Plague

Question 1

—Egypt in 541 AD
—
—North Africa, Europe, central and southern Asia, and Arabia
—
—ended in the mid-700s
—

—Europe1320s
—25 million deaths
—30% to 40% of the population

Europe alone (30% to 40% of the population

—China in the 1860s
—spread to Africa, Europe, and the Americas

United States, with disease primarily sylvatic plague and

present in western states.

—

Question 2

◦nonmotile, rod-shaped, facultative anaerobe with bipolar staining

• *◦safety pin appearance**
• *◦tests negative for urease, lactose fermentation, and indole**

Answer 2

—Y. pestis

Question 3

____________
◦highly virulent pathogen
◦causes the highly fatal systemic disease known plague
◦

—

Answer 3

—Yersinia Pestis

Question 4

◦enteric pathogens
◦relatively uncommon
◦rarely cultured from blood

Answer 4

—Yersinia enterocolitica,Yersinia pseudotuberculosis

Question 5

—ability to resist phagocytic killing
◦______________-
–dephosphorylate several proteins required for phagocytosis
–induce cytotoxicity by disrupting actin filaments
–initiate apoptosis in macrophages
–suppresses cytokine production
—

Answer 5

type III secretion system

Question 6

—two plasmids that encode virulence genes:

—

Answer 6

1.fraction 1 (f1) gene

2.plasminogen activator (pla) protease gene
–

Question 7

–codes for an antiphagocytic protein capsule

Answer 7

1.raction 1 (f1) gene

Question 8

–degrades complement components C3b and C5a
–degrades fibrin clots

Answer 8

.plasminogen activator (pla) protease gene

Question 9

—Zoonotic
—Humans as accidental hosts
—two forms of Y. pestis infection

Answer 9

1.urban plague
–Rats natural reservoir
2.sylvatic plague
–Causes infections in squirrels, rabbits, field rats, and domestic cats

Question 10

–Rats natural reservoir

Answer 10

1.urban plague

Question 11

–Causes infections in squirrels, rabbits, field rats, and domestic cats

Answer 11

1.sylvatic plague

Question 12

◦Pigs, rodents, livestock, and rabbits
◦

Answer 12

—Y. enterocolitica

Question 13

◦Wild animals, and game birds

Answer 13

—Y. pseudotuberculosis

Question 14

◦maintained in rat populations
◦Spread among rats OR between rats (reservoir) and humans by infected fleas (vector)
◦Fleas become infected during a blood meal from a bacteremic rat
◦bacteria replicate in the flea gut

Answer 14

—Urban plague

Question 15

◦produces fatal infection in the animal reservoir
◦Infections acquired through:
–Ingestion of contaminated animals
–handling of contaminated animal tissues
◦human-to-human spread is uncommon

Answer 15

—Y. pestis

Question 16

◦common cause of enterocolitis
◦1 per 100,000 persons each year
◦90% of infections associated with consumption of contaminated meat, milk, or water
◦infections more common during the cold months
◦relatively uncommon cause of human disease

Answer 16

—Y. enterocolitica

Question 17

◦Flea bite
◦incubation period of <7 days
◦General malaise
◦high fever
◦Headache and chills occur suddenly at the end of the incubation period
◦painful bubo in the groin or axilla
–Most flea bites will occur on the legs, so the inguinal nodes are most frequently affected (boubon is Greek for “groin”)
◦Death occurs oin less than 2 weeks
–75% mortality rate
◦Gangrene

Answer 17

—Bubonic plague

Question 18

◦Incubation period 2 to 3 days
◦fever and malaise
◦Highly infectious
◦mortality rate > 90%
◦

Answer 18

—Pneumonic plague

Question 19

◦ingestion of contaminated food products(pork), unpasturized milk or water
◦Incubation period 1 to 10 days (average, 4 to 6 days)
◦diarrhea, fever, and abdominal pain that last as long as 1 to 2 weeks
–Can persist for months
—

Answer 19

—Y. enterocolitica

Question 20

–involves terminal ileum
–Presentations may vary with age
–Very young: febrile diarrhea (blood and pus)
–Older kids/ young adults: Pseudoappendicitis
–can mimic acute appendicitis if mesenteric lymph nodes enlarge
–Adults: enterocolitis with postinfective sequelae like reactive arthritis
—
◦
—

Answer 20

◦Enterocolitis

Question 21

—Other manifestations
◦septicemia,
◦arthritis,
◦intraabdominal abscess,
◦hepatitis
◦osteomyelitis
◦blood transfusion–related bacteremia
–can grow at 4° C
–
—Distinguishing features
–Motile at 25ºC
–Non-motile at 37ºC
–Cold growth
–
—

Question 22

—Diagnosis

◦Usually supportive care

Answer 22

◦Stool culture, 25ºC, cold enrichment—Treatment

Question 23

What is the treatment?

Answer 23

◦For immunocompromised : Supportive care
–Flouroquinolones or third generation cephalosporins