Prevalence and antimicrobial resistance in Salmonella enterica isolated from broiler chickens, pigs and meat products in Thailand-Cambodia border provinces.

This study aimed to examine the prevalence and antimicrobial resistance (AMR) of Salmonella isolates from broiler chickens, pigs and their associated meat products in the Thailand-Cambodia border provinces. A total of 941 samples were collected from pigs and broiler chickens at slaughter houses and from carcasses at local fresh markets in Sa Kaeo, Thailand (n = 554) and Banteay Meanchey, Cambodia (n = 387) in 2014 and 2015. From these samples, 345 Salmonella isolates were collected from Sa Keao (n = 145; 23%) and Banteay Meanchey (n = 200; 47%) and assayed for antimicrobial susceptibility, class 1 integrons and extended-spectrum ß-lactamase (ESBL) genes. Serovars Typhimurium (29%) and Rissen (29%) were the most common serotypes found in Thai and Cambodian isolates, respectively. Multidrug resistance was detected in 34% and 52% of isolates from Sa Keao and Banteay Meanchey, respectively. The majority of the Thai isolates were resistant to ampicillin (72.4%), whereas most Cambodian isolates were resistant to sulfamethoxazole (71%). Eleven isolates from Sa Keao and 44 from Banteay Meanchey carried class 1 integrons comprising resistance gene cassettes. The most common gene cassette array was dfrA12-aadA2 (61.1%). Six isolates were ESBL producers. The ß-lactamase genes found included blaTEM-1 , blaCTX-M-55 and blaCMY-2 . Some of these class 1 integrons and ESBL genes were located on conjugative plasmid. In conclusion, multidrug-resistant Salmonella are common in pigs, chickens and their products in the Thailand-Cambodia border provinces. Our findings indicate that class 1 integrons play a role in spread of AMR in the strains in this study.

SURVEILLANCE IN 2013 OF AVIAN INFLUENZA VIRUS FROM LIVE-BIRD MARKETS IN BANGKOK, THAILAND.

Live-bird markets have been implicated in transmission of avian influenza viruses, most recently of influenza A (H7N9) in China. Low pathogenic avian influenza (LPAI) viruses, such as H7N9, cause asymptomatic infections in poultry, and active surveillance is required to detect infection and to prevent transmission to humans. Although limited numbers of live birds for consumption are sold in Bangkok live bird markets (LBM), transmission of H7N9 in nearby China has prompted a program of active surveillance for avian influenza in Bangkok LBM to determine LPAI viruses. In November 2013, Bangkok One Health team organized avian influenza surveillance in all nine districts of Bangkok with LBMs. Oropharyngeal swabs (n = 834), sera (n = 375) and fresh feces (n = 420) were taken from 400 chickens, 20 ducks, 20 geese and 394 pet birds from 75/87 shops. Additionally, drinking water (n = 208) and waste water (n = 26) were collected. Samples were tested for influenza A viruses using RT-PCR. In addition, samples were inoculated in eggs and tested by hemagglutination (HA) and hemagglutination inhibition (HI) assays using H5N1- and H7N9-specific antigens. Sera were tested by HI assay using similar antigens. No sample was found positive for influenza A virus. These data provide evidence that avian influenza viruses, including LPAI viruses such as H7N9, were not circulating in Bangkok LBMs during the period surveyed.

GENETIC AND IMMUNOLOGICAL EVIDENCES OF BORRELIA BURGDORFERI IN DOG IN THAILAND.

Lyme disease is a tick-borne zoonotic disease caused by spirochete Borrelia burgdorferi. It is transmitted from animals to humans by the bite of infected ticks of the genus Ixodes. Although Lyme disease has been reported in China and Japan, the disease has never been reported in Thailand. Blood samples and ticks were collected from 402 dogs from 7 and 3 animal clinics in Chiang Mai and Phuket Provinces, Thailand, respectively. Blood samples were tested for antibodies against B. burgdorferi, Anaplasma spp, Ehrlichia spp and Dirofilaria immitis using a commercial kit, and positive blood samples were subjected to nested PCR assay for B. burgdorferi fla, ospA and ospC, amplicons of which also were sequenced. Only one dog (from Chiang Mai) was positive for B. burgdorferi, with 97% to 100% genetic identity, depending on the sequences used for comparison, with strains from United State of America. All 376 ticks collected were Rhipicephalus sanguineus, but no tick was found on the infected dog. Further investigations of the infection source and vector are needed to understand potential risks of Lyme disease to dogs and humans in Thailand.

