Per- and polyfluoroalkyl substances: using comparative medicine to understand exposure and adverse health outcomes in people and their pets.

One of the important human health benefits of keeping pets may be to serve as an early warning system for indoor childhood exposure to toxic chemicals such as per- and polyfluoroalkyl substances (PFAS). The stain-resistant properties and environmental stability of PFAS make them a preferred choice for protective coatings and lubricants, and they have been used for years in various manufacturing and industrial processes around the world. Although the use of PFAS has arguably improved many commercial products, they have been linked to adverse health outcomes such as developmental delays, liver damage, immune suppression, disruption of endocrine and reproductive systems, and some cancers. The current body of literature suggests that serum PFAS levels in dogs and cats are analogous to their human counterparts and that household pets experience similar changes in blood chemistry markers. The proximity of small children and household pets to PFAS-treated carpets and floors, in addition to their tendency to put things into their mouths, potentially allows pets to serve as sentinels for household PFAS exposure. To assess the suitability of pets as indicators for exposure, researchers need to understand the most likely sources of PFAS exposure for household pets and identify the biomarkers of biological effects in those animals. Understanding these parameters may alert veterinary clinicians to potential sources of contamination in the home and ultimately protect the lives of the children and animals who live there.

Current per- and polyfluoroalkyl substance (PFAS) research points to a growing threat in animals.

Per- and polyfluoroalkyl substances (PFAS) are man-made chemicals that are colorless, odorless, and oil and water repellent. Their widespread use in manufacturing and industrial processes has resulted in environmental contamination found across the world. Exposure to PFAS can lead to a variety of adverse human health outcomes such as increased cholesterol, liver damage, immune suppression, and disruption of endocrine and reproductive systems. Exposure to this family of chemicals is considered a significant public health threat. Though nearly every human and animal around the world has been exposed, most of what is known regarding health effects and toxicological processes of PFAS in animals stems from human epidemiological and laboratory animal studies. Discoveries of PFAS contamination on dairy farms and concerns for companion animals have increased interest in PFAS research related to our veterinary patients. In the limited studies published to date, PFAS has been demonstrated in serum, liver, kidneys, and milk of production animals and has been linked to changes in liver enzymes, cholesterol levels, and thyroid hormones in dogs and cats. This is further addressed in the companion Currents in One Health by Brake et al, AJVR, April 2023. There is a gap in understanding the routes of exposure, absorption of PFAS, and adverse health effects among our veterinary patients. The purpose of this review is to summarize the current literature on PFAS in animals and discuss the implications for our veterinary patients.

Antimicrobial-resistant non-typhoidal Salmonella enterica prevalence among poultry farms and slaughterhouses in Chitwan, Nepal.

BACKGROUND AND AIM: Antibiotic-resistant infections are one of the leading threats to public health globally. Indiscriminate use of antibiotics in food animal production is an important driver of resistance, particularly among foodborne pathogens such as non-typhoidal Salmonella enterica (NTS). While there has been extensive research on antimicrobial-resistant (AMR) S. enterica in India and China, there have been few studies in countries in South Asia, including Nepal. This is particularly important with the rise of commercial poultry farming in Nepal as a means of economic development and nutritional subsistence. This descriptive study seeks to identify the prevalence and resistance patterns of NTS serotypes focusing on Chitwan, Nepal's leading poultry producing district. MATERIALS AND METHODS: A mixture of purposive and judgment sampling of 18 poultry farms and 20 slaughterhouses representing a broad geographic distribution across multiple municipalities in Chitwan was conducted in May 2019. Environmental samples taken from poultry farms included: Water, litter, feces, feed, farm swabs, and eggshell swabs. Biological samples taken from nearby slaughterhouses included: Muscle, heart, liver, skin, cecum, crop, and spleen. Samples were cultured and tested for the presence of NTS. Positive isolates were serotyped and tested for antimicrobial susceptibility to seven antibiotics known to be important to both human and animal health regionally. Farm practices were also characterized through a survey, the results of which are detailed in the accompanying paper. RESULTS: Out of 708 samples (288 environmental and 420 biological), 103 (15%) tested positive for NTS (9% of environmental; n=26, 18% of biological; n=77). The percentage of positive environmental and biological samples varied by source. Environmental sample positive rates were water (27.5%), feces (10.6%), litter (8.6%), farm swabs (5%), feed (1.8%), and eggshells (0%). Biological sample positive rates were skin (28%), heart (23%), crop (20%), muscle (15%), liver (15%), spleen (15%), and cecum (12%). Out of 103 positive S. enterica isolates, 48.5% were identified as Salmonella Typhimurium, 35% Salmonella Enteritidis, 7.8% Salmonella Gallinarum, 4.9% Salmonella Virchow, and 3.9% were Salmonella Agona. Of the 103 positive isolates, 80 (78%) were resistant to at least one antibiotic, and 21 (20%) were multidrug-resistant (MDR). CONCLUSION: NTS is highly prevalent among Chitwan's growing poultry industry with higher rates of positivity found in slaughterhouse samples compared with environmental samples from farms. In addition, a high rate of AMR (78%) was revealed, and an extremely concerning number of those were shown to be MDR (20%). This baseline data has important implications for poultry production and consumption in the region. Further research will elucidate the extent to which this contamination and drug resistance is impacting the health of the local population and help inform treatment and management strategies.Note: The characterization of the poultry industry and practices that might be linked to NTS contamination in the Chitwan district are detailed in the previous paper in this series (www.veterinaryworld.org/Vol.14/February-2021/14.pdf).

