Foodborne bacteria in the Cambodian meat value chain: Emphasis on the risk of Salmonella in chicken and pork from traditional markets to household consumption

Foodborne pathogens, such as Salmonella and Staphylococcus aureus, pose a high risk to human health globally. Using quantitative microbial risk assessment (QMRA), this thesis estimated the risk of salmonellosis to Cambodian consumers eating contaminated chicken and pork salad. Chicken meat and pork samples (n=204 each) were collected from traditional markets in 25 provinces in Cambodia for analyses of Salmonella and also S. aureus. Practices used for preparing chicken and pork salads in 93 Cambodian households were surveyed and used to design an experiment assessing Salmonella cross-contamination from raw meat to ready-to-eat salad in four scenarios. Salmonella prevalence in chicken meat and pork was found at 42.6% (87/204) and 45.1% (92/204), respectively, with mean Salmonella concentration of 10.6 MPN/g in chicken meat and 11.1 MPN/g in pork. Salmonella contamination, salad consumption and dose-response were modelled using Monte Carlo simulations with 10,000 iterations. The QMRA model showed that the annual estimated risk of salmonellosis from consuming chicken salad, pork salad and both salads was 11.2% (90% CI 0.0-35.1), 4.0% (0.0-21.3) and 14.5% (0.0-33.5), respectively. Thus one in 10 chicken salad consumers in Cambodia was at risk of contracting salmonellosis annually. The factor with the most decisive influence on risk estimates was crosscontamination while preparing salad, followed by high prevalence of Salmonella on chicken meat/pork at the market. These results indicate a need to implement control measures, including monitoring the safety of retail chicken and pork at markets and improving hygiene in practices and equipment used during salad preparation in households

Prevalence and associated risk factors of Toxocara vitulorum infections in buffalo and cattle calves in three provinces of Central Cambodia

The prevalence and associated risk factors of Toxocara vitulorum infection in buffalo and cattle calves was studied in 3 provinces in central Cambodia. Fecal samples were collected from 517 calves between the age of 1-15 weeks and processed for nematode egg counts by a modified McMaster method. A total of 64 calves were found to excrete T. vitulorum eggs in their feces (12.4%; 95% exact CI: 9.7-15.5). The mean fecal egg count was 2,798 EPG (SD=16,351; range=0-224,400). A multivariable generalized linear mixed model showed higher odds of T. vitulorum infection for buffalo versus cattle, for animals aged 4-8 weeks versus younger and older ones, and for animals with strongyle infection. There was no association with fecal consistency. Farmers should be aware of the potential impact of T. vitulorum, and treat their calves at the age of 2-3 weeks with anthelmintics such as benzimidazoles or pyrantel

Quantitative risk assessment of salmonellosis in Cambodian consumers through chicken and pork salad consumption

Salmonella is a globally important foodborne bacterial pathogen that poses a high risk to human health. This study aimed to estimate the risk to Cambodian consumers from acquiring salmonellosis after consuming chicken and pork salad, using a quantitative microbial risk assessment (QMRA). Chicken and pork salads are typical Cambodian dishes containing raw vegetables and boiled chicken meat or pork. As previously described, chicken meat and pork samples (n = 204 of each) were collected from traditional markets in 25 Cambodian provinces to generate data on Salmonella contamination. Salad preparation and consumption practices were surveyed in 93 Cambodian households and this information was used to design an experiment to assess Salmonella cross-contamination from raw meat to ready-to-eat salad. In the part of the study reported here, data on consumption, Salmonella in salad, dose-response, and predicted salmonellosis were modeled using Monte Carlo simulations at 10,000 iterations. The prevalence of Salmonella in chicken meat and pork were set to 42.6 and 45.1%, respectively, with average most probable number (MPN) per gram of Salmonella in chicken meat was 10.6 and in pork 11.1 MPN/g, based on an earlier study. Half of the interviewed households cooked meat for the salad directly after purchase. The QMRA model showed that the modeled annual risk of salmonellosis from consuming chicken salad, pork salad and both chicken and pork salad were 11.1% probability of illness per person per year (90% CI 0.0–35.1), 4.0% (90% CI 0.0–21.3), and 14.5% (90% CI 0.0–33.5), respectively. The factors most influencing the estimate were cross-contamination while preparing the salad, followed by the prevalence of Salmonella in chicken meat and pork at the market. The wide confidence interval for the incidence was mainly due to the variability in reducing bacteria concentration by cooking and salad consumption. The predicted risk of salmonellosis due to chicken and pork salad consumption is high, and the study provides evidence supporting control measures of improving the safety of retailed chicken and pork obtained from markets to households and improving food preparation methods in the household

Experimental cross-contamination of chicken salad with Salmonella enterica serovars Typhimurium and London during food preparation in Cambodian households

