Foodborne Disease Outbreaks Linked to Foods Eligible for Irradiation, United States, 2009-2020.

Food irradiation can reduce foodborne illnesses but is rarely used in the United States. We determined whether outbreaks related to Campylobacter, Salmonella, Escherichia coli, and Listeria monocytogenes were linked to irradiation-eligible foods. Of 482 outbreaks, 155 (32.2%) were linked to an irradiation-eligible food, none of which were known to be irradiated.

Multistate nontyphoidal Salmonella and Shiga toxin-producing Escherichia coli outbreaks linked to international travel-United States, 2017-2020.

Enteric bacterial infections are common among people who travel internationally. During 2017-2020, the Centers for Disease Control and Prevention investigated 41 multistate outbreaks of nontyphoidal Salmonella and Shiga toxin-producing Escherichia coli linked to international travel. Resistance to one or more antimicrobial agents was detected in at least 10% of isolates in 16 of 30 (53%) nontyphoidal Salmonella outbreaks and 8 of 11 (73%) Shiga toxin-producing E. coli outbreaks evaluated by the National Antimicrobial Resistance Monitoring System. At least 10% of the isolates in 14 nontyphoidal Salmonella outbreaks conferred resistance to one or more of the clinically significant antimicrobials used in human medicine. This report describes the epidemiology and antimicrobial resistance patterns of these travel-associated multistate outbreaks. Investigating illnesses among returned travellers and collaboration with international partners could result in the implementation of public health interventions to improve hygiene practices and food safety standards and to prevent illness and spread of multidrug-resistant organisms domestically and internationally.

Salmonella Outbreaks Associated with Not Ready-to-Eat Breaded, Stuffed Chicken Products - United States, 1998-2022.

Not ready-to-eat (NRTE) breaded, stuffed chicken products (e.g., chicken stuffed with broccoli and cheese) typically have a crispy, browned exterior that can make them appear cooked. These products have been repeatedly linked to U.S. salmonellosis outbreaks, despite changes to packaging initiated in 2006 to identify the products as raw and warn against preparing them in a microwave oven (microwave) (1-4). On April 28, 2023, the U.S. Department of Agriculture proposed to declare Salmonella an adulterant* at levels of one colony forming unit per gram or higher in these products (5). Salmonella outbreaks associated with NRTE breaded, stuffed chicken products during 1998-2022 were summarized using reports in CDC's Foodborne Disease Outbreak Surveillance System (FDOSS), outbreak questionnaires, web postings, and data from the Minnesota Department of Health (MDH)† and the U.S. Department of Agriculture's Food Safety and Inspection Service (FSIS). Eleven outbreaks were identified in FDOSS. Among cultured samples from products obtained from patients' homes and from retail stores during 10 outbreaks, a median of 57% of cultures per outbreak yielded Salmonella. The NRTE breaded, stuffed chicken products were produced in at least three establishments.§ In the seven most recent outbreaks, 0%-75% of ill respondents reported cooking the product in a microwave and reported that they thought the product was sold fully cooked or did not know whether it was sold raw or fully cooked. Outbreaks associated with these products have occurred despite changes to product labels that better inform consumers that the products are raw and provide instructions on safe preparation, indicating that consumer-targeted interventions are not sufficient. Additional Salmonella controls at the manufacturer level to reduce contamination in ingredients might reduce illnesses attributable to NRTE breaded, stuffed chicken products.

Appliances Used by Consumers to Prepare Frozen Stuffed Chicken Products - United States, May-July 2022.

Frozen stuffed breaded raw chicken products have repeatedly been implicated in Salmonella outbreaks (1). These products are partially cooked to set the breading, often making them appear cooked (2). Despite their appearance, these products need to be cooked to an internal temperature of 165°F (74°C) to ensure that they are safe to eat. Producers began implementing labeling changes in 2006 to more clearly identify these products as raw; many warn against using microwave ovens (microwaves) to prepare them and provide validated cooking instructions solely for conventional ovens (ovens) (3,4). However, outbreaks continued to occur after implementation of these labeling changes (4). To describe the demographic characteristics of persons who prepare frozen stuffed chicken products and which appliances they use to prepare them, data from a May-July 2022 representative panel survey were analyzed. Although most (82.7%) respondents used an oven as one of their cooking methods, more than one half (54.0%) of respondents also used another appliance, including 29.0% who used a microwave. Oven use was lower among respondents with household income <$25,000 (68.9%), and who lived in mobile homes or other portable types of homes (66.5%). Among respondents who reported using microwaves to cook these products, 8% reported using a microwave with ≤750 W of power, which might be insufficient to thoroughly cook such products (1,5,6). Economic and other factors might influence some groups' access to recommended cooking appliances. Companies could consider implementing additional interventions that rely less on labeling and consumer preparation practices and focus on controlling or reducing levels of Salmonella in these products, such as selling them fully cooked, or monitoring and testing Salmonella levels, to ensure safety. These findings highlight challenges consumers might face in preparing frozen stuffed chicken products safely and can guide strategies for regulatory authorities and industry to prevent outbreaks and illnesses associated with them.

