On Pseudorabies in Carnivores in Denmark

Abstract

In the autumn of 1968 Pseudorabies was demonstrated in blue foxes (Alopex lagopus) on two fur farms in Jutland. The foxes had been fed with dead piglets from herds of swine belonging to the two farmers.

At the same time the disease was diagnosed in piglets from these herds. At the two fur farms there were, respectively, 34 and eight foxes in all; respectively 26 and two died with signs of pruritus. Only few of the surviving foxes had had the opportunity to eat piglets. Eight weeks after the period of disease no antibodies against psedorabies virus could be demonstrated in serum of three surviving foxes.

The virus content in various organs of six foxes submitted to the Laboratory was determined by titration in tissue cultures (Table 1).

The results indicate that the spreading of virus from the port of entry of the virus to the brain must have occurred by nervous routes.

The presence of virus in the tonsils of five of the six foxes and in the nasal mucosa of the sixth one, together with similar results from examination of dogs at this institute would seem to suggest that a transmission of the disease from these carnivores to other animals is possible.

Based upon the high virus titers in the medulla oblongata and pons, and with reference to similar results of examination of dogs and to a previous publication on Pseudorabies in Danish red foxes, it is concluded that these tissues must be the material of choice for demonstration of Pseudorabies virus in these carnivores.

Sammendrag

I efteråret 1968 diagnosticeredes Aujeszky’s sygdom hos blåræve (Alopex lagopus) på 2 pelsdyrfarme i Jylland. Rævene var blevet fodret med selvdøde pattegrise fra ejernes svinebesætninger, hvor sygdommen samtidig blev påvist ved isolation af virus. I de 2 besætninger med 34 og 8 ræve døde henholdsvis 26 og 2 ræve, alle med tegn på kløe. Kun få af de overlevende ræve havde haft mulighed for at æde de døde grise. Hos 3 overlevende ræve kunne ikke påvises Aujeszky-antistoffer 8 uger efter infektionen.

Ved titrering på vævskulturer måltes virusindholdet i forskellige organer hos 6 indsendte ræve (Tabel 1). På basis af de fundne resultater fastslås, at spredningen af virus fra det primære infektionssted må være foregået langs nervebanerne.

Påvisning af virus i tonsillerne hos de 5 af rævene og i næseslimhinden hos den 6., sammenholdt med lignende resultater fra egne undersøgelser af hunde, antyder muligheden for overførsel af smitte fra sådanne angrebne dyr til andre.

På grund af de høje virus-titre i medulla oblongata og pons hos alle 6 ræve, og under henvisning til tilsvarende resultater fra egne undersøgelser af 11 hunde og en tidligere publikation vedrørende vilde danske ræve, fremhæves det, at disse hjerneafsnit må være det bedste udgangspunkt for diagnosticeringen af Aujeszky’s sygdom hos disse kødædere.