How Important is Cryptosporidiosis (or Crypto)?
- Crypto is present on many farms. Estimates are typically about 30% of dairy farms.
- Over 30% of calf scour samples are positive for Crypto (single time-point samples)
- The death rate from affected scouring calves is typically 10% in uncomplicated infections, but may be as high as 30% in septicaemic (with signs of dehydration, shock, and hypothermia) calves with secondary infections.
What are the Specific Signs of Crypto scours?
- None. You are unable to distinguish it from other causes without faecal samples.
- Many calves with crypto, and rota scours lose their appetite.
- Scours from combined infections have more severe and longer lasting signs.
- Calves scouring usually have diarrhoea which may last 5 – 12 days before the calf recovers its appetite for milk. Typically this is 6 days.
How do I find out if Crypto is the cause of the scours in my calves?
- There are now tests which are available for use on-farm. Please consult your vet on how to interpret any results.
- Alternatively, ask your vet for sample pottles, and take samples from a minimum of 4 freshly scouring calves using one pottle per calf. Do not take samples from the floor. Ask your vet to test to identify crypto, and to also test to exclude rotavirus, coronavirus, E coli and other important causes such as salmonella.
- Some calves may have multiple infectious agents present, so veterinary advice will be important.
How do my calves get infected?
- On infected farms it is considered that some cows (typically 15%) may be shedding crypto at the time of calving (winter only).
- Any faecal matter on tractor trays used to carry calves, a shed used for calf rearing, implements used to feed calves, especially anything calves may find to lick or suckle.
Are all Calves at risk of developing Crypto Scours?
- Typically scours will only occur in calves up to about 25 days of age, but this is also commonly found with other causes of calf scours.
- Most calves show signs from 6 days of age through to 21 days with the highest numbers showing signs of scours about 8 -10 days.
- Many calves will become infected without showing signs. Scours may affect up to 30% (and sometimes more)of the calves being reared.
What are the actual costs of Crypto?
- Many costs cannot be identified easily. We know that experienced calf rearers work under tight constraints of time and budgets, and hospital mobs take a disproportionate amount of time.
- Scouring continues for a number of days, and younger calves seem to take longer to recover. So treatment is extremely time consuming with a depressive effect on the calf rearers.
- The actual delay in reaching weaning weight targets means numbers of calves being fed increase and this increases staff work loads until they are ready to wean.
- Crypto infections by themselves are not associated with high mortality rates, only prolonged recovery periods when scours develop. Antibiotics can be very important to limit mortality and add additional costs to calf rearing.
- When calves have mixed infections e.g crypto and rotavirus, mortality rates can climb alarmingly up to 25 – 30% of calves being reared. This is particularly important among those calves with inadequate colostrum immunoglobulin transfer.
- This group of calves can account for 75% – 80% of mortality and is primarily due to bacterial infections leading to blood borne infections. This group may get significant benefit from antibiotic treatment.
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