Veterinary Microbiology, 12 (1986) 289--294 289 Elsevier Science Publishers B.V., Amsterdam --Printed in The Netherlands Short Communication OCCURRENCE OF VIRULENCE MARKERS IN SPECIES OF YERSINIA ISOLATED FROM ANIMALS IN NIGERIA A.A. ADESIYUN, D.E. AGBONLAHOR ~, L.H. LOMBIN and J.K.P. KWAGA Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria and ~ National Veterinary Research Institute, Vom (Nigeria) (Accepted for publication 12 December 1985) ABSTRACT Adesiyun, A.A., Agbonlahor, D.E., Lombin, L.H. and Kwaga, J.K.P., 1986. Occurrence of virulence markers in species of Yersinia isolated from animals in Nigeria. Vet. Microbiol., 12: 289--294. Fourteen strains of Yersinia species isolated from apparently healthy pigs and cattle in Nigeria were screened for four virulence markers using six test systems. These were two in vitro assays, namely, calcium dependency and autoagglutination, both at 37°C, the Ser4ny test in guinea-pigs and the detection of heat-stable enterotoxin (ST) by the rabbit ileal loop test, the ligated intestine test in pigs and the infant mouse system. Seven of the 14 strains of Yersinia were positive for one or more of these tests. Six of nine strains of Y. enterocolitica and one of four Y. intermedia were positive in one or more tests. The only strain of Y. frederiksenii isolated was negative in all six test systems. All three strains of Y. enterocolitica, serotype 0:8 and the only serotype 0:3 isolated were positive in one or more tests. However, only two of five strains of Y. enterocolitica serotype 0:12, 26, the most frequently encountered, were positive. A good correlation was observed between test results of calcium dependency, autoagglutina- tion and Ser~ny assays. The results indicate that cattle and pigs have the potential to transmit virulent strains of Y. enterocolitica to human beings in Nigeria. INTRODUCTION Yersinia enterocolitica is an important human pathogen which is capable of causing a variety of human diseases, particularly gastroenteritis which is often accompanied by lymphatic tissue involvement (Delorme et al., 1974; Bottone, 1977; Marks et al., 1980). The pathogenicity of Y. entero- colitica has been associated with several characteristics considered markers of virulence such as biotype (Schiemann and Devenish, 1982), serotype (Une et al., 1977), autoagglutination at 37°C (Laird and Cavanaugh, 1980), calcium dependency at 37°C (Gemski et al., 1980), invasiveness in guinea- pig conjunctiva (the Ser~ny test) (Boyce et al., 1979), production of heat- stable (ST) enterotoxin (Pai and Mors, 1978; Robins-Brown et al., 1979) and production of diarrhoea in mice {Laird and Cavanaugh, 1980). 0378-1135/86/$03.50 O 1986 Elsevier Science Publishers B.V.