ARS | Publication request: Influence of eye surface area on spray vaccination dosage rates

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 10, 2010
Publication Date: November 15, 2010
Citation: Purswell, J.L., Mayer, J.J., Evans, J.D., Branton, S.L., Davis, J.D. 2010. Eye surface area and dosage rates for spray vaccination. Avian Diseases. 54(4):1310-1315.

Interpretive Summary: Spray application of Mycoplasma gallisepticum (MG) vaccines is a labor and time saving means of mass vaccination of layer chickens. Recent assessment of spray characteristics of nozzles commonly used to apply MG vaccine in layer chicken operations has shown that the amount of respirable droplets (< 5 'm) from commonly used nozzles is negligible. The eye has been suggested as a route of vaccination, but no estimates of vaccine load delivered via spray application were found in the literature. Estimates of eye surface area were developed using digital imaging; 24 layer pullets were used for analysis and the mean eye surface area corrected for corneal curvature was found to be 0.609 cm2. This surface area was then used to estimate vaccine load for commercially available live MG vaccine sprayed through popular nozzles. Less than 3,000 cfu can be expected for direct deposition onto the surface of an eye.

Technical Abstract: Spray application of Mycoplasma gallisepticum (MG) vaccine saves both time and labor for the table egg industry. Optimization of spray application of vaccine is important in maintaining animal health and productivity. Previous work has shown that droplets produced by popular nozzles used for spray application are not respirable. The eye may play an important role as an avenue for vaccine exposure. Measuring the exposed surface area of the eye is critical for determination of vaccine deposition on the eye. Estimates of eye surface area were developed using image analysis methods. Based on this area and known deposition rates from popular spray nozzles, spray vaccinated layer chickens receive approximately 1/860th of a full dose of MG vaccine in the eye.