Exam #8: Zoonotic & Vector Borne Bacterial Infections II Flashcards

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1
Q

List the characteristics of Borelia.

A

Long spirochetes
Neither Gram -/+ (Gram negative like)
Mircoaerophilic

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2
Q

What diseases do Borrelia cause?

A
  • Lyme Disease

- Relapsing Fever

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3
Q

What species of Borrelia cause Lyme disease?

A

Borrelia burgdorferi

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4
Q

What is the leading vector-borne disease in the US?

A

Lyme Disease

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5
Q

What is the major vector of Lyme Disease?

A

Lxodes spp. (hard tick)

*hard ticks transmit Lyme disease

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6
Q

What animals are the reservoirs for Lyme Disease?

A

Mice

White-tailed deer

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7
Q

When is the early stage of Lyme Disease most frequently seen?

A

Summer

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8
Q

What are the symptoms of early stage 1 Lyme Disease?

A

Localized infection

  • Starts as a macule or papule lesion that enlarges to a bull’s-eye rash called “erythema migrans”
  • Malaise
  • Fever
  • Headache
  • Myalgia
  • Lymphadenopathy

*Erythema migrans is pathognomonic for Lyme Disease

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9
Q

What is the name of the bull’s eye rash?

A

Erythema migrans

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10
Q

What are the symptoms of early stage 2 Lyme Disease?

A

Disseminated Infection: bacteria disseminate via the bloostream

  • Arthralgia
  • Myalgia
  • Cardiac dysfunction
  • Neurologic signs consistent with meningitis and encephalitis
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11
Q

What are the symptoms of late stage Lyme Disease?

A

Arthritis

  • One ore more joints with the knee being the joint most commonly infected
  • Skin discoloration (grey & ashy)
  • Neurologic complaints (numbness, memory loss)
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12
Q

How is Lyme Disease diagnosed?

A
  • Symptoms
  • physical findings
  • hx of exposure
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13
Q

How is Lyme Disease streated?

A

Doxycycline & amoxicillin

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14
Q

How is Lyme Disease prevented?

A

Limit tick exposure

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15
Q

What causes epidemic relapsing fever?

A

Borrelia recurrentis

  • Louse-borne (lice)
  • this is NOT zoonotic
  • tranmission is human to human via the louse
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16
Q

What causes endemic relapsing fever?

A

Borrelia hermsii
- Tick-borne

*This is most common in the US

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17
Q

Describe the pathogenesis of relapsing fever.

A
  • Bite from a louse or tick
  • Dissemination via multiple organs through bloodstream
  • Evasion of the immune system via antigenic variation
  • Infection results in febrile & afebrile cycles, hence “relapsing fever”
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18
Q

What are the symptoms of relapsing fever?

A
Chills 
Fever 
Headache 
Muscle ache
Splenomegaly 
Hepatomegaly 

Symptoms last 3-7 days resolve, and then return after 7 days

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19
Q

Outline the antigen/antibody presence in blood smear & symptoms of relapsing fever.

A

Week 1= Latent period progressing to fever

  • Specific antibody produced
  • Fever improves
  • Antigenic variation

Week 2= progressive bactermia leading to fever again

  • Antibody produced
  • Fever resides
  • Antigenic varation

*Cycle continues

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20
Q

How is relapsing fever diagnosed?

A
  • Microscopy- Giemsa stained blood smear
  • Culture requires special media
  • Serological and molecular techniques can be used to confirm diagnosis
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21
Q

How is relapsing fever treated?

A

Tetracycleine or erythromycin

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22
Q

How is relapsing fever prevented?

A

Limit exposure to arthropod vectors

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23
Q

List the characteristics of Rickettsia.

A
  • Very small gram (-) coccobacilli
  • Obligate intracellular pathogens– facilitate their own uptake into endothelial cells, escape from phagosome into the cytoplasm–>lead to focal lysis of filopodia
  • Transmitted via arthropod bite
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24
Q

Describe the pathogenesis of Rickettsia.

A

Organisms infect vascular epithelium or small blood vessels

25
Q

What disease is caused by Rickettsia?

A

Rocky Mountain Spotted Fever (RMSF)

26
Q

What is Rocky Mountain Spotted Fever?

A
  • Most important rickettsial disease in the US

- A severe systemic febrile disease

27
Q

What are the two vectors for RMSF?

A

Dog tick= NOT in the Rocky Mountains

Wood tick= Rocky Mountian

28
Q

Where do most of the cases of RMSF occur?

A

NOT in the Rocky Mountains i.e. most commonly transmitted by the Dog Tick, not in the Rockies

29
Q

What are the symptoms of RMSF?

A
  • Initially presents with fever & rash over the extremities
  • Rash becomes raised and spreads to the torso (centripital spread i.e. outside–>in vs. centrifugal)
  • DIC
  • Thrombocytopenia
  • Pulmonary edema
  • Renal failure
  • GI hemorrhage
  • Shock
30
Q

How is RMSF diagnosed?