Prevalence of non-typhoidal Salmonella and risk factors on poultry farms in Chitwan, Nepal.

BACKGROUND AND AIM: Poultry is becoming an increasingly important source of protein in the Nepalese diet. The Chitwan region of Nepal is the hub of the emerging poultry industry. Little is known about the prevalence of non-typhoidal Salmonella (NTS) on poultry farms or the role of farm management practices that may contribute to the presence of NTS on farms. The role of poultry in the transmission of Salmonella enterica to humans is also poorly defined. This descriptive study seeks establish baseline data through estimation of the prevalence of NTS on broiler and layer operations in various farms of the Chitwan district of Nepal. MATERIALS AND METHODS: Based on district documents on poultry production and meat marketing, a purposive sampling of 18 commercial poultry farms comprising ten broilers farms and eight layers farms was conducted. Environmental samples including water, litter, feces, feed, farm, and eggshell swabs were randomly collected from each farm. Samples were cultured and tested for the presence of NTS; positives were serotyped, and antimicrobial susceptibility determined. A comprehensive farm and practice questionnaire was administered to each farm manager. RESULTS: The farm level point prevalence rate was 55% (10 of 18 farms) for S. enterica. Of the total 288 farm environmental samples collected, 26 samples (9%) were positive. The rate of isolation varied according to the origin of samples: Water (27.5%), feces (10.6%), litter (8.6%), farm swabs (5%), feed (1.8%), and eggshells (0%). Farm management variables/risk factors are summarized and categorized as non-modifiable and modifiable for analysis. Broiler operations were more likely to be positive than layer operations as were poultry houses with two or less open sides. All-in/all-out management style was found to be protective. Due to the small sample size (18 farms), no associations reached statistical significance. CONCLUSION: Based on environmental sampling results, NTS is highly prevalent on the poultry farms in the Chitwan district of Nepal. Certain risk factors are associated with finding NTS on farms. Our findings are generally in agreement with other studies in similar countries with rapidly emerging poultry industries. The identification of risk factors provides owners, technicians, and veterinarians with some guidance to help reduce the prevalence of NTS on farms. This baseline data are critical to understanding the epidemiology of zoonotic strain of NTS in the region and are necessary for the design of future studies and mitigation plans and underlines the need for a one-health approach to protect public health-related to Salmonella spp. from poultry farms.

Demographic and urban environmental variables associated with dog bites in Detroit.