A review and meta-analysis of non-typhoidal Salmonella in Vietnam: Challenges to the control and antimicrobial resistance traits of a neglected zoonotic pathogen.

Non-typhoidal Salmonella (NTS) is a food-borne zoonotic pathogen with important implications for human health. Despite its importance, the burden of NTS infections in Vietnam is unknown. We conducted a systematic review and a meta-analysis to describe the prevalence and phenotypic antimicrobial resistance (AMR) for NTS over time in Vietnam. Following PRISMA guidelines, we identified 72 studies from PubMed and Google Scholar containing data relevant to 'Salmonella', 'Salmonellosis', and 'Vietnam', or 'Viet Nam'. Of those, forty-two papers reporting prevalence of NTS, and twenty-six including data on phenotypic resistance were selected for meta-analysis. The prevalence of NTS ranged from 2% to 5% in humans and from 30% to 41% in samples from animals and the farm/slaughterhouse environment. Between 2000 and 2020 we observed a 27.3% (p = 0.044) increase in absolute terms in prevalence among individuals with enteric diseases and a 12.0% (p = 0.047) increase in aquaculture/seafood samples. The most commonly serovars identified across studies included S. Weltevreden (12.0%), followed by S. Typhimurium (10.1%), S. Derby (6.4%), S. London (5.8%), S. Anatum (4.4%), S. Rissen (3.9%), S. Enteritidis (3.7%), S. Albany (3.3%) and S. 4,[5],12:i:- (3.0%). Over the same period, there was an increasing trend in the pooled AMR prevalence for quinolones (15.6% relative increase), 3rd-, 4th-, and 5th-generation cephalosporins (23.7%), penicillins (16.1%), tetracyclines (12.9%), sulfonamides (8.8%), amphenicol (17.8%), and multidrug resistance (11.4%) (all p ≤ 0.014). A broad range of AMR genes (ARGs) were detected in both human and animal populations. The observed prevalence and AMR trends in Vietnam underscore the need of adopting a One Health strategy encompassing surveillance systems, research initiatives, and awareness campaigns to effectively address the challenges posed by NTS.

Field and laboratory investigation of highly pathogenic avian influenza H5N6 and H5N8 in Quang Ninh province, Vietnam, 2020 to 2021.

BACKGROUND: Avian influenza (AI) is a contagious disease that causes illness and death in poultry and humans. High pathogenicity AI (HPAI) H5N6 outbreaks commonly occur in Quang Ninh province bordering China. In June 2021, the first HPAI H5N8 outbreak occurred at a Quang Ninh chicken farm. OBJECTIVES: This study examined the risk factors associated with HPAI H5N6 and H5N8 outbreaks in Quang Ninh. METHODS: A retrospective case-control study was conducted in Quang Ninh from Nov 2021 to Jan 2022. The cases were households with susceptible poultry with two or more clinical signs and tested positive by real-time reverse transcription polymerase chain reaction. The controls were households in the same village as the cases but did not show clinical symptoms of the disease. Logistic regression models were constructed to assess the risk factors associated with HPAI outbreaks at the household level. RESULTS: There were 38 cases with H5N6 clade 2.3.4.4h viruses (n = 35) and H5N8 clade 2.3.4.4b viruses (n = 3). Compared to the 112 controls, raising poultry in uncovered or partially covered ponds (odds ratio [OR], 7.52; 95% confidence interval [CI], 1.44-39.27), poultry traders visiting the farm (OR, 8.66; 95% CI, 2.7-27.69), farms with 50-2,000 birds (OR, 3.00; 95% CI, 1.06-8-51), and farms with ≥ 2,000 birds (OR, 11.35; 95% CI, 3.07-41.94) were significantly associated with HPAI outbreaks. CONCLUSIONS: Combining biosecurity measures, such as restricting visitor entry and vaccination in farms with more than 50 birds, can enhance the control and prevention of HPAI in Quang Ninh and its spread across borders.

Captive wildlife management survey in Vietnam, 2015-2021.

