Lec17 Vector Borne and Zoonotic Infections

Question 1

What disease does rickettsia spp cause?

Answer 1

• spotted fevers and various types of typhus

Question 2

What disease does ehrlichia chaffeenis cause?

Answer 2

human monocytic ehrlichiosis [HME]

Question 3

What disease does anaplama phagocytophilum cause?

Answer 3

anaplasmosis aka human granulocytic ehrlichiosis

Question 4

What bacteria causes lyme disease?

Answer 4

borrelia burgdorferi

Question 5

What bacteria causes cat scratch disease?

Answer 5

bartonella spp

Question 6

Francisella tularensis-Tularemia
Leptsopira spp- Leptsopirosis
Yersinia pestis-Plague
Coxiella burnetii- Q Fever
Brucella spp- Brucellosis

Answer 6

xx

Question 7

What is the vector for b. burgdorferi?

Answer 7

tick [ixodes scapularis]

Question 8

What is the life cycle for b. burgdorferi?

Answer 8

• vector is ixodes ticks
• main reservoir in white footed mice
• deer are important for adult stage
• nymphs are responsible for most of the disease

Question 9

What are early signs of lyme disease?

Answer 9

at first its localized [3-30 days] at site of bite

• have bulls eye rash = erythema migrans
• mild systemic symptoms

Question 10

What are signs of early disseminated lyme disease?

Answer 10

1-4 months after bite

• cranial nerve [bell’s] palsy
• lymphocytic meningitis
• heart block, myocarditis
• disseminated rash

Question 11

What are signs of late lyme disease

Answer 11

• intermittent arthritis

- chronic neuro problems [radicular pain, paresthesias, lyme encephalopathy]

Question 12

How do you diagnose lyme disease?

Answer 12

• look at clinical picture
• IgG and IgM antibody tests
• – get false neg in early disease and early treatment
• – get falst pos from spirochetes, viral infection, prior infection
• PCR [for arthritis]
• culture and stains not used

Question 13

How do you treat lyme disease?

Answer 13

• oral doxycyclin for most
• amoxicillin for kids
• ceftriaxone IV with meningitis or heart block

Question 14

How is leptospirosis transmitted?

Answer 14

• endemic to raccoons
• raccoon transmits via urine to soil/mud/water where dogs lick it up and then transmit on via saliva or urine to humans
• can get it by coming into contact with something contaminated [touching] or ingesting

Question 15

How do you treat leptospirosis?

Answer 15

penicillin

Question 16

How do you diagnose leptospirosis?

Answer 16

serum antibodes

Question 17

What are micro properties of r. rickettsii?

Answer 17

• thin peptidoglycan layer so stains poorly with gram stain

- obligate intracellular organism

Question 18

What is natural reservoir of r. rickettsii? vector?

Answer 18

hard ticks = both

- american dog tick, wood tick, brown dog tick

Question 19

What is danger of r. rickettsii untreated?

Answer 19

23% case fatality rate

Question 20

What are signs of rocky mountain spotted fever?

Answer 20

• 2-14 day incubation
• fever, headache, rash, myalgias
• have peripheral distribution of rash
• get multi-organ involvement: resp distress, cardio instability, renal failure, encephalitis, GI involvemtn

Question 21

What do you use to stain for r. rickettsii?

Answer 21

• hyperimmune rabbit anti-R rickettssii antibody

Question 22

What is pathogenesis of r. rickettsii?

Answer 22

• targets endothelial cell
• induces its own phagocytosis by triggering actin rearrangement
• releases phospholipase to excape phagosome and enter cytoplasm
• uses host cell actin to propel itself nd spread to adjacent cell
• rash caused by foci of multiple adjacent infection endothelial clels

Question 23

What are effects of the damaged endothelium that r. rickettsii causes?

Answer 23

• get increased vascular permeability, edema, hypvolemia, hypotension, increased ADH so hyponatrema
• have procoagulant state and platelt consumption

Question 24

What is immune response against r. rickettsii?

Answer 24

• CD8 T cells needed to clear established infection

- have protective humoral response against OmpA/B

Question 25

What are micro properties of ehrlichia/anaplasma?

