Coccidiosis is one of the major poultry diseases and is caused by a protozoan of the family Apicomplexa, genus, Eimeria. The parasite is known to penetrate inner intestinal linings as they grow and multiply in different stages of their lifecycle. In so doing, they destroy the intestinal linings leading to bleeding, poor digestion, low absorption of nutrients, diarrhoea, and reduced growth rates.
The disease is referred to as ‘ubiquitous’, meaning it is found everywhere the poultry lives and forages. The disease is likely to become a threat in intensive poultry operations where stocking densities are high. When the disease is subclinical, the disease-causing organisms(oocysts) impair feed conversion, resulting in huge economic losses to farmers.
Characteristics of the oocysts
The organisms that live in the manure or soil can only be destroyed at temperatures of > 55 degrees centigrade for a minimum of 15 minutes. The organisms can barely withstand freezing temperatures.
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In the manure and soil, the organisms will survive for three to 9 months and remain active to cause disease if swallowed by the host. One oocyst can multiply within 12 days into >100 million oocysts. It is one of the organisms with enormous reproductive potential. In intensely reared populations as we do here, coccidiosis causing organisms can survive in the wet, moist litter multiply and be ready to be swallowed by the next bird.
Signs of the disease
The presence of loose faecal droppings, diarrhoea, mucoid faeces sometimes with fresh blood stain, should be an awakening call to farmers in intensive production. In cases of mild infection, farmers will notice poor growth rates and high feed costs due to poor feed utilisation.
In the event of disease, layer farmers who get 7-8 eggs per kilo feed during peacetime, will suddenly be confronted by drops of 3-4 eggs per kilo feed consumed.
In a flock of 5,000 pullets at peak production of 95 per cent, that is a loss of 41 per cent production per day, equivalent to Sh12,000 everyday revenue loss. In severe cases, there will be a sudden increase in daily mortality. It is important at this stage to send some dead birds or culled unthrifty ones for postmortem diagnosis by a veterinarian near you.
It is also important during the investigation of the outbreak to submit feed samples to special diagnostic laboratories to check for accidental omission or drug resistance of anticoccidial drugs for birds that are on such treatments.
Proper cleaning and disinfection
As mentioned at the beginning of this discussion, cocci organisms are found everywhere, thanks to wild birds, ducks, geese that roam around our chicken pens. The most common source of infection comes through from the previous flock that keep harbouring residual germs that must be eliminated or reduced by thorough cleaning and disinfection.
The use of aldehyde-based disinfectants can reduce the population of oocysts. The litter should be always kept dry by raising the drinkers to the level of the back of the bird and reducing water pressures for the nipple system of water administration.
Vaccination
There are broiler and layer live attenuated vaccines in the market that can be used to prevent infections. The two widely used vaccines are Paracox 5 for broilers and Paracox 8 and Evalon for long-living birds. The vaccines must contain all the important species of Eimeria and are administered by spray or through drinking water.
Use of drugs
Coccidiostats — compounds that inhibit but do not kill the parasites — can be used. There are other anticoccidial drugs available that will be prescribed, and they act by killing coccidia organisms. They are mixed with feed and are given on prescription only. Birds inlay should not be on this regiment.
The writer, Dr Watson Messo Odwako, Head Veterinarian at Kenchic Limited.
messo@kenchic.com
