Q-275. Determining Inactivation Rates of Viruses on Fomites

J. B. Henley, C. P. Gerba;
Univ. of Arizona, Tucson, AZ.

Data is lacking regarding the survival of pathogens on fomites. This information is necessary for the development of risk management models for use during bioterrorism and natural disease outbreak incidences. Using surrogate viruses is beneficial in gathering inactivation data that may be extrapolated to model environmentally transmitted pathogens. In this work, MS-2 coliphage, P22 bacteriophage, and poliovirus type-1 (PV-1) were used as surrogates to study the persistence of animal viruses on fomites. For each virus, a suspension in phosphate buffer was made and a total of 100 µl was inoculated in ten 10 µl droplets on stainless steel, cotton fabric, and laminar surfaces. Surfaces were maintained at room temperature and 40-60% relative humidity. Samples were collected at various times for up to 20 days after inoculation of the fomites. Surfaces were sampled by placing each surface in 10 mL of phosphate buffer and vortexing for 1-2 minutes. Samples were assayed to determine the number of infective viruses recovered from the surfaces. MS-2 and P22 experienced a 4 log reduction on cotton within the first 24 hours, whereas PV-1 did not experience a 4 log reduction on cotton until nearly 20 days. All of the viruses were reduced by 1 log on stainless steel within the first 2-3 days. However, P22 and PV-1 continued to decline in titer more rapidly on steel compared to MS-2. MS-2 and PV-1 had similar inactivation rates on laminar and declined in titer by 1 log within 1-2 days. P22 appears to inactivate more rapidly with a 3 log reduction within 24 hours. These data support that both virus type and surface type play significant roles in virus inactivation rates.