Cryptosporidium parvum is not host-specific and
outbreaks of calf diarrhoea may occur when there is a build up of
infection in mixed accommodation/grazing with young lambs.
Transmission from cats and vermin may also occur in some
situations. Whilst morbidity is high, mortality in uncomplicated
cases is rare. Large numbers of infective oocysts are
excreted leading to significant environmental contamination and
disease usually during the second half of the calving period.
Oocysts can survive for several months in cool and moist
conditions but infectivity in calf faeces is reduced after 1-4 days
of drying. Oocyst infectivity can be destroyed by exposure freezing
temperatures and ammonium hydroxide, hydrogen peroxide, chlorine,
10% formol saline, and 5% ammonia.
High stocking density of young beef calves indoors increases
the risk of cryptosporidiosis.
Possible mild case of cryptosporidiosis.
Mixed viral and cryptosporidiosis infections are common.
Cryptosporidiosis can exacerbate concurrent viral
Cryptosporidiosis is a zoonotic disease (readily transmitted to
humans) and has been frequently reported in school children
visiting open farms and petting zoos.
In clinical cases of cryptosporidiosis, diarrhoea is caused by
the physical loss of absorptive lining of the intestines
exacerbating concurrent viral infections necessitating supportive
fluid therapy and may cause significant losses. In some
instances, there is no diarrhoea despite isolation of
Cryptosporidium spp. from faecal samples.
Beef calves aged 14-21 days old are most commonly affected
(dairy calves are most frequently reared in single pens so there is
reduced risk of spread). There is yellow/green diarrhoea with
much mucus present. There is only mild dehydration but the
calf rapidly looses condition over 2-5 days and has a dull
tucked-up appearance. There is a reluctance to suck and
examination of the beef cow often reveals a full udder.
Mortality may result where calves are not given oral fluids to help
Debilitated calf with cryptosporidiosis.
Diagnosis is based upon demonstration of Cryptosporidia spp
oocysts on faecal smear after Giemsa stain; however, other
enteropathogens may be involved in causing the diarrhoea such as
rotavirus; mixed infections are common. Identification of organism
in stained gut sections of post mortem material is the preferred
method of confirming the role of cryptospiridia.
In uncomplicated cases ensure that the calf is properly hydrated
by using oral electrolyte solutions as necessary which may amount
to two litres adminisitered every 6-8 hours. Halofuginone
lactate is licensed for both the prevention and treatment of
diarrhoea caused by C. parvum. For prevention of
diarrhoea, calves should be dosed for seven consecutive days
starting within one to two days of birth. For treatment,
calves should be dosed for seven consecutive days starting within
one day of the onset of diarrhoea. Once several calves have
been diagnosed and treated for cryptosporidiosis, all subsequent
calves should receive prophylactic treatment with halofuginone.
There is no vaccine currently available.
Halofuginone lactate has a low toxicity index and the data sheet
instructions must be carefully followed such as using a syringe to
accurately dose calves.
The disease is difficult to control. Calves should be born in a
clean environment and fed three litres of colostrum within the
first six hours. Reducing the number of oocysts ingested may reduce
the severity of infection and allow immunity to develop. In
dairy herds, calves should be kept separate for at least the first
two weeks of life with strict hygiene at feeding. Great care must
be taken to avoid mechanical transmission of infection in the calf
house. All calves should be isolated from healthy calves during the
course of the diarrhea and for several days after recovery. Dairy
calf-rearing accommodation should be vacated and cleaned out on a
regular basis by practising an "all-in/all-out" management
General prevention/control measures include:
1. Not using same fields for calving/lambing because
cryptosporidia can infect both calves and lambs.
2. Change fields every year or when clinical cases occur
during that season.
3. Move newborn calves immediately to clean pasture.
4 Maintain high standards of hygiene if calves are housed
especially in the calving pens.
5 Avoid direct transmission from one group to another via
faecal material on boots, farm machinery such as tractors
Overcrowded calving accommodation can increase the risk of
Exemplary hygiene in the calving pens.
Calving outdoors may reduce the challenge of cryptosporidiosis
but presents many other challenges.