Crypto passes from animal to human

Diseases that can be transmitted from animals to humans are termed “zoonotic” diseases. One of the more common zoonotic diseases is that caused by the protozoan parasite cryptosporidium.

Over the past several weeks, I have heard from producers who have been infected by crypto or their children have been sick from it. One case involved several workers at the same dairy; the other case involved a small child who became sick after visiting the local community swimming pool. Both cases were diagnosed after the patients complained of diarrhea that persisted for several days.

Cryptosporidium infections start after the ingestion of feces-contaminated water or contact with contaminated objects. Many large outbreaks of this disease have been associated with community swimming pools or municipal water supplies. So often these crypto outbreaks are reported by newspapers as being caused by cattle infecting water supplies.

The fact is, there are many sources of infection that can be responsible besides the cow. The life cycle of cryptosporidium begins when an infective oocyst is ingested by either human or animal. Upon reaching the intestine, the oocyst sporulates and penetrates the cells of the small intestine.

Two types of oocysts are produced: a thick-walled oocyst and a thin-walled oocyst. The thick-walled oocyst has been known to survive in the environment for more than six months and is resistant to many disinfectants. The thin-walled oocyst can cause autoinfections, which can cause the disease to persist for several weeks. Shedding of the oocysts occurs when symptoms first appear and can last for several weeks after symptoms have subsided.

Because cryptosporidium is found in soil or water contaminated with feces, it can be spread easily to many different groups of people or animals. Individuals who handle cattle are just one group at risk for contracting the disease. Child-care workers, international travelers, swimmers and campers are also at risk because of potential exposure to contaminated material.

What are the symptoms?

Signs of the disease begin anywhere from two to 10 days after infection. The most common symptom is watery diarrhea due to the damage crypto causes in the absorptive surface of the intestine. Many people will complain of flu-like symptoms that include stomach cramps, nausea, vomiting and fever. Most of the time, these symptoms will last for one to two weeks.

People with weakened immune systems can have the infection develop into a chronic illness. Young animals tend to experience diarrhea and loss of appetite that can persist for more than a week. Dehydration is always the No. 1 problem during infection. Diagnosis of a crypto infection is done through a stool sample submitted to a laboratory.

Treatment of the infection is usually done by replacing the fluid loss due to diarrhea with electrolytes. This treatment is the same whether it is an animal or a human. Often a few days of electrolytes will help those affected by the parasite get over the symptoms. Concurrent infections or a poor immune system can lead to the need for more aggressive and long-term therapy.

Prevention and control of crypto infections begin with good hygiene. Always wash hands vigorously after contact with any potential fecal contamination. Small children on farms are susceptible because they tend to stick their hands into their mouths before washing them. Avoid swallowing untreated water from lakes, streams, swimming pools or shallow wells. If concerned about water, either filter it with an approved filter system or boil it to kill any potential cryptosporidium.

This article published in the October, 2011 edition of WISCONSIN AGRICULTURIST.

All rights reserved. Copyright Farm Progress Cos. 2011.