CORRELATION BETWEEN VIABLE COUNTS OF SALMONELLA-GALLINARUM IN SPLEEN AND LIVER AND THE DEVELOPMENT OF ANEMIA IN CHICKENS AS SEEN IN EXPERIMENTAL FOWL TYPHOID

Isogenic strains of Salmonella enterica serovar Gallinarum biovar gall inarum harbouring RFLP variants of the virulence plasmid and the paren t strains, were given orally to 1-week-old White Leghorn cockerels. Di fferences in viability and pattern of behaviour of the strains in the tissues were observed during the course of infection. Viable counts fr om the spleen and liver, the development of haematological changes in the form of anaemia, and pathological lesions were shown to be correla ted. None of the RFLP variants of the virulence plasmid in particular were associated with the development of the anaemia. Viable counts of approximately 10(4) CFU in spleen and liver were required for the deve lopment of significant pathological- and haematological changes. The r esults showed that the severity of the haematological changes was clos ely correlated to the number of bacteria in the tissues, and thereby a ssociated with the particular strain's ability to survive and multiply systemically.