Guidelines for the use of water sensitive paper in spray vaccination of poultry

What is water-sensitive paper?
Water sensitive paper (WSP) is a rigid paper with a specially coated, yellow surface. This surface is stained a dark blue colour when aqueous droplets come into contact with it. WSP is already widely used in agriculture to monitor the distribution of herbicide and pesticide sprays. After application of a spray, the WSP is retrieved from the target area and, once dry, the droplet pattern can be examined. The size and distribution of the blue spots reflect the size and number of spray droplets landing on the target area. Comparison can be made with known standards, or the blue spots can be assessed manually using a pen microscope such as the Micro Mike.*

WSP for Evaluation of Spray Vaccination
WSP can be used for a rough visual estimate of droplet size generated by the sprayer in use. Placing the papers at bird level, can show how the vaccine spray is distributed within a flock. Droplet density at various distances from the target areas can also be evaluated.
Because WSP is sensitive to water, the strips must be handled carefully once removed from their packaging. Moisture from human skin can affect the paper and plastic gloves are strongly recommended. The high relative humidity in certain type of houses can also affect the paper. To overcome this, the strips should be retrieved and evaluated as soon as possible after the spray has dried. Exposed strips can then be stored in a clear plastic folder to be examined or photographed later.
WSP can be used to monitor the application of respiratory vaccines, such as Nobilis MG 6/85, when applied to birds in cages. To test evenness of vaccination WSP strips are placed into empty cages at selected locations within the house. The important point is that cages at all levels (upper, middle, bottom) and positions within a cage row (front, middle, back) be evaluated. It is also advisable that the person actually spraying the vaccine is not aware of the exact position of the test cages to prevent an unintentional bias in the spray technique. The examination of the paper strips will reveal if large sections of the cage row are being missed. The use of sprayers with multiple spray nozzles can be evaluated to establish if the spray nozzles are properly positioned to reach the correct target area (bird head level) for each cage tier (it is common to find sprays that are directed too low and are spraying the legs and feet of the birds).

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