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ID Boards > Arthropod Infections > Flashcards

Arthropod Infections Flashcards

1
Q

tx lyme arthritis

A
  • initial: amox or doxy x28D
  • if no response: second PO course or CRO IV x14 days
  • Abx refractory lyme arthritis (Bb PCR negative, no viable organisms) - possibly autoimmune phenomenon = DMARDs, intra-articular corticosteroids, synovectomy
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2
Q

when to use parenteral tx for lyme disease

A

neuroborreliosis (though may be not necessary)

late lyme disease

carditis (initially)

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3
Q

dx of lyme arthritis

A
  • synovial fluid = inflammatory: 10-25k average (PMN pred)
  • PCR from synovial fluid - var sens based on abx pre-tx; spec 99% (non-standardized)
  • serology: ~100% (+) in blood; high titer, Bb IgG immunoblot

POINT: swollen knee + (+)serolgy = dx

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4
Q

Dx of lyme disease

A

(early local/EM - clinical dx)

  • first: total Ab screen (ELISA or EIA)
  • if+: second tier reflexes to immunoblots
  • IgM>2/3 bands (only if <4wks of sx) - HIGH rate of FP
  • IgG >5/10 bands (more reliable)

serology may remain + for decades (including IgM)

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5
Q

Lyme arthritis

A

recurrent mono- or oligo-arthritis

**knee most common!

other large joints possible (+ TMJ)

serum B burgorferi 2-tier testing ~100% sens

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6
Q

tx of lyme carditis

A

CRO, followed by doxy when block resolves

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7
Q

Early disseminated lyme disease

A

multiple EM - often smaller, less red than primary lesion

+ALWAYS ILL: fever, flu-like sx, HA

other assoc conditions: asepctic meningitis (lymphocytic), CN VII palsy (could also see 3, 6, 8), radiculoneuritis, mononeuritis multiplex

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8
Q

Dx of early localized lyme disease

A

characteristic rash + epi (70% exp flu-like illness)

(serology not recommended - 40-70% negative at this stage)

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9
Q

Early, localized lyme disease

A

EM - occurs 3-30 days (7-14 av) @ site of tick bite

–> >5cm = more secure dx

classic: “bull’s eye”

most common: homogenous, pink-red ovoid (comes b/f central clearing)

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10
Q

region of lyme disease

A

NE

mid-atlantic

upper midwest

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11
Q

tick-borne illness w/ spirochete

A

relapsing fever borrelia or B miyamotoi

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12
Q

morulae on blood smear

PMN:

monocyte:

A

PMN: anaplasma

monocyte: ehrlichia

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13
Q

suspect tick-borne illness (e.g. Ehrlichiosis), but no improvement with doxy

A

think of Heartland virus

(will likely be ill-appearing)

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14
Q

ascending motor paralysis without sensory loss

often PNW in summer mos

A

think of tick paralysis

2/2 neurotoxin in tick saliva

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15
Q

similar disease to HGA

meningoencephalitis in IC pts

leukopenia/dec plts, LFTs

epi = similar to Lyme disease

A

Borrelia miamotoi

Dx - blood smear (obs spirochetes), PCR, serology

tx - similar to Lyme

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16
Q

WW

seen commonly in refugee camps, famine, natural disaster areas

severe disease (TBRF), including jaundice

A

Louse-borne relapsing fever (Borrelia recurrentis)

vector: human body louse

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17
Q

relapsing fever, HA, myalgias, N/V

can progress to ARDS

AKI, thrombocytopenia

Western US

noted in rustic housing, rodent exposure

A

Tickborne Relapsing Fever (primarily B hermsii) - ornithodorus soft ticks

Tx: PCN, doxy

***can see Jarisch Herxheimer reaction up to 50%

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18
Q

tx of babesiosis

A
  • Severe: atovaquone PO + azithromycin IV x7-10 days
  • Mild-mod severity: azithro PO + atovaquone PO
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19
Q

Dx of babesiosis

A

WGS thin-blood smears: parasitemia range 0-80%, maltese cross = diagnostic (differentiates from malaria)

PCR now widely available

serology (IFA) - high titer or acute/conv c/w active/recent infection

(***low titer, negative smear = DONT TX)

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20
Q
A

Babesiosis

maltese cross tetrades in RBCs

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21
Q

increased LFTs, thrombocytopenia, anemia, parasitemia (>10%)

spp that resides in RBCs

wide range of illness (flu-like to fatal)

[RF for severe disease: asplenia, HIV, chemo, >55yo, SOT)

