The microbiological quality of raw and sour milk from local markets and smallholder dairy farms and associated potential risk for public health in The Gambia

Deckblatt-Impressum persönlicher Dank Inhaltsverzeichnis Tabellenverzeichnis Abkürzungsverzeichnis Einleitung Literaturübersicht Material und Methoden Ergebnisse Diskussion Schlussfolgerungen Zusammenfassung Summary Literaturverzeichnis Anhang DanksagungMilch wird als wesentlicher Lieferant von Energie, Proteinen und Kalzium angesehen, insbesondere für Kinder in Entwicklungsländern, die wenige Alternativen für diese Nährstoffe haben. Milch ist aber auch, vor allem in tropischen Ländern, ideal für das Wachstum von pathogenen Bakterien und Verderbniskeimen und kann für die Übertragungvon bakteriellen, viralen und parasitären Krankheiten verantwortlich sein. Pathogene Organismen in Milch können von der Kuh stammen aber auch vom Menschen und der Umgebung. In Gambia, wie in den anderen Ländern West-Afrikas, werden Kühe von Hand gemolken, nachdem das Kalb den Milchfluß durch kurzes Säugen stimuliert hat. Wasser ist an den Melkplätzen im allgemeinen nicht vorhanden und weder die Hände des Melkersnoch das Euter werden vor dem Melken gereinigt. Utensilien wie Melkeimer und Sammelbehälter werden nur unzureichend mit kaltem Wasser ausgespült. Mangelnde Kühlmöglichkeiten und lange Transportwege zu Milchhändlern, offenen Märkten und Konsumenten bieten Bakterien gute Bedingungen zur Vermehrung. Ziel dieser Arbeit war die Untersuchung des hygienischen Status der Milch, die in Gambia produziert und vermarktet wird und der Vergleich mit Grenzwerten, die für die Europäische Union oder Kenia als afrikanisches Vergleichsland gelten. Anhand der gewonnenen Information soll abgeschätzt werden, ob die auf Märkten angebotene Milch gesundheitsschädigend für Konsumenten sein kann. Dies ist besonders bedeutend in Ländern wie Gambia, in denen die öffentliche Gesundheitsversorgung unzureichend und ein Bewußtsein für lebensmittelbedingte Krankheiten kaum vorhanden ist. Für die Untersuchung wurden vier Märkte aus unterschiedlichen Verwaltungseinheiten Gambias ausgewählt. Die Milchverkäufer auf den jeweiligen Märkten wurden mit Hilfe von strukturierten Fragebögen interviewt; aus den Informationen wurde versucht, dieVermarktungskette von Milch zurückzuverfolgen und beliefernde Zwischenhändler und Produzenten zu identifizieren. Diese Vermarktungsketten bildeten die Grundlage für den Beprobungsplan. Dementsprechend wurden Milchproben auf unterschiedlichen Ebenen der Produktions- und Vermarktungskette genommen, angefangen mit Proben der Herdenmilchauf der Ebene der Produzenten über Proben der Sammelmilch auf der Ebene der Zwischenhändler bis zu den Endprodukten, die auf den Märkten den Konsumentenangeboten wurden. Roh- und Sauermilchproben wurden mikrobiologisch auf aerobe Gesamtkeimzahl, coliforme Bakterien, E. coli, Koagulase-positive Staphylokokken, Salmonella spp., Listeriaspp., H2S-reduzierende Clostridien und B. cereus untersucht. Die Ergebnisse wurden miteuropäischen und kenianischen Grenzwerten verglichen, um anhand der Standards für beide Regionen ein Gesundheitsrisiko für Verbraucher abzuschätzen. Es wurden 236 Rohmilch- und 142 Sauermilchproben untersucht. Die aerobe Gesamtkeimzahl lag bei 90,9% der Rohmilchproben mit über 2x10(hoch 6) KbE/ml außerhalb des Akzeptanzbereiches kenianischer Normen. Auch der Gehalt coliformer Bakterien lag bei 64% der Rohmilch- und 55% der Sauermilchproben über dem kenianischen Grenzwert von 5x10(hoch 4) KbE/ml. Keimzahlen über 1x10(hoch 5) KbE/ml E. coli wurden bei 22,6% der Rohmilch-und 23,7% der Sauermilchproben gefunden. 25% der Rohmilchproben enthielten mehr als 2x10(hoch 3) KbE/ml Koagulase-positive Staphylokokken und lagen damit über demeuropäischen Standard für Milch für die Herstellung von Milchprodukten. Listerien und Salmonellen konnten nur in Einzelfällen aus den Proben isoliert werden, Sporenbildner wie H2S- reduzierende Clostridien und Bacillus cereus wurden dagegen häufig nachgewiesen. 