Epidemiology and Infection

Research Article

Experimental studies on the comparative infectivity and pathogenicity of Streptococcus suis type 2. II. Porcine and human isolates in laboratory animals

I. D. Robertsona1 c1 and D. K. Blackmorea1

a1 Department of Veterinary Pathology and Public Health, Massey University, Palmerston North, New Zealand


Mice, rats, guinea-pigs and rabbits were inoculated with isolates of Streptococcus suis type 2. An isolate cultured from the tonsils of a healthy pig, produced disease in rabbits after intravenous inoculation but not in mice, rats or guinea-pigs. An isolate of S. suis type 2, that was pathogenic for pigs and had been cultured from a human patient with clinical disease, produced signs of neurological disease in mice, rats and rabbits following intravenous inoculation. There was an apparent dose response in mice with 31 % of mice receiving more than 106 organisms developing clinical disease, whilst mice receiving less than this did not develop disease. There were no detectable histopathological lesions in the brains or meninges of mice with nervous signs. It is proposed that the disease in mice may mimic that reported in humans and that mice may be a useful indicator species for determining the virulence of isolates cultured from pigs.

(Accepted May 03 1990)


c1 Address for reprints/correspondence: I. D. Robertson, School of Veterinary Studies, Murdoch University, Perth, 6150, Western Australia.