Investigation of risk factors for introduction of highly pathogenic avian influenza H5N1 virus onto table egg farms in the United States, 2022: a case-control study.

Introduction: The 2022-2023 highly pathogenic avian influenza (HPAI) H5N1 outbreak in the United States (U.S.) is the most geographically extensive and costly animal health event in U.S. history. In 2022 alone, over 57 million commercial and backyard poultry in 47 U.S. states were affected. Over 75% of affected poultry were part of the commercial table egg production sector. Methods: We conducted a case-control study to identify potential risk factors for introduction of HPAI virus onto commercial table egg operations. Univariate and multivariable analyses were conducted to compare farm characteristics, management, and biosecurity factors on case and control farms. Results: Factors associated with increased risk of infection included being in an existing control zone, sightings of wild waterfowl, mowing or bush hogging vegetation less than 4 times a month, having an off-site method of daily mortality disposal (off-site composting or burial, rendering, or landfill), and wild bird access to feed/feed ingredients at least some of the time. Protective factors included a high level of vehicle washing for trucks and trailers entering the farm (a composite variable that included having a permanent wash station), having designated personnel assigned to specific barns, having a farm entrance gate, and requiring a change of clothing for workers entering poultry barns. Discussion: Study results improve our understanding of risk factors for HPAI infection and control measures for preventing HPAI on commercial U.S. table egg farms.

Multidrug-Resistant Salmonella enterica Subspecies I Serovar 4,[5],12:i:- Isolates Recovered from Food Safety and Inspection Service-Regulated Products and Food Animal Ceca, 2007-2016.

Salmonella enterica subspecies I serovar 4,[5],12:i:- (Salmonella I 4,[5],12:i:-) is among the five most common serovars associated with human salmonellosis in the United States. In 2010, human infections with Salmonella I 4,[5],12:i:- which exhibited resistance to ampicillin, streptomycin, sulfonamides, and tetracycline (ASSuT) emerged as a public health concern. Outbreak investigations identified live animal settings, meat and poultry, and pets as confirmed and suspect sources of infection. To shed further light on possible sources of ASSuT-resistant Salmonella I 4,[5],12:i:- infections, we described isolates recovered from meat and poultry products regulated by the Food Safety and Inspection Service (FSIS) and from food animal ceca collected at FSIS-regulated slaughter establishments during 2007-2016. During the time period of interest, ASSuT-resistant Salmonella I 4,[5],12:i:- was found at low levels in multiple FSIS product classes including swine, turkey, cattle and chicken, which suggests this pathogen has a relatively wide host range. Monitoring trends in the various FSIS production classes over time and developing commodity profiles may help focus preventative strategies.

Factors associated with regulatory action involving investigation of illnesses associated with Shiga toxin-producing Escherichia coli in products regulated by the Food Safety and Inspection Service.

We described characteristics of the Escherichia coli O157 and Escherichia coli non-O157 illness investigations conducted by the United States Department of Agriculture's Food Safety and Inspection Service (FSIS) during the 5-year period from 2006 through 2010. We created a multivariable logistic regression model to determine characteristics of these investigations that were associated with FSIS regulatory action, which was defined as having occurred if a product recall occurred or if FSIS personnel performed an environmental health assessment (Food Safety Assessment) at the implicated establishment. During this period, FSIS took regulatory action in 38 of 88 (43%) investigations. Illness investigations in which FoodNet states were involved were more likely to result in regulatory action. Illness investigations in which state and local traceback, or FSIS traceback occurred were more likely to result in regulatory action. Reasons for lack of action included evidence of cross-contamination after the product left a regulated establishment, delayed notification, lack of epidemiological information, and insufficient product information.

Food worker experiences with and beliefs about working while ill.

