DEVELOPMENT OF A METHOD FOR THE RECOVERY OF ROTAVIRUSES FROM VEGETABLES AND ITS APPLICATION FOR ROTAVIRUS SURVIVAL ON CROPS.

Abstract

As the shortage of fresh water becomes more and more critical, alternative sources are being sought. The reuse of wastewater has become a viable option, particularly for agriculture and landscaping. However, the possible presence of the enteric pathogens, especially viruses, in wastewater has created concern about potential health risks associated with this practice. If wastewater is used for irrigation it may contaminate vegetable crops which are commonly eaten raw. Also, it may contaminate grass used for golf courses, school yards, and playgrounds where more people may be exposed. Rotaviruses may be of particular concern since they are a cause of infantile diarrhea and gastroenteritis in adults and have been a cause of waterborne disease outbreaks. No information, however, is available about the dissemination and survival of rotaviruses on uncooked food and landscaped areas. This information is necessary in developing criteria for determining safe uses of wastewater for crop irrigation. A method was developed for recovery of rotavirus from the surface of vegetables. The simian rotavirus SA-11, adsorbed onto the vegetable surfaces and effects of various eluents, pH, and exposure time, was evaluated to optimize recovery. The maximum recovery of rotavirus occurred with a solution of 3% beef extract at pH 8.0 after 5 minutes of exposure. Survival of rotavirus SA-11 on lettuce, radishes, and carrots stored at 4°C and room temperature was evaluated. Rotavirus SA-11 was able to survive up to 30 days at refrigeration temperatures and up to 25 days at room temperatures. Rotavirus survived longest on lettuce. The survival of coliphage and enteric viruses on grass was studied during winter and summer outdoors. Coliphage, poliovirus, and rotavirus SA-11 survived on two types of grass during winter and summer from 8 to 40 hours. Human rotavirus survived longer than the other enteric viruses, however, coliphage was more sensitive to inactivation. The occurrence of rotaviruses and enteroviruses in the secondarily treated sewage (activated sludge) was evaluated over a one year period. Total coliforms, pH, and turbidity were also determined. Rotavirus concentrations peaked during Spring and Winter while concentrations of enteroviruses peaked during May, September, and December. No correlation was found between the concentrations of total coliforms, rotaviruses and enteroviruses.