Coccidiosis occurs in all countries where confinement rearing and continuous farrowing are practiced. Although several coccidia of the genus Eimeria commonly infect one to three month old swine, clinical disease rarely occurs. Coccidiosis assumed greater importance with the introduction of confinement-rearing, continuous farrowing in warm buildings, and use of farrowing crates. Coccidiosis has re-emerged as a common cause of neonatal diarrhea, even in modern well-managed farms.
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The most commonly seen of all the Isospora species is Isospora suis in the pig. The eggs are subspherical, and the wall is colourless and thin.
When sporulated each one contains two sporocyts each with four sporozoites. Life Cycle There are essentially three stages in the Isospora life cycle.
The first is called sporogony and is the asexual stage of the parasite development. It occurs exogenously, and leads to the development of sporozoites in the oocysts. After this occurs, the oocysts are now deemed infective. The host ingests the infectious oocyst and the digestive enzymes break down the oocyst wall causing the release of infective sporozoites. The sporozoites then go on to penetrate the intestinal villus epithelium, namely the jejunum and the ileum.
Each sporulated oocyst contains 2 sporocysts each with 4 sporozoites. This stage will occur relatively quickly under optimal conditions of high humidity and temperatures between 20 and C.
The next step is schizogony. This is an asexual process which occurs endogenously. After the sporozoites invade the epithelia, they then form trophozoites. These trophozoites then form merozoites, which is known as merogony. Gametogony, which is sexual division occurs endogenously, namely in the intestinal cells. Merozoites then form either microgamonts male or macrogamonts female. Invasion of macrogametocytes containing cells by microgametocytes leads to fertilization, and the cycle continues.
Clinical Signs Clinical signs are due to destruction of the intestinal epithelium and sometimes the underlying connective tissue of the mucosa. There may be haemorrhage into the lumen of the intestine, catarrhal inflammation and diarrhoea.
There may be dysentry, tenesmus and dehydration. Anaemia is only seen in severely affected animals. Diagnosis Sugar or salt flotation methods enable oocysts to be observed in the faeces. Diarrhoea may precede a heavy output of oocysts, and may continue after the output has finished, therefore multiple faecal samples may be necessary to identify oocysts. The number of oocysts in a sample can vary and must be related to clinical signs and lesions, and the species observed must be found to be pathogenic to that host.
Other causes of diarrhoea should be ruled out before Isospora infection is diagnosed. Many nonpathogenic species can be found during episodes of diarrhoea, which will not allow a diagnosis of coccidiosis in that species. Treatment The life cycle of Isospora is self limiting and infection should resolve spontaneously within a few weeks unless reinfection occurs. Medication can shorten the length of clinical signs and lessen the likelihood of complications and death.
Sick animals should be isolated and treated individually if possible. Soluble sulfonamides such as sulfaquinoxaline are effective in most species. Amprolium can be used in large animals, and can be given as a preventative treatment to healthy in contact animals. Isospora in Cats and Dogs Isospora species in cats are I. Four species infect the dog: I. Clinical illness is uncommon but heavy infections have been reported in kittens and puppies.
In kittens, infection is usually seen at weaning. Clinical signs include: bloody diarrhoea, weight loss and dehydration. The illness can be associated with other infections and immunosuppression. Cats usually spontaneously eliminate the infection, but if they are clinically ill, trimethoprim-sulfa can be given. Isospora spp. Learning Resources.
Coccidiosis (Coccidia parasites)
The most commonly seen of all the Isospora species is Isospora suis in the pig. The eggs are subspherical, and the wall is colourless and thin. When sporulated each one contains two sporocyts each with four sporozoites. Life Cycle There are essentially three stages in the Isospora life cycle. The first is called sporogony and is the asexual stage of the parasite development. It occurs exogenously, and leads to the development of sporozoites in the oocysts.
Coccidiosis in swine: dose and age response to Isospora suis.
Transmissible gastroenteritis TGE Control and Prevention of Coccidiosis in Pigs A good level of hygiene in farrowing accommodation is necessary to minimize the spread of infection, and bedding should be destroyed and huts moved between litters. Disinfection can be used although available disinfectants are not particularly effective in combating I. Your veterinarian can provide advice on agents to combat the oocysts. Rodents also represent a potential means of spreading infection, and should be controlled Straw et al. Increased risk is associated with cross fostering piglets within 24 hours of birth Skampardonis et al. Treating Coccidiosis in Pigs Coccidial infection does not respond to antimicrobials Roberts and Walker, ; Taylor, or treatment via sows as they are not a major source of infection Straw et al.
Coccidiosis in Pigs