Zoonoses: What Impact On Food Safety?

 

Humans coexist in a complex, interdependent relationship with the companion, production, and wild animals we depend on for our food, livelihoods, and well-being, as well as with the environments we live and work in together.

The interface between humans, animals, and the environments we share can also be a source of diseases impacting public health and the social and economic well-being of the world population. Such diseases, transmissible from animals to humans through direct contact or though food, water, and the environment, are commonly referred to as “zoonoses.”

The above are the first two paragraphs from a World Health Organisation report on managing public health risks involved in human-animal-environment interaction.

From time immemorial, humans have come to depend on animals for a wide range of reasons, mainly for sustenance. This dependence dates back to pre-historic times when man was mainly a hunter. Since that time till now, this interaction has grown consistently more complex.

Of course, this interaction has not come without its challenges. A major part of these are zoonoses, diseases caused by pathogens that cross from animals to humans. Globally common zoonoses are Ebola Virus Disease, salmonellosis, bird flu, swine flu, rabies and so on. In fact, even HIV was a zoonotic disease transmitted from animals to man in the early part of the 20th century, though it has since evolved into a human-only disease.

According to Wikipedia, “zoonoses can be caused by a range of disease pathogens such as viruses, bacteria, fungi and parasites; of 1,415 pathogens known to infect humans, 61% were zoonotic.”

Wikipedia further states that zoonoses have different modes of transmission. In direct zoonosis the disease is directly transmitted from animals to humans through media such as air (influenza) or through bites and saliva (rabies). In contrast, transmission can also occur via an intermediate species (referred to as a vector), which carry the disease pathogen without getting infected.

Zoonoses have continued to have huge economic impacts globally. For example, according to the German Federal Institute for Risk Assessment, in 2006, the European Union lost over €6 billion to zoonoses. In Nigeria, the situation is not any different. From 2008 to 2017, the Federal Ministry of Agriculture stated that 26 states of the federation recorded cases of bird flu (avian influenza), including Bauchi, Kano, Katsina, Nassarawa, Plateau, Kaduna and Federal Capital Territory. According to Director, Veterinary and Pest Control Services, Federal Ministry of Agriculture and Rural Development, Gideon Mshelbwala, over 800 farms were affected, causing the Federal Government to pay out N674 million as compensation to 269 farmers.

Since the onset of bird flu in 2008, Nigeria has also grappled with some serious cases of zoonoses through diseases such as Ebola, Lassa Fever and, more recently, Monkey pox. Although the index case of Ebola in Nigeria was through human-to-human transmission, it is a documented fact that the disease is a zoonotic disease.

To have a grasp of the challenge posed by zoonoses, there is a need to briefly examine recent cases of zoonoses in the country.

Ebola

The index case of Ebola Virus Disease in Nigeria was a Liberian-American diplomat, Patrick Sawyer, who entered Lagos on July 20, 2014. By the time the disease was declared contained on September 22, 2014 in Nigeria, 20 cases and 8 deaths were confirmed, although this was a far cry from the 28, 675 cases and 11,315 deaths reported in other places.

Lassa Fever

Although the disease is reputed to have acquired its name from a village in Nigeria in 1969, only a few knew about the disease before 2016. According to the World Health Organisation’s Lassa Fever report on Nigeria, 501 suspected cases were reported as at June 2017, including 104 deaths. The disease continues to rear its ugly head in the country from time to time, since it is endemic in West Africa.

Monkeypox

As at October 27, 2017, 94 suspected cases of the disease have been reported across 11 states of the country, including Akwa Ibom, Bayelsa, Cross River, Delta, Ekiti, Enugu, Imo, Lagos, Nasarawa, Niger, Rivers, and the FCT. While only nine of the cases have been confirmed, there have fortunately no fatality. According to the Nigerian Centre for Disease Control, people could get Monkeypox if they are bitten or scratched by an animal, or contact animal blood in preparing bushmeat or have contact with an infected animal’s body fluids or sores. Monkeypox may also be spread between people through prolonged face-to-face contact, or through contact with body fluids or sores of an infected person, or items that have been contaminated with fluids or sores (clothing, bedding, etc.) However, Nigeria’s first encounter with the disease dates back to 1971.

Food-borne zoonotic disease

According to the European Food Safety Authority (EFSA), food-borne zoonotic diseases are caused by consuming food or drinking water contaminated by pathogenic (disease-causing) micro-organisms such as bacteria and their toxins, viruses and parasites. They enter the body through the gastrointestinal tract where the first symptoms often occur. Many of these micro-organisms are commonly found in the intestines of healthy food-producing animals. The risks of contamination are present from farm to fork and require prevention and control throughout the food chain.

The body further states that food-borne zoonotic diseases remain a significant and widespread global public health threat, with over 320,000 human cases reported each year in the European Union alone.

At the farm
  • Animal feed can be contaminated with bacteria such as Salmonella which can cause infection in animals and potentially lead to human infection from derived food products
  • Parasites may infect food producing animals
  • Milk can be contaminated by coming into contact with for example faeces or environmental dust
  • Animal skin and fur can be contaminated by faeces and environment
  • Eggs and different vegetables can also be contaminated at the farm
During slaughter
  • Meat can be contaminated by coming into contact with intestinal contents or animal skin
During further processing
  • Micro-organisms present in another raw agricultural product or on food contact surfaces may contaminate food
  • Infected humans handling food may contaminate food
In the kitchen
  • Microbes can be transferred from one food to another by improper use of kitchen utensils or by infected humans handling the food

According to EFSA, food can become contaminated at different stages of the food chain. These may include:

 

The body further stated that safe handling of raw meat and other raw food ingredients, thorough cooking and good kitchen hygiene can prevent or reduce the risk posed by these micro-organisms.

And herein lay the major challenge of food safety in Nigeria. Meat, poultry, dairy and egg products form a large part of our diet in Nigeria. Poor handling of these foods and undercooking have been found to be rampant in the country, greatly increasing the risk of foodborne zoonotic diseases in the country.

According to a research conducted by First HACCP, a Lagos-based safety consulting firm, many restaurants in the country prepare food in a way that could expose consumers of the food to health risk.

The Managing Consultant of First HACCP, Zainab Akanji was quoted by THISDAY to have said that 62 per cent of restaurants where workers used bare hands to handle raw beef, workers did not wash their hands after handling it and about 80 per cent of restaurant managers said that they did not always use a thermometer to make sure that their foods were cooked to the right temperature.

Post Author: David Chibueze

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