OBJECTIVE: To identify demographic and urban environmental variables associated with prevalence rates of dog bites per zip code in Detroit. DESIGN: Retrospective ecological study. SAMPLE: 6,540 people who visited any 1 of 15 hospital emergency rooms in the 29 zip codes in Detroit between January 1, 2006, and December 31, 2013, with a primary complaint of dog bite. PROCEDURES: The number of dog bites over the study period was determined per zip code. Data for the human population in each zip code in 2011 and demographic and urban environmental variables were obtained from federal, state, and municipal databases. The prevalence rate of dog bites in each zip code was calculated, and regression analysis was used to identify variables associated with this outcome. RESULTS: Results of multivariate analysis indicated that demographic variables (eg, gender, age, and education) accounted for 23.2% (adjusted R2 = 0.232) of the variation in prevalence rates of dog bites per zip code, whereas urban environmental variables (eg, blight, crime with weapons, and vacancy rate) accounted for 51.6% (adjusted R2 = 0.516) of the variation. CONCLUSIONS AND CLINICAL RELEVANCE: Findings suggested that demographic variables had poor association with variation in prevalence rates of dog bites per zip code, whereas urban environmental variables, particularly crime, vacancy rate, and blight, were better associated. Thus, public health and education policies need to address these urban environmental issues to lower the prevalence of dog bites in distressed urban areas.

Epidemiological Study of Mycobacterium bovis Infection in Buffalo and Cattle in Amazonas, Brazil.

Bovine Tuberculosis (BTB) is an endemic disease in about one hundred countries, affecting the economy causing a decrease in productivity, condemnation of meat, and damaging the credibility on international trade. Additionally, Mycobacterium bovis the major causative agent for BTB can also infect humans causing a variety of clinical presentations. The aim of this study was to determine BTB prevalence and the main risk factors for the Mycobacterium bovis prevalence in cattle and buffalos in Amazonas State, Brazil. Tissue samples from 151 animals (45 buffalo and 106 cattle from five herds with buffalo only, 22 herds with cattle only, and 12 herds with buffalo and cattle) were obtained from slaughterhouses under State Veterinary Inspection. M. bovis were isolated on Stonebrink medium. The positive cultures were confirmed by polymerase chain reaction (PCR) testing. The apparent herd and animal prevalence rates were 56.4 and 5.40%, respectively. Regarding animal species, the apparent prevalence rates were 3% in cattle and 11.8% in buffalo. Generalized Linear Mixed Models (GLMM) with random effect were used to assess the association with risk factors on the prevalence. Species (buffalo), herds size (>100 animals) and the presence of both species (buffalo and cattle) in the herd were the major risk factors for the infection by Mycobacterium bovis in the region. The findings reveal an urgent need for evidence-based effective intervention to reduce BTB prevalence in cattle and buffalo and prevent its spread to the human population. Studies are needed to understand why buffalo are more likely to be infected by M. bovis than cattle in Amazon. Recommendations for zoning, use of data from the inspection services to generate information regarding BTB focus, adoption of epidemiological tools, and discouragement of practices that promote the mixing of cattle and buffalo, were made.

Prevalence of Bovine Leukemia Virus Antibodies in US Dairy Cattle.

OBJECTIVE: To estimate current US herd-level and animal-level prevalence of bovine leukemia virus (BLV) in dairy cows and characterize epidemiologic features. DESIGN: Cross-sectional observational study design and survey. ANIMALS: 4120 dairy cows from 103 commercial dairy herds in 11 states across the US. PROCEDURES: Milk samples were collected from dairy cows through routine commercial sampling and tested for anti-BLV antibodies by antibody capture ELISA. Based on the ELISA results of a sample of an average of 40 cows per herd, within-herd apparent prevalence (AP) was estimated by a directly standardized method and by a lactation-weighted method for each herd. Within-herd AP estimates were summarized to give estimates of US herd-level and animal-level AP. Differences in AP by lactation, region, state, breed, and herd size were examined to characterize basic epidemiologic features of BLV infection. RESULTS: 94.2% of herds had at least one BLV antibody positive cow detected. The average within-herd standardized AP was 46.5%. Lactation-specific AP increased with increasing lactation number, from 29.7% in first lactation cows to 58.9% in 4th and greater lactation cows. Significant differences were not observed based on region, state, breed, or herd size. CONCLUSIONS AND CLINICAL RELEVANCE: These results are consistent with a historical trend of increasing prevalence of BLV among US dairy cattle. Given the findings of other studies on the negative impacts of BLV infection on milk production and cow longevity, these findings are clinically relevant for veterinarians counseling dairy clients on the risks of BLV to their herds.

