Caseous lymphadenitis in goats: The dose of infection and the serologicai response

Abstract

Goats were infected intradermally with caseous pus containing between 1 x 105 and 5 x 10¹ colony forming units(CFU) of Corynebacterium pseudotuberculosis. Animals infected with doses of equal and above 1 x 10² CFU of theorganism developed caseous lesions in regional draining lymphnodes while those infected with lesser closes developed none. On serological examination, 3/6 animals infected with equal to or less than 1 x 10³ CFU and 214 infected with equal to or less than 1 x 10² CPU had no positive bacterial agglutination and antitoxin antibody titres respectively. These results indicated that caseous lymphadenitis (CLA) is a highly contagious disease since a relatively low dose (1 x 1² CPU) of C. pseudotuberculosis injected intradermally could induce CLA lesions in draining Iymphnodes. The serological response in terms and rate and extent appeared to depend on the dose of infection.