The Effect of Altering Metabolic Rate on the Mortality and Incubation Time of Rabies ∗

Summary

Studies were made to determine if raising or lowering the metabolic rate of experimental animals would increase or decrease the incubation period of rabies virus.

The metabolic rate of mice, rats, hamsters, and guinea pigs was increased from 17 to 84% with iodinated casein with no significant change in the incubation period or mortality rate of rabies when compared to control animals. The host metabolic rate was decreased by thyroidectomy, hypophysectomy, or propylthiouracil in the diet. In most cases the incubation period of the treated groups did not differ significantly from the rabies controls. However, in thyroidectomized rats with the metabolic rate decreased 13% there was a significant delay in the onset of rabies symptoms (p = .10). In mice fed PTU the mean metabolic rate ranged from a 2.2% increase to a 4% decrease. An analysis of 216 mice suggests a delaying effect in the onset of rabies symptoms and a higher survival rate for mice with PTU in the diet than controls with a normal diet. It is suggested that the decreased metabolic rate of a host could delay virus propagation and give more time for active and passive treatment and possibly increase the chances of survival for an animal exposed to rabies virus.