Q-224. Detection and Characterization of Waterborne Gastroenteritis Viruses in Urban Sewage and Sewage-Polluted River Waters in Caracas, Venezuela

J. Rodriguez-Diaz, L. Caraballo, E. Vizzi, F. Liprandi, H. Takiff, W. Q. Betancourt;
Venezuelan Inst. for Sci. Res., Caracas, VENEZUELA.

The detection and molecular characterization of pathogenic human viruses in urban sewage has been extensively used to derive information on circulating viruses in given populations throughout the world. In this study, we applied a similar approach to provide an overview of the epidemiology of waterborne gastroenteritis viruses circulating in urban areas of Caracas. Influent samples were collected from various sewage treatment facilities from the city of Caracas including water samples from a river heavily polluted with urban sewage. Ultracentrifugation followed by elution with 0.25 N glycine buffer was used to concentrate virus particles, and viral RNA and DNA was extracted from sample concentrates (100 µL) with TryzolTM reagent along with guanidine thiocyanate extraction. Nested polymerase chain reaction was used for detection of human adenovirus (HAdv) while reverse-transcription plus nested, semi-nested or direct polymerase chain reaction was used for detection of enterovirus, hepatitis A virus (HAV), group A rotavirus, norovirus genogroups I and II (GGI and GGII), sapovirus, and astrovirus. Positive samples for rotaviruses were further genotyped with primers for VP4 (P type) VP7 (G type) and NSP4 (NSP4 genogroup gene). HAdv, enterovirus, rotavirus, and norovirus GGII were more frequently detected (≥80%) in sewage and river water samples than HAV, astrovirus, sapovirus, and norovirus GGI (≤10%). Although most rotavirus-positive samples could be G- and P-typed, a few samples were untypeable. The most frequent types found in all samples were G1, [P4], and NSP4 B. Some samples contained the following mixed genotypes: G1+G9, G1+G10, [P8]+[P4], NSP4 A+B, and NSP4 B+C. This study reveals relevant epidemiological data on distribution and persistence of waterborne gastroenteritis viruses in different localities of Caracas. Important etiologic agents of viral gastroenteritis present in natural waters indicate potential public-health risks that had not been previously addressed in this geographical area.