Non-typhoidal Salmonellae are common foodborne pathogens that can cause gastroenteritis and other illnesses in people. This is the first study to assess the transfer of Salmonella enterica from raw chicken carcasses to ready-to-eat chicken salad in Cambodia. Twelve focus group discussions in four Cambodian provinces collected information on typical household ways of preparing salad. The results informed four laboratory experiments that mimicked household practices, using chicken carcasses inoculated with Salmonella. We developed four scenarios encompassing the range of practices, varying by order of washing (chicken or vegetables first) and change of chopping utensils (same utensils or different). Even though raw carcasses were washed twice, Salmonella was isolated from 32 out of 36 chicken samples (88.9%, 95% CI: 73.0–96.4) and two out of 18 vegetable samples (11.1%, 95% CI: 1.9–36.1). Salmonella was detected on cutting boards (66.7%), knives (50.0%) and hands (22.2%) after one wash; cross-contamination was significantly higher on cutting boards than on knives or hands (p-valu

Quantitative risk assessment of salmonellosis in Cambodian consumers through chicken and pork salad consumption

Salmonella is a globally important foodborne bacterial pathogen that poses a high risk to human health. This study aimed to estimate the risk to Cambodian consumers from acquiring salmonellosis after consuming chicken and pork salad, using a quantitative microbial risk assessment (QMRA). Chicken and pork salads are typical Cambodian dishes containing raw vegetables and boiled chicken meat or pork. As previously described, chicken meat and pork samples (n = 204 of each) were collected from traditional markets in 25 Cambodian provinces to generate data on Salmonella contamination. Salad preparation and consumption practices were surveyed in 93 Cambodian households and this information was used to design an experiment to assess Salmonella cross-contamination from raw meat to ready-to-eat salad. In the part of the study reported here, data on consumption, Salmonella in salad, dose-response, and predicted salmonellosis were modeled using Monte Carlo simulations at 10,000 iterations. The prevalence of Salmonella in chicken meat and pork were set to 42.6 and 45.1%, respectively, with average most probable number (MPN) per gram of Salmonella in chicken meat was 10.6 and in pork 11.1 MPN/g, based on an earlier study. Half of the interviewed households cooked meat for the salad directly after purchase. The QMRA model showed that the modeled annual risk of salmonellosis from consuming chicken salad, pork salad and both chicken and pork salad were 11.1% probability of illness per person per year (90% CI 0.0-35.1), 4.0% (90% CI 0.0-21.3), and 14.5% (90% CI 0.0-33.5), respectively. The factors most influencing the estimate were cross-contamination while preparing the salad, followed by the prevalence of Salmonella in chicken meat and pork at the market. The wide confidence interval for the incidence was mainly due to the variability in reducing bacteria concentration by cooking and salad consumption. The predicted risk of salmonellosis due to chicken and pork salad consumption is high, and the study provides evidence supporting control measures of improving the safety of retailed chicken and pork obtained from markets to households and improving food preparation methods in the household

Quantitative microbial risk assessment of salmonellosis from chicken and pork salad consumption in Cambodian households

Introduction: Salmonella is an important foodborne bacterial pathogen that causes high risk to human health globally. Purpose: This study aimed to estimate the risk of Cambodian consumers of acquiring salmonellosis after consuming contaminated chicken and pork salad using a quantitative microbial risk assessment. Methods: Chicken meat and pork samples (n=204 each) were collected from traditional markets in 25 provinces for Salmonella analyses. Practices of cooking chicken and pork salad from 93 Cambodian households were surveyed and used to design an experiment to assess Salmonella cross-contamination from raw meat to ready-to-eat salad. Data on Salmonella contamination, salad consumption and dose response (alpha=0.00853 and beta=3.14) were modelled using Monte Carlo simulations with @Risk at 10,000 iterations. Results: The prevalence of Salmonella in chicken meat and pork were 42.6% (87/204) and 45.1% (92/204) respectively. The average concentration of Salmonella in chicken meat was 10.6 MPN/g, and in pork 11.1 MPN/g. Half of the interviewed households processed and cooked meat for salad directly after purchasing. The QMRA model showed that the annual risk of salmonellosis estimated from consuming chicken salad, pork salad and mixtures of chicken and pork salads were 11.2% (90%CI 0.0 – 35.1), 4.0% (90%CI 0.0 – 21.3), and 14.5% (90%CI 0.0 – 33.5), respectively. The factors with the highest influence on the estimate were cross-contamination while preparing salad, followed by the prevalence of Salmonella on chicken meat and pork at the market. A wide confidence interval in the estimated incidence was mainly due to the variability in the degree of reduction in bacteria concentration by cooking, and salad consumption pattern. Significance: The risk of salmonellosis due to chicken and pork salad consumption appears to be high. Control measures may include improving the safety of retailed chicken and pork at markets and improving hygiene practices and equipment during salad preparation at household

