Contamination du lait cru et de l’attiéké vendus sur les marchés informels à Abidjan (Côte d’Ivoire) par le groupe Bacillus cereus et analyse des risques

ABSTRACT IN ENGLISH In Côte d’Ivoire, although milk and attiéké play an important role in human nutrition, they could represent a poisoning risk to the consumer, due to poor hygiene throughout the production chain. This study aimed to contribute to the poisoning risk reduction linked to the consumption of local raw milk and attiéké contaminated with B. cereus group. For this, milk and attiéké production systems from farm to retail in Abidjan were studied. The risk of foodborne illness associated with the consumption of milk and attiéké was assessed using a questionnaire with 188 consumers of milk and 360 consumers of attiéké, respectively. On the one hand, 320 samples from the farms including 150 milk samples and on the other hand 16 samples of freshly prepared attiéké and 306 samples attiéké sold on the informal markets were collected and analyzed according to EN ISO 7932: 2004. The isolates were identified by polymerase chain reaction (PCR) and characterized by toxigenic and antibiotypic. In addition, the resistance of B. cereus group spores to hydrothermal warm up of attiéké was evaluated. The results showed that B. cereus group was found in 41.2% of milk of the samples taken from seller’s pooled milk with a mean load of 2.9 ± 1.0 log (CFU/mL). The prevalence of B. cereus group in attiéké samples taken from the informal markets was 25.2% and an average load of vegetative cells and spores were 2.4 ± 1.1 log (CFU/g) and 2.3 ± 1.1 log (CFU/g) respectively. B. thuringiensis (41.9%) and B. cereus sensu stricto (36.0%) were the isolated species. The majority virulence genes found were cytK-2 (80.8%), hblD (72.1%) and nheC (70.9%). The isolates were highly resistant to tetracycline (94.8%), ciprofloxacin (94.8%) and chloramphenicol (94.2%). The probability of consuming milk and attiéké contaminated with B. cereus group is 21.6% and 16.0% respectively. In total 12.6% and 18.9% of consumers reported that they contracted a foodborne illness after unheated milk and attiéké consumption respectively and the most symptoms were diarrhea and abdominal pain. The hydrothermal warm up of attiéké with a temperature greater than or equal to 90°C for at least 15 minutes reduced the concentration of B. cereus spores from 4.2 in attiéké into 1.8 ± 1.0 log (CFU/g) and D90°C was 8.5 ± 1.9 min for the quantities of attiéké varying from 150 to 450 g. The maximum duration of the milk sale at ambient temperature is 40 min while, the consumption deadline of attiéké warmed up at 90°C was 18 hours. In conclusion, milk and attiéké produced and sold in informal markets in Abidjan represents a risk for consumers’ health and B. cereus group species are one possible cause. It is recommended to heat the milk to boiling temperature and to warm up attiéké for at least 15 min at 90°C before consumption if clean milk and attiéké production cannot be assured. ABSTRACT IN FRENCH En Côte d’Ivoire, le lait et l’attiéké jouent un rôle important dans la nutrition humaine, mais peuvent représenter un risque de toxi-infection pour le consommateur. L’objectif de cette étude était de contribuer à la réduction du risque de toxi-infection suite à la consommation de lait cru local et d’attiéké contaminés par le groupe B. cereus. A cet effet, les systèmes de production à la commercialisation du lait et de l’attiéké à Abidjan ont été étudiés. Le risque de toxi-infections lié à la consommation du lait et de l’attiéké a été évalué à l’aide d’un questionnaire avec respectivement 188 consommateurs de lait et 360 consommateurs d’attiéké. D’une part, 320 échantillons issus des fermes dont 150 échantillons de lait et d’autre part, 16 échantillons d’attiéké fraîchement préparé et 306 échantillons d’attiéké en vente sur le marché, ont été collectés et analysés selon la norme EN ISO 7932 : 2004. Les isolats présomptifs du groupe B. cereus ont fait l’objet d’une identification par réaction de polymérisation en chaîne (PCR) et d’une caractérisation toxigénique et antibiotypique. Enfin, la résistance des spores du groupe B. cereus au réchauffage hydrothermique de l’attiéké a été évaluée. Les résultats ont montré que le groupe B. cereus a été isolé dans 41,2 % de lait de vente avec une charge moyenne de 2,9 ± 1,0 log (UFC/mL) et dans 25,2 % d’attiéké en vente avec une charge moyenne en cellules végétatives et en spores respectivement de 2,4 ± 1,1 log (UFC/g) et 2,3 ± 1,1 log (UFC/g). B. thuringiensis (41,9 %) et B. cereus sensu stricto (36,0 %) ont été les espèces identifiées. Les gènes de virulence majoritaires ont été cytK-2 (80,8 %), hblD (72,1 %) et nheC (70,9 %). Les isolats ont été très résistants à la tétracycline (94,8 %), à la ciprofloxacine (94,8 %) et au chloramphénicol (94,2 %). La probabilité de consommer du lait et de l’attiéké contaminé par le groupe B. cereus a été respectivement de 21,6 % et 16,0 %. Au total, 12,6 % et 18,9 % des consommateurs ont rapporté une toxi-infection suite à la consommation respectivement de lait cru et d’attiéké non réchauffé et les symptômes les plus évoqués ont été la diarrhée et les douleurs abdominales. Le réchauffage hydrothermique de l’attiéké à une température supérieure ou égale à 90 °C pendant au minimum 15 min a réduit la concentration en spores de B. cereus dans l’attiéké, de 4,2 à 1,8 ± 1,0 log (UFC/g) d’attiéké et le D90 °C a été de 8,5 ± 1,9 min pour des quantités d’attiéké variant de 150 à 450 g. La durée maximale de vente du lait à la température ambiante a été de 40 min alors que le délai limite maximal de consommation de l’attiéké réchauffé à 90 °C a été de 18 h. En conclusion, le lait et l’attiéké vendus sur les marchés informels à Abidjan représentent un risque de toxi-infection pour le consommateur et les bactéries du groupe B. cereus sont l’une des causes possibles. Il est recommandé de chauffer le lait jusqu’à ébullition et de réchauffer l’attiéké à la vapeur d’eau pendant au moins 15 min à 90 °C avant toute consommation, si les bonnes pratiques d’hygiène ne peuvent pas garantir la sécurité de ces aliments

