Vetech Laboratories Inc.

(Presented at the 55th Annual ASTMH Meeting in Atlanta - Nov. 12-16, 2006)

Control of Coccidiosis in Poultry with Live Vaccines as
a Model for the Control of Malaria

Eng-Hong Lee Vetech Laboratories Inc., Guelph, Ontario, Canada

Coccidiosis is a common protozoan disease of commercial chickens and turkeys. This disease has been well controlled for over five decades with anticoccidial drugs but with declining efficacy because of the emergence of drug resistance against existing drugs and with no new drugs on the horizon. However, with the introduction of the concept of uniform exposure (Lee, 1986), several live vaccines of multiple Eimeria spp have also been used successfully for the past 2 decades on at least 10 billion commercial birds.

These live vaccines do not merely complement the use of medications but can also be used synergistically in the control of coccidiosis. They may also serve as useful tips for the control of malaria a disease caused by fellow Apicomplexan parasites of coccidia.

Comparable performance between vaccine and medication allows the rotating or selective use of either vaccine or medication
Drug sensitive vaccine strains can be used to salvage drug resistant anticoccidials (or antimalarials in malaria) by the displacement of field strains (Mathis & McDougald, 1989, Chapman, 1994)
Use of vaccine first followed with a brief period or medication to mitigate possible vaccine reaction (Lee, 2001) can be a synergistic use of vaccine and medication
Like malaria, there is no cross-species or cross-strain protection observed in coccidiosis
Strangely, 3 or 4 more commonly used commercial vaccines containing 4 to 7 species of Eimeria spp can be used in rotation and perform equally well with vaccines containing fewer species
Antigenic gene transfer from a pathogenic species (or strains) into a less pathogenic Eimeria spp (Lee and Seligy, 1999) may be used to reduce the number of species or strains required in vaccines
To date, no dead vaccines have been shown to successfully control coccidiosis in commercial poultry

References:

1. Chapman, H.D. and A.B. Kacker. (1994). Sensitivity of field isolates of Eimeria from two broiler complexes to anticoccidial drugs in the chicken. Poult. Sci. 73(9):1404-8.

2. Lee, E-H. (1986). Canadian Patent 1,204,057.

3. Lee, E-H (2001). United States Patent 6,306,385.

4. Mathis, G.F. and L.R. McDougald. (1989). “Restoration of drug sensitivity on turkey farms after introduction of sensitive coccidia during controlled-exposure immunization.” In: Yvové P. (Ed). Coccidia and intestinal coccidiomorphs, INRA, Paris, France. pp. 339-343.

5. Lee, E-H and V. Seligy. (1999). Canadian Patent 2,098,773.