MSU Extension Dairy

Though recent reports indicate that humans safely recover from Highly Pathogenic Avian Influenza (HPAI/H5N1), there is still a risk of illness, especially for farm workers exposed to potentially infected animals. As the HPAI outbreak continues to evolve, it is important that farms implement precautions to protect human and animal health. Currently the USDA reports that nine states have at least one dairy herd with positive HPAI tests. Due to the nature of the job and the current understanding of HPAI pathology, milking technicians are at higher risk of exposure and infection. Therefore, it is important to communicate the risks and precautions parlor employees should take to mitigate the risk of infection.

Why is there a higher risk for milkers?

According to the Center for Disease Control and Prevention (CDC), those who have job-related exposure to infected animals are at greater risk of contracting HPAI. This risk may also be higher for milkers or other workers in direct contact with the unpasteurized milk of infected cows. In April (2024) Texas reported the first case of a farm-worker infected linked to dairy cattle. USDA analysis from nasal swabs, tissue and milk showed that the highest concentration of virus shedding is found in milk prior to pasteurization. According to their report virus replication in the dairy cow mainly occurs in the udder. Therefore, unpasteurized milk droplets are considered as a primary medium of infection to other mammals including humans.

How can milkers be infected?

Milking technicians are constantly exposed to raw (unpasteurized) milk. Several steps that occur during the milking procedure increase exposure including fore-stripping, CMT testing/sampling or leaking cows. Milk can also be found in equipment, used towels, work clothes and many other areas of the parlor floor, walls etc. Additional risk is present in dairies that use raw milk to feed calves. If milk is not pasteurized on the farm prior to feeding, the risk can potentially extend to calf feeders and other employees who are in contact with the raw milk. However, many of these processes are vital for the optimal functioning of a dairy farm. This highlights the importance of increasing awareness and implementing strategies to reduce the risk for dairy farm workers.

What practices should be employed every day?

Standard hygiene practices and the use of personal protective equipment (PPE) should be reviewed and updated if necessary. Hands should be washed with hot, soapy water prior to starting a shift and before taking breaks. After a shift ends, the employee should shower (highly recommended) or wash hands and face with water and soap. Parlor employees should wear the following PPE throughout their shift:

Gloves: Should be worn 100% of the time in the parlor (including cow “pushers” who step inside the milking pit. Gloves should be instantly replaced if torn.

Clothing: Clean clothing is recommended. If outerwear protection is used (e.g. aprons or arm sleeves) they should be rinsed after each shift. Work attire should remain at the farm or kept separated from other clothing at the milker’s home. If no outerwear is used, work clothes should be kept and washed at the farm.

Boots: Preferably impermeable and slip-resistant shoes should be used while working in the parlor. These should be cleaned prior to a shift and often rinsed if stepping in manure or other areas outside the milking pit (e.g. the holding pen) boots should be disinfected with chlorinated water at the end of each shift.

Is there anything extra to add to mitigate HPAI infection?

Additional protective equipment can be employed. Any equipment that protects the worker from milk droplets can aid in reducing the risk of infection. Impermeable aprons and sleeves can be added to protect arms and clothes. If the herd is confirmed positive MSU Extension recommends the following:

• Workers should wear safety glasses to protect the eyes from milk splashes. Current guidance from the CDC also establishes the use of N95 masks or respirators for workers exposed to animals positive for HPAI. If visibility becomes problematic due to the high humidity environment in the parlor, a face shield can be used to protect the face from milk droplets.
• Workers should avoid touching the face, eyes and nose area during their shift. If needed, use a clean disposable towel and quickly discard after use.
• Dispose of gloves every time the worker exits the parlor area.
• Disinfect and wash prior to lunch breaks, bathroom use or anytime workers exit the parlor. New gloves should be used when they return to the milking floor.
• MSU Extension recommends that farms provide a container (pan or bucket) with chlorinated water next to the door to the milking floor so workers can step in to clean their boots every time they exit the parlor. Is important to rinse the boots to remove manure or sand prior to disinfection.
• Do not provide raw milk to cats or other animals, especially if the herd is positive for HPAI as this can lead to further spreading of the disease and presents an additional risk of infection.

Although current information suggests that HPAI presents a low risk to humans and those affected have recovered successfully without any major setback, we should still employ methods to reduce the risk of infection and limit the spread of this disease. HPAI still presents clinical symptoms in humans that may vary in severity and length. Therefore, any action to mitigate the risk of infection will lead to a safer work environment

For additional questions or recommendations, contact Martin J Carrasquillo-Mangual at carrasq1@msu.edu, or reach out to your local MSU Extension dairy extension educator.

This article is also available in Spanish.