Cryptosporidiosis and Kid Care
Cooperative Extension Agent, Washington State University
I became aware of Cryptosporidiosis when I worked with a dairy farmer who lost a large number of young calves with diarrhea (scours) that didn't respond to the usual treatments. Even though they ate, they lost weight and dehydrated as diarrhea continued. Nothing worked to keep them from dying in a few days. Later, the disease was diagnosed as Cryptosporidiosis. Veterinarians confirmed that herds in Washington and Oregon were having problems with Cryptosporidiosis.
There are eleven species of Cryptosporidia, intestinal protozoan parasites similar to coccidia. None of the eleven are host-specific and can infect different species. Discovered in mice in 1907, it has since been detected in calves, lambs, pigs, goats, mice, rabbits, chickens, cats, dogs, geese, most undomesticated animals, and humans.
There are still many unanswered questions about how Cyrptosporidium attacks the host animal, although its life cycle starts with the oocyst. The oocyst, kind of like an egg, is formed on the lining of the intestinal wall. Once oocysts are shed in the feces, the cells inside divide until eight small organisms, called sporozoites, are present. Outside the animal, the oocyst is dormant but becomes active when it is eaten. Oocysts are able to infect other animals within 48 hours after being shed from the host animal. After ingestion, they break open and release the sporozoites in the rumen or stomach. Sporozoites attach themselves between the cells lining the intestine where they continue to grow and multiply into merozites. Merozites form into either more oocysts or sporozoites. The formation of sporozoites from merozoites allows Cryptosporidium to continue its life cycle inside the animal. Thus, oocysts that die outside the host animal will not limit Cryptosporidium from multiplying inside infected animals.
The exact mechanism of how Cryptosporidium affects the animal is still unknown. It is thought that the sporozoite interacts with and receives nutrients from the intestinal cell it lives next to. This disrupts and kills the cell. As the intestinal cells die, nutrients, such as water and minerals, are rapidly excreted into the intestinal cavity. The organism does not kill the host animal - death occurs due to the severe diarrhea that results. Secondary infections in animals weakened by cryptosporidiosis can also result in death.
Symptoms and Diagnosis
Symptoms of acute cryptosporidiosis include lack of appetite, weight loss, and diarrhea which is usually yellow to yellowish-brown in color and of a creamy texture. The rapid loss of nutrients and fluids during diarrhea results in severe dehydration. Since instestinal tract cells are disrupted, absorption of feed nutrients is restricted, and the animal loses more nutrients through the digestive tract than it takes in. This also disrupts the kid's immune system and makes it more susceptible to infection by other bacteria (secondary infection). When body stores of nutrients such as minerals and protein are used up, death quickly follows.
Kids between five and twenty-one days old are the most susceptible. Once kids become infected, they pass oocysts in their feces in about five days. The primary mode of transmission is by fecal-oral spread. Animals eating fecal-contaminated material (food, water or bedding) can become infected. For example, an infected kid can contaminate the walls and floor with fecal matter. If the next kid coming into the same housing area licks on the contaminated walls, it can become infected. Oocysts are thought to survive for long periods of time outside the animal.
Some animals do not develop into chronic cases and become carriers. After infection, animals either resist the organism, develop a mild infection that is self limiting, or soon sicken and die. Self-limiting infections run their course and clear up in a few days similar to the flu in humans. Some animals may exhibit fevers or signs of respiratory distress, but these may be secondary conditions from opportunistic microorganisms that have infected the animal in its weakened condition.
The extent to which a kid is infected seems to be dependent on its age and immune status. Younger animals are much more susceptible to infection than adults. In studies done with lambs, five-day-old lambs had diarrhea for 9-10 days and suffered from a high rate of mortality. Sixty-day-old lambs showed no symptoms when they were infected, and adult sheep completely resisted infection. There is an indication that adults develop an immunity to Cryptosporidium, yet this immunity does not seem to be passed to their offspring.