22,3% der Rohmilch- und 14,4% der Sauermilchproben enthielten H2S-reduzierendeClostridien und in 17% respektive 12,7% waren B. cereus auffindbar. Die mangelhafte hygienische Qualität der Milch ist zum einen auf die schlechten hygienischen Verhältnisse beim Melken zurückzuführen und zum anderen auf die ungenügende Reinigung der Melkutensilien und Milchgefäße. In die Milch gelangte Keime finden gute Bedingungen zur Vermehrung, da die Milch nicht gekühlt wird und die Wege zum Verbraucher meist lang sind. Die Ergebnisse dieser Arbeit geben Gründe zu der Annahme, dass der Verzehr von sowohl roher als auch von fermentierter Milch in Gambia Krankheitssymptome auslösen kann. Rückschlüsse auf die tatsächlichen Gesundheitsrisiken durch den Verzehr von lokaler Milch zu ziehen bleibt dennoch schwierig. Fehlende Labordiagnosen bei menschlichen Erkrankungen mit gastrointestinalen Symptomen, das Fehlen von Systemen zur Rückverfolgung von kontaminierten Lebensmitteln und das fehlende Bewußtsein der Bevökerung für Gesundheitsrisiken durch Lebensmittel im Allgemeinen lassen nur Vermutungen über das tatsächliche Risiko zu.Milk is considered as being an attractive source of energy, proteins and calcium especiallyfor children in developing countries, who have only few alternatives for these nutrients.But milk is equally suitable for the growth of spoilage and pathogenic bacteria and can bethe vehicle for the transmission of bacterial, viral and parasitic diseases. Pathogens in milk can derive from the cow but also from the milker or the environment. In The Gambia, as in other West-african countries, cows are milked by hand, after the stimulation of milk let-down by a suckling calf. Water is usually not available at the milking place and neither themilker s hands nor the udder is cleaned before milking. Milking equipment and containers are inadequately rinsed with cold water. The lack of cooling facilities and long distances between producers, traders and consumers provide optimal conditions for the growth of bacteria. The objective of this study was the identification and quantification of bacterial contaminants and pathogenic agents in milk at producer s, trader s and vendor s level and the comparison with hygiene standards of the European Union and Kenya. Results of this investigation were used to evaluate the potential risk for consumers in The Gambia. This is particularly important in countries such as The Gambia, where the public healthinfrastructure is insufficient and the public awareness for health risks related to food is more or less inexistant. Four local markets in different Divisions were selected and milk vendors were interviewed using structured questionnaires. With the information acquired through the interviews, existing milk marketing chains were identified, which served as a basis for the sampling of milk along the marketing ways. Raw and fermented milk samples were tested for total bacterial count, coliform bacteria, E.coli, coagulase-positive Staphylococci, Salmonella spp., Bacillus cereus, Listeria spp.and H2S- reducing Clostridia. The results were compared with European and Kenyanhygiene standards to estimate the potential risk for consumers of milk in The Gambia. 236 raw and 142 fermented milk samples were investigated. The total bacteria count of 90.9%of raw milk samples was above Kenyan standard with a highest acceptable count of 2x10(hoch6) cfu/ml. 64% of raw milk and 55% of fermented milk samples contained more than 5x104cfu/ml, which is the acceptance limit in Kenya. E.coli counts above 1x104 cfu/ml were found in 22.6% of raw milk and 23.7% of fermented milk. 25% of raw milk samplesexceeded the European acceptance limit of 2x103 cfu/ml coagulase-positive Staphylococci.Listeria spp. and Salmonella spp. were only isolated in a few samples. Sporeforming bacteria such as Bacillus cereus and H2S- reducing Clostridia were more frequentlyisolated. 22.3% of raw milk and 14.4% of fermented milk contained H2S- reducing Clostridia. Bacillus cereus could be found in 17% of raw milk and in 12.7% of fermented milk. The poor hygienic quality of milk is mainly caused by the poor hygienic conditions around milking and to the inadequate cleaning of milking equipment and containers. Bacterial contaminants in milk find good conditions for growth as milk is not cooled and usually transported over long distances to traders and consumers. Results of this study lead to the assumption that the consumption of both raw and fermented milk in The Gambia poses a public health hazard. However, poor public health infrastructure, lack of laboratory confirmed cases and the low public awareness for food-borne diseases in general make it difficult to establish a direct relationship between the high contamination of milk and the health risk for consumers

