Mycotoxin problem in Africa: Current status, implications to food safety and health and possible management strategies

Mycotoxins are natural contaminants of cereals and other food commodities throughout the world and they significantly impact human and animal health. Mycotoxins are toxic secondary metabolites prod...

An overview of mycotoxin contamination in foods and its implications for human health

Mycotoxin occurrence in grains and the role of postharvest management as a mitigation strategies. A review

During investigations on street food vendors’ materials, seventy samples of three types of dish washing water (E1, E2, E3), eighty-five pieces of money, eighty utensils were collected for microbiological assessment. Hands microbiological status of one hundred twenty-five consumers and seventy sellers were also assessed. The analysis revealed that 100% of E1 washing waters were very impure, while, 44.5% of second washing water (E2) were impure, 44.5% very impure and 11% acceptable. 45.45% of E3 washing water were acceptable, 27.27% impure and 27.27% very impure. The spoons and the dinner plates were sometimes contaminated with unacceptable levels (above 102) of different bacteria such as, coliforms and Staphylococcus aureus (P  0.05). Knives microbiological examination revealed presence of numerous bacteria (8.6 x 105 cfu/knife) such as coliforms, S. Aureus, Salmonella and Shigella. Pieces of money analysis revealed presence of coliforms and S. aureus. These data showing pathogen bacteria in food vending sites indicates hygiene monitoring failure.

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Hygienic status assessment of dish washing waters, utensils, hands and pieces of money from street food processing sites in Ouagadougou (Burkina Faso)

Data collected from street-vended food enterprises and on vendors in west African countries revealed that, they provide a variety of ready-to-eat foods to a high proportion of the populations. Nevertheless, their handling and trading practices are not permit to obtain safe food. While, street-vended foods are easily contaminated by food borne pathogen and others chemicals compounds. The street-vended foods contamination mechanisms were identified and improvement pathways were suggested. Indeed, Food Safety Objective (FSO) concept developed by FAO and WHO, can be used as ideal strategy for safe street food production. However, to reach this goal, the Critical Control Points (CCP), Microbiological and Risks Assessment (MRA), and hygienic status during street food production and sale were gathered. By assembling and analyzing the data, the safety assurance for safe street food obtaining was evaluated at every step of production chain. The data were juxtaposed to FSO concept frame work and applied along the street-vended food production chain. We applied Performance Objective (PO) and Control Measure (CM) respectively at operational levels, measure at relevant points of risk and points, that permit reduction of all contamination risks along the chain, to enhancing safe food obtaining. The FSO concept could help government to elaborate guidance for street foods production, vending and consumption, producers and vendors, training about HACCP pre-requisites and information for global view on safe street-vended food (SSF) production. This will be an important task for the primary health care system aiming at "health for all".

Street-Vended Foods Improvement: Contamination Mechanisms and Application of Food Safety Objective Strategy : Critical Review

The major part of the population of Ouagadougou, Burkina Faso, have their breakfast, dinner and lunch in street food shops. The characteristics of street food vendors are indicated. It appeared clearly that women play a major part (75%) in street food sale. Vendors have only a slight knowledge of food processing and of hygienic practices. There is a high proportion (about 50%) of people among them. This dietary habit has some negative aspects on the consumers' health. Ours studies clearly showed that hygienic practices during sales operations are not respected by all categories of vendors of food products. Also, it was observed that street food vendors sometimes sit close to the waste water drainage system and solid wastes. Sometimes, the food is not covered and it is manipulated by consumers in areas infested by flies and others insects. The water used to wash the materials is of poor quality. The second aspects of our studies showed that, in most cases, when the safety and hygienic practices were not respected, the food became a true microorganism culture medium under tropical climatic conditions. A table reports microbial analysis and contamination rates of some important street foods consumed in Ouagadougou. In general these results showed the failure of microbial quality of some food which is not preheated (milk product, fruit juice, vegetable, fruit) and in the case of food which is not reheated after a long time of exposition (dry meat and meat on sticks). The presence of Salmonella and Shigella species in some food represents a serious danger for consumers. These aspects were observed with most street food vendors. It probably makes street food the source of most diseases caused by bacteria and other microorganisms.

[Microbial quality assessment of some street food widely consumed in Ouagadougou, Burkina Faso].

A Ouagadougou, les aliments de rues sont vendus essentiellement par les femmes (75 %) de differents âges, pres de 50 % des vendeurs sont illettres et n'ont pas tous recu de formation en bonnes pratiques de fabrication et d'hygiene. Notre etude a montre qu'il existe des risques de contamination au cours des operations de vente des aliments de rue. L'environnement de vente des aliments chez les vendeurs sedentaires est souvent insalubre, a cause de la presence d'insectes (de grillons, de mouches et de moustiques dans les jarres d'eau), de la proximite de toilettes publiques, de caniveaux d'eaux residuaires, de flaques d'eau a odeur desagreable envahissante. L'etude de la qualite microbiologique des aliments de grande consommation collectes aupres des differentes categories de vendeurs a montre la presence d'une flore aerobie mesophile abondante, composee de differents germes comme les staphylocoques, les coliformes, les salmonelles, les shigelles et les streptocoques. La presence des salmonelles et shigelles rend certains aliments impropres a la consommation.

