STUDIES ON YERSINIOSIS IN HUMAN AND SELECTED ANIMAL POPULATIONS IN JOS AND ITS ENVIRONS

Yersinia enterocolitica and Yersinia pseudotuberculosis are important food and water borne pathogens that has recently emerged world wide. This study was aimed at characterizing the prevalence of Yersinia enterocolitica and Yersinia pseudotuberculosis in human and selected animal populations in Jos and its environment. Three thousand stool samples from human and selected animal species from 5 different locations in Jos and its environs were surveyed over a period of three years. Human samples were made up of equal number of 750 apparently healthy individuals and 750 diarrhoeic subjects. The samples were analysed bacteriologically for the presence of Yersinia species using appropriate culture methods and selected molecular techniques. Presumptive identification was made based on characteristic morphological appearances of the colonies. No pathogen was recorded among the healthy subjects indicating that there are no asymptomatic patients of Yersinia in Jos. Of the seven hundred and fifty (750) diarrhoeic patients screened, (46)6.1% were positive for Yersinia enterocolitica and Yersinia pseudotuberculosis. Among the positive subjects were 13 who had undergone appendectomy previously. The total percentage of occurrence of the Yersinia organisms among males and females were (21) 2.8% and (25) 3.3% respectively. Of the 1500 animal samples screened, (749) 49.9% were found infected with Y. enterocolitica (532) 35.4% and Y. pseudotuberculosis (217) 14.5%). High occurrence rate was recorded in pigs (271) 18.1%, followed by Sheep (189) 12.6%, poultry (163) 10.9%, and Dogs (126) 8.4%. High prevalence rate was recorded in Vom (231) 15.4%, Bukuru (182) 12.1%, and Bassa (128) 8.5%. The women in Bassa had the highest occurrence of yersiniosis, (9) 1.2%. Experimentally infected laboratory animals for pathogenicity test, at post mortem showed black spotted, necrotic lesion on the liver with evidence of gastroenteritis in rabbits. Unlike the European countries where Y. enterocolitica serotype 0:3 predominates, biotypes 1A, 1B and serotype 0:9 were found prevalent among strains of Y. enterocolitica isolated in this part of the world. Two principal DNA based methods polymerase chain reaction (PCR) and enlongated pulsed field gradient electrophoresis (PFGE), were used to characterize Y. enterocolitica and Y. pseudotuberculosis in this study. All strains of Y. enterocolitica isolated in Jos, Plateau State, Nigeria, were differentiated by PCR which exhibited a characteristic differential genomic feature from the French isolates used as control, whereby arginine is replaced with guanine at position 320 on the sequence nucleotide bond. The PFGE based on NOtI enzymes profiles differentiated Yersinia enterocolitica and Yersinia pseudotuberculosis strains into 4 and 7 variants respectively. The overall incidence of Y. enterocolitica and Y. pseudotuberculosis infections was low in the population studied but a striking geographic and demographic variation was noted. Statistically, the distribution of Yersinia species in humans ranked highest amongst the age groups 11-20 and in pigs amongst animals (P0.05). This work represents the first attempt to map out novel potential virulent markers of Y. enterocolitica and Y. pseudotuberculosis in Plateau State, Nigeria, using multispacer typing (MST) and PFGE technology. The prevalence of yersiniosis in Jos suggests that animals and animal products can serve as reservoir host for Yersinia species. xv