Coccidiosis in chickens

Poultry coccidiosis is one of the most common diseases in the world. It generates economic losses due to mortality, reduced body weight plus the expenses related to preventive and therapeutic control, while also predisposing birds to necrotic enteritis.

Coccidiosis is a common parasitic disease of chickens caused by single-celled protozoan parasites of the genus Eimeria which are commonly referred to as coccidia, explained Dr Hector Cervantes of Phibro Animal Health Corp during a presentation at the 2008 North Carolina.

Diagnosis of Coccidiosis

Despite most flocks are raised with anticoccidial drugs added to their feed, drug resistance - especially to chemical anticoccidials or feed mixing errors - may lead to clinical coccidiosis. Birds with clinical cases of coccidiosis frequently display a typical 'sick bird' attitude with depression, prostration, huddling under the heat source as if chilled, soiled vents and watery or bloody droppings. One of the first signs of clinical and even subclinical coccidiosis may be paleness. In birds that have recently died, post mortem examination should start with examination of the intestinal tract and the caeca for the presence of gross lesions.

Clinical signs of coccidiosis in chickens

Characteristics of lesions will depend on the species of Eimeria affecting the intestine. Important diagnostic data to determine which Eimeria species is affecting a particular flock include:

• Location

• Aspect

• Severity of the lesions

Most common Eimeria species for poultry:

• E. acervulina

• E. brunetti

• E. maxima

• E. necatrix

• E. tenella

• E. adenoeides

• E. meleagrimitis
  

Coccidiosis Treatment

In spite of our best efforts, cases of clinical coccidiosis may occur from time to time, according to Dr Cervantes. This could be due to a variety of reasons. These include:

• the feed mill inadvertently omitting the the anticoccidal drug or including too low a dose

• the birds may have been offered the withdrawal feed for too long a period of the feed, or

• the coccidia involved might have suddenly developed resistance against the drug.

Keep in mind that outbreaks of coccidiosis may also occur due to more indirect causes, warned Dr Cervantes, for example, birds that are immuno-compromised or with a deficient immune system (regardless of the cause) are more likely to suffer from outbreaks of coccidiosis. Also, if there is wet litter in the house, the high number of infective eggs may overwhelm the best preventive drug. Management practices that restrict access to light, water or feed - whether intentional or accidental - or increase stocking densities can also increase the problem. Prompt resolution of the problem can prevent significant losses to the producer. Key points to remember regarding treatment are:

• Pick for treatment the drug most likely to be effective for the type of coccidiosis that you want to control

• Ensure the water lines have been flushed and do not contain residues of other drugs or water-administered supplements (vitamins, electrolytes, etc.)

• Sulphonamides are more stable and effective at neutral to alkaline water pH

• Remember that the required withdrawal periods varies between sulphonamides, and

• Be mindful of label directions and withdrawal periods to ensure efficacy and avoid tissue residues.

Therefore, Dr Cervantes recommends using an antibiotic growth promoter in the feed with solid anti-clostridial activity (such as virginiamycin) when live coccidiosis vaccines are used. Another important factor to consider when live coccidiosis vaccines are used is the amount of moisture of the litter. Very dry litter is undesirable because in slows the development of protective immunity against coccidiosis in vaccinated birds. Finally, 'seeding' of the house with the vaccine oocysts, and the quality and nutrient content of the feed.

Yours in the garden Farm2Markt. Stay safe.