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Skin MS: Week 3 > Tick-borne Illnesses > Flashcards

Tick-borne Illnesses Flashcards

1
Q

3 kinds Tick-borne pathogens

A

Bacteria (Borrelia), Euk. parasites (Babesia), Viruses (TB encephalitis virus)-Europe

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2
Q

3 kinds ticks carrying disease in US

A 
Ixodes scapularis (in MN, East Coast, southeast)
Ixodes pacificus (West Coast)
Amblyomma americanum (southeast)
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3
Q

Ixodes scapularis carries 3 diseases

A

Lyme disease, Anaplasmosis, Babesiosis (all growing in incidence and range), specifically in MN (note, w/ CC, expanding into Canada)

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4
Q

Tick life cycle

A

Larva - Hatch from eggs, lack pathogen → BLOOD MEAL → Nymph - taken one blood meal, may have acquired pathogen → Adult - multiple blood meals, may have acquired pathogen

nymph and adult (female) transmit disease

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5
Q

Main reservoir host of Ixodes scapularis

A

White footed mouse

deer only fed on by adult ticks

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6
Q

Onset of illness most frequently when

A

may through september

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7
Q

What to do if find attached tick?

A

Try to estimate duration of tick-attachment (bacterial transmission takes >24 hrs, parasites even longer, viruses shorter time? → NOTE: This number is kind of made up, look for new research)
Remove tick with forceps or gloved fingers
Clean area with disinfectant
No value in submitting tick for analysis
Observe bite site for 30 days (for characteristic rash)
Seek medical assistance for febrile illness

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8
Q

Disease Prevention

A

DEET-repellent on skin, Permethrin on clothing, light colored clothing, socks outside pants, daily inspection of skin and removal of ticks

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9
Q

Where are ticks

A

@ Interface between woodlands/grassy areas - Ticks in grassy areas, hosts in woods

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10
Q

Cause of Lyme Disease

A

Borrelia burgdorferi

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11
Q

Acute stage sometimes presents with characteristic rash, Arthritis-like symptoms in chronic stages

A

Lyme Disease

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12
Q

B. burgdorferi characteristics/virulence factors

A

Fastidious, micro-aerophilic spirochaete ,Grows best at 32C on BSK medium
Flagella - move in corkscrew manner
Longer than they are wide (20-30 micrometers, 0.3 wide)

Surface proteins are host-dependant
OspA in tick, OspC in human
Can disseminate widely in mammal
Remain in midgut of insect until blood meal, then migrate to salivary glands

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13
Q

Various species of BB

A

Various species
B. burgdorferi sensu lato (worldwide)
Bb sensu stricto (USA) → LD
B. garinii, B. afzelii, B. miyamotoi

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14
Q

Cause Human Granulocytic Anaplasmosis (HGA) - transmitted by those I. scapularis and pacificus

A

Anaplasma phagocytophilum

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15
Q

Group of bacteria spread by arthropod vector:
Require living cell for growth – obligate intracellular parasite.
BUT have metabolic enzymes, cell walls, and utilize O2.
extremely small (~0.5 μm in diameter)
Gram negative
Often pleomorphic in shape

A

Rickettsia (barely bacteria)

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16
Q

2 species of rickettsia

A

A. phagocytophilum, Ehrlichia chaffeensis

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17
Q

Features of A. phagocytophilum

A

Replicates in midgut epithelial cells – tick
Some bacteria make it to the salivary glands which are the cells that will be transmitted to initiate mammalian infection
Colonizes neutrophils – mammalian system
In neutrophils, hijacks endocytic pathway to make a vacuole in which to replicate
Morulae = form intracytoplasmic cluster of bacteria

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18
Q

A. phagocytophilum replicated in __________ in ticks

A

midgut epithelial cells

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19
Q

From which area in tick are cells transmitted to initiated mammalian infection (a. phagocytophilum)

A

salivary glands

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20
Q

What do A. P. colonize in mammals?

