The incidence of crypto diarrhea is higher on dairy farms where calves are raised in close confinement and the moist environment is conducive to the transmission of these protozoa.
However, large animal veterinarians are also starting to find it in beef herds in Western Canada.
Crypto is a protozoa with a similar life cycle to coccidian, which is probably much more familiar to Canadian cattle producers.
Bringing in dairy calves to be adopted by beef cows can be a source of infection. Use calves only from your own herd if possible.
Crypto is usually caused by the species C. Parvum in cattle. It is transmissible to humans, so be careful when handling diarrheic calves.
Cleaning and disinfecting areas where calves have been is particularly important.
Most human cases result from exposure to sick calves. Producers, farm dairy workers and veterinary students are especially at risk.
As with all zoonotic diseases, people under stress or immunosuppressed are highly susceptible. Clean boots and coveralls and wash hands, particularly after dealing with diarrheic calves. Treat diarrheic calves last to avoid carrying the oocysts (eggs) between calves.
The organism is similar to coccidia because the oocysts are passed in the manure in large numbers. Calves ingest the oocysts, which damage the large intestine and the end of the small intestine.
We see it primarily in calves from three to 30 days of age. Watch for calves that seem unresponsive to treatment and diarrhea that is yellow and foamy.
The organism destroys the inner lining of the intestine, so the milk comes through essentially undigested and calves dehydrate.
Crypto often appears with scours, so producers may be dealing with two diseases at the same time. It is why producers must use all the preventive steps in their power to avoid a scours outbreak, such as providing a new calving area, lots of room and bedding, and good nutrition for the dam, which boosts colostrum quality.
Make sure calves are up and sucking within a couple hours. If in doubt, supplement with home stored frozen colostrum or good colostrum substitutes such as Headstart.
Producers should vaccinate their cows and heifers for scours. However, the good scours vaccines cover the most common causes of viral and bacterial scours in calves but not the protozoan (coccidia and cryptosporidiosis) causes.
The initial diagnosis has always been one of the more significant issues in the past.
Veterinarians investigating scours outbreaks have often suspected that crypto was involved but it was hard to prove.
Fecal tests can be done, and labs are getting better at spotting it. However, its oocysts are much smaller than worm eggs so they can be hard to see, even with a microscope.
A new method called entericheck by Biovet Labs, in which a strip is inserted into the manure, is a sensitive and specific check.
As well, the acid-fast stain smears a manure sample on a microscope slide stain, and the oocysts become visible when they take up the stain. It worked well at our clinic.
The combination of all three methods has greatly improved the diagnostic rate of crypto. Veterinary clinics can order the acid-fast stain.
Treatment is another problem with crypto.
The standard treatments, such as electrolytes, are always warranted, and veterinarians will prescribe sulfa drugs similar to coccidiosis treatment. However, the best treatment method is to reduce the number of organisms being excreted.
Halofuginone is a drug that can be used for this purpose. It was used in Canada for a few years under an ex-perimental drug release, so it has a successful track record.
Calves in subsequent calvings are put on it for seven days in a row when an outbreak occurs or after a first case is diagnosed. It controls the crypto by breaking the life cycle and substantially reducing the number of oocysts that are produced.
It is an oral product and given at two cc per 10 kilograms daily. Dose it carefully because unlike most products, the safety margin is low.
Double the dose and producers could get depressed calves, blood in the diarrhea and other signs similar to the disease itself. Don’t give more medication if those signs show up.
Four times the dose can be fatal. Be sure to check with a veterinarian before using.
Always treat calves on a full stomach and don’t start treatment if they are already sick. Sick calves should be isolated, and the isolation area cleaned and disinfected.
The oocysts can be killed by high temperatures. The key is keeping the oocyst numbers down.
Resistance develops with age, which is why the disease is never seen in older cattle.
Producers should make sure their veterinarian rules out cryptosporidiosis if they find unusual diarrhea and frothy content that looks like undigested milk because the treatment is much different than other neonatal diarrheas.
Roy Lewis works as a technical services veterinarian part time with Merck Animal Health in Alberta.