Environmental virology: from detection of virus in sewage and water by isolation to identification by molecular biology--a trip of over 50 years.

Environmental virology began with efforts to detect poliovirus in sewage and water more than 50 years ago. Since that time, cell-culture methods useful for detection of enteroviruses have been replaced by molecular biology techniques for detection of pathogens (hepatitis A and E viruses, caliciviruses, rotaviruses, and astroviruses) that do not grow in cell culture or grow with great difficulty. Amplification of viral nucleic acid using the polymerase chain reaction (PCR) is the current preferred method. PCR or RT-PCR (to detect RNA viral genomes) is rapid, sensitive, specific, and quantitative. Method shortcomings include potential inhibition by substances in some environmental samples and an inability of test results to distinguish between infectious and noninfectious virus. Current questions involving use of PCR/RT-PCR tests for public health purposes include: What is the public health significance of a positive test, and should direct tests for viruses replace current public health-monitoring programs?