The Control Of Drug Resistance in Coccidia

The clinical observation of the coccidal broiler out-breaks in commercial broiler, layer and breeder replacement flocks, during the past 8 years, has revealed a constant development of resistance against many prevalent anti coccidal medicines. This phenomenon is on increase every year. The long-term exposure to a particular drug will produce a loss in its sensitivity eventually developing longer lasting resistance. The drug resistance is a genetic phenomenon and once established in line coccidia, will remain for many years or until selection pressure and genetic drift forces return to sensitivity in the population of those coccidia.

The successful strategy for the prevention of damage due to coccidiosis is to maintain low infection pressure of coccidiosis in broiler, layer & breeder replacement houses. Where the infection pressure in low, most anti-coccidials will be able to keep the situation under check and thus one can take the full advantage of additional defense mechanism of the chickens such as maternal immunity development. Thus a balance use of ionospheres and synthetic products is the best way to control the coccidiosis pressure, and subsequent drug resistance.

A good management and healthy flock of course is also essential. The farm manager has to plan a day rest period for the product being used. The product of identical mode of action (same group of ionospheres) need to be given a rest period together. The farmer has to be fully aware of disease situation through regular monitoring the birds and littre from a diagnostic lab. to avoid further out-breaks. This consists of lesion scoring to indicate the severity of infection and also the identification of the particular coccidial species by microscope examination. Whereas the oocyts count of litter will provide information with isolated out-breaks of coccidia and a serious build up of resistance in the rearing premises of the farm. The proper planning of shuttle program consisting of use of ionospheres & synthetic coccidiostate are to be used alternatively in combinations to achieve the proper control of coccidiosis.

The iteration with immunosuppressive viruses, such as IBD and MDV and simultaneous bacterial infection of Colistridium and E.Coli will aggravate the mortality of the flock and this has to be distinguished from the outbreak due to drug resistance of coccidia. Most recently the use of coccidial vaccine gas reduced the resistance be interbreeding between vaccine and wailed coccidian. However, this strategy can only be used according to the feasibility of the flock being reared. A concerted effort is required be feed mills, and the farm owners to check the serious development of drug resistance in coccidian, otherwise the cost of production of poultry will increase tremendously due to mortality losses and poor production performance.