Understanding Zoonotic Diseases and How We Can Prevent Them

Estimated reading time: 6 minutes

By Justin Long, Writer at Switch4Good

 

Let’s be brutally honest—most people don’t see zoonotic illnesses, which are diseases that can be transmitted from animals to humans, as a real and immediate threat. They’re more like background noise. An emerging disease might capture the headlines for a day, like when 16,243 pounds of raw beef products were recalled due to possible E. coli contamination, only to fade into obscurity with life continuing as usual (1). This was precisely the case with COVID-19 in early 2020. Initially, it was just another back-page news item, and no one paid it much attention. Then, in March 2020, Tom Hanks and Rita Wilson tested positive and were immediately quarantined in Australia. Suddenly, we took notice—if it could happen to them, no one was safe. Fast forward a few weeks and states were issuing stay-at-home orders, livelihoods were in jeopardy, and you might be one of many who found themselves bartering with strangers for a roll of toilet paper in exchange for a box of penne pasta. The devastation was swift and relentless.

Despite this collective trauma, we continue with behaviors that make another pandemic inevitable. With the rate of infectious diseases rising, this isn’t mere speculation—it’s a certainty (2). We are hurtling toward the next outbreak, and if we don’t change course, it’s only a matter of time before it strikes again. The real question is: how deadly will the next one be?

Animal agriculture, while historically central to food production, presents significant risks to human health through zoonotic diseases. These diseases have been responsible for some of the most severe public health crises, including swine flu and the recent COVID-19 pandemic. Transitioning to plant-based agriculture offers a promising solution to these challenges, addressing both health and environmental concerns.

The Zoonotic Disease Threat

The prevalence of zoonotic diseases has risen due to factors such as:

Intensive Farming Practices: High-density animal farming facilitates disease spread among animals and humans. For instance, large-scale poultry farms have been hotspots for avian influenza outbreaks, where chickens are kept in crowded, unhygienic conditions with little space to move (3).

Global Trade and Travel: The international movement of animals and animal products spreads pathogens. For example, African swine fever spread through the global trade of pigs and pork products, causing significant economic losses (4).

Deforestation and Habitat Encroachment: Human expansion for ruminants exposes us to new pathogens. Deforestation for cattle ranching in the Amazon has led to increased human exposure to various wildlife diseases, such as those transmitted by rodents and mosquitoes (5).

Climate Change: Altered ecosystems and weather patterns influence disease emergence and spread. Warming temperatures are expanding the habitats of mosquitoes, increasing the spread of diseases like malaria (6).

Zoonotic Diseases Linked to Animal Agriculture

Several zoonotic diseases are directly linked to animal agriculture, including:

Avian Influenza (Bird Flu)

Avian Influenza (H5N1) is a notable zoonotic disease associated with animal agriculture (7). It primarily affects birds, including domestic poultry like chickens, ducks, and turkeys. Recently, the virus has also been detected in dairy cows. The disease is caused by influenza type A viruses and can result in high mortality rates among birds.

Transmission to Humans: Humans can contract avian influenza through direct contact with infected birds, their droppings, or contaminated surfaces. While human-to-human transmission is rare, it remains a concern.

Impact on Human Health: Avian influenza in humans can range from mild respiratory symptoms to severe illness and death. The H5N1 strain of avian influenza has had a reported mortality rate of approximately 50% in confirmed cases (8). It is important to note that the number of cases is relatively low compared to other strains of influenza, but H5N1 is particularly troubling due to its high fatality rate among those infected.

Swine Influenza (Swine Flu)

Swine Influenza (H1N1) is another zoonotic disease linked to animal agriculture. It primarily affects pigs but can also infect humans.

Transmission to Humans: Humans can contract swine influenza through direct contact with infected pigs, their saliva, or contaminated surfaces. Human-to-human transmission is more common with swine flu compared to avian flu.

Impact on Human Health: Swine influenza in humans can range from mild respiratory symptoms to severe illness and death. The H1N1 strain caused a global pandemic in 2009, leading to thousands of deaths and economic disruption (9).

Salmonellosis

Salmonellosis is a bacterial infection often transmitted through contaminated meat, poultry, eggs, and dairy products. It is caused by Salmonella bacteria and is a common foodborne illness.

Transmission to Humans: Humans can contract salmonellosis through the consumption of contaminated food products, particularly those of animal origin, or by coming into contact with infected animals or people. Poor handling and cooking practices can also increase the risk of infection.

Impact on Human Health: Salmonellosis can cause symptoms such as diarrhea, fever, and abdominal cramps. In severe cases, the infection can spread to the bloodstream and cause serious illness or death, particularly in vulnerable populations like young children and the elderly (10).

E. coli

E. coli infections are often linked to contaminated beef and dairy products. Escherichia coli (E. coli) bacteria can cause severe illness in humans, particularly the strain O157.

Transmission to Humans: Humans can contract E. coli through the consumption of contaminated food products, especially undercooked ground beef, unpasteurized milk, cheeses, and raw vegetables.

Impact on Human Health: E. coli infections can lead to severe gastrointestinal symptoms, including bloody diarrhea and abdominal cramps. In some cases, particularly among young children and the elderly, the infection can be potentially life-threatening (11).

Economic Ramifications of Zoonotic Diseases

Healthcare Costs: The expenses for diagnosing, treating, and managing zoonotic disease outbreaks can be immense, straining public health systems.

Lost Revenue and Decreased Assets for Farmers: Farmers face financial losses due to animal culling, reduced productivity, and restrictions on the sale of affected livestock.

Higher Prices for Consumers: The disruptions in supply chains and decreased production lead to higher prices for consumers, impacting food affordability and accessibility.

The Solution

A plant-based food system offers a viable alternative to the risks posed by zoonotic diseases. Here’s how it can help:

Eliminating Zoonotic Disease Reservoirs:

• By eliminating the farming of animals, we decrease the reservoirs of zoonotic pathogens.
• Plant-based agriculture does not involve the same risks of disease transmission that are inherent in animal farming.

Improving Public Health:

• A plant-based diet can lower the risk of chronic diseases such as heart disease, diabetes, and certain cancers (12).
• Reducing the reliance on animal products can diminish the threat of antibiotic resistance, which is exacerbated by the overuse of antibiotics in animal farming (13).

Environmental Benefits:

• Plant-based agriculture has a lower environmental footprint, reducing greenhouse gas emissions, deforestation, and water usage.
• A healthier environment contributes to overall public health and reduces the conditions that can lead to zoonotic disease outbreaks.

Economic and Social Benefits:

• Shifting to plant-based agriculture can create new economic opportunities and jobs (14)(15).
• This pivot can also reduce healthcare costs associated with zoonotic diseases and diet-related illnesses.

Conclusion

The transition to a plant-based future presents a comprehensive solution to the risks posed by zoonotic diseases. By reducing our reliance on animal agriculture, we can protect public health, promote environmental sustainability, and create a more resilient and equitable food system.