In Vietnam, breeding and raising a wide range of wildlife species in captive wildlife facilities (CWFs) are common practices but little information on the captive wildlife population is available. We conducted surveys and developed software to create a captive wildlife facilities management (CWFM) system. This database provides up-to-date information on the distribution of CWFs, the number of species, and individuals according to the level of protection outlined by the government and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) categories. CWFs were located in all provinces and regions, but differed in distribution, number of species and individual animals. The Mekong River Delta region recorded the highest number of CWFs (35.3%) and the highest number of animals (43.1%). In 2021, 95 species belong to the highest level of protection group were being raised at 1824 CWFs; 137 species in 4554 CWFs in CITES appendix II, appendix III, government list IIB; and 139 species in 1499 CWFs belong to the common wildlife. The overall number of CWFs in 50 provinces decreased by a negative compound annual growth rate of -7.2%. However, it is crucial to continue to monitor the changing dynamics to assess the risks of disease transmission from zoonoses originating from wildlife. We recommend periodic compulsory reporting of CWF activities using the CWFM system.

Estimation of a Within-Herd Transmission Rate for African Swine Fever in Vietnam.

We describe results from a panel study in which pigs from a 17-sow African swine fever (ASF) positive herd in Thái Bình province, Vietnam, were followed over time to record the date of onset of ASF signs and the date of death from ASF. Our objectives were to (1) fit a susceptible-exposed-infectious-removed disease model to the data with transmission coefficients estimated using approximate Bayesian computation; (2) provide commentary on how a model of this type might be used to provide decision support for disease control authorities. For the outbreak in this herd, the median of the average latent period was 10 days (95% HPD (highest posterior density interval): 2 to 19 days), and the median of the average duration of infectiousness was 3 days (95% HPD: 2 to 4 days). The estimated median for the transmission coefficient was 3.3 (95% HPD: 0.4 to 8.9) infectious contacts per ASF-infectious pig per day. The estimated median for the basic reproductive number, R0, was 10 (95% HPD: 1.1 to 30). Our estimates of the basic reproductive number R0 were greater than estimates of R0 for ASF reported previously. The results presented in this study may be used to estimate the number of pigs expected to be showing clinical signs at a given number of days following an estimated incursion date. This will allow sample size calculations, with or without adjustment to account for less than perfect sensitivity of clinical examination, to be used to determine the appropriate number of pigs to examine to detect at least one with the disease. A second use of the results of this study would be to inform the equation-based within-herd spread components of stochastic agent-based and hybrid simulation models of ASF.

One Health Surveillance Highlights Circulation of Viruses with Zoonotic Potential in Bats, Pigs, and Humans in Viet Nam.

A One Health cross-sectoral surveillance approach was implemented to screen biological samples from bats, pigs, and humans at high-risk interfaces for zoonotic viral spillover for five viral families with zoonotic potential in Viet Nam. Over 1600 animal and human samples from bat guano harvesting sites, natural bat roosts, and pig farming operations were tested for coronaviruses (CoVs), paramyxoviruses, influenza viruses, filoviruses and flaviviruses using consensus PCR assays. Human samples were also tested using immunoassays to detect antibodies against eight virus groups. Significant viral diversity, including CoVs closely related to ancestors of pig pathogens, was detected in bats roosting at the human-animal interfaces, illustrating the high risk for CoV spillover from bats to pigs in Viet Nam, where pig density is very high. Season and reproductive period were significantly associated with the detection of bat CoVs, with site-specific effects. Phylogeographic analysis indicated localized viral transmission among pig farms. Our limited human sampling did not detect any known zoonotic bat viruses in human communities living close to the bat cave and harvesting bat guano, but our serological assays showed possible previous exposure to Marburg virus-like (Filoviridae), Crimean-Congo hemorrhagic fever virus-like (Bunyaviridae) viruses and flaviviruses. Targeted and coordinated One Health surveillance helped uncover this viral pathogen emergence hotspot.

Highly pathogenic avian influenza (H5N1) in Myanmar, 2006-2010.

Highly pathogenic avian influenza (HPAI) virus subtype H5N1 was first reported in Myanmar in 2006. In this study, we have characterized 6 HPAI (H5N1) viruses recovered from 2007-2010 as well as three additional available nucleotide sequences representing Myanmar AI outbreaks. Phylogenetic analysis showed that the Myanmar viruses belong to HPAI (H5N1) clades 7, 2.3.2 and 2.3.4. The result suggested that the HPAI (H5N1) viruses recovered from Myanmar had been introduced into the country by multiple introductions. Genetic analysis of the viruses confirmed the HPAI characteristics of the viruses.

Zoonotic pathogens and diseases detected in Vietnam, 2020-2021.

