Fomites can serve as routes of transmission for both enteric and respiratory pathogens. The present study examined the effect of low and high relative humidity on fomite-to-finger transfer efficiency of five model organisms from several common inanimate surfaces (fomites). Nine fomites representing porous and nonporous surfaces of different compositions were studied. Escherichia coli, Staphylococcus aureus, Bacillus thuringiensis, MS2 coliphage, and poliovirus 1 were placed on fomites in 10-l drops and allowed to dry for 30 min under low (15% to 32%) or high (40% to 65%) relative humidity. Fomite-to-finger transfers were performed using 1.0 kg/cm 2 of pressure for 10 s. Transfer efficiencies were greater under high relative humidity for both porous and nonporous surfaces. Most organisms on average had greater transfer efficiencies under high relative humidity than under low relative humidity. Nonporous surfaces had a greater transfer efficiency (up to 57%) than porous surfaces (<6.8%) under low relative humidity, as well as under high relative humidity (nonporous, up to 79.5%; porous, <13.4%). Transfer efficiency also varied with fomite material and organism type. The data generated can be used in quantitative microbial risk assessment models to assess the risk of infection from fomite-transmitted human pathogens and the relative levels of exposure to different types of fomites and microorganisms. I nanimate objects, or fomites, are a potential reservoir in the transmission of pathogens either directly, by surface-to-mouth contact, or indirectly, by contamination of fingers and subsequent hand-to-mouth, hand-to-eye, or hand-to-nose contact (1-5). Bodily fluids such as saliva, mucus, nasal secretions, blood, urine, and feces may all potentially contain pathogens that can be transmitted via fomites (6-9). A number of studies have shown that enteric and respiratory pathogens are capable of surviving from hours to months on fomites, depending on the numbers deposited, the type of microorganism, and the variable environmental conditions (10-12). Several studies have shown that inanimate surfaces found in day care centers (8,(13)(14)(15)(16)(17), schools (18), office buildings (19), homes (20-27), public areas (28), or hospitals (12, 29-33) can be reservoirs for secondary modes of transmission, with contaminated hands playing a critical role as a route of exposure.The efficiency of transfer of a pathogen to the hand from the fomite is important in modeling the potential for its transmission (11,(34)(35)(36). This information can be used to understand the spread of disease in indoor environments and the potential for designing surfaces that reduce transfer efficiency and/or are antimicrobial (5). The purpose of this work was to better elucidate the transfer efficiencies of several different types of organisms under control conditions to provide data that may be used in quantitative microbial risk assessment (QMRA) models. (ii) Gram-negative and Gram-positive bacterial inoculum preparation. Frozen aliquots of E. coli an...

bInanimate surfaces, or fomites, can serve as routes of transmission of enteric and respiratory pathogens. No previous studies have evaluated the impact of surface disinfection on the level of pathogen transfer from fomites to fingers. Thus, the present study investigated the change in microbial transfer from contaminated fomites to fingers following disinfecting wipe use. Escherichia coli (10 8 to 10 9 CFU/ml), Staphylococcus aureus (10 9 CFU/ml), Bacillus thuringiensis spores (10 7 to 10 8 CFU/ml), and poliovirus 1 (10 8 PFU/ml) were seeded on ceramic tile, laminate, and granite in 10-l drops and allowed to dry for 30 min at a relative humidity of 15 to 32%. The seeded fomites were treated with a disinfectant wipe and allowed to dry for an additional 10 min. Fomite-to-finger transfer trials were conducted to measure concentrations of transferred microorganisms on the fingers after the disinfectant wipe intervention. The mean log 10 reduction of the test microorganisms on fomites by the disinfectant wipe treatment varied from 1.9 to 5.0, depending on the microorganism and the fomite. Microbial transfer from disinfectant-wipetreated fomites was lower (up to <0.1% on average) than from nontreated surfaces (up to 36.3% on average, reported in our previous study) for all types of microorganisms and fomites. This is the first study quantifying microbial transfer from contaminated fomites to fingers after the use of disinfectant wipe intervention. The data generated in the present study can be used in quantitative microbial risk assessment models to predict the effect of disinfectant wipes in reducing microbial exposure. Inanimate objects and surfaces (fomites) are known to be a reservoir for the transmission of pathogens in the environment directly, by surface contact with the mouth or abraded skin, or indirectly by contamination of fingers and subsequent hand-to-mouth, hand-toeye, or hand-to-nose contact (1, 2). Previous laboratory studies have modeled food preparation in domestic kitchens to better understand cross-contamination of food-borne pathogens (3, 4). The occurrence and spread of pathogens throughout the home and health care settings have also been studied to better understand the role of fomites in pathogen exposure and acquired infections (5-11). The potential for pathogen transfer from contaminated fomites to fingers is a concern in health care environments; particularly those in close proximity to the patient that are frequently touched (12-25). Health care-acquired infections caused by methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible S. aureus, and Clostridium difficile are associated with high morbidity and mortality (18,20,22,(26)(27)(28)(29)(30). Most nosocomial and foodborne pathogens can persist on fomites for weeks or even months (18,19,31,32) and on fingers for up to several hours (33-35). Pathogen presence and survival on fomites in domestic homes, public places, hospitals, and other health care facilities are important factors in evaluating potential health risks t...

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