A
  • Epidemiology & clinical signs
  • Serology (severe disease may develop before antibody titers are high enough for diagnosis)
  • Molecular or immunohistochemical techniques
31
Q

How is RMSF treated?

A

Doxycycline

32
Q

How is RMSF prevented?

A

Limiting exposure to ticks

33
Q

List the characteristics of Ehrlichia.

A

Small gram (-) intracellular pathogens

34
Q

What do Ehrlichia parasatize?

A

Primarily monocytes & granulocytes

35
Q

What is a morulae? What are morulaes associated with?

A

Ehrlichia replicate & form colonies within vacuoles known as morulae

36
Q

What causes HME? What is HME? What is the principle vector?

A

HME= Human monocytic ehrlichiosis
- Ehrlichia chaffeensis

Lone star tick

37
Q

What causes HGE? What is HGE? What is the principle vector?

A

HGE= Human granulocytic ehrlichiosis
- Anaplasma phagocytophilum

lxodes ticks

38
Q

Describe the pathogenesis of Ehrlichia & Anaplasma.

A
  • Intracellular location protects from humoral immune response
  • Bacteria derail phagolysozome maturation
  • Activating macrophage with INF-gamma appears to resolve infection
39
Q

What are the symptoms of Ehrlichia & Anapalsma?

A
  • 60 % are asymptomatic
  • Remaining 40% are severe enough to require hospitalization

Multi-system zoonosis with malaise, fever, chills, headache, and myalgia

  • Petechial rash
  • Cough
  • Dyspnea
  • Resp. distress
  • CNS dysfunction
40
Q

How is Ehrlichiosis diagnosed?

A
  • Serological & molecular techniques

- Detection of morulae in blood smear

41
Q

How is Ehrlichiosis treated?

A

Tetracycline

42
Q

List the characteristics of Coxiella burnetii.

A
  • Small Gram (-) pleomorphic bacterium
  • Obligate intracellular pathogen
  • Reside and replicate in fully acidified phagolysosomes i.e. they don’t interrupt phagolysosome fusion like some of the others that we have covered
43
Q

What is the difference between a small cell variant & large cell variant?

A

Small cell= have some characteristics of spores

  • Resistant to high temperature, osmotic pressure, and UV light
  • Can survive in the environment for months
  • This is the form of C. burnetii that is infective

Large cell= small cell variants that have grown into large cells; these then divide and the cycle repeats

44
Q

What is the primary reservoir for Coxiella burnetii?

A

Farm animals
Dogs
Cats

*Note that ticks are an important vector for animals, but NOT man

45
Q

How is Coxiella burnetii transmitted?

A

Inhalation of small variants

46
Q

What are the symptoms of acute Query fever?

A
  • Generalized disease resembling flu
  • Followed by fever, chills, malaise, arthralgias, myalgias, severe headache, and photophobia
  • Pneumonia may develop
  • Abnormal liver function, CNS dysfunction, and vascular inflammation may be present

*Note that infection during pregnancy may lead to premature birth, abortion, or stillbirth

47
Q

What are the symptoms of chronic Query Fever?

A
  • Mainly endocarditis or hepatitis

- Acute signs of infection absent

48
Q

How is Query fever diagnosed?

A

Molecular and serological techniques

49
Q

How is Query Fever treated?

A

Tetracycline (Doxycycline)

50
Q

How is Query Fever prevented?

A

Inactivated whole cell vaccine

51
Q

List the characteristics of Bartonella.

A

Small slight curved Gram (-)

52
Q

What two human diseases are caused by Bartonella?

A

Bartonella quintana–>Trench Fever

Bartonella henselae–>Cat Scratch Fever

53
Q

How is Bartonella transmitted?

A

Trench fever is transmitted by the human body louse

  • It is present in the feces of lice
  • As the louse is taking a blood meal, when you scratch & break the skin, you introduce the feces into your wound
  • Generally seen in the homeless population

Cat Scratch Fever is transmitted by flea feces that are introduced into the body via a cat scratch or bite

54
Q

What are the symptoms of Trench Fever?

A

Relapsing fever, headache, and dizziness that lasts 1-3 days & recurs every 4-6 days

55
Q

How is Trench Fever diagnosed?

A
  • Serology

- Isolation of organisms from blood

56
Q

How is Trench Fever treated?

A

Aminoglycoside (gentamicin) or macrolide (erythromycin)

57
Q

What are the symptoms of Cat Scratch Fever?

A
  • Fever and lymphadenopathy in the region of inoculation
  • A papule may develop at the site of inoculation
  • Symptoms generally resolve without complication
58
Q

How is Cat Scratch Fever diagnosed?

A
  • Cultivation
  • Serology
  • Molecular analysis
59
Q

How is Cat Scratch Fever treated?

A
  • Treatment is generally NOT necessary

- Antibiotic use questioned