An Overview of Cryptosporidiosis in Calves
contributed article by Dr. Vince Collison, Collison Embryo | Collison Veterinary Services, Rockwell City, Iowa
There are many causes for diarrhea in young calves, but one infection we’ve seen with higher frequency in the past couple of years is Cryptosporidiosis. The infection is caused by a coccidian parasite called Cryptosporidium parvum (Crypto). In many herds there is a good vaccination program given pre-calving to cows to prevent scours.
Also, many herds give oral products to calves at birth that are antibodies for common infections such as E. coli, Corona virus, Rota virus, and Clostridium type C. When we see calf scours in herds that utilize these types of control measures, Cryptosporidium is high on the list.
Crypto is an organism that is infective across other species as well. In addition to calves, it can be carried by sheep and goats. It can also affect birds and humans as well. We had one herd this year that had large numbers of wild geese in a pasture with a large pond. Crypto was very hard to control in this pasture and we suspected that these geese may have been causing some of the problems with the spread.
Many animals can be carriers of Crypto and not show any symptoms of disease. This organism is shed in the feces and is sporulated at that time, which makes it infective immediately. Calves that ingest Crypto can show symptoms within four days.
Symptoms of Crypto
Crypto will affect the entire intestinal tract, but has an affinity for the small intestine. This causes a malabsorption and maldigestion syndrome. This is why many calves affected by Crypto appear to have diarrhea that looks like undigested milk. It also affects the large intestine as well and causes the calf to be unable to reabsorb fluids back into its system resulting in dehydration.
Currently there are no medications that work for the treatment or prevention of Crypto. Since there are no vaccines available, prevention is centered around sanitation. Also, since it is shed in the feces, proper cleaning of calving pens and calving areas are critical to prevent spreading. Getting new calves out to clean areas post calving can greatly reduce the spread. Crypto is very resistant to most disinfectants. Ammonia at 5 percent is effective and also drying of the pens to desiccate the organism, probably give the best results.
Once infected, it can take up to seven days for a calf to get over Crypto. Treatments revolve around keeping calves hydrated and treating for any secondary causes of diarrhea. Most times calves can be given oral fluids with electrolytes to control dehydration with good results.
If calves are depressed, it is necessary to have an electrolyte product with sodium bicarbonate to control acidosis. Almost all calves with diarrhea that need oral fluids will need something for acidosis. As calves become over one week old, they will become more depressed from the effects of acidosis.
One thing I see with producers is that they will often not be aggressive enough when giving oral fluids. When diarrhea is severe, it may take up to four times per day to keep up with the fluids and electrolytes that the calf is losing. Also, the sooner you start giving fluids, the better chance the calf has of not getting too depressed or dehydrated.
If a calf gets overly dehydrated, it may be necessary to give IV fluids to a calf. There are also some oral products available that provide probiotics, MOS, and charcoal. We have used some of these and feel there are benefits to using them. These would be ancillary treatments and oral fluid therapy is still the main focus when treating Crypto.
Diagnosis of Crypto
Diagnosis of Crypto is hard to do on a fecal sample. The oocysts are five microns and can be easily overlooked on a routine fecal. We have had good results sending a rectal swab in to the diagnostic lab and running a diarrhea PCR panel. Often this comes back as only Crypto. Negative results on the other causes of infection mentioned tells me our methods of controlling those infections are working.
As mentioned before, Crypto can be spread to humans. If you’re treating calves with suspected Crypto, be very careful to wash your hands and take measures to prevent the spread to yourself. When dealing with calf diarrhea, work closely with your herd veterinarian to establish an accurate diagnosis and form a treatment protocol.
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Dr. Vince Collison is co-owner of Collison Embryo and Veterinary Services PAC
in Rockwell City, Iowa.