A remote digital memory composite to detect cognitive impairment in memory clinic samples in unsupervised settings using mobile devices

Remote monitoring of cognition holds the promise to facilitate case-finding in clinical care and the individual detection of cognitive impairment in clinical and research settings. In the context of Alzheimer's disease, this is particularly relevant for patients who seek medical advice due to memory problems. Here, we develop a remote digital memory composite (RDMC) score from an unsupervised remote cognitive assessment battery focused on episodic memory and long-term recall and assess its construct validity, retest reliability, and diagnostic accuracy when predicting MCI-grade impairment in a memory clinic sample and healthy controls. A total of 199 participants were recruited from three cohorts and included as healthy controls (n = 97), individuals with subjective cognitive decline (n = 59), or patients with mild cognitive impairment (n = 43). Participants performed cognitive assessments in a fully remote and unsupervised setting via a smartphone app. The derived RDMC score is significantly correlated with the PACC5 score across participants and demonstrates good retest reliability. Diagnostic accuracy for discriminating memory impairment from no impairment is high (cross-validated AUC = 0.83, 95% CI [0.66, 0.99]) with a sensitivity of 0.82 and a specificity of 0.72. Thus, unsupervised remote cognitive assessments implemented in the neotiv digital platform show good discrimination between cognitively impaired and unimpaired individuals, further demonstrating that it is feasible to complement the neuropsychological assessment of episodic memory with unsupervised and remote assessments on mobile devices. This contributes to recent efforts to implement remote assessment of episodic memory for case-finding and monitoring in large research studies and clinical care

Microbiological safety of aged meat

The impact of dry-ageing of beef and wet-ageing of beef, pork and lamb on microbiological hazards and spoilage bacteria was examined and current practices are described. As ‘standard fresh’ and wet-aged meat use similar processes these were differentiated based on duration. In addition to a description of the different stages, data were collated on key parameters (time, temperature, pH and aw) using a literature survey and questionnaires. The microbiological hazards that may be present in all aged meats included Shiga toxin-producing Escherichia coli (STEC), Salmonella spp., Staphylococcus aureus, Listeria monocytogenes, enterotoxigenic Yersinia spp., Campylobacter spp. and Clostridium spp. Moulds, such as Aspergillus spp. and Penicillium spp., may produce mycotoxins when conditions are favourable but may be prevented by ensuring a meat surface temperature of −0.5 to 3.0°C, with a relative humidity (RH) of 75–85% and an airflow of 0.2–0.5 m/s for up to 35 days. The main meat spoilage bacteria include Pseudomonas spp., Lactobacillus spp. Enterococcus spp., Weissella spp., Brochothrix spp., Leuconostoc spp., Lactobacillus spp., Shewanella spp. and Clostridium spp. Under current practices, the ageing of meat may have an impact on the load of microbiological hazards and spoilage bacteria as compared to standard fresh meat preparation. Ageing under defined and controlled conditions can achieve the same or lower loads of microbiological hazards and spoilage bacteria than the variable log10 increases predicted during standard fresh meat preparation. An approach was used to establish the conditions of time and temperature that would achieve similar or lower levels of L. monocytogenes and Yersinia enterocolitica (pork only) and lactic acid bacteria (representing spoilage bacteria) as compared to standard fresh meat. Finally, additional control activities were identified that would further assure the microbial safety of dry-aged beef, based on recommended best practice and the outputs of the equivalence assessment.info:eu-repo/semantics/publishedVersio

