Zoonotic or vector borne diseases II

Question 1

What occupations and activities are at high risk of zoonoses?

Answer 1

Occupations:
Farmer/rancher
Hunter
Veterinarian
Slaughterhouse worker

Activities at risk:
Drinking unpasteurized milk
Swimming
Preparing food
Owning pet
Visitng petting zoo

Question 2

What does Francisella tularensis cause?

Answer 2

Rabbit Fever
AKA
Tularemia
AKA
Glandular fever

HIGHLY INFECTIOUS!!!!

Question 3

How is Francisella tularensis transmitted?

Answer 3

Arthropod bite

Break through skin

Exposure to conjunctiva or other mucosal membranes

Aerosol

Ingestion

Question 4

What are characteristics of Francisella tularensis?

Answer 4

Facultative Intracellular Pathogen

• Small Gram negative coccobacilli
  stains poorly
• Specific fluorescently-labeld antibody used to ID organism in tissues, sputum, or culture
• Grows inside macrophages

Question 5

What are the spectrum of diseases encompassed by Tularemia?

Answer 5

Ulceroglandular: Follows primary infection of skin

Oculoglandular: Contaminate eye (conjunctiva) with infected material

Pneumonic: Transmission via aerosol or via secondary spread to the lung

Typhoidal: Ingestion of organism; symptoms similar to typhoid fever

Question 6

How is tularemia diagnosed?

Answer 6

Serology

Culture - aspirates of bubos, sputum, blood, gastric washings

Question 7

What are characteristics of Brucellae?

Answer 7

Facultative intracellular parasites of the Reticular endothelial system

Transmitted to humans through infected milk, milk products
or
direct contact with infected animals

Question 8

What are symtpoms of chronic Brucellosis?

Answer 8

Incubation period: 2-8 weeks

Fever, night sweats, headaches, chills, myalgia, weight loss

Organs of RES often NOT enlarged

Question 9

What are complications of Brucellosis?

Answer 9

Hepatic lesions

Arthritis

Meningitis

Endocarditis

Question 10

What is the pathogenesis of Brucellosis?

Answer 10

Enters via mucous membranes, skin, ingested, or inhaled –> engulfed by PMNs and macrophages –> goes to regional lymph nodes –> Multiply within macrophages –> phagocytic cells of the RES

-> Either: STOP
or
Granulomas with recurrent bacteremia

Question 11

What is the cause of “Classical” Trench Fever?

Answer 11

Bartonella quintana spread by body louse

Reservoir: Humans

Causes Febrile bacteremia in immuno-competent patients

Causes Bacillary angiomatosis and endocarditis in immuno-compromised patients

Question 12

What is the cause of Carrión’s disease?

Answer 12

Bartonella bacilliformis

1st Phase: Oroya fever (hemolytic anemia)
2nd Phase: Verruga peruana

Reservoir: Human
Vector: Sand fly

Question 13

What is the cause of Cat Scratch disease?

Answer 13

Bartonella henselae

Reservoir: cats

Causes inflammation in immuno-competent patient

Causes bacillary angiomatosis in immuno-compromised patients

Question 14

What are characteristics of Rickettsiaceae?

Answer 14

• Obligate intracellular bacteria that are usually transmitted by arthropods
• Fastidious, Gram(-) coccobacilli
• visible in Giemsa stain
• Require host cell for many functions
• Spread from cell-to-cell requires actin polymerization (like shigella and listeria)

Question 15

What are clinical manifestations of Rickettseae infection?

Answer 15

Skin rash

Fever

Severe headache

malaise

prostration

enlargement of the spleen and liver

Pathogenesis: Vasculitis caused by proliferation of teh organisms in the endothelial lining of small arteries, veins, capillaries. Vascular lesions are prominent in the skin

Question 16

What causes Rocky Mountain Spotted Fever?

Answer 16

Rickettsia rickettsii

Spread by Dog ticks - passed by full sized tick

Rash of RMSF is similar to measles but is also on palms and soles of feet (where as measles is not)

Question 17

What causes rickettsial pox?

Answer 17

Rickettsia akara

Mite-borne (rodent –> mite –> human)

Cosmopolitan distribution in US

Rash is more like chickenpox (papulovesicular) with eschar at site of mite bite

Question 18

What is the cause of epidemic typhus?

Answer 18

Rickettsia prowazekii

Spread by body louse

Not in US - found in places of war (i.e. Somalia)

Question 19

What is the cause of endemic or murine typhus?

Answer 19

Rickettsia typhi

Disease occurs worldwide (including US)

Flea-borne

Rodent vector

Question 20

What causes scrub typhus?

Answer 20

Orientia tsutsugamusushi

Mite (chiggers, red mites) borne

Reservoir: rodent

Doesn’t occur naturally in US

Question 21

What are characteristics of Anaplasma and Ehrlichia?

Answer 21

Obligate intracellular bacteria

Survive in cytoplasmic vacuoles of mammalial hematopoetic cells
(in contrast to Rickettsia and Orientia that live in endothelial cells)

Question 22

What is the pathogenesis of Anaplasma phagocytophilum?

Answer 22

Primarily infects grnulocytes (neutrophils and rarely eosinophils)

Often referred to as the agent off HGE

Transmitted by Ixodes scapularis (can co-transmit with Lyme disease)

Question 23

What are characteristics of Ehrlichia chaffeensis (HME)?

Answer 23

Obligate intracellular bacteria that survive in cytoplasmic vacuoles

Morula can be found in cells

Spread by Lone star tick (Amblyomma americanum)

Question 24

What is the cause of Q fever? Characteristics?

Answer 24

Coxiella burnetii

Humans infected through contact with cattle, goats, sheep

Ticks probably important in animal to animal transmission

Atypical pneumonia as presentation
Rarely, endocarditis