Module 7: Case Studies: Health and Environmental Impacts of Specific Foods

Antimicrobial Resistance

The WHO defines antimicrobial resistance (AMR) as the “resistance of a microorganism to an antimicrobial medicine to which it was previously sensitive.”(1) Because the microorganism is resistant to antibiotics, infections caused by AMR bacteria often lead to prolonged illness and greater risk of death. Therefore, antibiotic resistance among humans is harmful to global health. Inappropriate use, or excessive use, of antimicrobial medicines (antibiotics) favors the emergence of AMR bacterial strains.

An excessive amount of antibiotics is being used in agriculture to treat diseases of food-producing animals. In fact, about half of all antibiotics in Europe are prescribed for animals. In the United States, about 70% of all antibiotics are used in the agricultural industry.(2) The WHO also agrees that antibiotic usage in humans pales in comparison to antibiotic usage for agricultural purposes, such as for cattle, poultry farming, hog farming, fish farming, and honeybee hives. The WHO estimates that antibiotic use in the agri-business industry is at least 1,000-fold greater in absolute tonnage compared with use in humans.(3) However, as has been the case among humans, the excessive use of antibiotics in agriculture has created AMR. Furthermore, resistant bacteria in animals are being transferred to humans through infected feces, both during the slaughter process and when spread on crops. Scientists estimate that in the Netherlands, one third to one half of human resistance stems from antimicrobial resistance in livestock.(4)

The risk of AMR is particularly high in nations where national policies on AMR are weak or inadequate. Therefore, global health organizations have stepped in to deal with AMR issues. Broadly, WHO policies on AMR include having governments take the following actions:

      1. Commit to a comprehensive national plan to fight AMR. The government should create a national steering committee to guide actions of stakeholders.
      2. Strengthen surveillance and laboratory capacity to allow for rapid detection and solutions to infections.
      3. Guarantee uninterrupted access to essential, quality medicines, including antimicrobials.
      4. Ensure rational use of antimicrobials through the promotion of national guidelines for treatment.
      5. Develop a proper organizational structure to manage policies for the control of infections.
      6. Research new tools to combat AMR (and improve current diagnostic tests and antimicrobials) and incentivize industries to do the same.(5)


Specifically, FAO and the WHO are collaborating with a partner in Kenya, the Kenya Medical Research Institute (KEMRI), to strengthen national policies, systems for detection, and regulation of AMR risks in the poultry, beef, and pig sectors. The central task of this project is to identify the critical stages at which preventative or corrective actions can be implemented most effectively. The WHO and FAO are working on another project in Cambodia to assess and manage the public health risks associated with salmonella and campylobacter. The overall goal of this project is to facilitate the sharing of information among organizations, so that they can use a more integrated approach to address AMR risks at all stages.

Climate Change and Food Safety

Scientists generally agree that climate change is associated with increased global temperatures, trends towards stronger storm systems, increased frequency of heavy precipitation events and droughts, and rising sea levels. Therefore, climate change has implications on food yields in addition to food safety. Although the source of climate change is generally due to developed nations (and their high demand for energy and food), climate change is expected to cause the greatest harm to the developing world.(6)

Seasonality and temperature affect the prevalence of some diseases. For example, weeks of elevated temperatures increase the prevalence of salmonellosis and campylobacteriosis. Furthermore, higher temperatures and humidity increase the susceptibility of animals to disease, which can then be transmitted to humans. Excessive temperatures and humidity predispose cattle to bacterial syndromes, one of which is mastitis. Aquatic animals also become vulnerable, as the metabolic processes of fish are influenced by temperature, salinity, and oxygen levels.(7) Climate change may also change the incidence of foodborne zoonoses, thereby increasing the use of veterinary drugs, which could lead to AMR.

Climate change also affects the mycotoxin contamination of crops. For example, in Italy, since 2003, frequent hot and dry summers have increased the occurrence of A. flavus, leading to a serious outbreak of aflatoxin contamination.(8) Maize is also heavily affected by droughts, as the crop requires relatively high levels of water. Species of the fungus genus Fusarium often live in close association with maize, and during a drought, Fusarium symbionts and A. flavus both produce more of their respective mycotoxins.(9) This phenomenon spreads up the food chain, to a point where humans are at a greater risk of mycotoxin contamination.

