Experiments with Teschen Disease (Virus Encephalomyelitis of Swine)

Abstract

Experiments with Teschen disease have shown that the causative agent is a neurotropic virus of small size (no larger than 10–15 mμ), with a limited and unique host range. Although efforts to adapt it to a host other than the pig were unsuccessful, the virus apparently survived in tissue culture for 17 days, and there was a suggestion that it might have multiplied. The disease produced in pigs on intracerebral, intranasal, or oral inoculation was a severe encephalomyelitis with a characteristic clinical and pathological picture easily distinguishable from poliomyelitis, to which it has often been likened. Animals which had been fed infected CNS were studied for the presence of viremia and for fecal excretion of virus. Viremia was found to occur early in the incubation period, as long as 10 and 12 days before the appearance of paralysis. The results were negative late in the incubation period and after onset of the disease. Virus was not demonstrated in the feces of orally infected animals. Attempts to develop a complement fixation test were unsuccessful and the intracerebral neutralization test in pigs proved unsatisfactory for demonstrating antibodies. No antigenic relationship was demonstrated to the following neurotropic viruses with which the virus of Teschen disease was compared: Lansing and Y-SK strains of poliomyelitis, Theiler's TO, FA, and GD VII strains of mouse encephalomyelitis; St. Louis, eastern equine, western equine, and Japanese B encephalitis; louping ill; and Russian spring-summer encephalomyelitis. The attempt will not be made to establish the position of Teschen disease virus taxonomically among the so-called family of poliomyelitis viruses, in view of the evidence pointing to its exclusion from this family.