The widespread public health crisis caused by Covid-19 raises serious concerns about the risks of zoonotic diseases—those that jump from animal species to humans and crop up in unexpected ways, with serious consequences. Other zoonotic diseases, including Ebola, MERS, HIV, bovine tuberculosis, rabies and leptospirosis cause over 2 billion cases of human illness and more than 2 million human deaths each year, according to several organizations, including the International Fund for Animal Welfare and the Zoological Society of London. Those numbers have risen exponentially in the months since the outbreak of Covid-19—also a zoonotic disease believed to have been transmitted from wildlife to humans.
The National Park Service has known for years that cattle and wild elk in the Point Reyes National Seashore are infected with Johne’s disease (pronounced Yo-Nees). A contagious, chronic and ultimately fatal wasting disease that afflicts over 68 percent of dairy herds in the United States, Johne’s has spilled over into a variety of other domestic and wild animal species, including beef cattle, sheep, goats, bison, deer and elk.
There is mounting evidence that the Johne’s bacteria, Mycobacterium avium ssp. paratuberculosis, or MAP, can spread to humans, too. Dr. Michael Collins is a lead scientist at the Johne’s Information Center at the University of Wisconsin’s School of Veterinary Medicine, a clearinghouse for research on the disease, and has studied Johne’s in the elk at Point Reyes.
“MAP is a promiscuous, insidious, zoonotic, food-borne pathogen that threatens the economic viability of livestock producers, the health and well-being of wildlife, zoological collections of wild ruminants (many of which are endangered), and humans,” Dr. Collins said.
He explained, “MAP is an equal opportunity infection. It attacks cattle of all breeds on farms of all sizes and types… This is not a problem caused by so-called ‘factory farms.’ Organic dairies are just as likely to have a Johne’s disease problem as any other… It deserves far more research funding and control-program investment than it currently receives.”
According to the United States National Advisory Committee on Microbiological Criteria for Foods, “MAP bacteria can survive for a year or more in cattle feces, water and soil… and can come into contact with food crops that result in human exposure.” MAP has been detected in ground beef, raw and pasteurized milk, cheese and infant formula.
The bacteria have been linked to human inflammatory diseases, most notably Crohn’s, a painful, debilitating inflammatory bowel disease with no known cure. Many lines of research are underway to definitively prove that MAP is a causative agent, including a successful clinical trial using antibiotics that target MAP bacteria in patients with Crohn’s disease.
According to Dr. Collins, that study could provide “a final piece of evidence indicating that MAP is the cause of Crohn’s disease. This would heighten the need for veterinary medicine, animal agriculture, and relevant governmental agencies concerned with food safety to limit contamination of food and water by MAP.”
Johne’s disease is spread in the environment through fecal-contaminated water and soils. The dairy cows in the seashore produce 100 million pounds of manure annually. Ranchers routinely liquefy the manure and spread it on pastures as slurry. Susceptible wildlife, such as elk, come into contact with it.
Livestock manure that washes into the streams that drain into Drakes Estero, Abbotts Lagoon, Tomales Bay and the Pacific Ocean also raises serious health concerns.
Creeks in the seashore tested for fecal bacteria and other contaminants have been found to be highly contaminated. In 2013, the park was listed among the top 10 most polluted waterways in the State of California. Kehoe Creek is particularly problematic, due to its history of high levels of fecal coliform contamination and the fact that it drains directly to one of the national seashore’s most popular beaches. Exposure to these bacteria can cause serious human illness.
Some 3 million annual visitors share the seashore with 6,000 cattle, of which nearly 4,000 are dairy cows. Yet the park service doesn’t test the cattle for Johne’s disease, or address Johne’s disease in its draft environmental impact statement on ranching and elk management. Given the known impacts to wildlife and the potential human risks from the disease, the park service needs to take precautions—not pretend the problem doesn’t exist.
Close-to-home outdoor recreation is considered essential for people’s physical and mental well-being. National parks have never been more in demand. The park service has a responsibility to ensure the health and safety of the millions who seek respite and recreation in the Point Reyes National Seashore. Johne’s disease is a risk that the park service needs to face up to and address.
Deborah Moskowitz has managed community health clinics and worked as an analyst and project director for a firm specializing in the design and implementation of software systems for California county public health departments. She lives in San Anselmo.