Risk of infection associated with a wastewater spray irrigation system used for farming

The use of wastewater for agricultural purposes involves the potential risk of infection from microorganisms in the wastewater. The application of partially treated wastewater on farms has been reported in one study to be associated with human illness, but this has not been confirmed. In the present study, workers at a land application system involving low-pressure spray irrigation of corn fields with wastewater were followed through a growing season to determine if they had an increased risk of infection as compared with a control population of the same socioeconomic group who had no direct exposure to wastewater. Enteroviruses were recovered from the wastewater used for irrigation, but not from the air during spraying. There was no increase in clinical illness among the workers and there was no evidence of an increased risk of infection. The workers who seemed at greatest risk, those who cleaned the spray nozzles, had higher antibody levels to one enterovirus, coxsackievirus B5, but acute symptomatic infections with viral excretion were not documented. This study indicates that there is very limited risk of infection among workers using partially treated wastewater for agriculture purposes.