The constant battle against ‘crypto’

Cryptosporidiosis or ‘crypto’ is the leading cause of scour in young calves and its prevalence is becoming more and more common on Irish dairy farms.

It is a very frustrating infection to deal with because it is almost impossible to eradicate and very difficult to treat.

Cryptosporidiosis is caused by a parasite called cryptosporidium. It is highly infectious and is passed on to other calves when they ingest oocytes that have been residing in the environment or shedded from an infected calf.


It is usually seen in young calves between one to four weeks-of-age. It is a life-threatening scour and can cause a calf to quickly deteriorate if gone unnoticed.

The symptoms occur rapidly; calves begin to scour and shed huge quantities of oocytes in the dung to the surrounding area. They become severely dehydrated, weak and find it difficult to get up.

Some calves can become infected, but do not show any signs, but still spread the infection through the oocytes in their dung.

If you are suspicious of your calves having cryptosporidiosis, the best way to diagnose is through the collection of a dung sample and submission to a lab for testing.

Prevention and treatment

The best way to prevent cryptosporidium from taking hold on the farm is through the thorough cleaning and disinfection of all calf housing before calving begins.

However, since we are now in the midst of calving it is too late for this; so what we can do is prevent the infection from spreading if it takes hold.

Preventative measures:
  • Ensure all calves receive adequate colostrum (at least 3L) within the first two hours of birth;
  • Isolate sick calves immediately and keep them isolated for at least a week after scouring stops;
  • Clean out and disinfect pens after each group of calves;
  • Don’t mix new-born calves with calves older than three to four days;
  • Use separate feeding equipment for all infected calves;
  • Use a foot bath to disinfect wellies after coming in contact with infected calves.

Sick calves should be re-hydrated immediately with electrolytes in milk or water. At least 2L should be given and this should be repeated two to three times throughout the day.

Although, the calf is sick and may have a reduced appetite; it is important that calves are fed their daily feed as normal – to give them enough energy to fight the infection.

Halocur is a product commonly used in the treatment and prevention against cryptosporidiosis. Infected calves should be dosed immediately with 8ml for seven consecutive days.

Additionally, it is recommend that once the infection has taken hold on the farm, any young calves or newly-born calves are dosed thereafter with Halocur – as a preventative measure against infection.