Coccidiosis

Coccidiosis: Description, Causes and Risk Factors:Group name for diseases due to any species of Coccidia; a common and serious protozoan disease of many species of domestic animals and birds and many wild animals kept in captivity; both intestinal and pulmonary coccidiosis have been reported in humans with HIV/AIDS.Coccidiosis is one of the most common and economically important diseases of chickens worldwide. It is caused by a parasitic organism that damages the host's intestinal system, causing loss of production, morbidity and death. A recent estimate put the annual global impact of coccidiosis at more than US$300 million.Coccidiosis is spread when one bird eats fecal material from an infected bird, which contains the infective stage of the Coccidia. The oocysts in the droppings need moisture and warmth to mature before they can infect other birds, but in the right conditions, can do so very quickly (24 hr). Oocysts can remain alive in poultry sheds for more than a year and they are very resistant to most disinfectants.Seven species of Eimeria are known to infect chickens. These are Eimeria acervulina, E. brunetti, E. maxima, E. mitis, E. necatrix, E. praecox, and E. tenella. Although any of these species may be found in a poultry operation, E. acervulina, E. maxima, and E. tenella appear to be most prevalent in the U.S. This protozoan parasite exists as a highly resistant oocyst form in litter. The oocysts vary in size, with E. maxima being the largest (about 20 x 30 microns) and E. mitis the smallest (about 14 x 16 microns). The oocysts are discernable only by use of a compound microscope. Due to the wide range of oocyst sizes, it is nearly impossible to distinguish between different species of Coccidia. Molecular techniques have been developed that uses DNA extracted from the parasite to speciate the oocysts.Outbreaks of coccidiosis may occur if the level of coccidiostat in the feed is too low, if the birds are not eating enough or if the coccidiostat is withdrawn too early (before immunity has developed). Lack of vitamins A and K will cause the outbreak to be more severe as will other diseases that reduce the general resistance of the bird.Symptoms:Symptoms may include:Droopiness.
  • Paleness of the comb.
  • Diarrhea.
  • Blood in the droppings.
  • Depression
  • Loss of condition.
  • Paleness.
  • Ruffled feathers.
Diagnosis:Definite diagnosis can be confirmed only by laboratory examination. Material scraped from the lining of the gut is examined under a microscope and the Coccidia are identified based on shape, size and location in the gut. Species can also be accurately diagnosed by DNA testing.Treatment:Chemotherapy has been the main approach for controlling coccidiosis in chickens. Anti-coccidial drugs are usually used preventatively; if a farmer were to wait for overt signs of disease before treating the flock, morbidity and mortality would be high and the economic damage already done. Almost all commercial, intensively farmed flocks are administered anti-coccidial drugs prophylactically. When given at the correct low preventative doses, Eimeria species are able to complete their life-cycles without large numbers of infective oocysts building up in the environment. Such subclinical infections result in the development of strong, specific natural immunity without overt disease.coccidiosisEffective live vaccines are now available in Australia. These ensure the birds are exposed early in life and develop immunity to the most virulent species of Coccidia. For effective vaccination, it is essential to closely follow the manufacturer's recommendations.NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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