State Laws Requiring Hand Sanitation Stations at Animal Contact Exhibits-United States, March-April 2016.

In the United States, animal contact exhibits, such as petting zoos and agricultural fairs, have been sources of zoonotic infections, including infections with Escherichia coli, Salmonella, and Cryptosporidium (1-4). The National Association of State Public Health Veterinarians recommends handwashing after contact with animals as an effective prevention measure to disease transmission at these exhibits (4). This report provides a list of states that have used law, specifically statutes and regulations, as public health interventions to increase hand sanitation at animal contact exhibits. The report is based on an assessment conducted by CDC's Public Health Law Program, in collaboration with the Division of Foodborne, Waterborne, and Environmental Diseases in CDC's National Center for Emerging and Zoonotic Infectious Diseases. The assessment found that seven states have used statutes or regulations to require hand sanitation stations at these exhibits (5). Jurisdictions seeking to improve rates of hand sanitation at animal contact exhibits can use this report as a resource in developing their own legal interventions.

Vital Signs: Epidemiology of Sepsis: Prevalence of Health Care Factors and Opportunities for Prevention.

BACKGROUND: Sepsis is a serious and often fatal clinical syndrome, resulting from infection. Information on patient demographics, risk factors, and infections leading to sepsis is needed to integrate comprehensive sepsis prevention, early recognition, and treatment strategies. METHODS: To describe characteristics of patients with sepsis, CDC and partners conducted a retrospective chart review in four New York hospitals. Random samples of medical records from adult and pediatric patients with administrative codes for severe sepsis or septic shock were reviewed. RESULTS: Medical records of 246 adults and 79 children (aged birth to 17 years) were reviewed. Overall, 72% of patients had a health care factor during the 30 days before sepsis admission or a selected chronic condition likely to require frequent medical care. Pneumonia was the most common infection leading to sepsis. The most common pathogens isolated from blood cultures were Escherichia coli in adults aged ≥18 years, Klebsiella spp. in children aged ≥1 year, and Enterococcus spp. in infants aged <1 year; for 106 (33%) patients, no pathogen was isolated. Eighty-two (25%) patients with sepsis died, including 65 (26%) adults and 17 (22%) infants and children. CONCLUSIONS: Infection prevention strategies (e.g., vaccination, reducing transmission of pathogens in health care environments, and appropriate management of chronic diseases) are likely to have a substantial impact on reducing sepsis. CDC, in partnership with organizations representing clinicians, patients, and other stakeholders, is launching a comprehensive campaign to demonstrate that prevention of infections that cause sepsis, and early recognition of sepsis, are integral to overall patient safety.

Notes from the field: Adverse events associated with administration of simulation intravenous fluids to patients--United States, 2014.

On December 23, 2014, the New York State Department of Health (NYSDOH) was notified of adverse health events in two patients who had been inadvertently administered nonsterile, simulation 0.9% sodium chloride intravenous (IV) fluids at an urgent care facility. Simulation saline is a nonsterile product not meant for human or animal use; it is intended for use by medical trainees practicing IV administration of saline on mannequins or other training devices. Both patients experienced a febrile illness during product administration and were hospitalized; one patient developed sepsis and disseminated intravascular coagulation. Neither patient died. Staff members at the clinic reported having ordered the product through their normal medical supply distributor and not recognizing during administration that it was not intended for human use.

Q Fever Outbreak Among Travelers to Germany Who Received Live Cell Therapy--United States and Canada, 2014.