Michigan Clostridium difficile hospital discharges: frequency, mortality, and charges, 2002-2008.

OBJECTIVE: Clostridium difficile (C. difficile) causes an intestinal bacterial infection of increasing importance in Michigan residents and health-care facilities. The specific burden and health-care costs of C. difficile infection (CDI) were previously unknown. We evaluated the frequency, mortality, and health-care charges of CDI from Michigan hospital discharge data. METHODS: The Michigan Department of Community Health purchased discharge data from all Michigan acute care hospitals from the Michigan Health and Hospital Association. We extracted all hospital discharges from 2002 through 2008 containing the International Classification of Diseases, Ninth Revision code for intestinal infection due to C. difficile. Discharges were stratified by principle diagnosis and comorbidity level. Total hospitalization charges were standardized to the 2008 U.S. dollar. RESULTS: From 2002 through 2008, 68,686 hospital discharges with CDI occurred. The annual rate increased from 463.1 to 1096.5 CDI discharges per 100,000 discharges. CDI discharge rates were substantially higher among the elderly, females, and black people. Of all CDI discharges, 5,924 (8.6%) patients died. The mean total health-care charge for the time period was $67,149, and the annual mean increased 35% from 2002 to 2008. Hospital charges varied significantly by race/ethnicity and age. People with Medicaid insurance accrued the highest charges. CONCLUSION: Across Michigan, the CDI burden is growing substantially and affecting vulnerable populations. Surveillance utilizing hospital discharge data can illuminate trends and inform intervention targets. To reduce disease and health-care charges, increased prevention and infection-control efforts should be directed toward high-risk populations, such as the elderly.

Public health surveillance for methicillin-resistant Staphylococcus aureus: comparison of methods for classifying health care- and community-associated infections.

OBJECTIVES: We compared 3 methods for classifying methicillin-resistant Staphylococcus aureus (MRSA) infections as health care associated or community associated for use in public health surveillance. METHODS: We analyzed data on MRSA infections reported to the Michigan Department of Community Health from October 1, 2004, to December 31, 2005. Patient demographics, risk factors, infection information, and susceptibility were collected for 2151 cases. We classified each case by the health care risk factor, infection-type, and susceptibility pattern methods and compared the results of the 3 methods. RESULTS: Demographic, clinical, and microbiological variables yielded similar health care-associated and community-associated distributions when classified by risk factor and infection type. When 2 methods yielded the same classifications, the overall distribution was similar to classification by 3 methods. No specific combination of 2 methods was superior. CONCLUSIONS: MRSA categorization by 2 methods is more accurate than it is by a single method. The health care risk factor and infection-type methods yield comparable classification results. Accuracy is increased by using more variables; however, further research is needed to identify the optimal combination.

Case-control study of disease determinants for non-typhoidal Salmonella infections among Michigan children.

BACKGROUND: Infections with Salmonella serotypes continue to be a significant global public health problem. In addition to contaminated foods, several other sources contribute to infections with Salmonella serotypes. We have assessed the role of socioeconomic factors, exposure to food, and environmental sources in the etiology of non-typhoidal Salmonella infections in Michigan children. FINDINGS: A case-control study among Michigan children aged

Veterinarian injuries associated with bovine TB testing livestock in Michigan, 2001.

Testing all the cattle in an entire state with a uniform procedure for each animal affords an opportunity to relate human injury data to a known number of animals handled while carrying out a standardized procedure. Our objective was to describe the type and incidence density of injuries associated with TB-testing a large number of cattle herds, and to delineate the various factors associated with the risk of injury. A survey was mailed to all veterinarians (N = 259) who had completed at least five official bovine TB (bTB) herd tests in Michigan in 2001. We collected data regarding basic demographics and health status, work experience, veterinary specialty, and practice information. Each veterinarian was also requested to complete a separate injury questionnaire for each injury received while TB testing livestock in 2001. Accurate addresses were found for 247 eligible veterinarians, 175 (71%) of whom returned the survey. Thirty-six veterinarians reported a total of 53 injuries (10 major, 12 minor and 31 self-treated). Hands (29%) and legs (21%) were the anatomic locations most frequently injured, with sprains/strains (30%) and abrasion/contusion (30%) the most common types of injuries sustained. The overall incidence density of injuries was 1.9 per 10,000 animals tested. Female gender (RR = 3.3), being employed by the government (RR = 4.5), and smoking (RR = 6.0) were significantly associated with a higher rate of injury. Significant colliniearities were found between some risk factors associated with an increased rate of injury and participants thought 81% of their injuries could have been prevented. These results are explained by the administrative structure of the bTB testing program in Michigan, and the changing demographics of the veterinary workforce.

