**3. Outcomes of food poisoning**

#### **3.1. Short-term outcomes**

Like any other health condition, food poisoning can be measured in terms of morbidity and mortality. However, due to the lack of population-based data, it is not possible to establish exactly the mortality rate due to food poisoning; rather, it is the case fatality rate (CFR) that is calculated from the number of people who have been affected after eating the offending food. The morbidity due to food poisoning can be measured by its incidence and prevalence.

Usually, the prevalence of acute food poisoning in patients attending health facilities has been determined as well as the factors associated with such episodes. In several African countries, the prevalence of acute food poisoning in patients seen at Emergency Departments of hospitals ranges from 0.5 to 11.5% [72, 73, 78, 161, 162]. As for chronic food poisoning, it is even more difficult to estimate its prevalence because of the diagnostic limitations [67, 163]. However, as explained below, the prevalence of health conditions resulting from chronic food poisoning can also be estimated.

In general, morbidity and mortality are higher in elderly individuals due to their increased susceptibility, age-associated comorbidities such as decreased immunity, decreased produc‐ tion of gastric acid and intestinal motility, malnutrition, lack of exercise. It has been reported that elderly persons are more likely to die from food poisoning events implicating toxinreleasing bacteria [7, 14].

It is estimated that over 3 million cases of acute food poisoning and 20,000 deaths occur annually due to exposure to pesticides in foods [164]. The following observations illustrate the extent of the problem in some African countries. It has been reported that more than 200,000 people die of food poisoning annually in Nigeria from foodborne pathogens [23, 165].

In the case of cholera, several outbreaks have been reported in African countries. In refugee camps, because of unsanitary conditions, environmental contaminants and improper food handling, outbreaks of foodborne diseases are common. Notable examples include the July 1994 outbreak, in which 14,000 deaths were recorded in refugee camps in Goma, Democratic Republic of the Congo. Another outbreak in April 1997 led to a total of 1,521 deaths among 90,000 Rwandan refugees residing in temporary camps in the Democratic Republic of the Congo, yielding a CFR of 1.69% [166, 167].

In Angola, an outbreak of cholera in February 2006 was reported in several provinces including the capital city, Luanda. In total, 26,979 cases were identified and 1,085 deaths were registered or a CFR of 4% [168]. In South Africa, an outbreak of cholera from November 2008 to April 2009 was resulted in over 12,000 suspected cases, 1,144 laboratory-confirmed cholera cases and 57 deaths, a CFR of 0.5% [169]. Previously, a breakdown in the drinking water pipeline system in a South African suburb caused an outbreak of typhoid, causing illness in nearly 4,000 persons as well as several deaths [170].

Recent data show that cholera is ever present in African countries. As shown in the Figure 4, the most affected countries are the Democratic Republic of the Congo, Mozambique, Kenya, Nigeria and Tanzania. The most recent report suggests that the cumulative number of cases of cholera in Tanzania was 4,835 cases that resulted in 68 deaths, a CFR of 1.4% [171].

Source: WHO/AFRO (2015). Epidemic alert and response. Available online at: www.afro.who.int/en/clusters-a-pro‐ grammes/dpc/epidemic-a-pandemic-alert-and-response/outbreak-news/4764-outbreak-bulletin-vol-5-issue-5-31-octo‐ ber-2015.html.

**Figure 4.** Cholera cases and deaths in African countries, January to September 2015.

With regard to mycotoxins, the outbreak of acute aflatoxicosis in Kenya in 2004 was one of the most severe food poisoning events involving contaminated maize; it has affected a total of 317 people resulting in a massive CFR of 39% [113, 172].

In Madagascar, acute food poisoning associated with consumption of fish or other marine animals contaminated by ciguatera is common from October to May each year. In 2013, a total of 116 cases and 1 death (CFR: 0.8%) were reported [173].

Finally with regard to incidence of food poisoning, the following Table 1 illustrates the situation in several African countries.


Source: World Health Organization (2002). World Health Statistics 2002. WHO, Geneva.

**Table 1.** Incidence of foodborne salmonellosis in some countries.

The mean incidence of foodborne salmonellosis ranges from 5.36 to 79.20 per 1,000 people [174]. This suggests that the morbidity due to this type of food poisoning is important in the African continent. As will be discussed further, this requires interventions particularly because long-term effects may also result from food poisoning.

