Lecture 18 Yersinia

بسم الله الرحمن الرحيمبسم الله الرحمن الرحيم

GENUS: GENUS: YERSINIAYERSINIAProf. Khalifa Sifaw Ghenghesh

Yersinia pestisYersinia pestis

PlaguePlague Infected Fleas (Infected Fleas (Xenopsylla cheopisXenopsylla cheopis) )

are the Major Mechanism of are the Major Mechanism of

Transmission.Transmission.

Rodents >>Rodents >>

Clinical SyndromesClinical Syndromes

i. i. Bubonic PlagueBubonic Plague:: Incubation period: Incubation period:

– << 7 days after flea bite. 7 days after flea bite. High fever and painful bubo in the groin and High fever and painful bubo in the groin and

axilla.axilla. Untreated Untreated Bacteremia > 75% mortality Bacteremia > 75% mortality

raterate

ii. ii. Pneumonic PlaguePneumonic Plague:: Bubonic Disease >Pneumonic Plague > Bubonic Disease >Pneumonic Plague >

Exhales the Organism in Droplets.Exhales the Organism in Droplets.

Highly infectiousHighly infectious Incubation period:Incubation period:

– 2 to 3 days, with fever and malaise2 to 3 days, with fever and malaise– pulmonary signs within one daypulmonary signs within one day

Untreated Untreated > 90% mortality rate> 90% mortality rate

Yersinia pestisPuss from bubo/Gram-negative rods

LABORATORY DIAGNOSIS

Aspirate from Buboes, Aspirate from Buboes, Pus from the Area of Flea Bite, Pus from the Area of Flea Bite, Sputum, Throat Swab or Blood.Sputum, Throat Swab or Blood.

Transport Media >>Transport Media >>

Yersinia pestis on Sheep Blood Agar (72hrs)

TREATMENT– StreptomycinStreptomycin

CONTROL– A Quarantinable Disease.– Control of Urban Plague:– Garbage Disposal.

Y. enterocolitica Y. pseudotuberculosis

– Enterocolitis: Diarrhea, fever and abdominal painInfection can mimic acute appendicitisMore common in children

– Other infections:Septicemia, arthritis, hepatitis, and osteomyelitis

– Epidemic outbreaks due to Y. enterocolitica:

Contaminated meat and milk