The main aim of this review was to assess the incidence of Pb, Hg and Cd in seafood from African countries on the Indian and the Red Sea coasts and the level of their monitoring and control, where the direct consumption of seafood without quality control are frequently due to the poverty in many African countries. Some seafood from African Indian and the Red Sea coasts such as mollusks and fishes have presented Cd, Pb and Hg concentrations higher than permitted limit by FAOUN/EU regulations, indicating a possible threat to public health. Thus, the operationalization of the heavy metals (HM) monitoring and control is strongly recommended since these countries have laboratories with minimal conditions for HM analysis.

The occurrence of Harmful Algal Blooms (HABs) and bacteria can be one of the great threats to public health due to their ability to produce marine toxins (MTs). The most reported MTs include paralytic shellfish toxins (PSTs), amnesic shellfish toxins (ASTs), diarrheic shellfish toxins (DSTs), cyclic imines (CIs), ciguatoxins (CTXs), azaspiracids (AZTs), palytoxin (PlTXs), tetrodotoxins (TTXs) and their analogs, some of them leading to fatal outcomes. MTs have been reported in several marine organisms causing human poisoning incidents since these organisms constitute the food basis of coastal human populations. In African countries of the Indian Ocean and the Red Sea, to date, only South Africa has a specific monitoring program for MTs and some other countries count only with respect to centers of seafood poisoning control. Therefore, the aim of this review is to evaluate the occurrence of MTs and associated poisoning episodes as a contribution to public health and monitoring programs as an MT risk assessment tool for this geographic region.

Microcystins (MCs) are cyanotoxins produced mainly by freshwater cyanobacteria, which constitute a threat to public health due to their negative effects on humans, such as gastroenteritis and related diseases, including death. In Mozambique, where only 50% of the people have access to safe drinking water, this hepatotoxin is not monitored, and consequently, the population may be exposed to MCs. The few studies done in Maputo and Gaza provinces indicated the occurrence of MC-LR, -YR, and -RR at a concentration ranging from 6.83 to 7.78 µg·L⁻¹, which are very high, around 7 times above than the maximum limit (1 µg·L⁻¹) recommended by WHO. The potential MCs-producing in the studied sites are mainly Microcystis species. These data from Mozambique and from surrounding countries (South Africa, Lesotho, Botswana, Malawi, Zambia, and Tanzania) evidence the need to implement an operational monitoring program of MCs in order to reduce or avoid the possible cases of intoxications since the drinking water quality control tests recommended by the Ministry of Health do not include an MC test. To date, no data of water poisoning episodes recorded were associated with MCs presence in the water. However, this might be underestimated due to a lack of monitoring facilities and/or a lack of public health staff trained for recognizing symptoms of MCs intoxication since the presence of high MCs concentration was reported in Maputo and Gaza provinces.

Tetrodotoxin (TTX) is a potent marine neurotoxin with bacterial origin. To date, around 28 analogs of TTX are known, but only 12 were detected in marine organisms, namely TTX, 11-oxoTTX, 11-deoxyTTX, 11-norTTX-6(R)-ol, 11-norTTX-6(S)-ol, 4-epiTTX, 4,9-anhydroTTX, 5,6,11-trideoxyTTX, 4-CysTTX, 5-deoxyTTX, 5,11-dideoxyTTX, and 6,11-dideoxyTTX. TTX and its derivatives are involved in many cases of seafood poisoning in many parts of the world due to their occurrence in different marine species of human consumption such as fish, gastropods, and bivalves. Currently, this neurotoxin group is not monitored in many parts of the world including in the Indian Ocean area, even with reported outbreaks of seafood poisoning involving puffer fish, which is one of the principal TTX vectors know since Egyptian times. Thus, the main objective of this review was to assess the incidence of TTXs in seafood and associated seafood poisonings in the Indian Ocean and the Red Sea. Most reported data in this geographical area are associated with seafood poisoning caused by different species of puffer fish through the recognition of TTX poisoning symptoms and not by TTX detection techniques. This scenario shows the need of data regarding TTX prevalence, geographical distribution, and its vectors in this area to better assess human health risk and build effective monitoring programs to protect the health of consumers in Indian Ocean area.

The objective of this work was to screen the EU-regulated lipophilic and cyclic imine toxins in four bivalve species (Atrina vexillum, Pinctada imbricata, Anadara antiquata, and Saccostrea Cucculata) from the Mozambican coast in the Indian Ocean. Toxins were extracted and analyzed according to the EU reference method for the determination of lipophilic toxins in shellfish via LC–MS/MS, but no regulated toxins were found in the analyzed species. However, pinnatoxins (PnTX G, E, and F) were detected in A. vexillum, P. imbricata, and A. antiquata. Higher levels of the PnTX G were determined for A. vexillum (7.7 and 14.3 µg·kg⁻¹) than for P. imbricata (1.6 and 2.4 µg·kg⁻¹), and for A. antiquata (4.5 and 5.9 µg·kg⁻¹) with both hydrolyzed and non-hydrolyzed extracts, respectively. The higher levels of PnTX G determined in the hydrolyzed extracts indicate the high potential of this species to esterify pinnatoxins, in particular PnTX G.

The occurrence of mycotoxins poses a threat to public health in Mozambique, with several cases of poisoning in humans caused by aflatoxins after consumption of groundnuts and maize reported before 1975. Over time, the control and monitoring of mycotoxins in agricultural and non-agricultural food and feed seem to have dropped significantly in Mozambique. So, the objective of this review is to recommend the implementation of monitoring and control of mycotoxins and fungal development. From our review, we note that data regarding mycotoxins in Mozambique are very limited and this makes it difficult to assess the spatial and temporal occurrence of mycotoxins in Mozambique. The scarcity of data does not mean that mycotoxins do not occur in Mozambique because the few studies that are available have confirmed the presence of mycotoxins in food and feed at concentrations above permissible limits in many countries of the world. This situation indicates a need for the creation of mycotoxin monitoring programmes involving the ministries of agriculture and public health (in coordination with universities) at the national level. Significance: This review provides relevant information that can help local authorities in Mozambique to implement a mycotoxin monitoring programme.