The most common type of bacteria found in goat milk is Staphylococcus aureus. Certain strains of S. aureus are responsible for diseases, such as mastitis in mammals and also stomach upset in humans.
Scientists assessed the prevalence of the bacteria on 30 goat dairies in North Carolina, USA, by testing approximately 500 milk samples, 500 swabs from the noses of goats and 100 swabs from the noses or hands of people milking the goats. Most of the dairies milked by hand and just used the milk for home consumption; at 28 of the 30 dairies, they consumed raw milk.
Almost half the goats had S. aureus in their noses and 26 per cent of milkers had the bacteria on their hands or noses. The good news is despite the prevalence of the bacteria, it rarely contaminated the milk; only 6 of 497 milk samples tested positive for it. In fact, the scientists write “One could speculate that milkers represented more potential to transmit S. aureus to goats, as compared to goats transmitting S. aureus to humans.”
The milking procedures varied among the farms. For example, on 10 per cent of the farms, milkers wore gloves all the time and on 70 per cent, gloves were never worn. Dairy or baby wipes were usually used to clean the teats before milking and just over half the dairies used a pre-dip. At almost all (93 per cent) of the farms a teat dip was used after milking; most used iodine but others used chlorhexidine, bleach or peroxide.
The scientists point out that “Udder preparation leading to a clean and dry udder is important, as well as having both hands and udders clean and dry. A recommended practice is washing with an udder solution, followed by careful drying. Options include disposable towels, reusable cloth towels or dairy wipes. The teats should then be dried with individual paper towels or cloths.”
Anderson, Kevin L., Rachael Kearns, Roberta Lyman, Maria T. Correa. 2019. Staphylococci in dairy goats and human milkers, and the relationship with herd management practices. Small Ruminant Research. Volume 171, February, Pages 13-22.