Quantitative risk assessment of salmonellosis in Cambodian consumers through chicken and pork salad consumption

Salmonella is a globally important foodborne bacterial pathogen that poses a high risk to human health. This study aimed to estimate the risk to Cambodian consumers from acquiring salmonellosis after consuming chicken and pork salad, using a quantitative microbial risk assessment (QMRA). Chicken and pork salads are typical Cambodian dishes containing raw vegetables and boiled chicken meat or pork. As previously described, chicken meat and pork samples (n = 204 of each) were collected from traditional markets in 25 Cambodian provinces to generate data on Salmonella contamination. Salad preparation and consumption practices were surveyed in 93 Cambodian households and this information was used to design an experiment to assess Salmonella cross-contamination from raw meat to ready-to-eat salad. In the part of the study reported here, data on consumption, Salmonella in salad, dose-response, and predicted salmonellosis were modeled using Monte Carlo simulations at 10,000 iterations. The prevalence of Salmonella in chicken meat and pork were set to 42.6 and 45.1%, respectively, with average most probable number (MPN) per gram of Salmonella in chicken meat was 10.6 and in pork 11.1 MPN/g, based on an earlier study. Half of the interviewed households cooked meat for the salad directly after purchase. The QMRA model showed that the modeled annual risk of salmonellosis from consuming chicken salad, pork salad and both chicken and pork salad were 11.1% probability of illness per person per year (90% CI 0.0–35.1), 4.0% (90% CI 0.0–21.3), and 14.5% (90% CI 0.0–33.5), respectively. The factors most influencing the estimate were cross-contamination while preparing the salad, followed by the prevalence of Salmonella in chicken meat and pork at the market. The wide confidence interval for the incidence was mainly due to the variability in reducing bacteria concentration by cooking and salad consumption. The predicted risk of salmonellosis due to chicken and pork salad consumption is high, and the study provides evidence supporting control measures of improving the safety of retailed chicken and pork obtained from markets to households and improving food preparation methods in the household

Experimental cross-contamination of chicken salad with Salmonella enterica serovars Typhimurium and London during food preparation in Cambodian households

Non-typhoidal Salmonellae are common foodborne pathogens that can cause gastroenteritis and other illnesses in people. This is the first study to assess the transfer of Salmonella enterica from raw chicken carcasses to ready-to-eat chicken salad in Cambodia. Twelve focus group discussions in four Cambodian provinces collected information on typical household ways of preparing salad. The results informed four laboratory experiments that mimicked household practices, using chicken carcasses inoculated with Salmonella. We developed four scenarios encompassing the range of practices, varying by order of washing (chicken or vegetables first) and change of chopping utensils (same utensils or different). Even though raw carcasses were washed twice, Salmonella was isolated from 32 out of 36 chicken samples (88.9%, 95% CI: 73.0–96.4) and two out of 18 vegetable samples (11.1%, 95% CI: 1.9–36.1). Salmonella was detected on cutting boards (66.7%), knives (50.0%) and hands (22.2%) after one wash; cross-contamination was significantly higher on cutting boards than on knives or hands (p-value < 0.05). The ready-to-eat chicken salad was contaminated in scenario 1 (wash vegetables first, use same utensils), 2 (wash vegetables first, use different utensils) and 3 (wash chicken first, use same utensils) but not 4 (wash chicken first, use different utensils) (77.8%, 11.1%, 22.2% and 0%, respectively). There was significantly higher Salmonella cross-contamination in scenario 1 (wash vegetables first, use same utensils) than in the other three scenarios. These results show how different hygiene practices influence the risk of pathogens contaminating chicken salad. This information could decrease the risk of foodborne disease in Cambodia and provides inputs to a quantitative risk assessment model

Perspectives on antimicrobial resistance in livestock and livestock products in ASEAN countries

Antimicrobial resistance (AMR) in bacteria, particularly in foodborne pathogens, has increasingly become apparent in most parts of the world including ASEAN countries, creating great impact on economy, human and animal health and international food trade. The tendency of bacterial pathogens to become multidrug resistant (MDR) is the most serious concern in AMR. The ASEAN Economic Community (AEC) will be fully established in 2015 and ASEAN cooperation has acknowledged the significance of food safety, of which AMR is one of the major concerns. There is a need for all ASEAN nations to harmonize its AMR monitoring and surveillance programmes in order to strengthen the control and institute prevention strategies in the region. Currently, public health systems dealing with monitoring and control in ASEAN countries are still highly diverse and require a unifying action. National monitoring and control programmes for AMR have not been successfully established in most ASEAN countries and a regional-cooperative programme has yet to be set in place. Therefore, a review of current AMR situations in ASEAN member states shall be useful for future development and establishment of monitoring and control programmes within the region