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

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

(early local/EM - clinical dx) first: total Ab screen (ELISA or EIA) if+: second tier reflexes to immunoblots IgM\>2/3 bands (only if \ 5/10 bands (more reliable) serology may remain + for decades (including IgM)

_Severe_: atovaquone PO + azithromycin IV x7-10 days _Mild-mod severity_: azithro PO + atovaquone PO

Arthropod Infections Flashcards by Clayton Mowrer

tx lyme arthritis

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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when to use parenteral tx for lyme disease

neuroborreliosis (though may be not necessary)

late lyme disease

carditis (initially)

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dx of lyme arthritis

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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Dx of lyme disease

(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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Lyme arthritis

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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tx of lyme carditis

CRO, followed by doxy when block resolves

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Early disseminated lyme disease

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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Dx of early localized lyme disease

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

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

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Early, localized lyme disease

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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region of lyme disease

mid-atlantic

upper midwest

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tick-borne illness w/ spirochete

relapsing fever borrelia or B miyamotoi

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morulae on blood smear

PMN:

monocyte:

PMN: anaplasma

monocyte: ehrlichia

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

think of Heartland virus

(will likely be ill-appearing)

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ascending motor paralysis without sensory loss

often PNW in summer mos

think of tick paralysis

2/2 neurotoxin in tick saliva

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similar disease to HGA

meningoencephalitis in IC pts

leukopenia/dec plts, LFTs

epi = similar to Lyme disease

Borrelia miamotoi

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

tx - similar to Lyme

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seen commonly in refugee camps, famine, natural disaster areas

severe disease (TBRF), including jaundice

Louse-borne relapsing fever (Borrelia recurrentis)

vector: human body louse

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relapsing fever, HA, myalgias, N/V

can progress to ARDS

AKI, thrombocytopenia

Western US

noted in rustic housing, rodent exposure

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

Tx: PCN, doxy

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

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tx of babesiosis

Severe: atovaquone PO + azithromycin IV x7-10 days
Mild-mod severity: azithro PO + atovaquone PO

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Dx of babesiosis

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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Babesiosis

maltese cross tetrades in RBCs

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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

Babesiosis

Vector: Ixodes scapularis

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

Babesia

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Northern MW/NE (some in the South)

LFTs, leukopenia, thrombocytopenia

rash rare

anaplasma

Vector: Ixodes scapularis

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maculopapular or petechial rash (1/3)

hepatitis, leukopenia, thrombocytopenia

MW and E US

Human Monocytic Ehrlichiosis (E chaffeensis)

Vector: Lone Star Tick

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1. **HME** - in monocyte, "mulberry dot next to nuclei" 2. **HGA**

Rickettsial Diseases According to Location (quick review slide)

R prowazekii (Epidemic typhus) vs R typhi (Endemic typhus) * vector * who * severity * tx * prevention

flying squirrel rare in US, but generally sporadic on East Coast

epidemic typhus (R prowazekii)

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%

O tsutsugamushi (\>70 strains): Scrub typhus ## Footnote _vector_: trombiculid mite (chiggers)

Partial Ddx of Vesicular Rash

* HSV, VZV * Pox viruses * Rickettsialpox * African tick bite fever * Queensland tick typhus

urban area autumn F single eschar + papulovesicular/maculopapular rash

think R akari (Rickettsialpox) Vector = mouse mites

MCC of fever in returning travelers

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

Africa F, neck soreness, LAD inoculation/multiple eschars

**R africae - African Tick Bite Fever** _Vector_: Amblyomma ticks (cattle, ungulates) tick will have multiple feeding spots and not stay attached

Pacific coast: northern baja -\> S Oregon most commonly HA, F eschar

**Pacific Coast Tick Fever** Rickettsia philipii _Vector_: Dermacentor occidentalis

Southeastern US, gulf coast HA, myalgia single/multiple eschars

**R parkeri (American Boutonneuse Fever)** **Maculatum Fever** if in Southern S America (Argentina, Brazil, Uruguay)

Preferred dx methods of RMSF

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

Serious complications with RMSF

can have microangiopathic complications --\> gangrenous features + MOF

pathogen a/w endemic (murine) typhus

rickettsia typhi

pathogen a/w louse-borne epidemic typhus

rickettsia prowazekii

pathogen a/w boutonneuse (Mediterranean) fever

rickettsia conorii

pathogen a/w tick-borne relapsing fever

borrelia hermsii borrelia turicatae

pathogen a/w louse-borne relapsing fever

borrelia recurrentis (transmitted by human louse - Pediculus humanus)

pathogen a/w scrub typhus

orientia tsutsugamushi

late manifestations of lyme

* arthritis * CN palsies (7 MC) * aseptic meningitis (lymphocytic)

blue-red discoloration on distal extremities w/ swelling occurs of mos-yrs skin becomes thin/atrophic +/- sclerotic plaques

acrodermatitis d/t Lyme (late manifestation)

tick borne illness not responsive to doxy

babesiosis | (can co-infect w/ lyme)

* What is it? * Dx * Vector

* morula in **neutrophil** * HGA * Ixodes ticks

* What is it? * Dx * Vector

* morula w/in a **monocyte** * HME * amblyomma americanum (Lone Star Tick)

co-infections that can occur with HGA and HME

tularemia STARI

parasite burden that = severe disease in babesiosis

\>5%

triad of: fever, rash, HA leukocytosis/leukopenia + thrombocytopenia + anemia + abn LFTs in the summer mos rapidly progressive +/- tick exposure

**Must think of RMSF**

RMSF vectors

* dermacentor variabilis (dog tick) * dermacentor andersoni (wood tick) * rhipicephalus (dog tick) * amblyomma americanum (Lone Star tick)

co-infection that can occur with RMSF

tularemia

large city in NE US black eschar at bite site F, malaise, disseminated vesicular rash

consider rickettsialpox Rickettsia akari (from house mites)

SE US rash similar to RMSF black eschar at site of bite

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

fever + HA + flu-like sx **(qwk-10 days)** a/w poor hygiene/socioecomonic setting **SW** region of US

tickborn relapsing fever - d/t **Borrelia recurrentis, B hermsii, B parkeri** ornithodoros soft ticks

dx of TBRF

Giemsa stain of blood smear - spirochetemia can also perform PCR or serology

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

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

inoculation eschar in SE Asia

consider scrub typhus (Orientia tsutsugamushi) via chigger

returning traveler + febrile illness w/ mosquito exposure + thrombocytopenia shock

dengue

returning traveler + febrile illness w/ mosquito exposure + joint pains mild disease overall

chik

returning traveler + febrile illness w/ mosquito exposure + transaminitis jaundice no vaccine prior to travel

yellow fever

returning traveler + febrile illness w/ water exposure + hyperbili \>\>\> transaminitis conjunctival suffusion

lepto

the only vectorborne illness that can be transmitted sexually

Zika

Key distinct clinical features of malaria spp 1. falciparum 2. vivax 3. ovale 4. malariae 5. knowlesi

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

tx for severe/complicated malaria | (end-organ damage, parasitemia \>5%)

IV quinine + (doxy, tetra, or clinda) hospitalize - monitor QTc/QRS

antimalarial meds side notes: * pregnancy * special consideration for malariae or ovale

* pregnancy - quinine or chloroquine. **Avoid primaquine** * malariae/ovale - use **primaquine** x14 days to clear hyponozoites

malaria ppx

* atovaquone-proguanil in most places * can use chloroquine in susc areas * mefloquine in pregnancy * vivid dreams, insomnia, dizziness