Transmission of foodborne pathogens from ill food workers to diners in restaurants is an important cause of foodborne illness outbreaks. The U.S. Food and Drug Administration recommends that food workers with vomiting or diarrhea (symptoms of foodborne illness) be excluded from work. To understand the experiences and characteristics of workers who work while ill, workplace interviews were conducted with 491 food workers from 391 randomly selected restaurants in nine states that participated in the Environmental Health Specialists Network of the Centers for Disease Control and Prevention. Almost 60% of workers recalled working while ill at some time. Twenty percent of workers said that they had worked while ill with vomiting or diarrhea for at least one shift in the previous year. Factors significantly related to workers having said that they had worked while ill with vomiting or diarrhea were worker sex, job responsibilities, years of work experience, concerns about leaving coworkers short staffed, and concerns about job loss. These findings suggest that the decision to work while ill with vomiting or diarrhea is complex and multifactorial.

Rabies epidemiology, risk assessment, and pre- and post exposure vaccination.

Rabies should always be considered in the differential diagnosis of a neurologic disease in a mammal with an unknown vaccination status. Public health veterinarians are available to assist in risk assessment as well as coordination of animal testing. This article discusses the pathogenesis of rabies and clinical presentation in several domestic species. Prevention, North American prevalence and distribution, exposure considerations, and post-exposure prophylaxis are also discussed. Veterinarians in private practice have an integral role in protection of people and domestic animals against rabies.

Producer attitudes and practices related to antimicrobial use in beef cattle in Tennessee.

OBJECTIVE: To evaluate knowledge, attitudes, and management practices involving antimicrobial use among Tennessee beef producers. DESIGN: Mail survey. SAMPLE POPULATION: A population-based, stratified random sample of 3,000 beef producers across the state. PROCEDURES: Questionnaires were mailed to beef producers. Questions focused on producer practices related to education, biosecurity, veterinary use, and the purchase and use of antimicrobials. Operation types were categorized as either cow-calf only or multiple operation type (MOT). Associations between various factors and antimicrobial use were evaluated by use of multivariable logistic regression, with the outcome variable being any antimicrobial use (injectable or by mouth) in the past year. RESULTS: Of 3,000 questionnaires mailed, 1,042 (34.7%) were returned. A significantly higher proportion of producers with MOTs reported giving antimicrobials by mouth or by injection than did producers with cow-calf only operations. In addition, higher proportions of producers with MOTs than producers with cow-calf only operations reported treating with macrolides, florfenicol, ceftiofur, and aminoglycosides. In the multivariable analysis, herd size>50 cattle, participation in Beef Quality Assurance or master beef producer certification programs, quarantining of newly purchased animals, use of written instructions for treating disease, and observation of withdrawal times were associated with a higher likelihood of antimicrobial use. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that producers who engaged in more progressive farming practices were also more likely to use antimicrobials. Incorporating training on judicious antimicrobial use into educational programs would likely increase awareness of best management practices regarding antimicrobial use.

Analysis of risk factors associated with Salmonella spp. isolated from U.S. feedlot cattle.

Contamination can occur at a number of stages during farm-to-fork processing. Preharvest intervention is an ongoing area of interest in reduction of risk of foodborne illness. This study examined risk factors associated with detection of Salmonella from cattle in U.S. feedlots. During two visits to 73 feedlots, 25 fresh fecal samples were collected from each of three pen floors. Associations between management and demographic factors and culture status were evaluated using logistic regression. Factors positively associated with culture-positive status included brewers' grains (odds ratio [OR] = 26.35; confidence interval [CI], 10.33-67.20), corn gluten (OR = 10.35; CI, 5.98-17.91), or cottonseed hulls (OR = 8.34; CI, 3.58-19.42) in the ration, and sourcing animals in a pen from multiple herds of origin (OR = 5.17; CI, 2.32-11.51). Factors negatively associated with positive culture status included urea (OR = 0.27; CI, 0.16-0.44), alfalfa, clover, or sorghum silage (OR = 0.31; CI, 0.12-0.79), and antimicrobials of the tetracycline class in the ration (within 2 weeks before sampling, OR = 0.04 and CI, 0.02-0.09; more than 2 weeks before sampling, OR = 0.23 and CI, 0.06-0.80). Since 18.3% of positive samples were on a single operation, a second model was constructed after excluding data from this operation. Three additional variables were retained in the second model, including grain-processing method (OR for dry roll, cracked, or unprocessed grain = 2.99; CI, 1.55-5.75), soybean meal (OR = 2.74; CI, 1.58-4.75), and use of a coccidiostat in the ration (OR for no coccidiostat = 4.50; CI, 2.03-10.01). Considering the increasing use of by-products of the biofuel industry as feeds, further investigation of the association between feeding brewers' grains and corn gluten and Salmonella recovery is warranted.

