There are presently more than 18 known aflatoxins most of which have been insufficiently studied for their incidence, health-risk, and mechanisms of toxicity to allow effective intervention and control means that would significantly and sustainably reduce their incidence and adverse effects on health and economy. Among these, aflatoxin B1 (AFB1) has been by far the most studied; yet, many aspects of the range and mechanisms of the diseases it causes remain to be elucidated. Its mutagenicity, tumorigenicity, and carcinogenicity—which are the best known—still suffer from limitations regarding the relative contribution of the oxidative stress and the reactive epoxide derivative (Aflatoxin-exo 8,9-epoxide) in the induction of the diseases, as well as its metabolic and synthesis pathways. Additionally, despite the well-established additive effects for carcinogenicity between AFB1 and other risk factors, e.g., hepatitis viruses B and C, and the hepatotoxic algal microcystins, the mechanisms of this synergy remain unclear. This study reviews the most recent advances in the field of the mechanisms of toxicity of aflatoxins and the adverse health effects that they cause in humans and animals.

This review aims to update the main aspects of aflatoxin production, occurrence and incidence in selected countries, and associated aflatoxicosis outbreaks. Means to reduce aflatoxin incidence in crops were also presented, with an emphasis on the environmentally-friendly technology using atoxigenic strains of Aspergillus flavus. Aflatoxins are unavoidable widespread natural contaminants of foods and feeds with serious impacts on health, agricultural and livestock productivity, and food safety. They are secondary metabolites produced by Aspergillus species distributed on three main sections of the genus (section Flavi, section Ochraceorosei, and section Nidulantes). Poor economic status of a country exacerbates the risk and the extent of crop contamination due to faulty storage conditions that are usually suitable for mold growth and mycotoxin production: temperature of 22 to 29 °C and water activity of 0.90 to 0.99. This situation paralleled the prevalence of high liver cancer and the occasional acute aflatoxicosis episodes that have been associated with these regions. Risk assessment studies revealed that Southeast Asian (SEA) and Sub-Saharan African (SSA) countries remain at high risk and that, apart from the regulatory standards revision to be more restrictive, other actions to prevent or decontaminate crops are to be taken for adequate public health protection. Indeed, a review of publications on the incidence of aflatoxins in selected foods and feeds from countries whose crops are classically known for their highest contamination with aflatoxins, reveals that despite the intensive efforts made to reduce such an incidence, there has been no clear tendency, with the possible exception of South Africa, towards sustained improvements. Nonetheless, a global risk assessment of the new situation regarding crop contamination with aflatoxins by international organizations with the required expertise is suggested to appraise where we stand presently.

The sensitivity of nine strains of Listeria to nisin was determined as well as the minimum inhibitory concentration of nisin necessary to completely inhibit growth of these strains. All strains tested were variably sensitive to nisin and different MIC values were obtained, ranging from 740 to 10(5) IU/ml in trypticase soy agar and from 1.85 to 10(3) IU/ml in MRS agar. The inhibition of L. monocytogenes ATCC 7644 in TSB trypticase at different pH values and in sterilized and nonsterilized cottage cheese by nisin (37 X 10(2) IU/ml and 2.55 X 10(3) IU/g, respectively) also was investigated. This bacterium was completely inhibited after 24 h at pH 5.0 and above. At pH 4.5, 4.0, and 3.5, it was inhibited within 24 h. In cottage cheese no Listeria survivors were found at 24 h at 37 and 4 degrees C whether or not the cheese had been sterilized when as many as .35 X 10(6) cell/g were added at zero time.

North African countries have a rich tradition in food technology, and many traditional foods of animal or plant origin are still widely consumed and highly appreciated. In fact, these foods play an important role in the economy and food security in these countries. Yet, they are still mainly prepared at the household level under poor sanitary conditions and marketed through informal routes. They thus remain beyond any official control for their compliance to national regulatory standards. Therefore, their consumption is anticipated to put the public health at risk, although such risk has never been estimated on a scientific basis due to the lack of consumption patterns, epidemiological data, and appropriate surveillance programs. The scarcity of scientific studies on the incidence of hazards in this specific category of foods adds to the difficulties in conducting scientifically sound risk assessment or profiling studies. This review provides a brief description of technologies of the most popular traditional foods of animal and plant origin in North Africa and discusses the potential microbiological risks associated with their consumption and the food safety challenges that they raise. The review also aims to draw the attention of stakeholders including decision makers in North African countries to the imperious need to assess or profile the health risks associated with their consumption, and consequently, take the necessary measures to reduce such risks. A tentative risk profiling of selected traditional North African foods is presented using as a template the “risk categorization model for food retail/food service establishments” developed by Health Canada.