CAFO’s and human Infectious diseas

By Dr. Madeline Luke

A world without antibiotics is a world full of pain…

A bit of history and biology: Antibiotics were lifesavers for humans –no more graveyards full of dead civilians and soldiers because of strep throat, wound infections, urine infections, pneumonia. But in 1948, Dr. Thomas Jukes at Lederle Pharmaceutics discovered that chicks fed aureomycin, a form of tetracycline, grew better and heavier than chicks without the antibiotic. Subsequent studies showed a 4-12% weight advantage1 from the drug and this was enough to launch the widespread use of antibiotics as growth promoters. This was a game-changer for the meat industry. Now, abundant, cheap, more profitable meat could be produced by faster-growing animals in smaller quarters, cared for by less labor.

“Medically important “antibiotics used for growth promotion was finally banned in the US in 2017. The CDC, FDA, WHO, AMA, American Academy of Pediatrics, Infectious Disease Society of America, American Public Health Association and the National Academy of Science2 among others had raised concerns over issues of antibiotics resistance from this practice for years. However, antibiotic use in feed and water as prevention of bacterial infection is still allowed in the US if prescribed by a veterinarian. The human equivalent is a doctor prescribing penicillin to be placed in the school lunches for the whole elementary school to prevent strep throat because one kid got strep or putting anti -Tuberculosis drugs in the water supply of lower-income, crowded neighborhoods.

The 2017 FDA list of “medically important antibiotics” 3 approved for use with veterinarian oversight included 44 discrete chemicals. In addition to drugs familiar to human medicine, like tetracycline, macrolides similar to erythromycin, penicillin, and sulfa drugs, the list also included a few standouts like carbadox, an anti -swine dysentery drug which has been banned in Australia, Canada, and the EU over concerns regarding human cancers and birth defects. The FDA unsuccessfully tried to ban it here in 2016. Virginiamysin, a streptogramin drug is closely related to Synercid, the treatment of last resort for a multidrug-resistant superbug that causes serious human blood infections. Also approved was Tiamulin, a relative of lefamulin which was just approved for use in human pneumonia. They are members of a completely novel group of antibiotics that are valuable as older antibiotics become less effective. Mixed in with antibiotics are 2 formulations of progesterone used for weight gain and birth control and 2 beta-agonists- asthma inhaler type medications- that promote lean weight and an arsenic compound.

In 2017, 2,022,932 kgs of antibiotics were sold for US swine; in 2018 the year after growth promotion was banned as a permissible use, 2,521,157 kgs were sold. The number of pigs went up 2.9% but the percentage increase of antibiotics sold for swine use went up 17%.4

Is this a trend or a one-time aberration? Are farms stockpiling? Are the animals sicker? Are the producers and veterinarians ignoring the growth promotion ban?

Why is this important to human health?

Bacteria are always one step ahead of people.

They constantly mutate (make small changes in their genes) or share genetic material (bacteria have sex!) that allow some to resist a threat, such as an antibiotic. The good news is that often the genetic change that gives resistance may also cost that bacteria in another fashion so if the antibiotic pressure is off, the “wild strain” or un-mutated bacteria may come back. Just the right change to allow a bacteria to survive one or more antibiotics may be a very rare occurrence but with an estimated 10 31 bacteria in the world, the question is not when a drug-resistant bacteria will occur but when.

Furthermore, plasmids or interferons are pieces of DNA that carry resistance to several antibiotics at the same time. Bacteria share these freely among their neighbors. So these “superbugs” will survive not only one but multiple antibiotics.

According to CDC’s ”Antibiotic Resistance Threats in the United States,” 2019 (2019 AR Threats Report) more than 2.8 million antibiotic-resistant infections occur in the U.S. each year, and more than 35,000 people die5as a result. The report for 2013 estimated ”only”2million antibiotic-resistant infections and “only “23,000 deaths. A review of the CDC Foodborne Outbreaks 2018-20, Selected Investigations report6 shows that of 6 E.coli outbreaks involving non- processed domestic food, 4 involved multidrug-resistant bacteria. This includes the Yuma Arizona romaine lettuce that was irrigated with water downstream from a cattle CAFO. 210 people became ill with 96 hospitalizations, 27 cases of kidney failure, and five deaths. Resistance to seven antibiotics was present in this particular E.coli. Of seven salmonella outbreaks, four contained multidrug resistance bacteria.

In 2018, the US animal antibiotic market was estimated at 2 billion dollars annually 9. The Meat Institute states10:

1. Decreased use of low dose preventive antibiotics would increase the need for higher dose therapeutic antibiotics because actual illness would require more drugs. Would vaccines, better husbandry practices, lower density farms have a similar effect? Studies from Iowa and Denmark support this.11,12
2. Antibiotic resistance comes from the medical community. The meat producers and drug industry ignore the significant body of scientific reports that link antibiotic exposure in animals to resistant bacteria in animals, and then to farmworkers, hospitalized patients, contaminated food, water, air, and soil. The O’Neill review in 2015 found that of 139 peer-reviewed research articles that address the issue of antibiotic use in agriculture, only 7 or 5% argued there was not a link while 100 or 72% found evidence.13 Genetic testing is hard to refute.
3. The drugs used in animals are not meds used for humans. Tetracycline account for 44% of animal use but only 4% of human use.10Doxycycline, a close relative of tetracycline, is now one of the drugs used to treat community-acquired Methicillin-Resistant Staph(MRSA).
4. Preventive antibiotic use allows for more abundant and cheaper meat. This is likely true. But Emory researchers estimated the annual cost of antibiotic-resistant infections in the US was 2.2 billion dollars annually as of 2014.

Pigs and influenza A…

Every year, researchers make a guess as to what type of flu vaccine should be made. Influenza A mutates rapidly but usually not in a major way, so the vaccines can be at least partially effective. Periodically, however, a big change or shift occurs; there is no effective vaccine and no previous human immunity and that is a pandemic.

Shifts occur when viruses from different species end up in the same cell and swap genetic material. Since swine can be infected by not only swine but also bird and human influenza viruses, they are thought to be a potential "mixing vessel" from which a virus with pandemic potential could emerge. Genome reassortment is also frequently seen in waterfowl. Influenza viruses are identified by 2 surface characteristics ”H” and “N”.

The 1918 or H1N1 pandemic may have been a direct jump from pig to human or vice versa. The H1N1 virus which has pig and bird traits has persisted in hogs since then but causes only mild disease, it is not reportable or tested for. H1N1 has been reported to be more common in large, dense populations of pigs, and people who work in these CAFO’s are much more likely to show signs of the previous infection with H1N1. The most recent influenza pandemic was the swine flu of 2009 caused by the H1N1pdm09 virus. This novel virus is thought to have originated from a pig CAFO in Mexico and contains genetic material from North American and European swine and birds. It was responsible for an estimated 60 million infections, 274,000 hospitalizations, and 12,500 deaths in the US alone.

Gregory Gray, director of the Center for Emerging Infectious Disease at the University of Iowa Public Health wrote the following about the swine flu pandemic:

“But the same economy-of-scale efficiencies that allow CAFOs to produce affordable meat for so many consumers also facilitate the mutation of viral pathogens into novel strains that can be passed on to farmworkers and veterinarians...”

“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.”…..

Bacteria, viruses- and we have not even addressed fungi, prions (Mad Cow disease)-share a common space with humans, birds, mammals, and fish. They have been around a lot longer than us. Do we really need to have CAFO’s that can give them an advantage?