The Transmission, Detection and Occurrence of Viruses on Indoor Environmental Fomites

Viruses cause 60% of human infections and are probably the most common cause of infectious disease acquired indoors. Rapid spread of viral illness in indoor establishments facilitates disease morbidity and mortality. The goal of this dissertation is to clarify the role of fomites in the viral infection cycle. Research methods include investigation of published literature, and the use of polymerase chain reaction (PCR) for viral detection. The Appendix A study reviewed published literature to assess the significance of fomites in the transmission of ten common respiratory and enteric viruses (rhinovirus, respiratory syncytial virus (RSV), influenza A, parainfluenza 1 (HPIV1), coronavirus, rotavirus, calicivirus, hepatitis A virus (HAV), astrovirus and adenovirus). Results suggest that fomites play an important role in the transmission of common viral pathogens, and the use of disinfectants may limit the spread of viral disease. The Appendix B study examined PCR primer detection limits by determining the time length viruses can be isolated on fomites. Results indicated that poliovirus 1 and hepatitis A virus could be detected for up to 60 days. Parainfluenza 1 virus isolation yielded detection at 30 days and 50 days. Norovirus isolation yielded detection at 20 days and 30 days. Influenza virus isolation results were inconsistent, yielding no initial detection and detection up to 20 days. Appendix C assessed the occurrence of human parainfluenza 1 virus (HPIV1) on surfaces in office settings. HPIV1 was detected on 37% of fomites. HPIV1 was detected most on desktops (47%), and least on light switches (19%). Study results indicated a statistically significant difference between positive fomites in different buildings (Chi-square p < 0.011), and between building cubicles and conference room fomites (Chi-square p < 0.011). Appendix D evaluated the prevalence of influenza A virus on surfaces in day care and home settings. Influenza A was isolated on 23% of fall day care fomites and 53% of spring day care fomites. Influenza was isolated on 59% of home fomites sampled during March, and no influenza was detected on home fomites sampled during the summer. Overall, Influenza A virus was isolated on over 50% of fomites in homes and day care centers