How to Multiply the Most Dangerous Diseases Very Quickly

diseases caused by cafo

Story at-a-glance -

  • An outbreak of one of the world’s most dangerous viruses, Nipah virus, started on crowded pig farms
  • China is facing a surge in human H7N9 bird flu infections since October 2016, with cases occurring primarily among poultry farmers
  • Farmed fish and shrimp are also contributing to the emergence and spread of new diseases

By Dr. Mercola

It was not long ago — within the last 50 years — that small family farms were responsible for raising most of the food that Americans ate.

In the early 1970s, when the first large-scale concentrated animal feeding operations (CAFOs) appeared — first for egg-laying hens — it was with the notion that this "modern" way of rearing livestock was more efficient and profitable.1

By 1980, chickens, pigs, beef and dairy cows raised on CAFOs were commonplace, and today most meat sold in the U.S. comes from these massive, industrialized operations. The cheap meat they produce is not without consequence, however.

When you buck the laws of nature and attempt to industrialize farming instead of raising animals the right way — with good food and access to the outdoors that allows animals to live naturally — it's a recipe for disease.

One of the World's Deadliest Viruses Came From Pig Farms

Nipah virus was named for the town where the first reported outbreak was identified: Kampung Sungai Nipah, Malaysia. The outbreak started in 1998 and ended up devastating the farming town, where close to 1 in 3 families lost loved ones.2

The virus, now considered by the World Health Organization (WHO) to be among those most likely to cause a global pandemic, can cause a respiratory syndrome or fatal encephalitis (inflammation of the brain).3 According to NPR:4

"The disease struck lightning fast. Young men would be healthy one day. The next day their brains would swell up. They couldn't walk. Or talk. 'They'd become comatose, and some of them became paralyzed,' says Dr. C.T. Tan, a neurologist at the University of Malaya, who took care of patients from Nipah.

Some people even had what looked like locked-in syndrome — they were conscious and awake but couldn't move or speak. There was nothing Tan could do. No cure, no treatment. About half the patients died."

The Malaysian government blamed the disease on mosquitoes, but there were signs suggesting otherwise, like the fact that only Chinese farmers raising pigs were getting sick — Muslims, who don't handle pigs, were not.

Dr. Kaw Bing Chua, then training in virology at the University of Malaya in Kuala Lumpur, first identified the cause of the illnesses (Nipah) as a paramyxovirus. According to NPR, "These viruses come from livestock, not mosquitoes. And they often infect the lungs. So they can spread rapidly through the air."5

When Chua informed officials of his findings, the Malaysian government took drastic measures and killed nearly 1 million pigs. The outbreak stopped, proving the pigs were harboring the virus, but it took another 10-plus years to reveal the full story.

Pig CAFOs Led to Deadly Disease Outbreak

As NPR reported, the Nipah outbreak occurred at a time when Malaysia's pork industry was booming:6

" … [F]armers changed the way they raised pigs. They started packing the pigs into tight quarters and industrializing the farms. They could produce more meat with fewer resources. But the productivity bump came with a cost: 'When a virus got into the pigs, it could multiply very quickly,' Tan says.

'The way people grow their food has changed; so has the way diseases spread. Agricultural industrialization was part of what triggered the outbreak.'"

It was eventually discovered that fruit bats are the natural host of Nipah virus, but the pigs were the intermediate hosts in the Malaysian outbreak. The fact that millions of pigs were being raised in close quarters, in unhealthy conditions, was what allowed the virus to take hold and spread quickly.

Since then, it's been revealed that Nipah virus spreads not only among non-human animals and from such animals to humans but may also be transmitted from humans to other humans. There is still no cure. "The primary treatment for human cases is intensive supportive care," WHO notes.7

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Surge in Human Bird Flu Cases in China

In 2015, a bird flu outbreak among U.S. poultry led to the destruction of millions of chickens and turkeys in three states (Minnesota, Wisconsin and Iowa) before spreading elsewhere in the U.S.

Even though there were supposed safeguards in place to contain deadly disease outbreaks from spreading, poultry veterinarians noted that those strategies failed, as the bird flu managed to spread across 14 states in five months.

Wild birds can carry the virus, which can then be brought onto poultry farms via contaminated feces, dirt and dust.

While it was initially assumed that the outbreak could be stopped by killing the infected birds and isolating the CAFOs that raised them, veterinarians then suggested the disease was actually transmitted between farms.8

China, meanwhile, is facing a surge in human H7N9 bird flu infections since October 2016. Since February 2013, about 1,250 H7N9 cases of H7N9 have been reported, but 460 of them have occurred in recent months, all of them in China so far (although it's though Vietnam is at risk). Scientific American reported:9

"Like all bird flu viruses, H7N9 originated in wild aquatic birds such as ducks. These viruses occasionally make their way into domestic poultry flocks, as H7N9 did.

