Sarah Cahill

Powdered Infant Formula as a Source of Salmonella Infection in Infants

Powdered infant formula is not sterile and may be intrinsically contaminated with pathogens, such as Salmonella enterica, that can cause serious illness in infants. In recent years, at least 6 outbreaks of Salmonella infection in infants that have been linked to the consumption of powdered infant formula have been reported. Many of these outbreaks were identified because the Salmonella strains were unique in some way (e.g., a rare serotype) and a well-established Salmonella surveillance network, supported by laboratories capable of serotyping isolates, was in place. Another common feature of the outbreaks was the low level of salmonellae detected in the implicated formula (salmonellae may be missed in routine testing). These outbreaks likely represent only a small proportion of the actual number of Salmonella infections in infants that have been linked to powdered infant formula. Managing this problem requires a multidimensional approach in which manufacturers, regulators, and caregivers to infants can all play a role.

Have foodborne parasites finally become a global concern

The report on the ranking of the foodborne parasites is the result of an international effort, coordinated and organized by FAO and WHO. The following experts participated in the ranking exercise: Pascal Boireau, Laboratory for Animal Health Maisons Alfort, France; Jorge E. Bolpe, Ministerio de Salud de la Provincia de Buenos Aires, Argentina; Allal Dakkak, Institut Agronomique et Veterinaire Hassan II, Morocco; Brent Dixon (co-chair of meeting), Health Canada, Canada; Ronald Fayer, United States Department of Agriculture, USA; Jorge E. Gomez Marin, Centro de Investigaciones Biomedicas de la Universidad del Quindio, Colombia; Erastus Kang’ethe, University of Nairobi, Kenya; Malcolm Kennedy, University of Glasgow, UK; Samson Mukaratirwa, University of KwaZulu-Natal, South Africa; K. Darwin Murrell, University of Copenhagen, Denmark; Tomoyoshi Nozaki, National Institute of Infectious Diseases, Japan; Ynes Ortega, University of Georgia, USA; Subhash C. Parija, Jawaharlal Institute of Postgraduate Medical Education and Research, India; Lucy Robertson, Norwegian School of Veterinary Science, Norway; Mohammad Bagher Rokni, Tehran University of Medical Sciences, Iran; Patrizia Rossi, Instituto Superiore di Sanita, Italy; Said Shalaby, National Research Center, Egypt; Paiboon Sithithaworn, Khon Kaen University, Thailand; Rebecca Traub (rapporteur of meeting), University of Queensland, Australia; Nguyen van De, Hanoi Medical University, Vietnam; Joke W.B. van der Giessen (Chair of meeting), National Institute of Public Health and the Environment, The Netherlands.Resources persons for this exercise were: Michael Batz, University of Florida, USA; Annamaria Bruno, Joint FAO/WHO Food Standards Programme; Verna Carolissen, Joint FAO/WHO Food Standards Programme; Steve Hathaway, Science and Risk Assessment Standards Branch, New Zealand; Iddya Karunasagar, FAO; Gillian Mylrea, World Organisation for Animal Health (OIE); Patrick Otto, FAO; Edoardo Pozio, Instituto Superiore di Sanita, Italy; and Andrijana Rajic, FAO.The secretariat was composed of: Sarah Cahill, FAO; Marisa Caipo, FAO; Mina Kojima, WHO; Simone Magnino, WHO; and Kaye Wachsmuth, International Public Health Consultant, USA.

Microbiological risk assessment in developing countries.

Microbiological risk assessment (MRA) has been evolving at the national and international levels as a systematic and objective approach for evaluating information pertaining to microbiological hazards in foods and the risks they pose. This process has been catalyzed by international food trade requirements to base sanitary measures on sound scientific evidence and appropriate risk assessments. All countries, including developing countries, need to understand and use MRA. MRA is resource intensive, as has been demonstrated by some of the the assessments undertaken in industrialized countries. However, when used in the appropriate circumstances MRA offers many benefits. The process of undertaking MRA improves the understanding of key issues, enables an objective evaluation of risk management options, and provides a scientific justification for actions. Although the gap between developing countries and some industrialized countries is quite extensive with regard to MRA, many developing countries recognize the need to at least understand and move toward using MRA. This process requires development of infrastructure and enhancement of scientific and technical expertise while making optimal use of limited resources. International organizations, such as the Food and Agriculture Organization of the United Nations, are in a position to provide countries with guidance, training, information resources, and technical assistance to develop and/or strengthen food safety infrastructure. Enhanced cooperation and collaboration at all levels are needed for such efforts to be successful and to ensure that MRA, as a food safety tool, is available to all countries.

A Rapid Systematic Review and Meta-Analysis of the Efficacy of Slaughter and Processing Interventions To Control Nontyphoidal Salmonella in Beef and Pork

