FIELD-EVALUATION OF A DOG OWNER, PARTICIPATION-BASED, BAIT DELIVERY SYSTEM FOR THE ORAL IMMUNIZATION OF DOGS AGAINST RABIES IN TUNISIA

We evaluated a dog owner, participation-based, bait delivery system fo r the oral immunization of dogs against rabies. In a field study in a semirural area of northern Tunisia, dog owners were asked to come to t emporary bait delivery sites. A total of 314 baits were given to 178 d og owners in four sites. The experimental baits used consisted of a fr eeze-dried core unit containing sulfadimethoxine (SDM) as a biological marker and an aromatized paraffin envelope. No vaccine was used. Prel iminary tests had shown that by using a rapid commercial card test, po sitive SDM serum levels were detected in more than 95% of dogs up to t wo days after bait ingestion. During the two days following bait deliv ery, we visited more than 95% of all households in the study area and took blood samples from as many owned dogs as possible. Unconsumed bai ts were recovered and human contacts with the bait matrix were recorde d. The campaign required 7.6 person-min per bait and 13.5 person-min p er dog owner for providing baits, gloves, and instructions. The estima ted average cost effectiveness ratio per dog accepting a bait was 1.7 US dollars. From the indications given by the dog owners and the resul ts of the SDM test, it was concluded that 85-90% of the owned dogs in the study area had consumed a bait at least partially. Of 314 baits de livered, 78.7% were fully consumed by dogs and 4.1% were recovered dur ing the household survey. The remaining baits (17.2%) that were not re covered were either not consumed or only partially consumed by the tar get dogs (3.7 baits per 100 inhabitants). These baits probably remaine d within the highly populated areas and were potentially accessible to other domestic animals and other nontarget species, including humans. Twenty-five unprotected human contacts with baits were recorded (1.7% of all inhabitants). Our study has demonstrated the potential of dog owner based bait delivery. This technique is simple and efficient, par ticularly if the human population is accustomed to mass immunization i n defined centers. Before applying this method on a large scale with l ive vaccine loaded baits, further studies should focus on minimizing t he number of human contacts with the vaccine bait, systematizing conta ct identification and establishing structures in ensuring proper treat ment if exposure to vaccine should occur.