Deadly parasite in cows pose risk to European dairy farms and human safety: Study

In humans, a single bowel movement can pass as many as 100,000,000 cryptosporidium parasites, and only 10 are required for another person to get an infection.

Chris Arnold 3 minute read December 9, 2021
Three cows in misty rural landscape at dawn.

Researchers looked for the parasite in both cows and their calves, and found several different strains of Cryptosporidium. GETTY

Dairy cows across Europe are playing host to a parasite that could be deadly to humans, researchers from the University of Kent say. 

The parasite Cryptosporidium has been found in more dairy cows than scientists originally thought, with as many as 25 per cent of cows spreading the tiny organism on 57 farms in Belgium, France, and the Netherlands.

The study was published in the medical journal Microorganisms

“This research is of major importance in terms of product value in the dairy farm industry and safety to human life,” Dr. Anastasios Tsaousis said in a statement. “The findings indicate Cryptosporidium levels to be so high as to be of severe concern to the European and U.K. dairy market.”

More commonly referred to as crypto, the Cryptosporidium parasite causes the diarrheal disease known as Cryptosporidiosis. The disease is often transferred through the feces of humans or animals infected with the parasite, and it was the leading cause of waterborne disease outbreaks from recreational water in the United States from 2001 to 2010, according to the Centres for Disease Control and Prevention

The parasite has an outer shell, according to Johns Hopkins, which makes it difficult to kill as it is resistant to standard water treatment chemicals, such as chlorine. In fact, the Kent study suggests that chlorine can actually make Cryptosporidium more infectious, rather than preventing infection. 

Researchers looked for the parasite in both cows and their calves, and found several different strains of Cryptosporidium, which suggests that it is not actually passed among the cows, but instead is found in the environment around them. They added that flooding could be a significant factor in how the parasite spreads. If a farm floods, the parasite could be swept up in the water and brought to another area where it was not previously found, and introduced to the water reservoirs. 

Our findings indicate that Cryptosporidium spp. [species] is widespread across dairy farms, with zoonotic C. parvum being the dominant species detected in calves across all the three countries included in this study,” the study reads. “In addition, all the C. parvum subtypes identified in this study have been linked with cryptosporidiosis in humans, highlighting the potential of cattle as a reservoir for C. parvum.”

There is a significant risk of death among children and the immunocompromised if they contract Cryptosporidium. A 2018 study funded by the Bill & Melinda Gates Foundation found that  Cryptosporidium was the fifth leading diarrheal illness in children less than five years old, and caused more than 48,000 deaths worldwide. 

Researchers added that additional studies should be conducted to find how cross border, and worldwide spread of Cryptosporidium occurs, which strains are most prevalent, and how to properly address the spread of the parasite. 

In humans, a single bowel movement can move as many as 100,000,000 Cryptosporidium parasites, and only 10 are required for another person to get an infection, the CDC reports. Cryptosporidium parasites can be spread by swallowing water from a pool, fountain, lake, or river. Outside of water, the parasite can live on surfaces such as bathroom counters or door handles, or baby changing tables. The disease cannot spread through contact with blood. 

Symptoms in humans include diarrhea, stomach cramps, dehydration, vomiting, fever, and weight loss, and usually last around one to two weeks in healthy people. 

For people who may potentially drink contaminated water, such as backpackers drinking from a stream, the CDC recommends boiling or filtering the water, as chlorine by itself will not kill the parasite. 

Chris Arnold is a Toronto-based freelance writer. He can be reached here


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