During September­November 2014, the New York State Department of Health (NYSDOH) was notified of five New York state residents who had tested seropositive for Coxiella burnetii, the causative agent of Q fever. All five patients had symptoms compatible with Q fever (e.g., fever, fatigue, chills, and headache) and a history of travel to Germany to receive a medical treatment called "live cell therapy" (sometimes called "fresh cell therapy") in May 2014. Live cell therapy is the practice of injecting processed cells from organs or fetuses of nonhuman animals (e.g., sheep) into human recipients. It is advertised to treat a variety of health conditions. This practice is unavailable in the United States; however, persons can travel to foreign locations to receive injections. Local health departments interviewed the patients, and NYSDOH notified CDC and posted a report on CDC's Epidemic Information Exchange to solicit additional cases. Clinical and exposure information for each patient was reported to the Robert Koch Institute in Germany, which forwarded the information to local health authorities. A Canada resident who also received live cell therapy in May 2014 was diagnosed with Q fever in July 2014. Clinicians should be aware of health risks, such as Q fever and other zoonotic diseases, among patients with a history of receiving treatment with live cell therapy products.

Examining Age and Food Irradiation Knowledge as Influential Factors on Purchase of Irradiated Foods - United States, August 2022.

Foodborne illness affects approximately 48 million Americans annually. Food irradiation is a safe and effective way to kill bacteria and extend a product's shelf-life. However, challenges to wider implementation of this technology include consumer hesitancy stemming from misconceptions about safety and lack of knowledge of irradiation's benefits. Research has shown that consumers are more willing to accept irradiation if informed about its safety. Due to increases in multistate foodborne outbreaks and consumers' growing concern and expectation of food safety, it is an opportune time to reconsider irradiation as a food safety tool. Consumer attitudes toward food safety differ by demographic characteristics; however, research on the association of demographic factors with attitudes on food irradiation are limited. Data collected from a survey (N=1,009) conducted in August 2022 were analyzed to describe the relationship between age and food irradiation knowledge as influential factors to purchase irradiated foods. More than half (56%) of respondents reported that learning more about irradiation would likely influence purchasing decisions; older adults were more knowledgeable about food irradiation. These findings suggest that age could be an important factor to consider when tailoring messaging as a prevention strategy around the benefits of food irradiation.

Responding to outbreaks of illness linked to unpasteurized milk: A needs assessment of state health and agriculture departments.

AIMS: Consumption of unpasteurized milk can result in severe illness or death. In the United States, the number of people who regularly consume unpasteurized milk is relatively low, but outbreaks resulting from unpasteurized milk outnumber outbreaks linked to pasteurized milk. The sale of unpasteurized milk for human consumption through interstate commerce is prohibited at the federal level, but laws among states vary considerably with respect to the sale of unpasteurized milk. Each state has a different perspective on responding to and preventing outbreaks of illness linked to consuming unpasteurized milk. METHODS AND RESULTS: We conducted a needs assessment of state health and agriculture departments to gather information on state-level strategies to prevent illnesses linked to consuming unpasteurized milk, characterize challenges states face, and identify areas where partners can support state efforts to prevent illnesses. We deployed a survey from 6 January 2021 to 1 March 2021, using a snowball sampling strategy and had 158 respondents. Of 115 respondents, 46 (40%) believed that state laws were ineffective in preventing illnesses, and 92 (80%) agreed that consumers continue to find ways to get unpasteurized milk despite laws restricting sale. Respondents from 19 states were aware of future legislative or regulatory efforts surrounding unpasteurized milk in their state, with 14 (74%) indicating these efforts would expand consumer access. The most common outbreak prevention strategies respondents mentioned included sharing knowledge and experiences with other public health and agriculture officials, providing information to inform legislative efforts, and communicating to the public about outbreaks. Most respondents (41/50, 91%) were interested in pursuing further efforts to prevent unpasteurized milk-associated illnesses in their state. CONCLUSIONS: The results from this needs assessment can be used to inform future strategies for preventing illness outbreaks associated with unpasteurized milk consumption.

Effect of Ground Beef Irradiation on Annual Nontyphoidal Salmonella and Escherichia coli O157 Burden and Direct Healthcare Costs in the United States: A Simulation Study.