Guidance on date marking and related food information: part 1 (date marking)

A risk‐based approach was developed to be followed by food business operators (FBO) when deciding on the type of date marking (i.e. ‘best before’ date or ‘use by’ date), setting of shelf‐life (i.e. time) and the related information on the label to ensure food safety. The decision on the type of date marking needs to be taken on a product‐by‐product basis, considering the relevant hazards, product characteristics, processing and storage conditions. The hazard identification is food product‐specific and should consider pathogenic microorganisms capable of growing in prepacked temperature‐controlled foods under reasonably foreseeable conditions. The intrinsic (e.g. pH and aw), extrinsic (e.g. temperature and gas atmosphere) and implicit (e.g. interactions with competing background microbiota) factors of the food determine which pathogenic and spoilage microorganisms can grow in the food during storage until consumption. A decision tree was developed to assist FBOs in deciding the type of date marking for a certain food product. When setting the shelf‐life, the FBO needs to consider reasonably foreseeable conditions of distribution, storage and use of the food. Key steps of a case‐by‐case procedure to determine and validate the shelf‐life period are: (i) identification of the relevant pathogenic/spoilage microorganism and its initial level, (ii) characterisation of the factors of the food affecting the growth behaviour and (iii) assessment of the growth behaviour of the pathogenic/spoilage microorganism in the food product during storage until consumption. Due to the variability between food products and consumer habits, it was not appropriate to present indicative time limits for food donated or marketed past the ‘best before’ date. Recommendations were provided relating to training activities and support, using ‘reasonably foreseeable conditions’, collecting time–temperature data during distribution, retail and domestic storage of foods and developing Appropriate Levels of Protection and/or Food Safety Objectives for food–pathogen combinations.info:eu-repo/semantics/publishedVersio

Update and review of control options for Campylobacter in broilers at primary production

The 2011 EFSA opinion on Campylobacter was updated using more recent scientific data. The relative risk reduction in EU human campylobacteriosis attributable to broiler meat was estimated for on‐farm control options using Population Attributable Fractions (PAF) for interventions that reduce Campylobacter flock prevalence, updating the modelling approach for interventions that reduce caecal concentrations and reviewing scientific literature. According to the PAF analyses calculated for six control options, the mean relative risk reductions that could be achieved by adoption of each of these six control options individually are estimated to be substantial but the width of the confidence intervals of all control options indicates a high degree of uncertainty in the specific risk reduction potentials. The updated model resulted in lower estimates of impact than the model used in the previous opinion. A 3‐log10 reduction in broiler caecal concentrations was estimated to reduce the relative EU risk of human campylobacteriosis attributable to broiler meat by 58% compared to an estimate larger than 90% in the previous opinion. Expert Knowledge Elicitation was used to rank control options, for weighting and integrating different evidence streams and assess uncertainties. Medians of the relative risk reductions of selected control options had largely overlapping probability intervals, so the rank order was uncertain: vaccination 27% (90% probability interval (PI) 4–74%); feed and water additives 24% (90% PI 4–60%); discontinued thinning 18% (90% PI 5–65%); employing few and well‐trained staff 16% (90% PI 5–45%); avoiding drinkers that allow standing water 15% (90% PI 4–53%); addition of disinfectants to drinking water 14% (90% PI 3–36%); hygienic anterooms 12% (90% PI 3–50%); designated tools per broiler house 7% (90% PI 1–18%). It is not possible to quantify the effects of combined control activities because the evidence‐derived estimates are inter‐dependent and there is a high level of uncertainty associated with each.info:eu-repo/semantics/publishedVersio

Guidance on date marking and related food information: part 2 (food information)

