Lyme Borreliosis

Question 1

What microorganism is responsible for lyme borreliosis?

Answer 1

borrelia burgdorferi

Question 2

What are the main vectors for B. burgdorferi?

Answer 2

THe Ixodes tick

either I. pacificus on west coast

or I. scapularis on the east coast and here

in layman’s terms this is the deer tick or black legged tick

Question 3

How long does an Ixodes tick need to be attached to ensure transmission of the bacteria?

WHy?

Answer 3

36 hours or longer

because when the tick isn’t feeding on something, the bacteria resides in the gut and it needs time to transfer to the salivary glands for transmission

Question 4

Where do Ixodes ticks reside in their environment?

Answer 4

on grass and low brush, NOT trees

Question 5

What are the three life stages of the deer tick? When will it pick up the bacteria? WHen will it transmit the bacteria to humans?

Answer 5

1. larval stage
2. nymphal stage
3. adult stage

They will pick up the bacteria during their first blood meal which makes the into a nymph.

When the infected nymph bites us, that’s when we get the disease

So, you CAN”T get infected by being fed on by alarval tick - it’s transtatial passage

Question 6

What are the two reservoir hosts for B. burgdorferi in the US? Do they get sick?

Answer 6

mice and deer

they don’t get sick

Question 7

How can you tell a deer tick from a wood tick?

Answer 7

a deer tick is much smaller and they have black legs and a black dorsal shield

wood ticks (dermcentor variabilis) are bigger, have brown legs, and a colored dorsal shield (only the adult forms will feed on humans)

Question 8

When is the peak month for Lyme Disease infections?

Answer 8

Summer - especially July

this coincides with the nymphal tick stage - it’s most active in July. THe adult form is more prevalent in the fall - but these usually aren’t attached to us as long as the nymph because we can see the adults better

Question 9

What are some of the bacterial characteristics of B. burgdorferi?

Answer 9

1. spirochete
2. micro-aerophilic
3. have 7 to 11 flagellae
4. grow at 32 degrees celsium on a BSK medium

Question 10

What trend has been seen in the number of reported cases of yme idsease per year?

Answer 10

It’s increasing - there may be more people being infected or we might just be better at recognizing it and reporting it.

Question 11

Is there any support for a “chronic lyme disease”?

Answer 11

Not really

if you’re treated, you will not have a chronic lyme disease, but if you are NOT treated, you might

Question 12

Is there any support for prescribing prolonged antibiotic therapy for persistent “symptoms”

Answer 12

no

Question 13

What are the 3 stages of lyme disease and when do they occur?

Answer 13

early localized —– 1-2 weeks

early disseminated ——- Weeks to months

Late (persistent) ——– Month-Years

Question 14

Describe what happens in early localized LB infection.

Answer 14

1. gradual onset of symptoms - usually starting with lowgrade constitutional symptoms
2. develop erythema migrans (60-80% of patient)

the rash will be erythematous, circular, at least 2 inches in diameter, painless, non-palpable, not itchy, no weeping (won’t necessarily be a bullseye rash)

Question 15

What are some lab results associated with early localized LB?

CBC? LFT? ESR? CRP?

Answer 15

CBC and LFT may have nonspecific changes

ESR and CRP may be elevated

Question 16

What symptoms can arrise in early disseminated LB?

Answer 16

multiple EM lesions

lymphadenopathy

arthralgias

migratory arthritis

bell’s palsy

radicular pain

polyneuritis

AV block

Question 17

What are some symptoms associated with late (persistent) LB?

Answer 17

chronic arthritis

acrodermatitis chronicum atrophicans (mostly in Europe)

neurological impairments

Question 18

What laboratory steps should you take to diagnose lyme disease?

Answer 18

serum screening with IFA, ELISA or EIA

Confirmatory serums with a western blott

You can also do PCR or culture

Question 19

In the antibody screening test with a western blot, what is the requirement for a lyme disease diagnosis?

Answer 19

for IgM, you have to have at least 2 bands out of 3 possible

FOr IgG you need to have at least 5 bands out of 10

Question 20

What are the issues with serologic testing for lyme disease?

Answer 20

1. poorly standardized
2. falst positive IgM results occur commonly
3. IgM and IgG antibodies may persist for years after initial infection, so it can be hard to tell whether it’s a new or old infection
4. early treatment may blunt of abrogat teh antibody response so you get a fals enegative

Question 21

Which persists longer, IgM or IgG?

Answer 21

IgG

Question 22

Does absolute antiboy titer correspond with severity of infection or new infection in someone who had a previous infection?

Answer 22

No

Question 23

What acute and chronic illnesses should be considered in a differential diagnosis for lymes disease?

Answer 23

acute: anaplasmosis, babesiosis, RMSF, enterovirus infection
chornic: chornic fatigue syndrome, fibromyalgia, depression

Question 24

A diagnosis of lyme disease is primarily a ____ diagnosis confirmed by ____.

Answer 24

a clinical diagnosis confirmed by lab studies

Question 25

What is the primary treatment for early localized LB?

Answer 25

doxycycline for 2 weeks

you can also use amozycillin or cefuroxime

Question 26

How does treatment differ for early localized LB and early disseminated LB?

Answer 26

you just use the same drugs for longer in early disseminated - a month instead of 2 weeks

Question 27

Doxycyclin and amoxicillin are also used when there is arthritic and CNS involvement, but wha tis considered best with cardiac involvement?

Answer 27

IV ceftriaxone

Question 28

Is prophylactic treatment after a tick bite useful?

Answer 28

Depends

it was helpful in a study that was done, but the n was pretty small and more people experienced harmful side effects from the dyxy than those that benefitted

Question 29

What are some methods that protect against tick bites?

Answer 29

1. DEET repellant on skin

Permethrin on clothin

light colored clothes so you can see them

socks outside pants

daily inspection of skin