What is coccidiosis?
Coccidiosis is a debilitating disease of cattle, sheep, goats, pigs, poultry and rabbits. It is caused by a type protozoan Eimeria or Isospora. It affects the intestines and liver and can cause poor thrive. As a result it is an economically important disease. It can affect animals of any age, but generally older stock are resistant, and animals one month to one year are most at risk. Coccidiosis is an opportunistic pathogen and causes severe disease when animals are under pressure and stressed e.g. poor nutrition, poor sanitation, or overcrowding, or after the stresses of weaning, shipping, sudden changes of feed, or severe weather. Coccidia are host-specific, and there is no cross-immunity between species of coccidia.
Where do animals pick it up?
It is commonly seen where large numbers of calves are housed together and there is a build up of oocysts (eggs) in the environment. Older healthy animals can be a source of infection. An infected animal may only ingest a small number of coccidia, but it can shed millions of eggs. Animals at pasture can be affected also and creep-fed lambs/calves are at risk of being exposed to this disease. Anywhere there is a build-up of faeces in the environment, there is a risk of coccidiosis. Oocysts do not survive well at temperatures below -30°C or above 40°C; within this temperature range, oocysts may survive ≥1 year. Therefore eggs can persist in the environment from one season to the next, hence why cleaning and disinfection of animal housing is so crucial.
What are the symptoms?
Coccidiosis mainly affects the gut lying, it invades and destroys it. Diarrhoea, often with blood and tenesmus (straining) are common signs. Fever, inappetence, ill-thrift, weight loss, emaciation, and in extreme cases, death can also occur. Rectal prolapses can also occur in extreme cases. However, many infections are subclinical.
How can I test for it?
Oocysts can be found in faecal samples, but because diarrhoea may come 1 – 2 days before the large shed of eggs, and diarrhoea can continue beyond the shedding of eggs, multiple samples may be required. Therefore, the results of faecal examinations must be related to clinical signs and intestinal lesions (gross and microscopic)
How do I treat Coccidiosis?
The life cycles of Eimeria and Isospora are self-limiting and end spontaneously within a few weeks unless reinfection occurs. Prompt medication may slow or inhibit reinfection and, thus, can shorten the length of illness, reduce discharge of oocysts, alleviate haemorrhage and diarrhoea, and lessen the likelihood of secondary infections and death. Sick animals should be isolated and treated individually whenever possible and to prevent exposure of other animals. There is no drug which will effectively treat clinical coccidiosis, but it is widely accepted that treatment is effective against reinfection and should therefore facilitate recovery. Various sulphonamides have also been used in the treatment of coccidiosis. They have limited efficacy against coccidia but may help to suppress secondary infections.
How do I prevent it?
Most coccidiostats have a depressant effect on the early stage life cycle and are therefore more appropriately used for control instead of treatment. Diarrhoea usually develops at the end of the parasitic life cycle, which means that severe damage to the intestines has already occurred and specific treatment at this stage is usually unrewarding. It is therefore recommended to use drugs prophylactically, i.e. during the risk period, to prevent the development of clinical disease. There are three narrow-spectrum anticoccidials registered for use in cattle in Ireland:Decoquinate, Diclazuril, Toltrazuril. These products are primarily indicated for the prevention of coccidiosis by administering them strategically in anticipation of disease. Farm history, age groups and stress trigger factors must be taken into consideration for effective timing. Avoid build up in the environment by maintaining strict hygiene and rotate grazing for young stock i.e do not turn young stock out into the same grazing every year. Creep feeders should be moved regularly, and water sources should not be leaking in order to prevent wet favourable conditions for spread.