A

Neutrophils –> make vacuoles in which to replicate

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21
Q

Form intracytoplasmic cluster of bacteria

A

morulae (i.e. A. phagocytophilum)

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22
Q

BB surface proteins

A

OspA in tick
OspC in humans
Need to switch before transmission

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23
Q

Responsible for Rocky Mountain Spotted Fever

A

Rickettsia rickettsii

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24
Q

How are RMSF/RR transmited?

A

different tick, transovarian (through eggs)

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25
What does RR do when it gets in body? (where go and how to replicate)
Does not require a specialized human cell to infect Spread through bloodstream, infect vascular epithelial cell Replicate in cytosol of cell, not in a vacuole
26
Cause of Babesiosis/type of pathogen
Babesia spp - parasite (i.e. microti)
27
Babesia = _______ paracite
apicomplexan, unicellular
28
Humans are ______ hosts, sexually reproduce in _________ (Babesia)
dead-end hosts, | mice erythrocytes
29
Virus example of tickborne disease
tick-borne encephalitis (TBEV) in Europe, Asia, former USSR | Related Flaviviridae family virus Powassan (POW) in US (rare)
30
Flaviviruses are (mostly) linear and_______, and are transmitted by the bite ________, primarily mosquitoes and ticks.
Flaviviruses are (mostly) linear and single stranded, and are transmitted by the bite arthropods, primarily mosquitoes and ticks.
31
Lyme Disease Presentation depending on stage
Early localized (w/in 30d) - Skin Early disseminated (days to weeks) - Skin, Cardiac, Neurologic Late disease (months to years) - Cardiac, neurologic, musculoskeletal
32
Early Signs and Symptoms
Fever, chills, HA, fatigue, muscle/joint aches and swollen lymph nodes EM rash in 70-80%
33
Lyme Carditis
(~1%) → 2nd or 3rd degree AV block - may require temporary pacing
34
Neurologic Lyme
(10-15%) → Bell’s Palsy (CN VII paralysis), Meningitis, Radiculitis
35
Lyme arthritis
Knees > other Joints, fewer systemic sxs 1 knee most common (monoarthritis) Oligoarthritis, shoulder/elbow/TMJ/wrist also occurs Swelling/effusion significant, pain less than other bacterial or crystalline Swelling may persist for months after successful tx Little joint destruction or dysfunction for most patients In untreated Lyme, 60% of pts may have arthritis which occurs in attacks that decrease over time
36
LD diagnosis
Erythema Migrans rash - sufficient for dx if exposure hx present Lab studies - not helpful in early lyme (too soon)
37
Lyme serology
NOT useful in pt with EM, high sensitive/specific in early disseminated and late (arthritis, carditis, neuro manifestations), CSF antibodies useful in CNS
38
Lyme PCR
PCR - Good predictive value in synovial fluid for dx of arthritis, not in others
39
2 step testing
EIA (highly sensitive) screening Positive or negative then Western Blot (specific) IgM (2 bands), IgG (5 bands) strict interpretation
40
LD treatment
Doxycycline - tx of choice (10-21 days) Amoxicillin in children/pregnancy cephalosporin for late stage
41
Prophylactic tx of LD
Nymph/adult I. scapularis tick has been attached for >36 hrs or is engorged Local rate of tick infectivity is >20% No contraindication to doxycycline Treatment is started w/in 72 hrs of removal Dose is doxycycline 200mg x 1 in adults (not amoxicillin)
42
Should test tick for LD
NO
43
PTLDS sxs
Joint pain, muscle pain, fatigue, malaise, cognitive problems
44
PTLDS tx
Direct tx at sxs, not "infection"
45
Lyme vaccine
Vaccine was on the market 1998-2002 (still available for dogs) Removed for many reasons
46
Human Granulocytic Anaplasmosis (HGA) causative agent
Anaplasma phagocytophilum
47
Human Monocytic Ehrlichiosis (HME) causative agent
Ehrlichia chaffeensis
48
Anaplasma phagocytophilum and Ehrlichia chaffeensis
