Raw milk, or milk that has not been pasteurized (heated to kill germs), is one of the riskiest sources of foodborne illness and can be contaminated with a variety of germs that can make people sick, according to the Centers for Disease Control and Prevention (CDC).

UK government
UK government

Health officials in Tennessee say the same thing: “Pasteurized milk is a prime example of one food that is much safer thanks to a simple heating process that destroys harmful bacteria,” said Tennessee Department of Health Commissioner John Dreyzehner, MD, MPH. “It has been recognized by the Centers for Disease Control and Prevention as one of the ten great public health achievements of the 20th century.”

John Dunn, DVM, MPH, director of foodborne disease prevention services for the Tennessee Department of Health, said drinking unpasteurized milk, sometimes known as “raw” milk, is “a spin of the roulette wheel” in how it may affect a person’s health.

“It’s true many people grew up on farms and drank raw milk from their cows and goats with no ill effects,” Dunn said. “It’s also true others weren’t as lucky, swallowing bacteria-laden milk that did great harm. Pasteurization destroys dangerous microorganisms without substantially altering the taste or nutritive value of milk.

A new study by the Centers for Disease Control and Prevention (CDC) reviewed outbreaks caused by raw milk in the United States during a 6-year period. From 2007 to 2012, 81 outbreaks associated with raw milk were reported to CDC in 26 states.

These outbreaks, which accounted for about 5 percent of all foodborne outbreaks with a known food source, caused 979 illnesses and 73 hospitalizations. The number of states where the sale of raw milk is legal increased from 22 states in 2004 to 30 in 2011. States where the sale of raw milk was legal in some form reported 81% of raw milk associated outbreaks.

Experts also found that raw milk led to much more severe illness and hospitalization than pasteurized milk. Young people under age 20 were disproportionately affected; 59% of raw milk associated outbreaks involved at least 1 child younger than 5 years old. This is especially troubling since children are more likely than adults to get seriously ill from the bacteria in raw milk. Reported outbreaks represent the tip of the iceberg. Because not all people who get a foodborne illness seek healthcare, get their illness diagnosed, or get reported to public health officials, the actual number of illnesses associated with raw milk likely is much higher.

Bacteria in raw milk can create a multitude of illnesses and damage to organs. Common symptoms of illness from drinking contaminated raw milk include vomiting, diarrhea, abdominal cramps, headaches, fever and body aches. While some may respond to medical treatment, others may suffer irreversible organ damage or death.

Some of the main culprits include:

Brucella melitensis- This organism is frequently seen in food borne infections associated with unpasteurized goat milk and cheese. Acute and chronic brucellosis can lead to complications in multiple organ systems. The skeletal, central nervous system, respiratory tract, the liver, heart, gastrointestinal and genitourinary tracts can all be affected. Untreated brucellosis has a fatality rate of 5%.

Campylobacter Image/CDC

Campylobacter jejuni- Campylobacter jejuni, the species most often implicated in infection causes diarrhea, which may be watery or sticky and can contain blood and white blood cells. Other symptoms often present are fever, abdominal pain, nausea, headache and muscle pain. The illness usually occurs 2-5 days after ingestion of the contaminated food or water. Illness generally lasts 7-10 days, but relapses are not uncommon (about 25% of cases).

There can be complications associated with campylobacteriosis; they include arthritis and neurological disorder Guillain-Barré syndrome. It is estimated that the latter is seen in one out of every 1000 cases of Campylobacter.

E. coli O157:H7- This organism has been directly linked with causing hemolytic uremic syndrome (HUS). Hemolytic uremic syndrome is likely linked to a shiga toxin produced by the bacteria. It causes a group of different problems (a syndrome) or symptoms in the patient. Though not completely understood, the following physiological reactions can occur:

First it causes the hemolysis of red blood cells. This is due to clotting problems caused by the clotting produced by platelets which clog up the capillaries and don’t allow the blood to flow freely.

Secondly, it can cause kidney failure where waste products build up in the blood because the ability of kidney to filter the blood becomes impaired. Most persons with HUS recover within a few weeks, but some suffer permanent damage or die.

Listeria moncytogenes- Those at greatest risk of serious listeria infection include pregnant women, newborns, the elderly, and adults with weakened immune systems (AIDS patients have a significantly high chance, up to 300 times, of contracting the disease).

Most healthy persons show no symptoms of this disease. Initial symptoms of food borne listeriosis include fever, muscle aches, fatigue and sometimes gastrointestinal symptoms, such as nausea, vomiting, or diarrhea. Primarily in high risk groups but occasionally in healthy adults, the infection can spread to the blood and central nervous system where it can cause sepsis and meningitis.

Mycobacterium bovis- General symptoms of M. bovis tuberculosis may include fever, night sweats, and weight loss. Other symptoms may manifest themselves depending on the part of the body affected by the disease: disease in the lungs may be associated with a cough; lymph node disease may cause swelling in the neck; and gastrointestinal disease may cause abdominal pain and swelling, and diarrhea. In rare instances, a person may die if the disease is left untreated.

Salmonella- This is an organism which can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems. Healthy persons infected with Salmonella often experience fever, diarrhea (which may be bloody), nausea, vomiting and abdominal pain.

In rare circumstances, infection with Salmonella can result in the organism getting into the bloodstream and producing more severe illnesses such as arterial infections (i.e., infected aneurysms), endocarditis and arthritis.

Pasteurization involves keeping the milk at a temperature of 145 degrees to 150 degrees F. for half an hour, at least, and then reducing the temperature to not more than 55 degrees F. This process not only kills pathogenic bacteria found in the milk, but eliminates many of the spoilage organisms that give the milk a longer shelf life.