8. Lyme Disease

Question 1

What is this a picture of? What is it classic for?

Answer 1

Classic target lesion of ECM (erythema chronicum migrans). Classic for Lyme disease

Question 2

Lyme disease: what are symptoms? what is the causative spirochete? carried by what animal?

Answer 2

Begins with characteristic expanding skin lesion, ECM, followed by neurologic, cardiac or joint abnormalities.

The caustive spirochete is Borrelia burgdorferi, carried by deer ticks.

Question 3

Lyme dz: epidemiology?

What geographic areas?

What months of the year?

Answer 3

Geography:

• Northeast (MA to Georgia)
• Midwest, Wisconsin, Minnesota
• CA/Oregon

Peak occurs in June and July (when tick nymphs feed on animals and humans)

Question 4

Lyme: what are the preferred animal hosts for the larval and nymphal stages of the deer tick? preferred host for the adult stage?

Answer 4

Larval/nymphal: white footed mouse (reservoir)

Adult: white tailed deer (not reservoir, does not get sick)

Question 5

How long does the tick have to remain on the person to transmit Lyme?

Answer 5

24 h before transmitting spirochete. has to become engorged with blood.

Question 6

Sx of early Lyme?

Answer 6

ECM (target rash) around site of tick bite.

Bacteremia with fever, chills, malaise, fatigue, arthralgia.

ECM lesions usually fade after 3-4 weeks even if untreated.

Question 7

Sx of late Lyme disease?

Answer 7

Disseminated -> secondary annular skin lesions in half of patients, diffuse erythroderma or urticaria.

Neuro involvement in 20%, including aseptic meningitis, Bells palsy, peripheral neuropathy

(incidentally, my aunt had Late Lyme - she got numbness and tingling over one whole arm. Took about 5 docs at DHMC to figure out what was going on).

May have cardiac involvement.

May also have arthritis (another card)

Question 8

If Late Lyme presents with arthritis in a patient, what will the arthritis look like?

Answer 8

Transitory/migratory in joints, tendons, bursa, muscle, bone.

Lasts only hours to days in a given location.

May have longer-lasting true arthritis in a few joints.

Question 9

These lesions are classic for what stage of Lyme dz?

How would you describe?

Answer 9

Late Lyme (Stage II). Secondary annular lesions, resemble the primary target lesion, but smaller and migrate less.

Question 10

what are sx of Chronic Lyme dz (Stage III)?

these sx will evolve over what time frame?

Answer 10

evolve over 6-12 m.

Sx: -chronic arthritis in a few large joints

• acrodermatitis chronica atrophicans
• subacute endephalopathy
• peripheral neuropathy

Question 11

what kind of tick is this? what characteristics tell you that it is the kind that carries Lyme?

Answer 11

Deer tick (larva on right, nymph on left, adult in center)

black legs and smooth-edged body shell

the NYMPH is the one that transmits dz

Question 12

what is this a pic of?

Answer 12

engorged deer tick

has to be engorged to transmit dz

Question 13

what is this a pic of?

Answer 13

Spirochetes from the gut of a deer tick.

This is what causes Lyme dz

Question 14

Why would spirochetes cause relapsing/remitting disease?

Answer 14

Stealthy organism: once your body makes antibodies to its outer lipoproteins, it can create a new lipoprotein coat

Question 15

In Stage II (Late) Lyme dz, what % of patients get arthritis?

Answer 15

60% get transitory arthritis

Question 16

Lyme disease tends to present in the same few months that viral meningitis is prevalent. How to tell them apart? (think about fever, duration of illness, CSF contents)

Answer 16

Lyme:

afebrile, Illness > 7 d, CSF has < 10% polys, ECM, may have cranial palsy, papilledema

Viral meningitis:

febrile, lasts < 3d, CSF has 50% polys

Question 17

Why is a dx for Lyme disease so tricky?

Answer 17

• tick bite recalled in only 30% of cases
• only 50% present with classic ECM rash
• cultures may not yield orgs
• ELISA for the spirochete has delayed reacivity
• PCR may give false negatives

Question 18

what is the best diagnostic test for Lyme?

Answer 18

serologic testing for immune response via ELISA.

• but immune response may be delayed -> neg result
• if pt was treated with abx, may not develop antibodies
• frequent false positives and cross-reactivity

Question 19

what test can help back up ELISA results?

Answer 19

Western blot for evidence of the spirochete. must be positive for 5 of possible 10 bands.

Question 20

The bottom line. Does Early Lyme require testing for dx? what about Late Lyme?

Answer 20

Early: in a patient with classic ECM, from an area with endemic Lyme, does not require lab confirmation

Late: requires objective evidence of clinical dz + lab evidence of infection (ELISA, serology). Symptoms would include Bell’s palsy, arthritis, aseptic meningitis, heart block

Question 21

Lyme: treatment.

what stage is treatment most effective?

Treatment for acute?

treatment for chronic?

Answer 21

Most effective if initiated during Early (stage I)

Acute: abx such as doxycycline.

Chronic: 4 week course of oral abx (doxy), or parenteral course of ceftriaxone. Less effective.

Question 22

Prevention of Lyme disease?

Answer 22

Control of deer/mice in endemic areas

tick removal (make sure to get the whole thing) within 24h

Long pants, insect repellent, wash clothes with repellent.

Question 23

differential Ddx of Lyme?

Answer 23

babesiosis

Erlichiosis

anaplasmosis

rocky mountain spotted fever

tularemia

Question 24

It’s important to not order Lyme serology too early: why?

Answer 24

It will be negative for a while even after the pt has gotten Lyme.

Question 25

What does this depict?

What symptoms does it cause? What is its distribution in the US?

Answer 25

Babesiosis

Causes hemolytic anemia, fever, splenomegaly.

Distribution in the US is the same as for Lyme

Question 26

What does this pic represent?

What other symptoms does this disease cause?

Answer 26

Rocky Mountain Spotted Fever

Rash starts around wrists, ankles, moves to palms.

Causes high fever, headache, can progress to vasculitis.