The use of serum antibody as a means to determine infections from exposure to wastewaters and refuse

Abstract

Surveys of serum antibodies to infectious agents have been used to evaluate the risks of infection from exposure to wastewater and wastewater sludge. In general, these studies have failed to show major risks from these kinds of exposures. Relatively few studies of the effects of exposure to refuse have been reported. In this review, seroepidemiologic studies are considered by type of infectious agent, including viruses, bacteria, parasites, fungi and algae, and by types of exposure to waste. In four of the five wastewater worker studies reviewed, there was only limited evidence that exposure to wastewater/sludge carried with it any risk of viral infection and this evidence was in most cases limited only to the subgroup of workers with the highest exposure levels. Antibody to hepatitis A virus (HAV) was elevated above that of controls in Copenhagen sewer workers but not in American wastewater workers. In the three studies of land application of wastewater, there was also only minimal evidence of infection from viruses. In a study of sludge application to farm land, no health effects were observed, although application rates were low. In the only two serologic studies of neighborhoods of wastewater treatment facilities, no evidence of infection from these facilities was reported. Infection from legionella was not reported to be associated with wastewater exposure. Leptospirosis has been shown to be a risk to those with wastewater contact, especially in sewers, but in recent years this risk has decreased. There is some evidence that garbage‐exposed workers may be at risk. Although a number of studies have found higher airborne levels of Gram‐negative bacteria at facilities processing refuse than at wastewater facilities, no serologic studies of these worker groups have appeared in the literature. There is some evidence that wastewater sludge compost‐exposed workers and heat‐dried sludge‐exposed workers had higher levels of antibody against endotoxin and that symptoms among workers at a refuse processing facility may be related to endotoxin exposure. Serologic studies have failed to show an increased risk of amebiasis and giardiasis as occupational diseases of wastewater workers, but stool examinations, the results of which have suggested such a risk, may be a better way to evaluate this risk. Despite problems with the design and analysis of data from seroepidemiologic studies, this approach has provided useful information on risks of infection in those exposed to wastewater and wastewater sludge.