FIELD-EVALUATION OF 2 BAIT DELIVERY SYSTEMS FOR THE ORAL IMMUNIZATIONOF DOGS AGAINST RABIES IN TUNISIA

Two bait delivery systems for the oral immunization of dogs against ra bies were tested in small scale field trials in a semi-rural area in T unisia: bait delivery to owned dogs during door to door visits of hous eholds (door to door baiting) and distribution of baits on transect li nes (transect line baiting), A prototype bait (DBL2) configured for in dustrial production and containing either sulfadimethoxine (SDM) as a systemic marker or Rhodamine B as a topical marker was used. The over- all proportion of dogs which took a bait and presented topical marker- staining after door to door baiting was 59.1%. The total time and cost s spent per bait accepting dog averaged 34 person minutes and US$4, re spectively. Unconsummated baits were readily recovered. No unprotected human contacts with baits were recorded. Door to door baiting is a ve ry specific but time-consuming method that enables a safe administrati on of vaccine baits to owned dogs. For transect line baiting, baits we re distributed at a density of ca 3000 baits per km(2) along double tr ansect lines. Baits were recovered after 20 h. According to the propor tion of SDM positive serum samples, 24.1% of owned dogs in the baiting area had consumed baits. Of all owned and ownerless dogs, presumably free-roaming during transect line baiting, > 40% had consumed baits. T he total time and costs spent per bait accepting dog averaged 48 perso n minutes and ca US$20, respectively. The household census revealed 32 direct human contacts with the bait matrix which corresponds to 1.4% of inhabitants. Placing baits on transect lines gives the possibility to vaccinate dogs not accessible by vaccination systems which base on dog owner participation. However, the method is not specific, less saf e than other systems, not easily accepted by the human population, and costly. (C) 1998 Elsevier Science Ltd. All rights reserved.