composted sludge in Philadelphia and Washington, D.C., showed higher antibody levels to compost -deri ved endotoxin. HEPATITIS: Hepatitis A requires serological (antibody) analysis since most infections are subclinical and are not manifested as overt disease. Hepatitis B is a major unconquered disease: some 200 million people are chronic carriers of the virus and a significantly minority of these go on to develop cirrhosis or cancer of the liver. There are reliable diagnostic procedures and a vaccine. Hepatitis B is transmitted via blood or bloodcontaminated materials; blood from skin and wounds or sores; tattooing acupuncture, or ear piercing without rigorous sterilization of equipment. Recent evidence indicates that sexual transmission is possible; semen and other genital secretions can transmit the virus; and saliva also contains the virus. There are strict disposal procedures for contaminated materials. AIDS: The Aids virus does not appear to survive outside the body. For infection to occur, considerable numbers of viruses must be involved. For example, of 1100 hospital workers who have experienced needle punctures with AIDS-contaminated materials, only 2 have developed antibodies and these involved deep intramuscular puncture wounds. For AIDS to be transmitted via sewage would involve blood in the urine or feces of the infected individual to be discharged in the sewer. Infection would have to involve contact of this material with cuts or broken skin. The AIDS virus may live for an hour in blood specimens kept at room temperatures which are close to body temperatures; otherwise, the virus seems to die off at cooler temperatures. This would seem to mean a low chance of survival in the sewer system. As with hepatitis B, there are strict disposal procedures for contaminated materials. NORWALK VIRUS is largely associated with epidemics of gastroenteritis in older children or adults. Infections are infrequent «5%) in children under 10 years; 50 60% of adults have serological evidence of infections.
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