A risk‐based approach was used to develop guidance to be followed by food business operators (FBOs) when deciding on food information relating to storage conditions and/or time limits for consumption after opening a food package and thawing of frozen foods. After opening the package, contamination may occur, introducing new pathogens into the food and the intrinsic (e.g. pH and aw), extrinsic (e.g. temperature and gas atmosphere) and implicit (e.g. interactions with competing background microbiota) factors may change, affecting microbiological food safety. Setting a time limit for consumption after opening the package (secondary shelf‐life) is complex in view of the many influencing factors and information gaps. A decision tree (DT) was developed to assist FBOs in deciding whether the time limit for consumption after opening, due to safety reasons, is potentially shorter than the initial ‘best before’ or ‘use by’ date of the product in its unopened package. For products where opening the package leads to a change of the type of pathogenic microorganisms present in the food and/or factors increasing their growth compared to the unopened product, a shorter time limit for consumption after opening would be appropriate. Freezing prevents the growth of pathogens, however, most pathogenic microorganisms may survive frozen storage, recover during thawing and then grow and/or produce toxins in the food, if conditions are favourable. Moreover, additional contamination may occur from hands, contact surfaces or contamination from other foods and utensils. Good practices for thawing should, from a food safety point of view, minimise growth of and contamination by pathogens between the food being thawed and other foods and/or contact surfaces, especially when removing the food from the package during thawing. Best practices for thawing foods are presented to support FBOs.info:eu-repo/semantics/publishedVersio

Update of the list of QPS‐recommended biological agents intentionally added to food or feed as notified to EFSA 15: suitability of taxonomic units notified to EFSA until September 2021

[EN]The qualified presumption of safety (QPS) approach was developed to provide a generic pre-evaluation of the safety of biological agents. The QPS approach is based on an assessment of published data for each agent, with respect to its taxonomic identity, the body of relevant knowledge and safety concerns. Safety concerns are, where possible, confirmed at the species/strain or product level and reflected by ‘qualifications’. The QPS list was updated in relation to the revised taxonomy of the genus Bacillus, to synonyms of yeast species and for the qualifications ‘absence of resistance to antimycotics’ and ‘only for production purposes’. Lactobacillus cellobiosus has been reclassified as Limosilactobacillus fermentum. In the period covered by this statement, no new information was found that would change the status of previously recommended QPS taxonomic units (TU)s. Of the 70 microorganisms notified to EFSA, 64 were not evaluated: 11 filamentous fungi, one oomycete, one Clostridium butyricum, one Enterococcus faecium, five Escherichia coli, one Streptomyces sp., one Bacillus nakamurai and 43 TUs that already had a QPS status. Six notifications, corresponding to six TUs were evaluated: Paenibacillus lentus was reassessed because an update was requested for the current mandate. Enterococcus lactis synonym Enterococcus xinjiangensis, Aurantiochytrium mangrovei synonym Schizochytrium mangrovei, Schizochytrium aggregatum, Chlamydomonas reinhardtii synonym Chlamydomonas smithii and Haematococcus lacustris synonym Haematococcus pluvialis were assessed for the first time. The following TUs were not recommended for QPS status: P. lentus due to a limited body of knowledge, E. lactis synonym E. xinjiangensis due to potential safety concerns, A. mangrovei synonym S. mangrovei, S. aggregatum and C. reinhardtii synonym C. smithii, due to lack of a body of knowledge on its occurrence in the food and feed chain. H. lacustris synonym H. pluvialis is recommended for QPS status with the qualification ‘for production purposes only’.S

Update of the list of QPS-recommended microbiological agents intentionally added to food or feed as notified to EFSA 16: suitability of taxonomic units notified to EFSA until March 2022

