Transmission of the South African strain of dourine to laboratory animals

Abstract

These results show that the South African strain of dourine like the chronic form of the disease in other countries is not readily transmitted to laboratory animals. But where the invasive power of the strain has been boosted by serial blood passage in equines it is easily transmitted to rabbit testicles and to white rats provided the rats are splenectomised. The rabbit-adapted parasite remains localised and shows little tendency to enter the blood stream. In the splenectomised white rat, the parasites rapidly increase in virulence and are soon adapted to normal white rats. The strain has been passaged over 50 times in normal white rats. Guinea pigs and rabbits, are resistant. The strain differs in this respect from our imported one which is virulent for these animals. What part bartonellosis plays in rendering splenectomised rats susceptible to the disease is not known. Both the rabbit-testicle and rat-adapted parasites were indistinguishable morphologically from the original strain, and from our imported strain. An antigen prepared from the rat strain gave the same results as our routine antigen when tested against sera from normal and dourine infected horses.