Pork is one of the major food sources of human salmonellosis worldwide, while beef products have been implicated in numerous foodborne outbreaks. As a result, effective interventions to reduce Salmonella contamination during beef and pork processing are of interest to both regulators and industry. We conducted a rapid systematic review and meta-analysis of literature investigating the efficacy of slaughter and processing interventions to control Salmonella in beef and pork. Review steps included: a comprehensive search strategy; relevance screening of abstracts; relevance confirmation of articles; data extraction; risk-of-bias assessment; meta-analysis (where appropriate); and a weight-of-evidence assessment. A total of 191 relevant experimental studies were identified. Two controlled trials indicated that hot water and steam treatments are effective at reducing the prevalence of Salmonella on beef carcasses (relative risk [RR] = 0.11, 95% confidence interval [CI]: 0.02, 0.58), while four trials found that pre-chill organic acid washes are effective at reducing Salmonella on pork carcasses (RR = 0.32, 95% CI: 0.13, 0.78), with high confidence in the estimates of effect. Four quasi-experimental studies found that post-exsanguination chemical washes were effective to reduce the prevalence of Salmonella on cattle hides, with low confidence in the specific estimate of effect; moderate confidence was found for the effect estimates of scalding (RR = 0.20, 95% CI: 0.14, 0.29) and singeing (RR = 0.34, 95% CI: 0.22, 0.52) of pork carcasses. The overall evidence supported enhanced reductions of Salmonella through a multiple-hurdle approach. In conclusion, various slaughter and processing interventions can contribute to reducing Salmonella on beef and pork carcasses, depending on the context of application; an appropriate combination should be selected, validated, and verified by establishment operators within their local conditions.

Application of a Rapid Knowledge Synthesis and Transfer Approach To Assess the Microbial Safety of Low-Moisture Foods.

Low-moisture foods (LMF) are increasingly implicated in outbreaks of foodborne illness, resulting in a significant public health burden. To inform the development of a new Codex Alimentarius code of hygienic practice for LMF, we applied a rapid knowledge synthesis and transfer approach to review global research on the burden of illness, prevalence, and interventions to control nine selected microbial hazards in eight categories of LMF. Knowledge synthesis methods included an integrated scoping review (search strategy, relevance screening and confirmation, and evidence mapping), systematic review (detailed data extraction), and meta-analysis of prevalence data. Knowledge transfer of the results was achieved through multiple reporting formats, including evidence summary cards. We identified 214 unique outbreaks and 204 prevalence and 126 intervention studies. Cereals and grains (n = 142) and Salmonella (n = 278) were the most commonly investigated LMF and microbial hazard categories, respectively. Salmonella was implicated in the most outbreaks (n = 96, 45%), several of which were large and widespread, resulting in the most hospitalizations (n = 895, 89%) and deaths (n = 14, 74%). Salmonella had a consistently low prevalence across all LMF categories (0 to 3%), but the prevalence of other hazards (e.g., Bacillus cereus) was highly variable. A variety of interventions were investigated in small challenge trials. Key knowledge gaps included underreporting of LMF outbreaks, limited reporting of microbial levels in prevalence studies, and a lack of intervention efficacy research under commercial conditions. Summary cards were a useful knowledge transfer format to inform complementary risk ranking activities. This review builds upon previous work in this area by synthesizing a broad range of evidence using a structured, transparent, and integrated approach to provide timely evidence informed inputs into international guidelines.

Rapid systematic review and meta-analysis of the evidence for effectiveness of primary production interventions to control Salmonella in beef and pork

Non-typhoidal Salmonella spp. (hereafter referred to as Salmonella) on beef and pork is an important cause of foodborne illness and death globally. A systematic review of the effectiveness of interventions to reduce Salmonella prevalence or concentration in beef and pork was undertaken. A broad search was conducted in Scopus and CAB abstracts. Each citation was appraised using screening tools tested a priori. Level 1 relevance screening excluded irrelevant citations; level 2 confirmed relevance and categorized studies. Data were then extracted, and intervention categories were descriptively summarized. Meta-analysis was performed to provide a summary estimate of treatment effect where two or more studies investigated the same intervention in comparable populations. The Grading of Recommendation, Assessment, Development and Evaluation (GRADE) approach was used to assess the confidence in the estimated measures of intervention effect for data subgroups.

Interventions to reduce non-typhoidal Salmonella in pigs during transport to slaughter and lairage: Systematic review, meta-analysis, and research synthesis based infection models in support of assessment of effectiveness

A systematic review of the effectiveness of interventions to reduce Salmonella prevalence or concentration in pork was undertaken. A broad search was conducted in two electronic databases. Each citation was appraised using screening tools designed and tested a priori. Level 1 relevance screening excluded irrelevant citations; level 2 confirmed relevance and categorized. Data were then extracted, and intervention categories were descriptively summarized. Meta-analysis was performed to provide a summary estimate of treatment effect where two or more studies investigated the same intervention in comparable populations. The Grading of Recommendation, Assessment, Development and Evaluation (GRADE) approach was used to assess the confidence in the estimated summary measures of intervention effect for each data subgroup. Data were also extracted from the control groups of 25 challenge trials captured by the review, to fit logistic regression models of Salmonella infection in pigs, using odds of infection as the outcome measure. The only intervention captured by the review which was significantly associated with reduced risk of Salmonella in field settings, was elimination of lairage, which is not currently feasible commercially. The logistic regression model for fecal Salmonella shedding in pigs with a random intercept for trial yielded the following predictors significantly associated with increased odds of infection: oral challenge route relative to intra-nasal, log increase in challenge dose, and elapsed time post-challenge. Univariable exact logistic regression modeling lymph node contamination post-challenge yielded the following predictors significantly associated with increased odds of Salmonella infection: younger animals relative to older ones; intra-nasal challenge route relative to oral route; and animals sampled within the first 7days post-challenge relative to those sampled at 14 or 21days. We hypothesize that the presence of absence of one or more of these predictors across studies could help to explain the inconsistent and/or non-significant findings reported for some interventions applied at lairage.