***MCC Blood transfusion-related infn in US

A

Babesiosis

Vector: Ixodes scapularis

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22
Q

Nantucket, Martha’s Vineyard, Long Island, Mid-Atlantic/NE, upper Midwest, WA, CA, MO (similar to Lyme)

A

Babesia

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23
Q

Northern MW/NE (some in the South)

LFTs, leukopenia, thrombocytopenia

rash rare

A

anaplasma

Vector: Ixodes scapularis

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24
Q

maculopapular or petechial rash (1/3)

hepatitis, leukopenia, thrombocytopenia

MW and E US

A

Human Monocytic Ehrlichiosis (E chaffeensis)

Vector: Lone Star Tick

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25
Q
A
  1. HME - in monocyte, “mulberry dot next to nuclei”
  2. HGA
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26
Q

Rickettsial Diseases According to Location (quick review slide)

A
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27
Q

R prowazekii (Epidemic typhus) vs R typhi (Endemic typhus)

  • vector
  • who
  • severity
  • tx
  • prevention
A
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28
Q

flying squirrel

rare in US, but generally sporadic on East Coast

A

epidemic typhus (R prowazekii)

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29
Q

Triangle: Japan - Eastern Australia - S Russia (rural). S China has endemic focus

severe F in 1/3 cases

Eschar + regional painful/draining LAD

rash

delirium

***can progress to meningitis/meningoencephalitis, MOF

fatality rate up 70%

A

O tsutsugamushi (>70 strains): Scrub typhus

vector: trombiculid mite (chiggers)

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30
Q

Partial Ddx of Vesicular Rash

A
  • HSV, VZV
  • Pox viruses
  • Rickettsialpox
  • African tick bite fever
  • Queensland tick typhus
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31
Q

urban area

autumn

F

single eschar + papulovesicular/maculopapular rash

A

think R akari (Rickettsialpox)

Vector = mouse mites

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32
Q

MCC of fever in returning travelers

A
  1. malaria
  2. typhoid
  3. ricketssial diseases
  • R africae most common (88%). Followed by murine typhus, mediterranean spotted fever, scrub typhus
  • occasionally RMSF, epidemic typhus, N Asian or Queensland tick typhus
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33
Q

Africa

F, neck soreness, LAD

inoculation/multiple eschars

A

R africae - African Tick Bite Fever

Vector: Amblyomma ticks (cattle, ungulates)

tick will have multiple feeding spots and not stay attached

34
Q

Pacific coast: northern baja -> S Oregon most commonly

HA, F

eschar

A

Pacific Coast Tick Fever

Rickettsia philipii

Vector: Dermacentor occidentalis

35
Q

Southeastern US, gulf coast

HA, myalgia

single/multiple eschars

A

R parkeri (American Boutonneuse Fever)

Maculatum Fever if in Southern S America (Argentina, Brazil, Uruguay)

36
Q

Preferred dx methods of RMSF

A

skin bx DFA - timely, 70% sens

PCR - R rickettsii-specific

Others: serology (acute/convalescent) - not timely, limited clinical value, though does cross-react w/ other SFG spp.
***LOTS of false positives

37
Q

Serious complications with RMSF

A

can have microangiopathic complications –> gangrenous features + MOF

38
Q

pathogen a/w endemic (murine) typhus

A

rickettsia typhi

39
Q

pathogen a/w louse-borne epidemic typhus

A

rickettsia prowazekii

40
Q

pathogen a/w boutonneuse (Mediterranean) fever

A

rickettsia conorii

41
Q

pathogen a/w tick-borne relapsing fever

A

borrelia hermsii

borrelia turicatae

42
Q

pathogen a/w louse-borne relapsing fever

A

borrelia recurrentis

(transmitted by human louse - Pediculus humanus)

43
Q

pathogen a/w scrub typhus

A

orientia tsutsugamushi

44
Q

late manifestations of lyme

A
  • arthritis
  • CN palsies (7 MC)
  • aseptic meningitis (lymphocytic)
45
Q

blue-red discoloration on distal extremities w/ swelling

occurs of mos-yrs

skin becomes thin/atrophic +/- sclerotic plaques

A

acrodermatitis d/t Lyme (late manifestation)

46
Q

tick borne illness not responsive to doxy

A

babesiosis

(can co-infect w/ lyme)

