Coccidiosis is caused by a parasite known as coccidia, which usually attacks the cells of the small intestine. There are three types – Eimera, Crytosporodia and Isospora. The most common (and most pathogenic) in pigs is Isospora suis. It usually affects suckling piglets from 7-14 days but may be found in growing and finishing pigs and boars that have been moved or housed in infected pens. Sows may be symptomless carriers.
 

SYMPTOMS 

 
IN PIGLETS
A yellow or grey/green diarrhoea that becomes more liquid and may eventually turn bloody.
Although piglets continue to suckle they become dehydrated.
Weight loss
 
IN WEANERS OR GROWERS
Poor growth
There may be a sloppy diarrhoea but not always
Faeces may become tinged with blood. 
Mortality is variable.
 
PROGRESSION OF THE DISEASE
Some resistant oocytes will pass from the pig in the faeces. In the presence of heat and moisture (eg in the litter house or farrowing pen) they develop rapidly into infected sporulated forms that are resistant to many disinfectants. Once ingested, these sporozites enter the cells lining the small intestine where they reproduce both sexually and asexually, infecting new cells and producing more oocytes.
 
CAUSES
Dirty pens.
Poor hygiene, especially in farrowing houses or crates.
Poor, wet floor surfaces.
Creep feeding on the floor.
Flies.
Faeces not regularly removed.
Continually used houses with no disinfection.
 
DIAGNOSIS
Faeces samples – preferably from a semi-recovered animal, or post-mortem. In the case of an outbreak it is worth sending in a live infected piglet for dissection.
 
TREATMENT
Some cocciostats such as Bacox 5% are partially effective although coccidiosis does not respond particularly well to antibiotics once the condition is established .
 
PREVENTION
Thorough disinfection of farrowing houses, crates, creeps etc after each litter. As Isospora is often resistant to disinfectants, steam or flame cleaning is ideal. If using disinfectants only Sodium or calcium hypochlorite or ammonia seems to be effective.
 
REF: The Pig Site www.thepigsite.com