And from there, the viruses can trigger sporadic human infections — generally among people who work in poultry production or who sell or buy live chickens at Asia's popular so-called wet markets."

How Serious a Threat Is H7N9?

WHO has said that risks to humans are still low, but about one-third of those infected have died. Further, Wenqing Zhang, head of the WHO's global influenza program, said 7 percent of the cases are resistant to anti-viral drugs.10

As Reuters reported, more than 1,000 bird flu outbreaks have been reported in both poultry farms and wild flocks in Europe, Africa and Asia since the start of 2017:11

"Most involve strains that are low risk for humans, but virologists and public health specialists are worried that the sheer number of different types and their presence in so many parts of the world at the same time, increases the risk of viruses mixing and mutating, and possibly jumping to people."

The U.S. government stockpiled 12 million doses of an H7N9 vaccine; however, the virus has since changed and it's thought the vaccine will not be as effective against the currently circulating strains. Scientific American also noted:12

"The genetic sequences of about a dozen H7N9 viruses from the southern Chinese province of Guangdong have mutated in a way that makes them more dangerous for chickens — and perhaps people."

Swine Flu H1N1 Blamed on CAFOs

Remember the swine flu pandemic of 2009? It turned out to be less severe than seasonal flu and was not the terrifying, deadly pandemic that health officials predicted it would be (prompting one of the largest, most inappropriate and unnecessary vaccine campaigns to date).

However, the H1N1 virus was easily spread from human to human, and it was identified in more than 170 countries.

Vaccine development remained the primary effort to stop the pandemic, while a review in the journal Environmental Health Perspectives pointed out wisely in 2009 that "one potential source of the original outbreak — factory swine farming in concentrated animal feeding operations (CAFOs) — … received comparatively little attention by public health officials."13

The review quoted Dr. Gregory Gray, director of the Center for Emerging Infectious Diseases at the University of Iowa College of Public Health, who explained that CAFOs are prime breeding grounds for novel virus strains that can be spread from animals to farm workers and eventually the general public — because of the continual introduction of new animals:14

"When respiratory viruses get into these confinement facilities, they have continual opportunity to replicate, mutate, reassort and recombine into novel strains … The best surrogates we can find in the human population are prisons, military bases, ships or schools.

But respiratory viruses can run quickly through these [human] populations and then burn out, whereas in CAFOs — which often have continual introductions of [unexposed] animals — there's a much greater potential for the viruses to spread and become endemic."

Antibiotic-Resistant MRSA Bacteria Found in CAFOs

It's not only viruses that may spread via CAFOs. Methicillin-resistant Staphylococcus aureus (MRSA), which can cause deadly infections of the skin, blood and lungs, was first discovered in pigs and pig farm workers in the Netherlands in 2004.

Since then, this livestock MRSA strain has spread across Europe, Canada and the U.S., causing both mild and life-threatening infections. In 2015, research published in Clinical Infectious Diseases revealed that current workers at pig farms are six times more likely to carry multi-drug resistant MRSA than those without exposure to CAFO pigs.15

They also observed active infections caused by livestock-associated Staphylococcus aureus (LA-SA). Worse still, aerosolized MRSA has been detected in the air inside and downwind of a pig CAFO, as well as in animal feed.16

Also revealing, people who have close proximity to pig CAFOs and areas where CAFO pig manure is applied to crop fields are more likely to be infected with MRSA, adding to the "growing concern about the potential public health impacts of high-density livestock production."17

'Nightmare Bacteria' Detected in US Pig CAFO

Even carbapenem-resistant enterobacteriacea (CRE), bacteria resistant to the class of antibiotics called carbapenems, have been detected in a U.S. pig farm.18 The finding surprised even the researchers, since carbapenem drugs are illegal to use in food-producing animals because of their importance to human medicine.

CRE was been dubbed a "nightmare bacteria" by the CDC's former director Dr. Tom Frieden because of their extreme resilience — it's nearly impossible to kill them with conventional antibiotics.19 CRE was found after researchers swabbed the floors and walls of the pig farm over a period of five months. A gene called bla IMP-27, which gives bacteria the ability to resist carbapenem antibiotics, was also detected.

The researchers suggested the bacteria may have been introduced to the farm from the outside and that other antibiotics used on the farm could be potentially contributing to its maintenance and spread.20 The researchers wrote:21

"The implication of our finding is that there is a real risk that CRE may disseminate in food animal populations and eventually contaminate fresh retail meat products … The emergence of [CRE] … has been described as heralding the end of the antibiotic era with their global expansion presenting an urgent threat to public health.

… These potential pathogens can harbor highly mobile genes that confer resistance to the most critically important, live-saving antimicrobial drugs."

