The pathogenesis of fowl thyphoid. The influence of anaemia and erythrocyte clearance on the susceptibility of the fowl to bacterial endotoxin

The possible influence of anaemia, and other related patho-physiological factors known to occur in fowl typhoid, on the susceptibility of the chicken to Salmonella gallinarum endotoxin were investigated. It was shown that anaemia per se did not increase susceptibility of the chicken to injected endotoxin. However, prior intravenous administration of either in vivo modified chicken or heterologous (rabbit) erythrocytes, or intramuscular injection of phenylhydrazine hydrochloride markedly decreased the LD₅₀ of the subsequently injected endotoxin. It is suggested that this increase in susceptibility to endotoxin was due to a blockaded reticulo-endothelial system, resulting from increased erythrophagocytosis of the foreign and altered erythrocytes.These findings were discussed in relation to the pathogenesis of S. gallinarum infection in chickens.