Vietnam has been identified as a country at high-risk for emergence and re-emergence of zoonotic diseases. The government of Vietnam recognized five priority zoonoses, including highly pathogenic avian influenza, rabies, leptospirosis, anthrax, and Streptococcus suis, and established a framework for One Health investigation and response to these diseases. From July 2020 to February 2021, quantitative data of zoonoses were collected from an online survey in 61 of 63 provinces based on either clinical diagnosis or laboratory confirmation. The responses were followed up by using in-depth interviews, and scientific literatures on zoonoses in Vietnam during 2010 to 2020 were reviewed. A total of 234 human health professionals and 95 animal health professionals responded to the survey. The proportion of clinical-based respondents was higher than laboratory-based respondents in both human health (130/234, 55.6%) and animal health (65/95, 68.4%) sectors. There were differences in the reported frequency of zoonoses between human and animal health professionals, and between clinical-based and laboratory-based respondents. Rabies was the most serious zoonotic disease based on the number of human cases and the geographic distribution. No human cases of avian influenza infection have been reported since 2015, although the H5 subtype viruses have been found in poultry. Besides, some bacterial, fungal, and parasitic zoonoses were detected in both humans and animals. Out of the 75 zoonoses identified, we recommend that the original five prioritized zoonoses, plus 24 additional zoonoses, should be targeted for future prevention, detection, and control under One Health approach in Vietnam.

Implications of partial culling on African swine fever control effectiveness in Vietnam.

The introduction of the African swine fever (ASF) into previously unaffected countries often overwhelms veterinary authorities with the resource demanding control efforts that need to be undertaken. The approach of implementing total stamping out of affected herds is taken as "default" control measure in many countries, regardless of the transboundary animal disease addressed, leading to a variety of challenges when implemented. Apart from the organizational challenges and high demand for human and financial resources, the total stamping out approach puts a high burden on the livelihoods of the affected farmers. After the spread of ASF throughout the country in 2019, Vietnam changed the culling approach enabling partial culling of only affected animals in the herd, in order to save resources, and reduce the environmental impact because of the carcass disposal and allow farmers to protect valuable assets. Until now, field data comparing these disease control options in their performance during implementation has not been evaluated scientifically. Analyzing the effect of the change in a control policy, the present study concludes that partial culling can on average save over 50% of total stock with an 8-day prolongation of the implementation of control measures. With 58% of farms undergoing partial culling scoring high on a time-livelihoods matrix, while total stamping out fails to score on livelihoods, much-needed clarity on the livelihood-protecting effects of alternative culling strategies is given. In the future, this will allow veterinary authorities to adjust control measures according to differing priorities, targeting peculiarities of ASF and acknowledging resource constraints faced.

Widespread presence of dfrA12 and its association with dfrA12-aadA2 cassette in Salmonella enterica isolates from swine.

One hundred and eighty-nine Salmonella isolates from swine were tested for susceptibility to nine antimicrobial agents, presence of dfrA12 and class 1 integrons containing dfrA12-orfF-aadA2 cassette. All isolates were multidrug resistant and exhibited highest resistance prevalence to trimethoprim (93%). Most isolates (89%) were intll-positive and 107 isolates (57%) carried dfrA12, all of which were resistant to trimethoprim. Forty-eight dfrA12-harboring strains (45%) were intl1-positive together with dfrA12-aadA2 gene cassette. Fifteen isolates contained dfrA12 but not intl1 and dfrA12-aadA2 cassette. The results indicated a wide distribution of dfrA12 and its role in dissemination of trimethoprim resistance among Salmonella isolates from fattening pigs.

Antimicrobial use in household, semi-industrialized, and industrialized pig and poultry farms in Viet Nam.