Human Mycobacterium bovis infection and bovine tuberculosis outbreak, Michigan, 1994-2007.

Mycobacterium bovis is endemic in Michigan's white-tailed deer and has been circulating since 1994. The strain circulating in deer has remained genotypically consistent and was recently detected in 2 humans. We summarize the investigation of these cases and confirm that recreational exposure to deer is a risk for infection in humans.

Vancomycin-resistant Staphylococcus aureus in the United States, 2002-2006.

BACKGROUND: This report compares the clinical characteristics, epidemiologic investigations, infection-control evaluations, and microbiologic findings of all 7 of the cases of vancomycin-resistant Staphylococcus aureus (VRSA) infection in the United States during the period 2002-2006. METHODS: Epidemiologic, clinical, and infection-control information was collected. VRSA isolates underwent confirmatory identification, antimicrobial susceptibility testing, pulsed-field gel electrophoresis, and typing of the resistance genes. To assess VRSA transmission, case patients and their contacts were screened for VRSA carriage. RESULTS: Seven cases were identified from 2002 through 2006; 5 were reported from Michigan, 1 was reported from Pennsylvania, and 1 was reported from New York. All VRSA isolates were vanA positive and had a median vancomycin minimum inhibitory concentration of 512 microg/mL. All case patients had a history of prior methicillin-resistant S. aureus and enterococcal infection or colonization; all had several underlying conditions, including chronic skin ulcers; and most had received vancomycin therapy prior to their VRSA infection. Person-to-person transmission of VRSA was not identified beyond any of the case patients. Infection-control precautions were evaluated and were consistent with established guidelines. CONCLUSIONS: Seven patients with vanA-positive VRSA have been identified in the United States. Prompt detection by microbiology laboratories and adherence to recommended infection control measures for multidrug-resistant organisms appear to have prevented transmission to other patients.

Epidemiologic attributes of invasive non-typhoidal Salmonella infections in Michigan, 1995--2001.

OBJECTIVES: To determine: (1) the incidence of invasive salmonellosis, (2) the distribution of specific Salmonella serotypes associated with invasive disease, and (3) the role of demographic characteristics in invasive salmonellosis in Michigan. DESIGN: We conducted a cross-sectional study using laboratory-confirmed cases of salmonellosis reported to the Michigan Department of Community Health between 1995 and 2001. METHODS: Average annual incidences (AAIs) for invasive salmonellosis were computed, and Poisson regression analysis was used to model the association between demographic attributes and invasive salmonellosis. RESULTS: Of 6797 cases of salmonellosis, 347 (5.1%) were characterized as invasive having an AAI of 0.5/100000. A covariate-adjusted Poisson model showed children aged <1 year to be at higher risk for invasive salmonellosis compared to adults aged 40-49 years (rate ratio (RR) 8.98, 95% confidence interval (CI) 5.69-14.17). No significant differences were found between males and females (RR 1.02, 95% CI 0.83-1.26), African-Americans and Caucasians (RR 0.95, 95% CI 0.64-1.42), and urban and rural residents (RR 0.98, 95% CI 0.76-1.26). Among the most common serotypes associated with invasive salmonellosis (Heidelberg, Typhimurium, and Enteritidis), Salmonella serotype Heidelberg had the highest blood invasiveness ratio (15.79/100). CONCLUSIONS: Children aged <1 year, especially of minority groups, are at higher risk for invasive Salmonella infections. Invasive salmonellosis may be included in the differential diagnosis of acute bacterial infections in young children with positive stool cultures for Salmonella.

A registry-based study on the association between human salmonellosis and routinely collected parameters in Michigan, 1995-2001.