Acute selenium toxicity associated with a dietary supplement.

BACKGROUND: Selenium is an element necessary for normal cellular function, but it can have toxic effects at high doses. We investigated an outbreak of acute selenium poisoning. METHODS: A case was defined as the onset of symptoms of selenium toxicity in a person within 2 weeks after ingesting a dietary supplement manufactured by "Company A," purchased after January 1, 2008. We conducted case finding, administered initial and 90-day follow-up questionnaires to affected persons, and obtained laboratory data where available. RESULTS: The source of the outbreak was identified as a liquid dietary supplement that contained 200 times the labeled concentration of selenium. Of 201 cases identified in 10 states, 1 person was hospitalized. The median estimated dose of selenium consumed was 41 749 microg/d (recommended dietary allowance is 55 microg/d). Frequently reported symptoms included diarrhea (78%), fatigue (75%), hair loss (72%), joint pain (70%), nail discoloration or brittleness (61%), and nausea (58%). Symptoms persisting 90 days or longer included fingernail discoloration and loss (52%), fatigue (35%), and hair loss (29%). The mean initial serum selenium concentration of 8 patients was 751 microg/L (reference range, < or =125 microg/L). The mean initial urine selenium concentration of 7 patients was 166 microg/24 h (reference range, < or =55 microg/24 h). CONCLUSIONS: Toxic concentrations of selenium in a liquid dietary supplement resulted in a widespread outbreak. Had the manufacturers been held to standards used in the pharmaceutical industry, it may have been prevented.

Relationship between herd size and annual prevalence of and primary antimicrobial treatments for common diseases on dairy operations in the United States.

Dairy operations in states representing 86% of the United States' national dairy herd were surveyed regarding the occurrence of common dairy diseases or disorders (digestive, respiratory, gastrointestinal, lameness, mastitis, navel infection) in specified production groups (weaned heifers, unweaned heifers, adult cows), and the most common antimicrobial preparation used to treat these conditions. Within disease and production group, disease frequency and characteristics of primary antimicrobial (drug class, availability, spectrum of activity, extra-label usage, withdrawal times) were compared among herd sizes (30-99, 100-499, and >/=500 cows) using chi-square or t-tests that accounted for the sampling design. The most common diseases were mastitis and lameness in cows, and gastrointestinal disease in unweaned calves, affecting 16, 11, and 15% of the target populations, respectively. Herd-level disease prevalence tended to increase as herd size increased, whereas within-herd prevalence tended to decrease as herd size increased. Broad-spectrum antimicrobials were selected as primary treatments by a majority of operations for nearly all diseases surveyed. When treating gastrointestinal disease, navel infection, or reproductive disorders, a majority of operations selected primary treatments not specifically labeled for that condition. Selection of over-the-counter preparations tended to decrease as herd size increased, whereas selection of broad-spectrum preparations tended to increase with herd size.

Assessment of the economic impact of porcine reproductive and respiratory syndrome on swine production in the United States.

