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Vaccination to counter coccidiosis in layers

- 24 November 2012
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Coccidiosis in poultry production has long been a major inhibitor to successful and economic production. In broiler and broiler breeder operations the impact of the disease on liveweight, feed conversion and flock evenness can result in damaging direct and consequential costs.


For pullet rearers and free-range egg producers the imperative to maintain health and output is just as critical. Due to the nature of the disease and the cycles of infection, close monitoring coupled with strategic medication is required to provide continuous protection.


Adapting to change


The rearer and layer sector is no stranger to the impact of changing legislation and regulation.


One such change for egg producers came in 2004 when, through an EU ruling, pullet rearers and layer units had to cease using one product that had been important in helping to control coccidiosis.


The challenge for pullet rearers was to continue to protect their birds from coccidiosis by adopting a new regime.


At this time in the UK a number of egg producers had already successfully been using a coccidiosis vaccine programme to protect their chicks and provide immunisation as they became productive.


Benefits of coccidiosis vaccination

  • Protection against all species of Eimeria.
  • Low or no issues of resistance in vaccinated flocks.
  • No residue issues for eggs or egg products.

This was partly due to the fact resistance to certain coccidiostats was increasingly becoming a problem, with producers reporting severe coccidiosis outbreaks in pullets and young laying flocks. Long-standing policies of rotating anticoccidials were not as effective as they had been and disease outbreaks were increasing despite the investment in medication.


Pullet rearers and egg producers were able to see how broiler breeder operations were achieving higher levels of protection through immunity and reaping the benefit of stabilising health on their units.


While the production systems were entirely different, coccidiosis challenge was a common concern and in these circumstances vaccination programmes using Paracox became well established.


Through oocyst counts, lesion scoring, feedback and monitoring, vets were able to assess the effective control of the disease and the financial benefits were easily calculable as outbreaks were reduced.


Wet smear test for coccidiosis
Coccidial oocysts from a wet smear of chicken intestine under the microscope.


Meeting the market


With only one vaccine available to provide protection against all the species of Eimeria affecting chickens, Paracox was adopted by a growing number of rearers and egg producers in the UK.


Four key disciplines central to successful vaccination

  1. Appropriate storage of the vaccine prior to use – following the specific recommendations on fridge temperatures and handling prior to application.
  2. Effective administration – from preparation of the sheds and bird environment through to the practical application method advised by the vet.
  3. Regular monitoring of birds post vaccination. Healthy birds are more likely to produce a good immune response.
  4. Daily assessment of litter quality – to ensure the correct dry/wet balance crucial to successful oocyst recycling, thus boosting immunity.

For those producers who had historically managed coccidiosis through the traditional anticoccidials the move to vaccination required a shift in approach and the adoption of new skills sets (see Four key disciplines central to successful vaccination ).


To support the transition, MSD Animal Health offers a support programme for producers. Full protocols for vaccine administration are discussed with each producer and their vet. Unit visits are undertaken if necessary to establish the most effective method for vaccine application.








What is coccidiosis? 


  • Coccidiosis is a disease caused by a microscopic, single-celled parasite called coccidia, which infects the cells of the intestinal wall in chickens and turkeys causing damage to the gut.
  • The coccidia infect the gut through the ingestion of oocysts, excreted by infected birds in their faeces.
  • If temperature and humidity are suitable, the excreted oocysts sporulate. Each sporulated oocyst contains four sporocysts which, once reaching the gut, generate sporozoites. These begin infecting the cells within six hours of ingestion.
  • The sporozoites destroy their host cell over a period of six days. Coccidia then completes its lifecycle by generating many daughter oocysts, which are shed in the faeces.


To help measure the effectiveness of vaccination, regular faecal sampling and oocyst counting during the early weeks following vaccination may be advised.


The pattern of oocyst output through time is related to the development of immunity. Information derived from intestinal lesions scoring also provides an important picture of the coccidiosis profile in the flock.


Sarah Rennie is the UK marketing manager at MSD Animal Health

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