Saturday , 20 October 2018

How safe is your milk?

Maneka Sanjay Gandhi
Imagine a new human mother who has a viral infection. Would any doctor allow her own baby to drink her milk? Of course not. When you drink milk, have you ever thought of the health of the cow that this milk came from?
According to veterinary studies, one of the most common diseases that cattle have is parainfluenza3, a viral disease. The PI3 virus infects the upper respiratory mucosa. While fatalities are rare, they predispose the animal to other recurrent infections. How many cows have you seen with a runny nose? Probably none, because no one looks at cows. But if you go to the commercial dairies around India you will see the classic respiratory signs of cough, fever, discharge from nose and eyes, increased respiratory rate and difficult breathing. There is no specific anti-PI3 therapy. Medicines are given for the secondary bacterial infections that follow. All the while, milking goes on.
Does this happen only in India? No, studies done by Reisinger, Bakos and Dinter, Abinanti and Gale and King, confirm the virus in cattle in their own countries. In Japan, Inaba etc. have shown that the virus is widely disseminated among cattle in Japan. These results are not very different from those reported by Hoerlein et al. in the United States and Bakos and Dinter in Sweden.
Now, come to the next step: scientists have found the virus not just in nasal discharges but in milk. In studies done by Inaba, the virus was isolated not only from nasal secretions but also from the milk of naturally infected cattle. At one farm the virus was recovered from milk in 14 of 58 cows (24 per cent), while nasal secretions were positive for virus in 14 of 50 animals (28 per cent). This finding suggests that milk also plays a role as the source of infection. The virus invades the mammary glands, multiplies there and is excreted in milk.
Is the virus zoonotic? Probably. So, when you drink milk, you stand a strong chance of getting your runny nose/fever and cough from it.
Is that the only danger lurking in milk?
Mastitis is an inflammation of the mammary gland and udder tissue, and is a major pandemic disease of dairy cattle. Milk-secreting tissues and various ducts throughout the udder can be damaged by bacterial toxins. Severe acute cases can be fatal, but even in cows that recover there are changes in the secretion of milk from the mammary glands.
Mastitis can be kept away if the milkers use good hygiene, good housing management, and good nutrition to promote cow/buffalo health. But is there a single animal in the dairy industry in India that is kept properly? Inspections of all the dairy nagars (land that has been given to cattle owners for the purpose of providing milk) across India show that cows stand knee deep in slush which is a combination of their own excreta, urine and water from the sewage pipe; most of them have runny noses and fever and almost all have mastitis brought on by bad, fermented, old hay, both used as bedding and food, the humidity, and the filthy hands that push and pull at their teats twice a day. Most of them have sores on their teats and bellow with pain during the milking. No dairy inspector has ever been to these cattle sheds, and they are so easily bribed that their money is sent home – the same way as the vets attached to slaughterhouses get their monthly payments. Mastitic cows need specialized handling, veterinary care and medicines and clean surroundings. This costs the owner too much, so he keeps milking till the day it becomes obvious that there is far too much blood in it. And then he sells the cow for slaughter.
Abroad, the milk is sometimes thrown away when it is discovered to be contaminated with parainfluenza and the bacteria from mastitis. In India we check for neither.
Mastitis is a scourge in every country and there is no vaccine for it. Abroad, entire herds are killed. It has made no difference to the spread of this disease.
The most obvious symptoms of clinical mastitis are abnormalities in the udder, such as swelling, heat, hardness, redness, pain and fever, sunken eyes, diarrhoea and lack of appetite. The milk is watery with flakes, clots, or pus.
The changes in milk constituents are caused by infection-fighting white blood cells attempting to eliminate the infective organisms, which may further be responsible for producing toxins which damage the milk-producing glands within the udder. There are changes in the protein composition in milk, with low quality blood serums leaching into it; casein, an important protein found in healthy milk, is significantly reduced in mastitic cows. An important complication is that casein is closely linked with calcium levels in milk production.
The pH of milk, normally around 6.6, can increase to 6.8 or 6.9 in mastitic cows. The presence of blood enzymes in milk from mastitic cows can affect the taste, and its ability to be made into other dairy products such as cheese or yoghurt.
An important paper, which should be sent to every government division in charge of dairy inspection, is called ‘Public health hazard due to mastitis in dairy cows’ by K. G Abdel Hameed , G Sender , Korwin-Kossakowska of South Valley University, Qena, Egypt and Polish Academy of Sciences Institute of Genetics and Animal Breeding, Jastrzebiec, Poland.
Milk from cows with mastitis, mixed into bulk milk, enters the food chain and poses a threat to human health. Milk and other dairy products are infected with staphylococcus aureus and streptococcus agalactiae – both the most common agents for mastitic infections.
704 mixed milk samples were collected from 275 cows kept in two herds in 2004/2005. One herd was kept very well and the other not so well, but not badly. The animals were milked twice a day and the milk mixed. The quality of milk was found within European standards as per their tests. The samples were analysed for the presence of s. aureus, str. agalactiae and other mastitis-causing organisms. 16.6 per cent contained s. aureus and 1.4 per cent contained str. agalactiae. 4.7 per cent contained atr. dysgalactiae, 2.9 per cent contained escherichia coli and 14.7 per cent contained other mastitis-causing organisms. Both herds were afflicted equally by sub-clinical mastitis attributed to s. aureus.
This is good milk. Find a single herd in India that is kept even semi-well.
If the cow has severe clinical mastitis, abnormalities of milk are easily seen and this milk normally would not enter the food chain. But when milk of cows with sub-clinical mastitis, ie with no visible changes, is mixed into bulk milk, it enters the food chain and can be dangerous to humans. Milk and other dairy products are frequently infected with s. aureus which cause nausea, vomiting and abdominal cramps, when ingested by humans and are responsible for staphylococcal food poisoning outbreaks [Kluytmans et al. 1997]. These toxins cannot be destroyed by heating or drying [National Mastitis Council 1996]. Str. agalactiae is considered a major cause of elevated somatic ( pus) cell count (SCC) in milk. As SCC rise because of mastitis, milk quality decreases due to the drop in lactose and casein. In humans, str. agalactiae has been described as a common reason for invasive infections in babies, but it also causes infections and mortality in adults, especially diabetics, pregnant and post-partum women, and immunocompromised patients [Schuchat 2001, Lerner et al. 1977].
Another public health concern are the antibiotic residues in milk due to extensive use of antibiotics in the treatment and control of the disease. The careless use of antibiotics, often done even without consulting doctors, results in residues in foods which can lead to severe reactions in people allergic to antibiotics and, at low levels, can cause the development of antibiotic-resistant strains of bacteria.
In fact, when clinical mastitis is detected, the cow is given an intramammary infusion of antibiotic, and her milk must be kept out of the food supply. Selling milk contaminated with antibiotics can lead the producer abroad to lose his permit. Not so in India where there are no permits to begin with.
Should you be drinking this milk, no matter what label the company has?

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