ORAL IMMUNIZATION OF FOXES (WILDLIFE CARN IVORES) - RESULTS IN HUNGARY

Because fox is the main reservoir of the sylvatic rabies in Europe, re duction of the number of foxes under 2 foxes/km(2) seemed to be the so lution. The reduction of the number of foxes proved to be unsuccessful . Later on it was recognized that only the immunization of foxes could be successful. For that reason, appropriate vaccine virus (effective after oral application) and a suitable bait should be developed (Figur e 1). Baits were distributed in squares (16 to 25 baits/km(2)) every h alf year by hand at first. Disadvantages of the manual distribution ar e, as follows: many participants are required for the distribution and their control is not easy; the organization is difficult; due to the relief and, natural waters and vegetation there are inaccessible areas (where the distribution is impossible!). The solution proved to be th e elaboration of aerial distribution. Its advantages are: the distribu tion of vaccine baits lasts for short time; a staff small in number is required; ensures a uniform distribution independent of the features of the terrain; human remissness can be eliminated (it can be controll ed more efficiently). The vaccine baits were distributed with equal di stances of 250 meter at first. Later on, the distance of bait distribu tion was 50 meter (in belts of 1000 meter, Figure 2). In both cases, 2 0 baits/km(2) were distributed. The vaccine bait contains the SAD-B19 virus strain of live, attenuated rabies fix virus (Fuchsoral). The fir st vaccination campaign was carried out in October 1992 covering and a rea of 5000 km(2). In 1993, this area was expanded to 6000 km(2). The cost of yearly two vaccination campaigns were around 40 million Hungar ian forints (around 400 000 US $). The oral vaccination was started fr om the borders of Austria and Slovenia (they started earlier to apply oral vaccination) moving on toward East (Figs 3 and 4) Veterinary surg eons, human doctors and professional hunters participate in the campai gns. Notices and posters are stuck up on the treated territory and als o the boradcasting and TV companies are informed to give utmost attent ion to the oral vaccination. Dogs should be kept closed (tied) in the treated territory for 14 days. A visible result was observed even afte r the first vaccination campaign (Figure 5). According to the experien ces, in the inaccessible areas of the Austro-Hungarian border rabies w as observed time by time. Thus, the Hungarian authorities proposed to the Austrian and Slovenian co-authorities to vaccinate the border area by aerial distribution of the same vaccine baits at the same time, li ving aside the country borders. For countries recently starting with o ral vaccination it is proposed to use a ''buffer zone'' besides the tr eated area. i. e. to start also the simultaneous vaccination of the ne ighbouring territory just after the second or third vaccination campai gn. One month after the vaccination campaign, 100 to 150 foxes were sh ot for laboratory investigations (fluorescent antibody test, antibody determination, tetracycline marker). 81% of the foxes tested took up t he baits. The number of foxes increases in the treated territory becau se the number of death decreases. After the fourth oral vaccination ca mpaign, no tables cases were observed in the. treated area during the second quarter of 1994 (Figs 6 and 7). Incidence of rabies cases betwe en July and October, 1994 are shown in Figs 8 and 9. By October, 1994, the vaccination of a further 6000 km(2) area was launched, moving tow ards the Eastern part of the country (Figure 12). The campaign involve s five counties. Further results can be expected from the increase of the treated area (establishment of a ''buffer zone'', Figs 10 and 11). Actually the costs are covered by the Hungarian veterinary service. I t is to be hoped that a part of the costs will be covered by EEC start ing from 1995.