a1 Department of Animal Pathology, University of Cambridge
1. In streptococcal infection of piglets the causative agent (PM streptococcus) was isolated from the throats of a high proportion of infected animals and from their apparently healthy litter-mates.
2. The PM streptococcus was isolated from the noses of three out of forty-three normal sows. In one sow the streptococcus was also isolated from the throat.
3. Bacteriaemia was induced in piglets up to the age of 17 days by inoculating into the nose and throat broth cultures of the PM streptococcus. Blood cultures were usually positive within 24 hr., and secondary involvement of the joints and meninges frequently occurred during the ensuing few days.
4. Serum taken from piglets 5 weeks after experimental infection and administered subcutaneously protected susceptible piglets against subsequent infection with PM streptococci.
5. The possibility of preventing streptococcal infection in piglets by active immunization of the sow is discussed.
(Received October 11 1965)
p1 Present address: Ontario Veterinary College, Guelph, Canada.
p2 Present address: McGarvie Smith Institute, Ingleburn, N.S.W., Australia.