Risk factors for veterinary hospital environmental contamination with Salmonella enterica.

Healthcare-associated infections in veterinary hospitals are commonly attributed to Salmonella enterica, particularly in large animal facilities, and are characteristically associated with widespread environmental contamination. The objective of this study was to investigate factors influencing the likelihood of identifying environmental contamination of a veterinary hospital with S. enterica, while exploring different analytic methods to model complex factors that may influence this ecology. Environmental surveillance samples were collected in a large veterinary hospital as part of a long-term infection control programme. Data were collected retrospectively from the electronic medical records database. Many easily measured variables were complex in nature (i.e., they represented variance that is unmeasured or unidentified as a specific factor) necessitating the use of alternative analytic methods (variable cluster and principal components analyses) to provide perspective regarding the complex data structure and latent factors that may be contributing to this ecology. Subsequently, multivariable logistic regression was performed using generalised estimating equations. Results suggest the probability of detecting Salmonella in the environment increased as demand on personnel increased (e.g., in a busy hospital). Veterinary personnel need to remain vigilant in implementing practices that we believe empirically will mitigate risk for widespread environmental contamination and sustained transmission among patients (i.e., rigorous hygiene for personnel and the environment).

Temporary carriage of bovine coronavirus and bovine respiratory syncytial virus by fomites and human nasal mucosa after exposure to infected calves.

BACKGROUND: In order to prevent spread of the endemic pathogens bovine coronavirus (BCoV) and bovine respiratory syncytial virus (BRSV) between herds, knowledge of indirect transmission by personnel and fomites is fundamental. The aims of the study were to determine the duration of viral RNA carriage and the infectivity of viral particles on fomites and human nasal mucosa after exposure to BCoV and BRSV. During two animal infection experiments, swabs were collected from personnel (nasal mucosa) and their clothes, boots and equipment after contact with calves shedding either virus. Viral RNA was quantified by RT-qPCR or droplet digital RT-PCR (RT-ddPCR), and selected samples with high levels of viral RNA were tested by cell culture for infectivity. RESULTS: For BCoV, 46% (n = 80) of the swabs from human nasal mucosa collected 30 min after exposure were positive by RT-qPCR. After two, four and six hours, 15%, 5% and 0% of the swabs were positive, respectively. Infective virions were not detected in mucosal swabs (n = 2). A high viral RNA load was detected on 97% (n = 44) of the fomites 24 h after exposure, and infective virions were detected in two of three swabs. For BRSV, 35% (n = 26) of the human nasal mucosa swabs collected 30 min after exposure, were positive by RT-ddPCR, but none were positive for infective virions. Of the fomites, 89% (n = 38) were positive for BRSV RNA 24 h after exposure, but all were negative for infective viruses. CONCLUSIONS: The results indicate that human nasal mucosa can carry both BCoV and BRSV RNA after exposure to virus shedding calves, but the carriage seems short-lived and the transmission potential is likely limited. High viral loads on contaminates fomites 24 h after exposure to infected animals, and detection of infective BCoV, indicate that contaminated fomites represent a significant risk for indirect transmission between herds.

Environmental sampling for avian influenza virus A (H5N1) in live-bird markets, Indonesia.

To identify environmental sites commonly contaminated by avian influenza virus A (H5N1) in live-bird markets in Indonesia, we investigated 83 markets in 3 provinces in Indonesia. At each market, samples were collected from up to 27 poultry-related sites to assess the extent of contamination. Samples were tested by using real-time reverse transcription-PCR and virus isolation. A questionnaire was used to ascertain types of birds in the market, general infrastructure, and work practices. Thirty-nine (47%) markets showed contamination with avian influenza virus in ≥ 1 of the sites sampled. Risk factors were slaughtering birds in the market and being located in West Java province. Protective factors included daily removal of waste and zoning that segregated poultry-related work flow areas. These results can aid in the design of evidence-based programs concerning environmental sanitation, food safety, and surveillance to reduce the risk for avian influenza virus A (H5N1) transmission in live-bird markets.

[Transmission of agents of the porcine respiratory disease complex (PRDC) between swine herds: a review. Part 2--Pathogen transmission via semen, air and living/nonliving vectors]. / Die Ubertragung von Erregern des porcine respiratory disease complex (PRDC) zwischen Schweineherden--eine Literaturübersicht. 2. Mitteilung--Ubertragung durch Sperma, Luft und belebte/unbelebte Vektoren.

