Aflatoxins in Uganda: an encyclopedic review of the etiology, epidemiology, detection, quantification, exposure assessment, reduction and control

Abstract

Uganda is predominantly an agricultural country where farming employ more than 60% of the population. Aflatoxins remain a scourge in the country, unprecedentedly reducing the value of agricultural foods and in high enough exposure levels, implicated for hepatocellular carcinoma, stunted growth in children and untimely deaths. This review synthetizes the country’s major findings in relation to the mycotoxin’s etiology, epidemiology, detection, quantification, exposure assessment, control and reduction in different matrices. It also highlights some of the management strategies for aflatoxin control that could be adopted in Uganda. Review results indicate that aflatoxins in Uganda is majorly produced by Aspergillus flavus and A. parasiticus and have been reported in maize (Zea mays L.), sorghum (Sorghum bicolor L.), sesame (Sesamum indicum), beans (Phaseolus vulgaris L.), sunflower (Helianthus annus), millet (Eleusine coracana), a bovine milk-based product, peanuts (Arachis hypogaea L.) and cassava (Manihot esculenta) with the highest content reported in cassava, beans and peanuts. The causes and proliferation of aflatoxigenic contamination of Ugandan foods have been largely due to poor pre-, peri- and post-harvest activities, poor government legislation, lack of awareness and low levels of education among farmers, agri-entreprenuers and consumers on the plague. Aflatoxin B1 is the most prevalent aflatoxin in Uganda. There is still limited research on aflatoxins in Uganda because the surveillance, reduction and control carry prohibitive costs. A few exposure assessments have been done especially in human sera and dependence on a single or a related set of foods with little diet diversity has exacerbated the risk of exposure to aflatoxins in Uganda because most of the staple foods are aflatoxin-prone. On the detection, control and reduction, these are still marginal, though some devoted scholars have devised and validated a sensitive portable device for on-site aflatoxin detection in maize as well as shown that starter cultures used for making some cereal-based beverages have the potential to bind aflatoxins. More effort should be geared towards awareness creation through training of farmers and traders in the cereal value chain as well as developing capacity to monitor aflatoxins. Vaccination against Hepatitis B and Hepatitis A should be emphasized to reduce the risk of development of liver cancer among the populace.

Trends in the incidence of cancer in Kampala, Uganda, 1991 to 2015

“…It is unlikely to be due to HIV (or its treatment) since liver cancer risk was not significantly related to HIV infection in a cohort study in Kampala 22 . Exposure to dietary aflatoxin is also known to be an important risk factor for liver cancer in Africa, 23 but there is little suggestion that there has been any substantial diminution in exposure in Uganda 24 …”

Medicinal Plants Used in Traditional Management of Cancer in Uganda: A Review of Ethnobotanical Surveys, Phytochemistry, and Anticancer Studies

“…In Northern Uganda, the use of shea (Vitellaria nilotica) butter, simsim (Sesame indicum L.), and groundnut (Arachis hypogea L.) pastes as substitutes for refined cooking oil and vaseline with the belief that the latter are carcinogenic is known. Unfortunately, recent reports have pointed out that some of these food items are contaminated with mycotoxins, particularly aflatoxins which are potential carcinogens [19,235].…”

“…3a-Hydroxytirucalla-8, 24-dien-21-oic, 3αhydroxytirucalla-7,24-dien-21-oic and 3β-fluorotirucalla-7,24-dien-21-oic acids [101], catechol (19), tyrosol, vanillic, and phloretic acids, limonene, phellandrenes, phydroxybenzaldehyde, dihydroxyphenylacetic acid, phydroxybenzoic acid, dihydroxybenzoic acid, pinoresinol, secoisolariciresinol [102], schweinfurthinol, coniferaldehyde, p-hydroxycinnamaldehyde, ligballinol, and amentoflavone [103] Cytotoxicity test on leukemia (CCRF-CEM) cells at 40 μg/mL showed that leaves and bark extracts induced more than 50% growth of this cell line. Fruit mesocarp oil extract and seed kernel oil extracts are expected to be vital for chemoprevention of cancers and other oxidative damage-induced diseases [104] Capsicum frutescens L. Capsaicin (20) and quercetin [105] Aqueous fruit extracts exhibited anticancer activity (though lower than capsaicin standard) when tested against prostate (PC-3) and breast (MCF-7) cancer cell lines in vitro [105] 8…”

“…In Uganda, the survival of cancer patients is alarmingly deplorable in comparison to other non-African third world nations [2,16]. e risk factors cited for the high cancer incidences in Uganda include acquisition from family lines, hormonal imbalances, consumption of mycotoxin (aflatoxin) contaminated foods, exposure to chemicals, irradiation, viruses, and bacteria [3,[17][18][19].…”

Update on mycotoxin contamination of maize and peanuts in East African Community Countries

“…Mycotoxins are secondary toxic metabolites of fungi that contaminate food in many different parts of the world with far-reaching consequences on human and animal health in addition to causing enormous economic losses [4][5][6][7][8]. Several studies have reported high mycotoxin levels in maize and peanuts from the East African community region [9][10][11][12][13][14][15]. Major mycotoxins of concern in maize and peanuts are Afl atoxins (AFT), Fumonisins (FBs), Zearalenone (ZEN), and Deoxynivalenol (DON) which are mainly produced by Aspergillus sp and Fusarium sp as shown in Table 2 [2,[16][17][18][19].…”