R. VAN BUSTELLE/THE IMAGE BANK
Raw milk and your health.
Well, the seasons continue to march along, and the dog days of summer are nearly over. As I drive from farm to farm, it is a never-ending source of joy to see the foals, calves, and lambs growing and frolicking in the pastures and to see the progress of this year's field crops growing to maturity. Veterinary medicine is a source of endless challenges, both physical and mental. If I accurately diagnose a sick animal at a farm, I turn around and am faced with questions from the owner that keep me thinking. Recently, I was faced with a question that was the impetus behind the topic for this article. A client had a goat that was the source of milk for herself and her young children. Her goat was diagnosed with a disease that is known to be transmitted in both cow and goat milk and she and the children had been drinking the goat's raw (unpasteurized) milk. She was concerned about contracting the disease and asked about the risk of infection to herself and her children.
The topic of raw versus pasteurized milk is a controversial one that always stirs up heated discussion. Many farm dwellers and food purists find raw milk more delicious and perhaps more nutritious than pasteurized milk. As a veterinarian, I took an oath to protect the well-being of animals and to ensure a safe food supply for humans. The drinking of unpasteurized milk should be an informed choice. There are hazards associated with the consumption of raw milk and there are effective methods of pasteurization available for home use. The sale of raw milk is a very small local market available to a small number of dairies that are required by law to adhere to very stringent sanitary requirements. The sale of raw milk is prohibited across state lines within the United States, but almost half of the states permit the sale of raw milk within state borders. The USDA has passed these regulations because of the known hazards associated with consuming raw milk. Pasteurization of milk was begun initially to prevent the passage of two important diseases from animal to humans through raw milk: brucellosis and tuberculosis. There are regions of the United States where these diseases have been eradicated through vigilant efforts by the government, producers, and veterinarians. So it may seem that the necessity for pasteurization of milk is antiquated; however, there exists an ever-growing number of additional infectious agents that have been isolated in raw milk.
There are two categories of diseases that are potentially transmitted in raw milk. The first category includes those causative agents that are secreted in the milk directly from the mammary gland. The second category includes fecal contaminants in milk. Many of these are not serious in immune-competent, healthy people. But babies that are chronically ill, older people, pregnant women, people infected with HIV, and those receiving cancer therapy are less able to withstand infection by such organisms and are more susceptible to disease. The American Veterinary Medical Association has taken a stand against the sale and consumption of raw milk. When raw milk is used in cheese production, a test is run on the milk to test for actual numbers of bacteria. This screening detects any lapses in sanitary procedures during milking which could lead to the increased possibility of potentially dangerous fecal contaminants in the milk. This is a protective measure required by law in the production of cheese because many soft cheeses are made with raw milk. Zoonotic diseases are those that are passed from animal to man. Ringworm, brucellosis, and E. coli are just three better known examples of such diseases. There are many zoonotic diseases potentially transmitted in raw milk. Some of these include: brucellosis, listeriosis, Q fever, cryptococcosis, leptospirosis, louping ill, meliodosis, staphylococcal food poisoning, toxoplasmosis, and tuberculosis. Many others are passed in raw milk through contamination of milk with feces containing the following bacteria: Campylobacteria, Escheriacoli, Yersinia, Salmonella, Cryptosporidia, and Listeria. The intent of this article is not to expound on the numerous potential pathogens that are found in raw milk, but rather to educate about the hazards of raw milk, and provide ample information to enable the home consumption of safely and accurately pasteurized milk.
Milk is the ideal host for many spoilage organisms, and pasteurization will increase the shelf life and decrease the bad flavors produced by such organisms. Pasteurizing milk is very simply the heating of milk to a specific temperature for a specific time to kill the microorganisms that can transmit disease to humans. The source of these bacteria varies widely; they can be excreted directly into the milk by the animal, they can come from fecal contamination of the milk, from contamination of the milking and storage equipment, or even from the handler of the milk.
The process of pasteurization dates back to the work of Louis Pasteur between I860 and 1867. He was also the inventor of the vaccine against rabies. Pasteurization and proper handling of the milk, in addition to destroying the potential disease causing bacteria, can greatly increase the storage life of milk by inactivating the enzymes, elements in the milk responsible for rancidity. The process of pasteurization does NOT significantly alter the nutritional content of milk.
Proper handling of both raw and processed milk is necessary to keep milk fresh, safe, and free of off flavors and to ensure maximum shelf life and purity. There are a few essential dos and don'ts of milk handling that will keep milk healthful and fresh.
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