The transmission of PRDC-pathogens (PRRSV, influenza virus A, PCV2, M. hyopneumoniae, A. pleuropneumoniae) between swine herds, which was summarized in the first part of the review, mainly occurs via pig movement. The risk of pathogen transmission by insemination with contaminated semen plays only a relevant role in the infection with PRRSV and PCV2. A risk of the aerogen transmission of pathogens between herds within a distance of 2 to 3 km is described for M. hyopneumoniae and PRRSV. Evidence for the other pathogens is not investigated. The PRDC-pathogens are frequently detected in wild boar populations. Therefore, the transmission between wild boars and domestic pigs seems possible by close contacts. PRRSV and M. hyopneumoniae can be transmitted by contaminated clothes and boots, but the use of sanitation protocols appears to limit their spread. Live vectors like rodents or birds seemed to have no special importance for the transmission of PRDC-pathogens.

Experimental evidence for transmission of Mycoplasma gallisepticum in house finches by fomites.

Ever since Mycoplasma gallisepticum emerged among house finches in North America, it has been suggested that bird aggregations at feeders are an important cause of the epidemic of mycoplasmal conjunctivitis because diseased birds could deposit droplets of pathogen onto the feeders and thereby promote indirect transmission by fomites. In this paper we bring the first experimental evidence that such transmission (bird-to-feeder-to-bird) does actually take place. House finches infected via this route, however, developed only mild disease and recovered much more rapidly than birds infected from the same source birds but directly into the conjunctiva. While it is certainly probable that house finch aggregations at artificial feeders enhance pathogen transmission, to some degree transmission of M. gallisepticum by fomites may serve to immunize birds against developing more severe infections. Some such birds develop M. gallisepticum antibodies, providing indication of an immune response, although no direct evidence of protection.

Survival of two avian respiratory viruses on porous and nonporous surfaces.

The transmission of pathogens from infected to susceptible hosts may occur through contaminated fomites and inanimate objects. This type of transmission depends on the ability of the pathogens to survive in the environment. In this report, we describe the survivability of two avian respiratory viruses, e.g., avian metapneumovirus and avian influenza virus on 12 different porous and nonporous surfaces. The viruses survived on some of the surfaces for up to 6 days postcontamination but not after 9 days. Both viruses survived longer on nonporous surfaces than on porous ones. One of the reasons for poor survival on porous surfaces could be inefficient elution of virus from these surfaces. These results should be helpful in determining how long the premises should be left vacant after an outbreak of these viruses has occurred in poultry houses.

Evaluation of fungicidal efficacy of benzalkonium chloride (Steramina G u.v.) and Virkon-S against Microsporum canis for environmental disinfection.

The aim of this study is to evaluate the antifungal efficacy of Steramina G u.v. (10% solution of alkyldimetylbenzylammonium chloride; Formenti Grünenthal) and Virkon-S (multipurpose system; Antec International) against Microsporum canis-infected hairs and spores. Samples were collected from a random sample of household cats and from subjects from catteries. Seventy M. canis-positive hairbrushes containing furs, keratin scales and other organic material were treated with each of the two disinfectants, using concentrations recommended by the manufacturer's instructions (2% and 1% for Steramina G u.v. and Virkon-S, respectively). Each brush remained in contact with the antifungal solution for 10 min. After this period, the brushes were air-dried, then seeded into mycobiotic agar, and incubated for up to 21 days at 28 degrees C. The disinfectants were considered effective if dermatophytes failed to grow. Steramina G u.v. was effective in 97.14% of samples and Virkon-S in 87.14%. The antifungal activity of Steramina G u.v. against M. canis was significantly higher (p < 0.05) than that of Virkon-S.

Quantitative risk assessment of Cryptosporidium species infection in dairy calves.

Cryptosporidium parvum is a zoonotic protozoan that infects many different mammals including cattle and humans. Cryptosporidiosis has become a concern for dairy producers because of the direct losses due to calves not performing well and the potential for environmental contamination with C. parvum. Identifying modifiable control points in the dynamics of infection in dairy herds will help identify management strategies that mitigate its risk. The quantitative risk assessment approach provides estimates of the risk associated with these factors so that cost-effective strategies can be implemented. Using published data from epidemiologic studies and a stochastic approach, we modeled the risk that C. parvum presents to dairy calves in 2 geographic areas: 1) the New York City Watershed (NYCW) in southeastern New York, and 2) the entire United States. The approach focused on 2 possible areas of exposure--the rearing environment and the maternity environment. In addition, we evaluated the contribution of many risk factors (e.g., age, housing, flies) to the end-state (i.e., total) risk to identify areas of intervention to decrease the risk to dairy calves. Expected risks from C. parvum in US dairy herds in rearing and maternity environments were 41.7 and 33.9%, respectively. In the NYCW, the expected risks from C. parvum in the rearing and maternity environments were 0.36 and 0.33%, respectively. In the US scenarios, the immediate environment contributed most of the risk to calves, whereas in the NYCW scenario, it was new calf infection. Therefore, within the NYCW, risk management activities may be focused on preventing new calf infections, whereas in the general US population, cleaning of calf housing would be a good choice for resource allocation. Despite the many assumptions inherent with modeling techniques, its usefulness to quantify the likelihood of risk and identify risk management areas is illustrated.