Immune-depressed animals are very susceptible to the disease. This refers to the total immune status, not just protection from cryptosporidiosis. Many situations can cause animals to lack immunity. Animals with severe infections are more susceptible to secondary infections. Feeding animals a balanced diet is essential in maintaining a proper immune response. Clean housing, clean bedding and proper ventilation all contribute to the ability to fight any infection more quickly. The most common problem with kids is receiving a deficient amount of colostral antibodies following birth. Whether caused by disease, an imbalanced ration or improper management, animals lacking adequate immunity are much more susceptible to cryptosporidiosis.
Cryptosporidium can be detected in stool specimens during fecal flotation analysis. Failure to find it mayoccur because these oocyst are very small and difficult to identify. Lack of the investigator to look for Cryptosporidium can allow it to go undetected.
A significant number of drugs have been tested and found ineffective for treating cryptosporidiosis, including most drugs normally used to treat coccidia. So far, no treatment has been found.
Once an animal has been diagnosed, supportive treatment is the only alternative at this time. Solutions of electrolytes and other nutrients given IV compensate for dehydration. Using a medicine to slow the scouring, such as Pepto Bismol, has shown some success in helping kids survive until the disease is no longer life-threatening. Kids should be kept warm and separated from other kids to prevent transfer of infection. Animals will recover in about 10 days if they survive the diarrhea.
The best control of cryptosporidiosis in goats comes from kids getting adequate immunity through colostrum soon after birth. Kids are born with no immunoglobulin (antibodies) in their blood. Colostral antibodies are absorbed and provide the necessary immune protection until the kid's own immune system begins to function. The kid's health is dependent on the amount of antibodies it receives through colostrum.
Just because a kid receives inadequate colostral antibodies does not mean it will die. Proper management and sanitation on the farm also protect the kid. Yet, when a kid is exposed to disease, there is a greater chance of death if the kid does not have adequate immune protection. A research study showed that dairy calves receiving no immunity from colostrum are four times more likely to die and twice as likely to become sick as calves receiving adequate colostral antibodies.
How soon after birth should a kid receive colostrum? As soon as possible! As everyone knows, kids lose the ability to absorb antibodies with time. The longer it waits to eat, the fewer antibodies are absorbed. A study with dairy calves showed that when they were fed colostrum at 6 hours after birth, they absorbed only 65% of available antibodies.
Turning our attention to the doe, the concentration of antibodies in her colostrum also decreases with time. Studies show that the doe reabsorbs antibodies after kidding. The longer the colostrum stays in her udder, the smaller the concentration of colostral antibodies. After 16 hours, less than 10% of the original concentration of antibodies remains in the doe's colostrum.
Facilities and Sanitation
As previously mentioned, sanitation is very important to kid health. Kidding and housing areas must be clean and dry. These areas must be completely cleaned after a kid leaves - just letting things dry out won't get the job done. Kids need dry, draft-free shelter and adequate ventilation. High levels of ammonia can cause respiratory problems in kids.
It is essential that buckets and bottles be cleaned between feedings. There is some evidence that Cryptosporidium can be found in saliva. During feeding, saliva from a contaminated kid can be left in a bottle or bucket. If kid feeding equipment is not cleaned between feedings, transfer of Cryptosporidium to other kids can occur.
Cryptosporidiosis kills kids. Once symptoms appear, there is a good chance they will end up dead. The best way to control the disease is to be sure all kids receive an adequate amount of immune protection through the colostrum.
Anderson, B.C., Cryptosporidiosis: A Review. Journal of American Vet Medicine Assn, Vol. 180:1455-1457, 1982.
Gay, C. & Bessor, T., Discussion on Feeding Colostrum, WSU, 1990.
Navin, T.R. & Juranek D.D., Cryptosporidiosis: Clinical,Epidemiologic, and Parasitologic Review, Reviews of Infectious Diseases Vol. 6:313-327, 1984.
Svatos, G., Pro-Immune 99 Adds Predictability to E. Coli Scours Control Programs, Topics in Veterinary Medicine, Vol, 1:12-19, 1990.
- Centers for Disease Control
Cryptosporidium parvum FDA/DSFAN Bad Bug Book