Bacterial risk assessment in informally produced milk consumption in Côte d’Ivoire

BACKGROUND: Fifteen dairy farms from five zones of Abidjan, Côte d’Ivoire, were characterized to assess the conditions of raw milk production and marketing, and detect whether Bacillus cereus presented a risk to the consumer. METHODS: In total, 119 udder milk, 113 udder skin swabs, 22 hand swabs of farmers, 14 mixture milk of shepherd, 14 utensils rinse water, 16 environment samples and water used to rinse material for milking in 5 farms were sampled. Three informal markets in these zones were visited and 17 retailer pooled milk samples were collected and analyzed. The isolated strains were characterized and their virulence genes were detected by polymerase chain reaction (PCR). Milk quality was determined by comparing the average count of B. cereus to the limits of acceptability. To assess the impact of the consumption of raw milk, a consumer survey was conducted on 188 clients selected randomly at informal markets. RESULTS: 26.6% (32/119) of raw milk samples taken directly from the cow’s udders, 28.6% (4/14) mixture milk of shepherd and 41.2% (7/17) of retailer pooled milk were contaminated by B. cereus. Regarding limits of acceptability, 28.6% (2/7) of retailer pooled milk samples met the standards, 28.6% (2/7) presented a potential risk of disease and 42.8% (3/7) posed a real risk of foodborne poisoning. The sources of contamination of milk by B. cereus were, by decreasing order of importance, the udder (73/113), the water (3/5), the environment (9/16), the milk vendor containers (7/17), the hands of the milker(s) (9/22) and the utensils (4/14). All B.cereus strains (88 strains) isolated were virulent and harbored at least one of the virulence genes hblA, hblC, hblD, nheA, nheB, nheC, bceT and cytK-2. The most frequent virulence genes were hblD (79/88), cytK-2 (79/88), nheC (65/88) and hblC (60/88), all involved in the aetiology of diarrheal syndromes. Among milk consumer’s respondents, 12.8% (24/188) reported episodes of symptoms including diarrhea (19/37), fever (5/37), bloating stomach (4/37), vomiting (3/37) and nausea (1/37). Severe cases requiring a stay of one to three days in hospital were reported by 12.5% (3/24) of those infected. SUMMARY: The probability of consuming milk contaminated by B. cereus was 22.2%. The occurrence of foodborne diseases was significantly related (p < 0.05) to the consumption of unpasteurized milk (Relative Risk (RR): 2.6, 95% CI 1.07 - 6.22). Milk quality could be improved by the introduction of good hygiene practices such as water quality, utensil washing and milk pasteurization. Awareness of stakeholders in the informal dairy sector is also crucial to reduce the risk of infection for the consumer

Contamination of raw milk with Bacillus cereus from farm to retail in Abidjan, Côte d'Ivoire and possible health implications

In Africa, milk and dairy products play an important role in human nutrition but could represent a risk to human health, due to poor hygiene throughout the production chain. This study aimed firstly to assess the contamination of raw milk produced in traditional dairy farms in Abidjan with Bacillus cereus from farm to retail and secondly to assess the associated health risk for consumers in informal markets using a participatory approach. In total, 320 samples including 150 milk samples were collected in 15 purposively selected traditional dairy farms from four sites of Abidjan and analysed according to EN ISO 7932:2004 with slight modification. In addition, a survey was conducted in the three informal markets with 188 individuals who bought milk. B. cereus was found in 27% of the udder milk samples while 41% of the samples taken from seller’s pooled milk contained B. cereus. Out of the 183 milk consumers, 14% reported daily consumption of unheated milk, indicating the high probability of exposure to B. cereus and other foodborne illnesses. After milk consumption, 13% of consumers reported that they contracted a foodborne illness. In conclusion, milk produced and sold in informal markets in Abidjan represents a risk for consumers’ health and B. cereus is one possible cause. Milk quality could be improved by good hygiene practices, strengthening and targeting educational interventions and effective monitoring throughout the production and delivery chain

Where literature is scarce: observations and lessons learnt from four systematic reviews of zoonoses in African countries

The success of a systematic review depends on the availability, accessibility and quality of literature related to the review question. This paper presents the literature found in four systematic reviews conducted for a selection of zoonotic hazards in four livestock value chains in Africa, as well as setting out the challenges in conducting the reviews. The protocol was designed following international standards, and addressed four questions around prevalence, risk factors, control options and impact of various hazards and populations. Searches were conducted in four online databases. Articles were screened for relevance, and quality was assessed before data extraction. Literature on zoonotic hazards was in general scarce and access to full articles was limited. Overall, 25–40% of papers were considered poor quality. The diversity of approaches and designs in the studies compromised the ability to generate summarized estimates. We found that the emphasis of veterinary research has been on livestock problems rather than public health issues, although this seems to be shifting in the last decade; we also found there are limited studies on impact and control. While increasing literature is being published around zoonoses in Africa, this is still inadequate to appropriately inform policy and guide research efforts