The use and misuse of antimicrobials in livestock production contributes to increasing antimicrobial resistance (AMR). Antimicrobial use (AMU), has been identified as a problem in Viet Nam. There were many identified drivers of AMU in Viet Nam such as lack of access to veterinary services, easy access to cheap over-the-counter antimicrobials, and insufficient farm biosecurity. This study included chicken farmers (n = 540) and pig farmers (n = 540) from household, semi-industrialized, and industrialized farms in the North, Central, and South of Viet Nam. The objective of this study was to determine farmers rationale behind AMU on their farms and their usage patterns. On pig farms, 98.1% of the farmers reported use of antimicrobials in their production. On chicken farms, 87.9% reported use of antimicrobials in their production. The results of the survey showed that the three main purposes of AMU were treatment of sick animals, disease prevention, and weight gain. Treatment accounted for 81.3% in pig farming and 62.1% in chicken farming. The main reason to start antimicrobial therapy in pig and chicken production was observation of the first clinical signs of disease (73.9% of the pig farmers and 74.9% of chicken farmers). The proportion of industrial pig farms performing diagnostic tests before using antimicrobials was singnificantly (p < 0.05) higher than household farms (OR = 45.3). The proportion of chicken farmers who used diagnostic tests before using antimicrobials on semi-industrial (OR = 4.1) and industrial farms (OR = 26.7) were significantly higher compared with household farms. Through encouraging the prudent use of antimicrobials in animal husbandry we can reduce the use of antimicrobials at the primary production level and thereby lowering the risk of AMR.

Quality testing of veterinary antimicrobial products used for livestock in Vietnam, 2018-2019.

Access to quality veterinary antimicrobial products contributes to efficient treatment of diseases in Vietnamese livestock and to reducing antimicrobial resistance (AMR). Poor quality antimicrobial drugs can lead to treatment failure, potentially influencing the inappropriate use of antimicrobials products, including increasing the dose, combining drugs, or changing to a broader spectrum antimicrobial. The objective of the study was to determine the actual concentration of antimicrobial active ingredient (AAI) in commercially available veterinary antimicrobial products as an indicator of their quality. A total of 144 veterinary antimicrobial products were purchased from randomly selected veterinary drug stores in 34 districts in eight provinces. For the qualitative analysis, we observed criteria linked to form, colour, and labelling information according to the Department of Animal Health regulations. For the quantitative analysis, high-performance liquid chromatography was used to determine the actual concentration of AAI in each sample. Of the 144 samples, 131 (91%) met the national standard of quality of being within ±10% of the labelled concentration. Ten antimicrobials (6.9%) contained less than half of the labelled content concentrations. Veterinary antimicrobial product quality control is an important part of addressing AMR. To support the national action plan to lower AMR, a veterinary drug quality control program should be implemented at all stages of the supply chain to assure high quality drugs and effective treatment of sick animals.

An Assessment of the Economic Impacts of the 2019 African Swine Fever Outbreaks in Vietnam.

The 2019 African swine fever (ASF) outbreaks in Vietnam imposed considerable impacts on the pig sector in Vietnam, resulting in the death or culling of nearly six million pigs, or more than 20% of the country's pig population. In order to assess the magnitude of the outbreak at sector level (both on farm and at value chain level), on livelihoods, and on the broader national economy, a comprehensive impact assessment was conducted using a mixed methods approach that integrated a value chain assessment with the use of quantitative modeling tools at sector and national levels. The results showed that the outbreak caused severe direct and indirect economic losses among farmers, particularly medium- and large-farmers whose livelihoods are largely derived from pig production. The outbreaks also affected other value chain actors due to a halving in the volume of pigs traded. At sector level, the outbreaks posed adverse impacts on the domestic supply and demand for pork, especially in the traditional sector. Meanwhile, the modern sector with higher levels of biosecurity and high technology growth was less likely to be affected and even benefited from the outbreak, which was evidenced by increased supply and income throughout the simulation period in this sector. At national level, different model simulation scenarios showed a sharp reduction in total gross domestic product (GDP) and a substantial loss of jobs. Improvements in the system of ASF compensation scheme are needed, both in terms of its administration, but also in its targeting, with greater emphasis needed on developing improved risk-sharing and funding mechanisms across national and local levels.

Antimicrobial Resistance Pilot Surveillance of Pigs and Chickens in Vietnam, 2017-2019.

Antimicrobial use (AMU) and antimicrobial resistance (AMR) are a growing public health and economic threat in Vietnam. We conducted a pilot surveillance programme in five provinces of Vietnam, two in the south and three in the north, to identify antimicrobial resistance (AMR) in rectal swab samples from pigs and fecal samples from chickens at slaughter points during three different points in time from 2017 to 2019. Escherichia coli (E. coli) and non-typhoidal Salmonella (NTS) isolates were tested for antimicrobial susceptibility using disk diffusion assay for 19 antimicrobial agents belonging to nine antimicrobial classes and Etest for colistin (polymyxin). Almost all E. coli (99%; 1029/1042) and NTS (96%; 208/216) isolates were resistant to at least one antimicrobial agent; 94% (981/1042) of E. coli and 89% (193/216) of NTS isolates were multidrug-resistant (MDR). Higher proportions of E. coli and NTS isolated from chickens were resistant to all antimicrobial classes than those isolates from pigs. There was a significantly higher proportion of MDR NTS isolates from the southern provinces of Ho Chi Minh City and Long An (p = 0.008). Although there were increasing trends of NTS in proportion of resistance to fluoroquinolone over the three surveillance rounds, there was a significant decreasing trend of NTS in proportion of resistance to polymyxin (p = 0.002). It is important to establish an annual AMR surveillance program for livestock in Vietnam to assess the impact of interventions, observe trends and drive decision making that ultimately contributes to reducing AMR public health threat.