Over 20% of E. coli O157 illnesses and over 5% of Salmonella illnesses are estimated to be attributable to beef consumption in the United States. Irradiating ground beef is one possible method to reduce disease burden. We simulated the effect of ground beef irradiation on illnesses, hospitalizations, deaths, and direct healthcare costs from ground beef-associated E. coli O157 and Salmonella illnesses in the United States. To estimate the fraction of illnesses, hospitalizations, deaths, and direct healthcare costs preventable by ground beef irradiation, we multiplied the disease burden attributable to ground beef; the estimated percentage of ground beef sold that is not currently irradiated; the percentage of unirradiated ground beef that would be irradiated; and the percentage reduction in risk of illness after irradiation. We multiplied this fraction by estimates of burden and direct healthcare costs to calculate the numbers or amounts averted. Model inputs were obtained from the literature and expert opinion. We used Monte Carlo simulation to incorporate uncertainty in inputs into model estimates. Simulation outcomes were summarized with means and 95% uncertainty intervals (UI). Irradiating 50% of the currently unirradiated ground beef supply would avert 3,285 (95% UI: 624-9,977) E. coli O157 illnesses, 135 (95% UI: 24-397) hospitalizations, 197 (95% UI: 34-631) hemolytic uremic syndrome cases, 2 (95% UI: 0-16) deaths, and $2,972,656 (95% UI: $254,708-$14,496,916) in direct healthcare costs annually. For Salmonella, irradiation would avert 20,308 (95% UI: 9,858-38,903) illnesses, 400 (95% UI: 158-834) hospitalizations, 6 (95% UI: 0-18) deaths, and $7,318,632 (95% UI: $1,436,141-$26,439,493) in direct healthcare costs. Increasing ground beef irradiation could reduce E. coli O157 and Salmonella burden in the United States. Additional studies should assess whether targeted irradiation of higher-risk ground beef products could prevent similar numbers of illnesses with less total product irradiated.

Salmonella Outbreaks Linked to Beef, United States, 2012-2019.

The Centers for Disease Control and Prevention (CDC) has identified nontyphoidal Salmonella as one of the top five pathogens contributing to foodborne illnesses in the United States. Beef continues to be a common source of Salmonella outbreaks, despite the implementation of interventions at slaughter and processing facilities to reduce contamination of beef. We described Salmonella outbreaks linked to beef in the United States during 2012-2019, examined trends, and identified potential targets for intervention and prevention strategies. We queried CDC's Foodborne Disease Outbreak Surveillance System (FDOSS) for all foodborne nontyphoidal Salmonella outbreaks linked to beef as the single contaminated ingredient or implicated food, with the date of first illness onset from 2012 to 2019. Information on antimicrobial resistance (AR) for outbreak-related isolates was obtained from CDC's National Antimicrobial Resistance Monitoring System (NARMS). We calculated the number of outbreaks, outbreak-related illnesses, hospitalizations, and deaths overall, by beef processing category and Salmonella serotype. During 2012-2019, 27 Salmonella outbreaks were linked to beef consumption, resulting in 1103 illnesses, 254 hospitalizations, and two deaths. The most common category of beef implicated was nonintact raw, ground beef (12 outbreaks, 44%), followed by intact raw (six outbreaks, 22%). Ground beef was responsible for the most illnesses (800, 73%), both of the reported deaths, and was the source of the largest outbreak. AR data were available for 717 isolates from 25 (93%) outbreaks. Nine (36%) of these outbreaks had isolates resistant to one or more of the antibiotics tested by NARMS, of which eight (89%) contained multidrug-resistant isolates. Several outbreaks reported highlight challenges faced during investigations, areas where further research may be warranted, and opportunities to prevent future outbreaks along the farm-to-fork continuum.

A Qualitative Evaluation of the Centers for Disease Control and Prevention Risk Communication Methods during Multistate Foodborne Outbreaks.

Many efforts across the farm-to-fork continuum aim to reduce foodborne disease and outbreaks. Real-time risk communication is an important component of the Centers for Disease Control and Prevention (CDC) efforts, especially during outbreaks. To inform risk communication with the public during multistate foodborne outbreaks, we conducted a series of focus groups of adults in the Washington, D.C., metropolitan area to understand attitudes, perceptions, behaviors, and how people receive information around foodborne disease outbreaks. Results from these focus groups provided insight on factors that might influence consumer perception and behavior during an outbreak. Perceived outbreak proximity and personal consumption of an outbreak vehicle were identified as also reported hearing about multiple outbreaks per year some drivers of perceived risk to an outbreak. Participants through a variety of sources and following recommended actions during an outbreak, implying some existing penetration of current risk messages for multistate foodborne outbreaks. Findings from these focus groups are a first step in increasing understanding of how CDC messages affect the consumers' ability to access and act upon reliable information to protect their health during outbreaks and serve as a baseline for further evaluation efforts of CDC risk communication strategy for multistate foodborne outbreaks.

Investigations of Possible Multistate Outbreaks of Salmonella, Shiga Toxin-Producing Escherichia coli, and Listeria monocytogenes Infections - United States, 2016.

