ELIMINATION OF FOX RABIES FROM BELGIUM USING A RECOMBINANT VACCINIA-RABIES VACCINE - AN UPDATE

To improve both safety and stability of the vaccines used in the field to vaccinate foxes against rabies by the oral route, a recombinant va ccinia virus, expressing the glycoprotein of rabies virus (VVTGgRAB) h as been developed. VVTGgRAB innocuity was verified in target species a nd in domestic animals as well as in numerous wild animal species that could compete with the red fox in consuming vaccine baits in Europe. Oral immunization of foxes, by distributing VVTGgRAB vaccine-baits, wa s undertaken in the whole of the infected area of Belgium (10 000 km(2 )). Five campaigns of fox vaccination covering the whole infected area were carried out from the autumn of 1989 until 1991. Each time, 150 0 00 vaccine-baits were dispersed by air at a mean density of 15 per km( 2). These campaigns induced a drastic decrease in the incidence of rab ies and the elimination of the disease from 80% of the initial infecte d area. Regarding the geographical evolution of rabies in Belgium and in adjacent regions in neighbouring countries, new spatial strategies for bait dispersal were planned for 1992, 1993 and 1994: successive re stricted campaigns were carried out along political borders only, Thes e campaigns induced a new decrease of incidence; no rabid foxes could be detected in 1993 in spite of an improved epidemiological surveillan ce. In 1994, rabies was confirmed again in 13 foxes collected in a reg ion situated close to the French border. These cases demonstrate the p ersistence of a focus of rabies on the border and justify further rest ricted campaigns of vaccination.