The Survival of Human Immunodeficiency Virus in Water, Sewage and Sea Water

Abstract

Drinking water treatment serves as an effective barrier against the transmission by water of enteric viruses. Current practices achieve a standard of less than 1 culturable enterovirus per 1,000 litres of treated water. The likely susceptibilty of HIV to water treatment processes has been assessed in the laboratory by comparing its resistance to environmental stress with that of poliovirus 2 for which quantitative information already exists. HIV cultured in a human T-cell line was added to samples of dechlorinated drinking water, settled raw sewage, and sea water. These were incubated at 16°C and sampled over 11 days. HIV was detected by serial dilution and subculture followed by fluorescent antibody tests for infected cells and by enzyme immune assay for p24 antigen. The survival of herpes simplex virus and poliovirus type 2 was assayed in parallel. The mean times required for a ten-fold decline in HIV concentration were calculated to be 1.8 days in tap water, 2.9 days in sewage, 1.6 days in sea water and 1.3 days in tissue culture fluid controls. A 10-fold decline of poliovirus 2 occurred after 23–30 days in sewage, sea water and tissue culture fluid but in tap water there was no significant decline over 30 days. Herpes simplex was the most sensitive virus requiring only 1.4 days to decline by a factor of ten in sewage. Controls in tissue culture fluid showed no significant change within 7 days. These tests suggest that although HIV was more robust than herpes simplex virus when associated with the organic matter found in sewage, it was more sensitive than poliovirus, an enterovirus widely used as an indicator of the efficiency of water treatment processes. This susceptibility makes it extremely unlikely that HIV poses any threat to disinfected water supplies.