PROBLEM/CONDITION: Salmonella, Shiga toxin-producing Escherichia coli (STEC), and Listeria monocytogenes are the leading causes of multistate foodborne disease outbreaks in the United States. Responding to multistate outbreaks quickly and effectively and applying lessons learned about outbreak sources, modes of transmission, and risk factors for infection can prevent additional outbreak-associated illnesses and save lives. This report summarizes the investigations of multistate outbreaks and possible outbreaks of Salmonella, STEC, and L. monocytogenes infections coordinated by CDC during the 2016 reporting period. PERIOD COVERED: 2016. An investigation was considered to have occurred in 2016 if it began during 2016 and ended on or before March 31, 2017, or if it began before January 1, 2016, and ended during March 31, 2016-March 31, 2017. DESCRIPTION OF SYSTEM: CDC maintains a database of investigations of possible multistate foodborne and animal-contact outbreaks caused by Salmonella, STEC, and L. monocytogenes. Data were collected by local, state, and federal investigators during the detection, investigation and response, and control phases of the outbreak investigations. Additional data sources used for this report included PulseNet, the national molecular subtyping network based on isolates uploaded by local, state, and federal laboratories, and the Foodborne Disease Outbreak Surveillance System (FDOSS), which collects information from state, local, and territorial health departments and federal agencies about single-state and multistate foodborne disease outbreaks in the United States. Multistate outbreaks reported to FDOSS were linked using a unique outbreak identifier to obtain food category information when a confirmed or suspected food source was identified. Food categories were determined and assigned in FDOSS according to a classification scheme developed by CDC, the Food and Drug Administration (FDA), and the U.S. Department of Agriculture Food Safety and Inspection Service (FSIS) in the Interagency Food Safety Analytics Collaboration. A possible multistate outbreak was determined by expert judgment to be an outbreak if supporting data (e.g., temporal, geographic, demographic, dietary, travel, or food history) suggested a common source. A solved outbreak was an outbreak for which a specific kind of food or animal was implicated (i.e., confirmed or suspected) as the source. Outbreak-level variables included number of illnesses, hospitalizations, cases of hemolytic uremic syndrome (HUS), and deaths; the number of states with illnesses; date of isolation for the earliest and last cases; demographic data describing patients associated with a possible outbreak (e.g., age, sex, and state of residence); the types of data collected (i.e., epidemiologic, traceback, or laboratory); the outbreak source, mode of transmission, and exposure location; the name or brand of the source; whether the source was suspected or confirmed; whether a food was imported into the United States; the types of regulatory agencies involved; whether regulatory action was taken (and what type of action); whether an outbreak was publicly announced by CDC via website posting; beginning and end date of the investigation; and general comments about the investigation. The number of illnesses, hospitalizations, cases of HUS, and deaths were characterized by transmission mode, pathogen, outcome (i.e., unsolved, solved with suspected source, or solved with confirmed source), source, and food or animal category. RESULTS: During the 2016 reporting period, 230 possible multistate outbreaks were detected and 174 were investigated. A median of 24 possible outbreaks was under investigation per week, and investigations were open for a median of 37 days. Of these 174 possible outbreaks investigated, 56 were excluded from this analysis because they occurred in a single state, were linked to international travel, or were pseudo-outbreaks (e.g., a group of similar isolates resulting from laboratory media contamination rather than infection in patients). Of the remaining 118 possible multistate outbreaks, 50 were determined to be outbreaks and 39 were solved (18 with a confirmed food source, 10 with a suspected food source, 10 with a confirmed animal source, and one with a suspected animal source). Sprouts were the most commonly implicated food category in solved multistate foodborne outbreaks (five). Chicken was the source of the most foodborne outbreak-related illnesses (134). Three outbreaks involved novel food-pathogen pairs: flour and STEC, frozen vegetables and L. monocytogenes, and bagged salad and L. monocytogenes. Eleven outbreaks were attributed to contact with animals (10 attributed to contact with backyard poultry and one to small turtles). Thirteen of 18 multistate foodborne disease outbreaks with confirmed sources resulted in product action, including 10 outbreaks with recalls, two with market withdrawals, and one with an FSIS public health alert. Twenty outbreaks, including 11 foodborne and nine animal-contact outbreaks, were announced to the public by CDC via its website, Facebook, and Twitter. These announcements resulted in approximately 910,000 webpage views, 55,000 likes, 66,000 shares, and 5,800 retweets. INTERPRETATION: During the 2016 reporting period, investigations of possible multistate outbreaks occurred frequently, were resource intensive, and required a median of 37 days of investigation. Fewer than half (42%) of the 118 possible outbreaks investigated were determined to have sufficient data to meet the definition of a multistate outbreak. Moreover, of the 50 outbreaks with sufficient data, approximately three fourths were solved. PUBLIC HEALTH ACTION: Close collaboration among CDC, FDA, FSIS and state and local health and agriculture partners is central to successful outbreak investigations. Identification of novel outbreak sources and trends in sources provides insights into gaps in food safety and safe handling of animals, which helps focus prevention strategies. Summarizing investigations of possible multistate outbreaks can provide insights into the investigative process, improve future investigations, and help prevent illnesses. Although identifying and investigating possible multistate outbreaks require substantial resources and investment in public health infrastructure, they are important in determining outbreak sources and implementing prevention and control measures.