47
Q
  • What is it?
  • Dx
  • Vector
A
  • morula in neutrophil
  • HGA
  • Ixodes ticks
48
Q
  • What is it?
  • Dx
  • Vector
A
  • morula w/in a monocyte
  • HME
  • amblyomma americanum (Lone Star Tick)
49
Q

co-infections that can occur with HGA and HME

A

tularemia

STARI

50
Q

parasite burden that = severe disease in babesiosis

A

>5%

51
Q

triad of: fever, rash, HA

leukocytosis/leukopenia + thrombocytopenia + anemia + abn LFTs

in the summer mos

rapidly progressive

+/- tick exposure

A

Must think of RMSF

52
Q

RMSF vectors

A
  • dermacentor variabilis (dog tick)
  • dermacentor andersoni (wood tick)
  • rhipicephalus (dog tick)
  • amblyomma americanum (Lone Star tick)
53
Q

co-infection that can occur with RMSF

A

tularemia

54
Q

large city in NE US

black eschar at bite site

F, malaise, disseminated vesicular rash

A

consider rickettsialpox Rickettsia akari (from house mites)

55
Q

SE US

rash similar to RMSF

black eschar at site of bite

A

consider spotted fever Rickettsia parkeria (from amblyomma maculatum - Gulf Coast tick)

56
Q

fever + HA + flu-like sx (qwk-10 days)

a/w poor hygiene/socioecomonic setting

SW region of US

A

tickborn relapsing fever - d/t Borrelia recurrentis, B hermsii, B parkeri

ornithodoros soft ticks

57
Q

dx of TBRF

A

Giemsa stain of blood smear - spirochetemia

can also perform PCR or serology

58
Q

recurrent fevers in homeless/poor hygiene (lasting 4-5 days, recurs over period of 5-6wks)

A

consider trench fever/louse-borne relapsing fever (Bartonella quintana) from pediculus humanus

59
Q

inoculation eschar in SE Asia

A

consider scrub typhus (Orientia tsutsugamushi) via chigger

60
Q

returning traveler + febrile illness w/ mosquito exposure

+

thrombocytopenia

shock

A

dengue

61
Q

returning traveler + febrile illness w/ mosquito exposure

+

joint pains

mild disease overall

A

chik

62
Q

returning traveler + febrile illness w/ mosquito exposure

+

transaminitis

jaundice

no vaccine prior to travel

A

yellow fever

63
Q

returning traveler + febrile illness w/ water exposure

+

hyperbili >>> transaminitis

conjunctival suffusion

A

lepto

64
Q

the only vectorborne illness that can be transmitted sexually

A

Zika

65
Q

Key distinct clinical features of malaria spp

  1. falciparum
  2. vivax
  3. ovale
  4. malariae
  5. knowlesi
A
  1. falciparum - can invade RBCs of all ages → causes the most severe disease
  2. vivax - invades reticulocytes. Can persist as hypnozoites in hepatocytes for mos-yrs → relapsing fevers long after return from trip
  3. ovale - same as above (can persist in hepatocytes)
  4. malariae - low-level parasitemia and mild disease typically
  5. knowlesi - SE Asia only (including Malaysia), can cause severe disease like falciparum
66
Q

tx for severe/complicated malaria

(end-organ damage, parasitemia >5%)

A

IV quinine + (doxy, tetra, or clinda)

hospitalize - monitor QTc/QRS

67
Q

antimalarial meds side notes:

  • pregnancy
  • special consideration for malariae or ovale
A
  • pregnancy - quinine or chloroquine. Avoid primaquine
  • malariae/ovale - use primaquine x14 days to clear hyponozoites
68
Q

malaria ppx

A
  • atovaquone-proguanil in most places
    • can use chloroquine in susc areas
  • mefloquine in pregnancy
    • vivid dreams, insomnia, dizziness
69
Q
A

P falciparum

  • banana shaped
  • severe disease
70
Q
A

P malariae

  • band trophozoite (right)
  • mild disease
71
Q
A

P ovale

  • round/oval
  • can have schuffner dots
72
Q
A

P vivax

  • schuffner dots
73
Q
A

P knowlesi

  • band trophozoite
  • looks like P malariae, but has severe presentation like falciparum
  • SE Asia only
74
Q

Latin America

red lesion at site of bite

progression to periorbital edema

A

Chagas (T cruzi)

Chagoma, then Romana sign

75
Q
A

RMSF

Tularemia

76
Q
A

RMSF

Tularemia

77
Q
A

Ehrlichia

Tularemia

STARI

78
Q
A

Anaplasma

Babesia

Lyme

79
Q
A

Anaplasma

Lyme

80
Q
A

RMSF (R ricketssia)

81
Q
A

Spotted fever (R parkeri)

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