Salmonellosis in Turkeys: Evaluation of Bacteriological and Serological Evidence of Infection

Bacteriological and serological studies were made of Salmonella infections in turkeys under three conditions; in commercial hatchery supply flocks and their embryo and poult progeny, in survivors of a natural infection over a ten-month period, and in experimentally infected adult turkeys.

The investigations revealed the following: 1. Carrier birds yielded Salmonella from cloacal swabs only intermittently which emphasized that failure to so isolate the organism did not necessarily indicate absence of infection in flocks. On the other hand, recovery of Salmonella from swabs or from dead-in-shell embryos foretold the likelihood of clinical disease in the progeny.

2. Bacteriological examination of ten per cent of the embryos from infected individual hatches did not regularly yield Salmonella but culture of a series of hatches revealed the disease status of the progeny.

3. The percentage of infected embryos in one hatchery which frequently disseminated S. typhimurium was estimated to range from two to twenty per cent in different hatches.

4. Environmental sanitation in the flock and hatchery appeared to be a major influence in the frequency of clinical outbreaks in the poults.

5. Two hatchery supply flocks were found to be infected with at least two serotypes; a third serotype appeared in the progeny of one in addition to the two in the parent flock.

6. Hatchery supply flocks with no history of clinical infection but having a latent infection transmitted the disease as readily as those which had survived clinical outbreaks.

7. The overall performance of the bacterial agglutination and hemagglutination tests demonstrated an equal but unsatisfactory degree of efficacy insofar as detection of infected birds was concerned. Both tests failed to identify half of the infected birds and also one infected flock.

8. A high incidence of non-specific reactions was observed in the hemagglutination tests of sera from non-infected birds. The number was greatly reduced by selecting strains whose extracts were more suitable for modifying erythrocytes. The possibility of the practical application of this test as a screening procedure would appear to depend on overcoming the problem arising from frequent non-specific reactions.