Evaluation de la qualité microbiologique de quelques aliments de rue dans la ville de Ouagadougou au Burkina Faso

Seven strains of Aspergillus spp. have been screened for their ability to produce aflatoxins in coconut broth media. Three were local isolates and four were reference strains obtained from the United States Department of Agriculture (USDA) and Centre for Disease Control and Prevention (CDC) Atlanta and used as positive and negative controls. All strains were previously cultivated in Aspergillus flavus and Aspergillus parasiticus agar to ascertain if they belong to A. flavus or A. parasiticus species. The qualitative ability of aflatoxin production was also previously performed by fluorescence emission under ultra violet light at 312 nm after 3 days of incubation at 30°C on coconut agar. Quantitative assessment of aflatoxin production was done by high performance liquid chromatography (HPLC) with post-column derivatisation after immunoaffinity column cleanup. The reference strains (NRRL5862, CDCB5333 and CDCB4571) and one of the local isolates (BfaS1) were aflatoxin producing species in coconut broth as assessed by HPLC. Per isolate aflatoxin B1 concentration after determination by HPLC was higher than the other types of aflatoxins identified. The strains NRRL5862 and CDCB5333 have, respectively produced the following quantities of aflatoxin B1: 73.67 and 165.73 ng/ml whereas aflatoxin B2 concentrations were, respectively 0.595 and 1.736 ng/ml.

Aflatoxigenic potential of Aspergillus spp. isolated from groundnut seeds, in Burkina Faso, West Africa

Mycotoxins are natural metabolites produced by fungi that can cause disease and death in human and animals alike, even in low concentrations. More than thirty mycotoxins that contaminate sorghum (Sorghum bicolor L.) and its derived products are known. This work aimed to investigate the presence of aflatoxin B1 and ochratoxin A in sorghum malt and beer, sampled between January and April 2012 in Ouagadougou. Mycotoxins in fifty samples of sorghum beer and twenty samples of sorghum malts have been purified using immunoaffinity columns, and later identified and quantified using high performance liquid chromatography (HPLC). Aflatoxin B1 and ochratoxin A were no found in any of the sorghum beer samples. However, 25% of the sorghum malt samples contained aflatoxin B1 with an average of 97.6 ± 88.2 ppb (p < 0.05), while none contained ochratoxin A above the level of 0.8 ppb (ochratoxin A limit of detection). From the samples collected in this study, consumption of sorghum beer seems to be safe concerning contamination in aflatoxin B1 and ochratoxin A but a dietary assessment of exposure should be conducted.

	 

	Key words: Aflatoxin B1, ochratoxin A, sorghum beer, sorghum malt, HPLC.

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Assessment of aflatoxin B1 and ochratoxin A levels in sorghum malts and beer in Ouagadougou

BACKGROUND Gastrointestinal infections are a global public health problem. In Burkina Faso, West Africa, exposure to Salmonella through the consumption of unhygienic street food represents a major risk of infection requiring detailed evaluation. METHODS Between June 2017 and July 2018, we sampled 201 street food stalls, in 11 geographic sectors of Ouagadougou, Burkina Faso. We checked for Salmonella contamination in 201 sandwiches (one per seller), according to the ISO 6579:2002 standard. All Salmonella isolates were characterized by serotyping and antimicrobial susceptibility testing, and whole-genome sequencing was performed on a subset of isolates, to investigate their phylogenetic relationships and antimicrobial resistance determinants. RESULTS The prevalence of Salmonella enterica was 17.9% (36/201) and the Salmonella isolates belonged to 16 different serotypes, the most frequent being Kentucky, Derby and Tennessee, with five isolates each. Six Salmonella isolates from serotypes Brancaster and Kentucky were multidrug-resistant (MDR). Whole-genome sequencing revealed that four of these MDR isolates belonged to the emergent S. enterica serotype Kentucky clone ST198-X1 and to an invasive lineage of S. enterica serotype Enteritidis (West African clade). CONCLUSION This study reveals a high prevalence of Salmonella spp. in sandwiches sold in Ouagadougou. The presence of MDR Salmonella in food on sale detected in this study is also matter of concern.

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Philippe A. Nikiema

Papers

[Microbial quality assessment of some street food widely consumed in Ouagadougou, Burkina Faso].

Evaluation de la qualité microbiologique de quelques aliments de rue dans la ville de Ouagadougou au Burkina Faso

Aflatoxigenic potential of Aspergillus spp. isolated from groundnut seeds, in Burkina Faso, West Africa

Assessment of aflatoxin B1 and ochratoxin A levels in sorghum malts and beer in Ouagadougou

Contamination of street food with multidrug-resistant Salmonella, in Ouagadougou, Burkina Faso.