Coccidiosis In Poultry

Coccidiosis is one of the most important diseases of poultry worldwide. In our country, it is a serious

problem and one of the biggest causes of economic losses. Coccidiosis mostly occurs in rainy

season, and is characterized by bloody diarrhoea and high mortality. It is mostly a disease of young

birds because immunity quickly develops after exposure and gives protection against later outbreaks. Coccidiosis inflicts heavy mortality in broilers and growers raised on deep litter. Outbreaks are
common between 3-6 weeks of age and rare in flocks of less than three weeks. However, author has observed coccidiosis in 7-dayold broiler chicks. Coccidiosis rarely occurs in layers because of prior exposure of coccidia resulting in immunity.It mainly occurs under conditions of overcrowding.

Spread

I. Ingestion of the infective form of oocysts (sporulated oocysts) is the only method of spread.

2. Oocysts can be spread mechanically by animals, insects, contaminated equipment, wild birds, and

dust. They are resistant to environmental extremes and to disinfection.

3. Spread from one farm to another is facilitated by movement of people and equipment between

farms, which may spread the oocysts mechanically.

Symptoms

Coccidiosis occurs in two forms: ( I) caecal coccidiosis, and (2) intestinal coccidiosis. Symptoms vary accordingly. Caecal coccidiosis is caused by Eimeria tenella. It is a severe disease associated with bloody droppings, high mortality, reduced weight gain, and emaciation (Fig. 92). The losses caused make this species one of the most harmful in chickens. Most of the mortality occurs between 5th and 6th day following infection.

Intestinal coccidiosis is caused mainly by E. necatrix. It is associated with severe weight loss, morbidity (number of birds affected in a flock), and mortality. Intestinal coccidiosis occurs in relatively older birds. Droppings of affected birds usually contain blood. Like E. tenella, E. necatrix is also most harmful. It has caused more than 25% mortality in commercial flocks.

Postmortem Findings

In caecal coccidiosis, caeca may be greatly enlarged and distended with clotted blood . In intestinal coccidiosis, the middle portion of the small intestine is usually distended to twice its normal size (ballooning) and the lumen may be filled with blood.Changes may extend throughout the small intestine in severe infections.

Diagnosis

I. The presence of faeces with blood, dysentery, or diarrhoea suggests coccidiosis.

2. However, postmortem examination is necessary to confirm diagnosis. Greatly enlarged caeca

distended with clotted blood confirm caecal coccidiosis, whereas small intestine distended with blood

confirms intestinal coccidiosis.

Treatment

Outbreaks of coccid iosis are usually t reated with water-soluble drugs, such as sulphonamides, amprolium, diclazuril and toltrazuril. Water medication is convenient and can be rapidly given.

Control

I. Use anticoccidial drugs for prevention. Most anticoccidials are formulated as feed additives, and broiler feed almost always contains an anticoccidial agent. The most widely used drugs are the ionophores, such as maduramicin, salinomycin, and monensin.

2. Maintain good hygiene. Good hygiene can greatly reduce the numbers of oocysts contaminating the environment. Moreover, good hygiene ensures that litter is kept dry so that it does not provide good sporulation condition.