Farmed Fish and Shrimp Are Also Spreading Disease

The problems that occur on land do not disappear once intensive farming moves to the sea, which is why industrial fish farming, or aquaculture, can easily be described as CAFOs of the sea. Raised in high numbers in crowded quarters, in unnatural environments and fed an unhealthy diet, "the consequence has been the emergence and spread of an increasing array of new diseases," according to a review published in the journal Veterinary Research.22

Among them is heart and skeletal muscle inflammation (HSMI), which has been detected in farmed fish in Norway and British Columbia. HSMI has been responsible for devastating commercial fish farms in Norway, where it is considered the No. 3 cause of mortality, according to a 2015 annual report by seafood company Marine Harvest.23

There's also the highly lethal infectious salmon anemia (ISA) virus, also known as salmon influenza. First detected in Norway in 1984, infection spread to other countries via egg imports. According to biologist Alexandra Morton, at least 11 species of fish in British Columbia's Fraser River have been found to be infected with European-strain ISA virus, yet the Canadian food inspection agency has aggressively refuted the findings.

Morton tested farmed salmon purchased in various stores and sushi restaurants around British Columbia, and samples tested positive for at least three different salmon viruses, including ISA, salmon alphaviruses and piscine reovirus, which gives salmon a heart attack and prevents them from swimming upriver. Worse still, Morton and colleagues have also found traces of ISA virus in wild salmon.24 For more details, check out the documentary Salmon Confidential.

A February 2017 study published in PLOS One supports Morton's findings; it identified HSMI on a British Columbia salmon farm25 and noted that outbreaks often occur after the fish are exposed to stressful events, such as algal bloom or treatment for sea lice (another plague of fish farms).26

A Simple Solution for a Complex Problem

While CAFOs promote the spread of disease, traditional farming practices combat it. At small, regenerative and diversified farms, where pigs, hens and cattle are raised together in a sustainable way, there are many reasons why disease is kept to a minimum, even without the use of antibiotics in animal feed.

The animals have more space to move around, for starters, making them hardier than those raised in confinement. They are weaned at a later age, which builds their immune systems. Even exposure to the sun, a natural sanitizer, is helpful, while a pig allowed to roll in mud enjoys a natural anti-parasitic. Scientific American further reported:27

"In a 2007 study, Texas Tech University researchers reported that pigs that had been raised outside had enhanced activity of bacteria-fighting immune cells called neutrophils when compared with animals raised inside."

You can do your part and help protect your health by rethinking where you buy your food. Choosing food that comes from small regenerative farms — not CAFOs — is crucial. While avoiding CAFO meats, look for antibiotic-free alternatives raised by organic and regenerative farmers. If you live in the U.S., the following organizations can help you locate these types of healthy farm-fresh foods:

American Grassfed Association

The goal of the American Grassfed Association (AGA) is to promote the grass-fed industry through government relations, research, concept marketing and public education. Their site also helps you locate an AGA-approved producer near you. provides lists of farmers known to produce wholesome raw dairy products as well as grass-fed beef and other farm-fresh produce (although not all are certified organic). Here you can also find information about local farmers markets, as well as local stores and restaurants that sell grass-fed products.

Weston A. Price Foundation

Weston A. Price has local chapters in most states, and many of them are connected with buying clubs in which you can easily purchase organic foods, including grass fed raw dairy products like milk and butter.

Grassfed Exchange

The Grassfed Exchange has a listing of producers selling organic and grass-fed meats across the U.S.

Local Harvest

This website will help you find farmers markets, family farms, and other sources of sustainably grown food in your area where you can buy produce, grass-fed meats and many other goodies.

Farmers Markets

A national listing of farmers markets.

Eat Well Guide: Wholesome Food from Healthy Animals

The Eat Well Guide is a free online directory of sustainably raised meat, poultry, dairy and eggs from farms, stores, restaurants, inns, hotels and online outlets in the United States and Canada.

Community Involved in Sustaining Agriculture (CISA)

CISA is dedicated to sustaining agriculture and promoting the products of small farms.


The FoodRoutes "Find Good Food" map can help you connect with local farmers to find the freshest, tastiest food possible. On their interactive map, you can find a listing for local farmers, CSAs and markets near you.

The Cornucopia Institute

The Cornucopia Institute maintains web-based tools rating all certified organic brands of eggs, dairy products and other commodities, based on their ethical sourcing and authentic farming practices separating CAFO "organic" production from authentic organic practices.

If you're still unsure of where to find raw milk, check out and They can tell you what the status is for legality in your state, and provide a listing of raw dairy farms in your area.

The Farm to Consumer Legal Defense Fund also provides a state-by-state review of raw milk laws. California residents can also find raw milk retailers using the store locator available at