Climate change also leads to more harmful algal blooms (HABs) in many marine and coastal regions. These algae can produce toxins harmful to humans, when contaminated seafood is ingested. Resulting illnesses include amnesic shellfish poisoning (ASP), diarrheic shellfish poisoning (DSP), neurotoxic shellfish poisoning (NSP), azaspiracid shellfish poisoning (AZP), paralytic shellfish poisoning (PSP), and ciguatera fish poisoning.(10) The toxins cause a variety of illnesses in humans, including respiratory and digestive problems, memory loss, seizures, lesions, and skin irritations.(11)


The term “bushmeat” refers to all wildlife species that are killed for meat, including elephants, gorillas, chimpanzees, forest antelopes, crocodiles, porcupines, bush pigs, cane rats, pangolins, monitor lizards, and guinea fowl. Bushmeat is often an essential part of the diet in remote rural areas. In more urban areas, bushmeat is considered a luxury item and is often consumed by the rich. In isolated regions, bushmeat is consumed by the poor. In fact, 98% of the animal protein consumed in parts of Cameroon consists of bushmeat. In the Congo basin, 4.5 to 5 million tons of bushmeat are consumed annually. The trading of bushmeat in the global market is valued at several billion dollars annually.(12)

Bushmeat is a global health concern, because consuming bushmeat has unique food safety risks. In addition to the microbiological hazards associated with other meat, bushmeat may contain emerging or re-emerging pathogens, such as bacillus anthrax, tubercle bacillus, and trichinella.(13) Many diseases can jump between non-human primates and humans, because of the similar genetic backgrounds. Therefore, consumption of bushmeat increases the risk of contracting zoonotic diseases. For example, simian immunodeficiency virus (SIV) has infected over 26 different species of African nonhuman primates, many of which are killed and consumed as bushmeat. Two of these SIVs, SIVcpz from chimpanzees, and SIVsm from sooty mangabeys, are the original causes of HIV in humans. SIVcpz and SIVsm have together been directly transmitted from the nonhuman primates to humans on more than seven different occasions.(14) Evidence also shows that HIV recombinants are appearing in regions where bushmeat hunting is greater. Not only does bushmeat pose additional microbial risks, but it also presents added chemical hazards, including the illegal, highly potent chemical pesticides used as bait.

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(1) WHO. "Antimicrobial Resistance." World Health Organization, Mar. 2012. Web. 24 May 2012.

(2) Levitt, Tom. "Overuse of Drugs in Animal Farming Linked to Growing Antibiotic-resistance in Humans." The Ecologist, 23 May 2011. Web. 24 May 2012.

(3) World Health Organization. Bulletin of the World Health Organization. Number 11. Vol. 88. WHO, 2010.

(4) Levitt, Tom. "Overuse of Drugs in Animal Farming Linked to Growing Antibiotic-resistance in Humans." The Ecologist, 23 May 2011. Web. 24 May 2012.

(5) World Health Organization. Bulletin of the World Health Organization. Number 5. Vol. 89. WHO, 2011.

(6) FAO. By Lee-Ann Jaykus, Marion Woolridge, J. Michael Frank, Marina Miraglia, Abigail McQuatters-Gollop, Cristina Tirado, Renata Clarke, and Mary Friel. Food and Agriculture Organization, 2008. Web. 24 May 2012.

(7) Ibid.

(8) Ibid.

(9) Ibid.

(10) Ibid.

(11) Ibid.

(12) Brashares JS, Golden CD, Weinbaum KZ, Barrett CB, Okello GV. Economic and geographic drivers of wildlife consumption in rural Africa. Proc Natl Acad Sci USA. 2011;108:13931–13936.

(13) Poirson, Jean-Michel. "Wild Meat/Bushmeat - Food Safety Implications." Lecture. Wild Meat, Bushmeat, Livelihoods, and Sustainability: Implications for Food Security, Zoonoses, Food Safety, and Biodiversity Conservation. Rome. 26 Oct. UN Food and Agriculture Organization. Web. 24 May 2012.

(14) BCTF. 2003. BCTF Fact Sheet: Global Human Health. Bushmeat Crisis Task Force. Washington, DC. 2 pages.