The qualified presumption of safety (QPS) approach was developed to provide a regularly updated generic pre-evaluation of the safety of microorganisms, intended for use in the food or feed chains, to support the work of EFSA's Scientific Panels. The QPS approach is based on an assessment of published data for each agent, with respect to its taxonomic identity, the body of relevant knowledge, safety concerns and occurrence of antimicrobial resistance. Safety concerns identified for a taxonomic unit (TU) are, where possible, confirmed at the species/strain or product level and reflected by 'qualifications'. In the period covered by this statement, no new information was found that would change the status of previously recommended QPS TUs. Of the 50 microorganisms notified to EFSA in October 2021 to March 2022 (inclusive), 41 were not evaluated: 10 filamentous fungi, 1 Enterococcus faecium, 1 Clostridium butyricum, 3 Escherichia coli and 1 Streptomyces spp. because are excluded from QPS evaluation, and 25 TUs that have already a QPS status. Nine notifications, corresponding to seven TUs were evaluated: four of these, Streptococcus salivarius, Companilactobacillus formosensis, Pseudonocardia autotrophica and Papiliotrema terrestris, being evaluated for the first time. The other three, Microbacterium foliorum, Pseudomonas fluorescens and Ensifer adhaerens were re-assessed. None of these TUs were recommended for QPS status: Ensifer adhaerens, Microbacterium foliorum, Companilactobacillus formosensis and Papiliotrema terrestris due to a limited body of knowledge, Streptococcus salivarius due to its ability to cause bacteraemia and systemic infection that results in a variety of morbidities, Pseudonocardia autotrophica due to lack of body of knowledge and uncertainty on the safety of biologically active compounds which can be produced, and Pseudomonas fluorescens due to possible safety concerns

Update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 13: suitability of taxonomic units notified to EFSA until September 2020

The qualified presumption of safety (QPS) approach was developed to provide a regularly updated generic pre-evaluation of the safety of biological agents, intended for addition to food or feed, to support the work of EFSA's Scientific Panels. It is based on an assessment of published data for each agent, with respect to its taxonomic identity, the body of knowledge, safety concerns and antimicrobial resistance. Safety concerns identified for a taxonomic unit (TU) are, where possible, confirmed at strain or product level, and reflected by 'qualifications'. In the period covered by this statement, no new information was found that would change the status of previously recommended QPS TUs. Of the 36 microorganisms notified to EFSA between April and September 2020, 33 were excluded; seven filamentous fungi (including Aureobasidium pullulans based on recent taxonomic insights), one Clostridium butyricum, one Enterococcus faecium, three Escherichia coil, one Streptomyces spp. and 20 TUs that had been previously evaluated. Three TUs were evaluated; Methylorubrum extorquens and Mycobacterium aurum for the first time and Bacillus circulans was re-assessed because an update was requested in relation to a new mandate. M. extorquens and M. aurum are not recommended for QPS status due to the lack of a body of knowledge in relation to use in the food or feed chain and M. aurum, due to uncertainty concerning its pathogenicity potential. B. circulans was recommended for QPS status with the qualifications for 'production purposes only' and 'absence of cytotoxic activity'. (C) 2021 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority

Evaluation of public and animal health risks in case of a delayed post‐mortem inspection in ungulates

The potential effects of a 24 or 72‐h delay in post‐mortem inspection (PMI) of ungulates on public health and monitoring of animal health and welfare was evaluated. The assessment used a survey of meat inspectors, expert opinion, literature search and a stochastic model for Salmonella detection sensitivity. Disease detection sensitivity at a delayed PMI is expected to reduce detection sensitivity to a variable extent, depending on the hazard and on the signs/lesions and organs involved. No reduction is expected for Trichinella detection in meat from susceptible animal species and any decrease in detection of transmissible spongiform encephalopathies (TSEs) will not exceed the current tolerance for fallen stock. A 24‐h delay in PMI could result in a small reduction in sensitivity of detection for tuberculosis, echinococcosis and cysticercosis. A greater reduction is expected for the detection of pyaemia and Rift valley fever. For the detection of Salmonella, the median model estimates are a reduction of sensitivity of 66.5% (90% probability interval (PI) 0.08–99.75%) after 24‐h delay and 94% (90% PI 0.83–100%) after 72‐h delay of PMI. Laboratory testing for tuberculosis following a sampling delay of 24–72 h could result in no, or a moderate, decrease in detection depending on the method of confirmation used (PCR, culture, histopathology). For chemical contaminants, a delay in meat inspection of 24 or 72 h is expected to have no impact on the effectiveness of detection of persistent organic pollutants and metals. However, for certain pharmacologically active substances, there will be a reduced effectiveness to detect some of these substances due to potential degradation in the available matrices (tissues and organs) and the non‐availability of specific preferred matrices of choice.info:eu-repo/semantics/publishedVersio