YERSINIAE Yersinia Morphology Important species Pathogenesis Disease caused

YERSINIAE

Yersinia • • Morphology Important species Pathogenesis Disease caused

Y. pestis - Morphology • Gram negative • Plump/ovoid • Bipolar staining/ Safety pin appearance • Pleomorphic

Pathogenesis Highly complex antigenic structure No serotypes 20 antigens Fraction I, V and W antigens, Pesticin, Coagulase, Fibrinolysin • Plague toxin- endotoxin and murine toxin = inhibit phagocytosis and intracellular killing of bacteria. • •

PLAGUE Ancient disease Himalayas/ Central Asia Epidemics/ pandemics Black death 14 th century - killed a quarter of humans on earth • 18 and 19 th century- less • • •

Plague Last pandemic- Hong Kong, 1894 India worst hit 1896 - 1918 – 10 million deaths Lessened , 1967 - 94 – no cases August 1994 - outbreak in Beed dist of Maharashtra • September 1994 – Surat, Gujarat • 6000 cases , 60 deaths • 2002 – Simla, 4 deaths • • •

Plague • Foci in India – Kolar, Beed – Latur, Rhoru, Uttaranchal • Types : Bubonic, Pneumonic, Septecemic • Spread/ Transmission : Flea bite, Droplet • No human carriers

Plague - A zoonosis • Rodents • Rat flea: Xenopsylla cheopis • Urban cycle • Domestic cycle

Diagnosis • Specimens • Methods : Gram stain, Wayson stain, Fluorescent stain, Culture: NA, BA, MA, CA Non lactose fermenting colonies on MA Identified by biochemical tests Animal inoculation Serology PCR

Disposal , Prophylaxis, Treatment • 0. 5% phenol for 15 min • Carcasses – 3% lysol • Killed vaccine • Streptomycin, Doxycycline

Other Yersinia • Y. enterocolitica – Gastroenteritis, Mesenteric adenitis, Bacteremia • Y. pseudotuberculosis - infections in rodents only

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