PURPOSE: Salmonella serotypes are among the most common bacterial causes of foodborne gastroenteritis in the United States, associated with approximately 1.4 million human illnesses annually. Studies on trends of the serotypes and host-related factors are necessary for the development of effective prevention plans for foodborne diseases caused by these pathogens. MATERIALS AND METHODS: To determine the epidemiologic trends of human infections with the most common Salmonella serotypes in Michigan, we analyzed cases of culture-confirmed salmonellosis at the Michigan Department of Community Health (MDCH) from 1995 to 2001. RESULTS: A total of 6797 cases were reported, with an average annual incidence per 100,000 population (AAI) of 9.9. Among cases for which information on Salmonella serotype were available (6292 cases), the most common serotypes were S. Typhimurium (1596 cases, 26%), followed by S. Enteritidis (1309, 22%), S. Heidelberg (466, 8%) and S. Newport (222, 4%). From 1998 to 2001, the incidence of S. Typhimurium and S. Enteritidis decreased significantly by 39% (95% confidence interval [CI], 49% to 26% decrease) and 32% (95% CI, 44% to 18% decrease) respectively. Whereas the incidence of S. Newport increased by 101% (95% CI, 25% to 225% increase) and S. Heidelberg remained stable. Infection with these serotypes frequently occurred in the summer months. As a group, infants had the highest AAI for all Salmonella serotypes (75.0), S. Typhimurium (21.9), S. Enteritidis (14.0), S. Heidelberg (5.4), and S. Newport (1.7). Among patients whose race was known, blacks had a significantly higher AAI compared to whites for S. Typhimurium (2.5 vs. 1.3; RR = 2.3, 95% CI, 1.6-3.3), S. Enteritidis (1.4 vs. 1.1; relative rate (RR) = 1.4; 95% CI, 1.1-1.6), S. Heidelberg (0.8 vs. 0.3; RR = 3.6; 95% CI, 2.8-4.6), and S. Newport (0.3 vs. 0.1; RR = 2.8; 95% CI, 1.9-4.2). Among patients whose ethnicity was known, Hispanics had a significantly higher AAI for S. Enteritidis compared to non-Hispanics (1.0 vs. 0.5; RR = 1.9; 95% CI, 1.2-3.0), but not different significantly for S. Typhimurium, S. Heidelberg, and S. Newport. CONCLUSION: This study revealed the emergence of S. Newport and the high incidence of the most common Salmonella serotypes among infants, people of African descent, and Hispanics. This information can be used by the state and local health departments of Michigan to enhance salmonellosis prevention efforts by rationalizing the allocation of appropriate public health resources and personnel.

Demographic risk factors and incidence of Salmonella enteritidis infection in Michigan.

Salmonella Enteritidis is a major cause of foodborne disease worldwide. In the United States, this serotype has been associated with significant morbidity and mortality accounting for about 17% of all human Salmonella infections. Data on risk factors associated with serotype-specific Salmonella infections have not been reported in Michigan before. We carried out this study using surveillance data to identify high-risk groups and regions for S. Enteritidis infection in Michigan. Results of this study may be used to develop better control and prevention measures against this common foodborne pathogen. We analyzed data on Salmonella infections collected by the Michigan Department of Community Health's surveillance system (1995-2001). We computed age, gender, and place of residence-specific incidences of S. Enteritidis infection in Michigan using population-based denominators. We used Poisson regression analysis to study the associations between S. Enteritidis infection and certain predictor demographic variables, while controlling for confounders and covariates. We found an overall 1.87/100,000 average annual S. Enteritidis incidence with 1.91/100,000 in females and 1.81/100,000 in males. A higher incidence of S. Enteritidis infection was associated with Michigan children<5 years old when compared with average national estimates (p<0.01). The final adjusted Poisson model revealed that children<1 year of age [RR: 9.75, CI: 7.99-11.90] and children 1-4 years of age [RR: 3.37, CI: 2.83-4.02] are at higher risk for S. Enteritidis infection compared to adults aged 15-39 years. No significant differences in incidence of S. Enteritidis infections were found between urban and rural dwellers or between genders (p>0.05). The incidence rate of S. Enteritidis infection in the Michigan pediatric population (<5 years) was found to be significantly higher than average national estimates, meriting immediate public health attention. Risk factors for S. Enteritidis infection in Michigan children should be identified in order to devise effective control and prevention measures.