Feasibility study of a field survey to measure antimicrobial usage in humans and animals in the Mekong Delta region of Vietnam.

BACKGROUND: Development of antimicrobial use (AMU) surveillance systems in humans and animals is a priority for many low- and middle-income countries; however accurate estimations are hampered by a diversity of animal production systems and metrics. The Mekong Delta region of Vietnam is a 'hotspot' of antimicrobial resistance and is home to a high density of humans and animal populations. OBJECTIVES: To measure and compare AMU using different metrics (standing population, biomass and population correction unit) in the Mekong Delta, and to explore the potential of field-based data collection methods in the design of AMU surveillance systems. METHODS: We collected AMU data from humans and animals (chickens, ducks, Muscovy ducks, pigs) from 101 small-scale farms in the Mekong Delta over a fixed period (90 days in humans, 7 days in animals). RESULTS: Humans used 7.1 DDDkg, or 175.9 mg of antimicrobial active ingredients (AAIs) per kg of standing body mass annually; animals consumed 60.9 ADDkg or 1324 mg. In the Mekong Delta humans represented 79.3% of the total body mass but consumed 29.6% of AAIs by weight. AAIs regarded of critical importance by WHO represented 56.9% and 50.2% of doses consumed by animals and humans, respectively. CONCLUSIONS: Using a One Health approach, we show that AMU can potentially be estimated from cross-sectional surveys, although results are hypothetical due to small sample size and are sensitive to the chosen population denominator. The methodology proposed here can potentially be scaled up be applied to design AMU surveillance in low-resource settings, allowing AMU reduction efforts to be focused on particular animal species.

Optimizing the early detection of low pathogenic avian influenza H7N9 virus in live bird markets.

In Southeast Asia, surveillance at live bird markets (LBMs) has been identified as crucial for detecting avian influenza viruses (AIV) and reducing the risk of human infections. However, the design of effective surveillance systems in LBMs remains complex given the rapid turn-over of poultry. We developed a deterministic transmission model to provide guidance for optimizing AIV surveillance efforts. The model was calibrated to fit one of the largest LBMs in northern Vietnam at high risk of low pathogenic H7N9 virus introduction from China to identify the surveillance strategy that optimizes H7N9 detection. Results show that (i) using a portable diagnostic device would slightly reduce the number of infected birds leaving the LBM before the first detection, as compared to a laboratory-based diagnostic strategy, (ii) H7N9 detection could become more timely by sampling birds staying overnight, just before new susceptible birds are introduced at the beginning of a working day, and (iii) banning birds staying overnight would represent an effective intervention to reduce the risk of H7N9 spread but would decrease the likelihood of virus detection if introduced. These strategies should receive high priority in Vietnam and other Asian countries at risk of H7N9 introduction.

A cross-sectional study of Salmonella in pork products in Chiang Mai, Thailand.

The occurrence of Salmonella in food of animal origin in Chiang Mai province was investigated by using a cross-sectional study during several phases of the pork production chain (cutting, transport, and retail) and of the environment in the cutting unit of a slaughterhouse. In total, 173 pork samples were obtained during the cutting phase, 173 samples from transported pork, 200 samples from retail products, and 300 samples from the slaughterhouse environment. Salmonella was detected in 55.5% of freshly cut pork, 70.5% of transported pork, and 34.5% of retail products. The five most prevalent Salmonella serotypes identified were Rissen (45.3%), Typhimurium (16.3%), Krefeld (10.6%), Stanley (6.3%), and Lagos (6.0%). Carcass contamination prior to cutting and in the slaughterhouse environment appeared to be important sources of Salmonella in transported pork and retail products. As Salmonella was also found during early stages of the slaughter process, attention should focus on all stages of the pork production chain to reduce contamination level and consumer risk of infection.