OBJECTIVE: To estimate the annual cost of infections attributable to porcine reproductive and respiratory syndrome (PRRS) virus to US swine producers. DESIGN: Economic analysis. SAMPLE POPULATION: Data on the health and productivity of PRRS-affected and PRRS-unaffected breeding herds and growing-pig populations were collected from a convenience sample of swine farms in the midwestern United States. PROCEDURE: Health and productivity variables of PRRS-affected and PRRS-unaffected swine farms were analyzed to estimate the impact of PRRS on specific farms. National estimates of PRRS incidence were then used to determine the annual economic impact of PRRS on US swine producers. RESULTS: PRRS affected breeding herds and growing-pig populations as measured by a decrease in reproductive health, an increase in deaths, and reductions in the rate and efficiency of growth. Total annual economic impact of these effects on US swine producers was estimated at dollar 66.75 million in breeding herds and dollar 493.57 million in growing-pig populations. CONCLUSIONS AND CLINICAL RELEVANCE: PRRS imposes a substantial financial burden on US swine producers and causes approximately dollar 560.32 million in losses each year. By comparison, prior to eradication, annual losses attributable to classical swine fever (hog cholera) and pseudorabies were estimated at dollar 364.09 million and dollar 36.27 million, respectively (adjusted on the basis of year 2004 dollars). Current PRRS control strategies are not predictably successful; thus, PRRS-associated losses will continue into the future. Research to improve our understanding of ecologic and epidemiologic characteristics of the PRRS virus and technologic advances (vaccines and diagnostic tests) to prevent clinical effects are warranted.

Risk factors associated with herd-level exposure of cattle in Nebraska, North Dakota, and South Dakota to bluetongue virus.

OBJECTIVE: To evaluate herd-level risk factors for seropositive status of cattle to 1 or more bluetongue viruses. ANIMALS: 110 herds of cattle in Nebraska, North Dakota, and South Dakota. PROCEDURE: Blood samples were collected before and after the vector season. Samples were tested for antibodies against bluetongue virus by use of a commercially available competitive ELISA. Factors evaluated included descriptors of geographic location and management practices. Trapping of insect vectors was conducted to evaluate vector status on a subset of 57 operations. A multivariable logistic regression model was constructed to evaluate associations. RESULTS: For the full data set, altitude and latitude were associated with risk of having seropositive cattle (an increase in altitude was associated with an increase in risk, and a more northerly location was associated with a decrease in risk of a premise having seropositive cattle). Import of cattle from selected states was associated with an increase in risk of having seropositive cattle. From the subset of herds with data on vector trapping, altitude and latitude were associated with risk of having seropositive cattle, similar to that for the full model. However, commingling with cattle from other herds was associated with a decrease in risk of seropositivity. CONCLUSIONS AND CLINICAL RELEVANCE: Findings reported here may be useful in generating additional hypotheses regarding the ecologic characteristics of bluetongue viruses and other vector-borne diseases of livestock. Sentinel surveillance programs are useful for documenting regionalization zones for diseases, which can be beneficial when securing international markets for animals and animal products.

Antimicrobial susceptibility patterns of Salmonella isolates from cattle in feedlots.

OBJECTIVE: To evaluate the antimicrobial susceptibility patterns of Salmonella isolates from feedlot cattle. DESIGN: Cross-sectional study. SAMPLE POPULATION: 263 Salmonella isolates. PROCEDURES: Fecal samples were collected from the floor of 2 pens in each of 100 feedlots. Two hundred eighty Salmonella isolates were recovered after bacteriologic culture from 38 pens. Of these, 263 isolates were available for antimicrobial susceptibility testing to 16 antimicrobials, using microbroth dilution breakpoint plates. RESULTS: Less than 5% of isolates were resistant to any of the antimicrobials tested, with the exception of sulfamethoxazole (15; 5.7%) and tetracycline (61; 23.2%). Most isolates (197; 74.9%) were susceptible to all antimicrobials tested, whereas 18 (6.8%) were resistant to 2 or more antimicrobials. The percentage of isolates with resistance to any antimicrobial varied by serotype. The percentage of isolates resistant to various antimicrobials was not related to concurrent use of antimicrobials in the feed. CONCLUSIONS AND CLINICAL RELEVANCE: With the exception of tetracycline and sulfamethoxazole, resistance of Salmonella isolates to any of the antimicrobials was uncommon. Most isolates were susceptible to all antimicrobials tested. Antimicrobial resistance was not related to the presence of antimicrobials in the ration being fed at the time of sample collection.