Answer 25

- tiny gram negative bacteria | - stain poorly

Question 26

What is pathogenesis of ehrlichia and anaplasma? how do they differ?

Answer 26

- intracellular infections - stay inside phagosome and inhiit lysosome/phagosome binding ehrlichia chaffeenis infects monocytes anaplasma phagocytophillum infects granulocytes

Question 27

What is vector of ehrlichia chafeenis?

Answer 27

- lone star tick [amlyomma americanum]

Question 28

What is vector of anaplasma phagocytophillum?

Answer 28

ixodes scapularis

Question 29

What are clinical signs of rickettsia, ehrlichiosis, anaplasmosis and how do you tell the difference between them in terms of appearance and labs?

Answer 29

all: seasonal, incubation 5-10 days, fever, headache, myalgia [muscle pain], malaise rickettsia: most start rash days 2-4 of illness, have macules/papules then petechiae, have low platelet, high LFT, low Na ehrlichiosis: 30% adults, 60% children get maculo-papular rash, low WBC, low platelets, high LFT anaplasmosis: rare to have rash, low WBC, low platelets, high LFT

Question 30

What do you PCR to diagnose rickettsia vs ehrlichiosis vs anaplasmosis?

Answer 30

rickettsia - PCR tissue ehrlichiosis and anaplasmosis - PCR blood

Question 31

Which of rickettsia, ehrlichiosis, anaplasmosis show a low sensitivity morula on blood smear to diagnose?

Answer 31

ehrlichiosis and anaplasmosis

Question 32

Which of rickettsia, ehrlichiosis, anaplasmosis would you use skin biopsy immuno-histochemistry to diagnose?

Answer 32

only rickettsia

Question 33

How do you treat rickettsia, ehrlichiosis, anaplasmosis?

Answer 33

- immediately go on doxycycline | - do not wait for lab conformation

Question 34

What is cat scratch fever? what is host? vector? signs?

Answer 34

- transmitted bartonella henselae by cat scratch - host is cat, vector is cat-flea - fever/lymphadenopathy close to exposure site - other organs involved less commonly - in immunocompromised can lead to bacillary angiomatosis

Question 35

What are micro properties of bartnoella henselae?

Answer 35

- associated with kittens - gram negative bacilli - difficult to visualize and grow [use warthin starry silver stain]

Question 36

How do you diagnose bartonella henselae?

Answer 36

- serology | - biopsy: granulomas and organism using special stain

Question 37

What is reservoir of coxiella burnetil? how is it transmitted?

Answer 37

- reservoir: cattle, sheep, goats - survives in environment and infected via inhalation - infects macrophages

Question 38

How is coxiella burnetil [Q fever] diagnosed?

Answer 38

- serology | - culture not done because it is a biohazard

Question 39

What is brucellosis?

Answer 39

- reservoir in cattle, goats, sheep, swine, dogs - symptoms of sweating, joint pain - transmitted from ingestine or close contact [inhaled, in conjunctivae, etc] - affect bone marrow, lymph nodes, spleen, liver

Question 40

What is the disease agent associated with lyme disease? geo distribution? reservoir? vector? symptoms of disease?

Answer 40

agent: B. burgdorferi distribution: northeast, midwest reservoir: white footed mouse, deer vector: ixodes scapularis disease: - early: erythema multiforme - early disseminated: skin, heart, CNS - late: joint, CNS

Question 41

What is the disease agent associated with RMSF? geo distribution? reservoir? vector? symptoms of disease?

Answer 41

agent: R. rickettsii distribution: southeast reservoir: hard ticks [dermacentor] vector: hard ticks disease: fever, headache, rash, life-threatening

Question 42

What is the disease agent associated with ehrlichiosis? geo distribution? reservoir? vector? symptoms of disease?

Answer 42

agent: E. chaffeensis distribution: southeast reservoir: deer, dogs vector: amblyoma americanum disease: fever, headache, low WBC, high LFT [liver function test], may have rash

Question 43

What is the disease agent associated with anaplasmosis? geo distribution? reservoir? vector? symptoms of disease?

Answer 43

agent: A. phagocytophillum distribution: northeast, midwest reservoir: white footed mouse and other mammals vector: ixodes scapularis disease: fever, headache, low WBC, high LFT