Abstract:
1. The incidence of calf paratyphoid in various countries and its relationship
to disease in adult cattle, in other species of animals, and in human beings
are reviewed.
2. The isolation of 507 strains of Salmonella from outbreaks of paratyphoid
in calves is reported. Of these 491 were identified as S. dublin, eleven as
S. typhi-murium, four as S. enteritidis, and one as S. bovis-morbificans. In
addition the isolation of twelve further strains of S. dublin from adult cattle is
recorded.
3. The significance of Salmonella dublin as an etiological agent in paratyphoid
of cattle, particularly calves, is discussed.
4. For the detection of S. dublin or other forms of Salmonella infection
either faeces, bile, blood or liver, and spleen cultures were made, and the suspected
sera tested for "0 " and "H" agglutinins. In some cases only one of these tests
was possible, but at other times two or more were performed. In. addition a
pathological study of the liver and spleen was made whenever possible. With
very few exceptions the results obtained from a pathological examination of
suspected organs corresponded to the results of the bacteriological study. But
in many positive cases of calf paratyphoid faeces and blood cultures were negative
and a negative agglutination test was obtained. Sometimes faeces cultures were
positive when the serological test was negative or vice versa. In other cases the
presence of a carrier was spotted first by a positive agglutination test. For
the detection of carriers, therefore, both faeces cultures and serological tests
should be performed.
5. The agglutinogenic response of infected, carrier, or immunized animals
generally resulted in the production of practically only "H" agglutinins. "0"
agglutinins were seldom present in significant amounts, and when they were
present the titre was generally extremely low in comparison with that of the "H" .
These results do not agree with the previous observations of Henning and his
co-workers (1939, 1946, 1942). These workers found that the sera of birds acting
as carriers of S. typhi-murium or of horses affected with a latent or chronic
S. abortus-equi infection responded chiefly to "0" agglutination, and that the
"H" agglutination was either poor or entirely absent.
6. The role played by rodents and the so-called Rat "Viruses" in the
dissemination of Salmonella infection is discussed.
7. The significance of S. dublin as an etiological agent of food infection in
human beings is discussed.