Preventing Human Salmonella Infections Resulting from Live Poultry Contact through Interventions at Retail Stores.

The number of outbreaks of Salmonella infections linked to live poultry contact increased from 1990 to 2016. In 2016, the number of human illnesses linked to live poultry was the highest reported, with more than 900 cases, including 209 hospitalizations and three deaths. Live poultry harboring Salmonella typically appear healthy but can intermittently shed bacteria in their droppings, contaminating their feathers, beaks, and the areas where they live and roam. Thus, both direct contact with poultry and indirect contact with anything in areas where animals live and roam can result in human Salmonella infection. To prevent Salmonella infections linked to live poultry, a One Health approach for control and prevention is required. This approach unifies animal and human health needs and takes into account the environments at the hatcheries where poultry are produced, the agricultural retail stores where poultry are sold, and the customers who own and raise poultry. Agricultural retail stores are the main point of sale for backyard poultry in the U.S. Therefore, stores can play a vital role in preventing infections by sourcing poultry from hatcheries that take steps to reduce Salmonella in the environment, by displaying poultry in areas that can be easily cleaned, and by using barriers that allow customers to view, but not touch, poultry from a distance. Retail store employees also have a role in preventing illnesses and contamination after the sale by educating customers about appropriate housing for live poultry in outdoor coops, barns, or other designated areas.

Two Imported Cases of Congenital Rubella Syndrome and Infection-Control Challenges in New York State, 2013-2015.

Rubella was declared eliminated in the United States in 2004. During 2013-2015, 2 infants with congenital rubella syndrome (CRS) were born in New York State. Both mothers were foreign born and traveled to Yemen during their pregnancy. Delayed consideration of CRS led to preventable exposures and a substantial public health response.

Impact of livestock hygiene education programs on mastitis in smallholder water buffalo (Bubalus bubalis) in Chitwan, Nepal.

A project implemented from 2003 to 2005 trained women in Chitwan District, Nepal, in hygienic dairy production using a process of social mobilization. The aim of this research was to assess if the prevalence of mastitis in water buffalo in the households of women who were trained was lower one year after training than in untrained households, if the training influenced knowledge and practices for the prevention or control of mastitis, and if these practices and knowledge were associated with a lower prevalence of mastitis. A total of 202 households from Eastern and Western Chitwan District were included in the study. Of these, 60 households had participated in the project and 142 had not. Milk samples were collected from 129 households (33 project households and 96 non-project households). Clinical mastitis was determined using visual inspection of udders and detection of macroscopic clots and flakes in milk. The California Mastitis Test was used to diagnose sub-clinical mastitis from milk samples, and the IDEXX SNAP test to identify the presence of tetracycline residues. The prevalence of mastitis in trained households (39.4%) was 43.78% of that in untrained households (60.4%), lower but not significantly so (p=0.08, 95% CI 0.17-1.12). Thirteen indicators of knowledge or practice for the control or prevention of mastitis were more likely to occur in trained households, four significantly so (not consuming milk from sick buffalo (p=0.001), using soap to wash hands before milking (p=0.001), discarding milk after antibiotic usage (p=0.01), and choosing appropriate flooring for their livestock (p=0.03)). Trained households that discarded milk from sick buffalo were 2.96 times more likely to have at least one animal with mastitis in the household (p=0.03, 95% CI 1.15-7.65). Trained households that knew to wash buffalos' teats after milking were less likely (OR 0.25) to have mastitis in their herd (p=0.02, 95% CI 0.08-0.80). Of the 138 buffalos tested, only one tested positive for tetracycline residues.