#### **3.2. Long-term outcomes**

#### *3.2.1. Chronic poisoning*

There are some evidence built from data of the last 50 years that chronic poisoning due to dietary aflatoxins, heavy metals, pesticides and other organic compounds has resulted in people being affected by several conditions. Mycotoxins are toxic and carcinogenic metabolites produced by fungi that colonize food crops; aflatoxins, the most prevalent mycotoxins have been linked to liver cancer and have also been implicated in child growth impairment and acute intoxication as reported above. On the other hand, fumonisins have been linked to oesophageal cancer and neural tube defects; ochratoxin A has been associated with renal diseases as described above [175–178].

There is evidence that the above conditions that affect some African populations may have resulted from exposures to the above chemicals through food and other means. In the case of aflatoxin, its presence has been detected in human breast milk of women from Sub-Saharan Africa and Arab countries [110, 111, 130, 179–182]. Similarly, the presence of endocrine disruptors, who are consumed through polluted waters and contaminated fishes and bush meat, has been confirmed also from analyses of breast milk, umbilical cords samples of women and children from several African countries [183–186].

With regard to heavy metals, their implication in chronic poisoning through the food chain has been demonstrated and explained above. The health consequences are also multiple; in the case of mercury, its neurotoxicity has been noted since the Mina Mata incident in Japan [187]. To date, it is now established that it causes cognitive deficits at low exposure levels and severe psychiatric and neurologic effects at very high levels of exposure. Its toxic effects on the kidney, cardiovascular and immune systems are well known as well as its developmental neurotoxicity in case of in utero exposure [188–191].

Consumption of fish contaminated with mercury is one of potential sources of human exposure besides mining and the use of mercury-containing cosmetics used for skin lightening in Africa [192, 193].

Another heavy metal, lead, it is a naturally occurring heavy metal whose exposure is associated with several adverse effects across different population subgroups. From several studies, the effects of lead on neurodevelopment and, in particular, its negative effects on intelligence quotient and behaviour have been documented [190, 191, 194, 195]. More recently, lead has been associated with other adverse health impacts, such as increased risks of attention deficit hyperactivity disorder in children and cardiovascular mortality in adults [196, 197]. Although foodstuffs have not been reported as major sources of exposures to lead, lead was found in contaminated dust and soils that growing children may consume or inhale as well as in contaminated ceramics, crayons, pencils and piped water [188, 198].

With regard to pesticide exposure among African populations, it is a public health concern because of their uncontrolled use coupled to weak regulatory enforcement [175, 199]. In addition, there is a lack of competencies to use them appropriately due to lack of training and access to relevant safety information and personal protective equipment [200]. Pesticides are used for pest control in several environments, such as in the home and in various forms of agriculture. It is not surprising that pesticides used in agriculture have been detected in rivers and lakes that are located around farming communities [201, 202].

Human exposure to pesticides used in agriculture is reportedly higher among farmworkers and their families. In a study conducted in Kenya, it was reported that breast milk samples taken from non-farmer urban Kenyan mothers up to 4 weeks postpartum had detectable levels of nine organochlorine pesticides including dichlorodiphenyltrichloroethane (DDT) (and its metabolite dihydrodiphenylethane (DDE), dieldrin and lindane. Similarly, DDT was also detected in breast milk of mothers residing in some areas of Kwazulu, South Africa and Ghana [203]. Collectively, these studies suggest both historical and ongoing pesticide exposures in individuals through agriculture and dietary sources [77, 184, 202, 203].

#### *3.2.2. Sequelae*

Several sequelae have been described in populations exposed to specific toxic agents. For African populations that have been exposed to several classes of pesticides through agricul‐ ture, the environment and foods, it is expected that they may experience similar adverse effects. Well-established sequelae include neurotoxicity, endocrine-disrupting adverse effects and birth defects documented agricultural communities [204–207].

With regard to heavy metals, it is estimated that each year 9,129 to 119,176 additional cases of bladder cancer, 11,844 to 121,442 of lung cancer and 10,729 to 110,015 of skin cancer worldwide are attributable to inorganic arsenic in food [208].

Other sequelae include stunted growth in children or being chronically underweight, sus‐ ceptibility to infectious diseases and hepatocellular carcinoma (HCC) or liver cancer. This cancer is the third leading cause of cancer deaths worldwide, with roughly 550,000–600,000 new HCC cases globally each year [209]. Aflatoxin exposure in food is a significant risk factor for HCC [175, 210].