Obligate intracellular gram negative rods (Rickettsias) | Tropism for WBC --> morulae
49
Anaplasma phagocytophilum and Ehrlichia chaffeensis | Reservoir hosts
Deer, white-footed mouse
50
Anaplasma phagocytophilum and Ehrlichia chaffeensis Tick vectors
Anaplasmosis - I. scapularis (Deer Tick) Erlichiosis - Amblyomma americanum (Lone star Tick) - southeast Direct transmission from deer carcass
51
Anaplasmosis | Erlichiosis - incubation period
2-14 days
52
Anaplasmosis/Ehrlichiosis sxs
Fever, chills, HA, myalgias | Rash uncommon
53
Anaplasmosis/Ehrlichiosis labs
Leukopenia, thrombocytopenia, mild increase in AST/ALT -- KEY
54
Anaplasmosis/Ehrlichiosis dx
Clinical scenario, with season, exposure history, and clinical presentation is most important Anaplasmosis --> Peripheral smear shows morulae (Latin for mulberry ~ blackberry) in neutrophils (60-80% of cases) Ehrlichiosis --> Peripheral smear insensitive (1-20% of cases) Blood PCR, Serology
55
Babesiosis dominant pathogen + characteristics
Babesia microti dominant pathogen in US Parasite Most common transfusion-associated infection in US Same distribution, vector as Lyme
56
Incubation period babesiosis
1-6 weeks
57
Clinical syndrome babesiosis
Gradual onset of fever, malaise, myalgia, arthralgia Labs may show elevated bilirubin Hemolytic anemia
58
Babesiosis dx
Peripheral smear Blood PCR Serology
59
Babesiosis tx
Quinine and clindamycin (difficult to tolerate) | Azithromycin and atovaquone (preferable unless severe)
60
A/E tx
Treatment: Doxycycline (Rifampin)
61
Rickettsia rickettsii →
Rocky Mountain Spotted Fever
62
Primary tick that transmits R. rickettsii in these states is the _______
American dog tick
63
Incubation period RMSF
2-14 days (mostly 5-7)
64
RMSF sxs
Fever Rash (occurs 2-5 days after fever) ~ 90% of cases Small, blanching, pink macules on the ankles, wrists, or forearms that evolve to maculopapules. Headache, Nausea, Vomiting, Abdominal pain (may mimic appendicitis or other causes of acute abdominal pain), Muscle pain, Lack of appetite, Conjunctival injection
65
RMSF tx
Doxycycline for everyone (Even kids) - chloramphenicol alternate but toxic
66
Tularemia pathogen
Francisella tularensis (gram negative coccobacillus)
67
F. tularensis hosts
Rodents, rabbits classically associated (many mammals)
68
Exposure to F. tularensis
``` Most commonly tick, biting flies Direct inoculation (handing dead animal) ```
69
Tularemia incubation period
3-5 days
70
Tularemia presentation
Abrupt fever, chills, headache, myalgia, sore throat Bite site commonly forms nonhealing ulceration/eschar Ulcero-glandular most common (60-70%) Pneumonic (~20%)
71
Tularemia dx
Labs nonspecific Cultures often negative (but notify lab of suspicion) Serology usually confirms (at 2 weeks)
72
Tularemia Tx
Aminoglycosides Doxycycline Fluoroquinolones
73
Virus causing meningoencephalitis | New England and Great Lakes region
Powassan
74
Caused by Colorado Tick Fever Virus Rocky Mountain distribution Usually mild, self-limited illness
Colorad Tick Fever
75
Borrelia hermsii or turicatae Western US Spirochetes detected in peripheral smears or CSF Treated with doxycycline, tetracycline, penicillin, or ceftriaxone
Relapsing Tick Fever
76
Tick to worry about in MN
Ixodes scapularis
77
Rickettsia are Gram ____
negative
78
EM rash (Lyme disease)
Begins at site of tick bite after a delay (average 7 days) Expands gradually over a period of days reaching up to 12 inches or more (30cm) May feel warm to touch but is rarely itchy or painful Sometimes clears as enlarges → Bulls-eye May appear on any area of the body Multiple rashes = disseminated1t
79
tx Anaplasmosis/erlichiosis
doxycycline (rifampin)
80
Lyme, _______ and ______ have same distribution vector
Anaplasma - Babesia microti ixodes scapularis

Skin MS: Week 3 (14 decks)

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