(Section C: Bacteriology) Lecture 24 Flashcards by Lucky Cat

When was Lyme Disease first recognized?

1975 in rural communities surrounding Lyme, Connecticut

How well did you know this?

Not at all

Perfectly

What was Lyme Disease first misdiagnosed as?

Rheumatoid arthritis
* Due to ‘polyarthritis’ symptoms

How well did you know this?

Not at all

Perfectly

Borrelia burgdorferi
* Gram stain
* Shape

Gram negative
Spirochete

How well did you know this?

Not at all

Perfectly

Describe:

Size proportions of Borrelia burgdorferi

Thin (~0.5 μm) and long (>10 μm)

How well did you know this?

Not at all

Perfectly

Where is Borrelia found?

Found throughout temperate zones in the Northern Hemisphere

How well did you know this?

Not at all

Perfectly

What is the main reservoir for Borrelia burgdorferi?

White footed mice
* Transferred to ticks

How well did you know this?

Not at all

Perfectly

What ticks are the primary transmitters?

Ixodes scapularis
Ixodes pacifica

How well did you know this?

Not at all

Perfectly

What areas do the ticks inhabit?

I. scapularis: East coast
I. pacifica: West coast

How well did you know this?

Not at all

Perfectly

How do ticks transmit disease?

Do not fly or jump
Sit on grasses/shrubs and wait for a host to pass by

How well did you know this?

Not at all

Perfectly

Besides humans, what else can get Lyme Disease?

Cat and Dogs
* Deers cannot get Lyme Disease because of their immune system

How well did you know this?

Not at all

Perfectly

Can Lyme Disease transmit between person-person?

No evidence

How well did you know this?

Not at all

Perfectly

Where are ticks bites often found?

Found often in ‘hard-to-see’ areas

How well did you know this?

Not at all

Perfectly

Ixodes life cycle

3 stages
* Larvae
* Nymph
* Adult

How well did you know this?

Not at all

Perfectly

Does Borrelia burgdoferi transfer between eggs and larvae?

No transmission between adult to egg

How well did you know this?

Not at all

Perfectly

What things can carry B. burgdorferi other than lice?

Mice
Squirrels
Birds

How well did you know this?

Not at all

Perfectly

How does Lyme Disease get into the host?

Inserts through a feeding tube with barbs

How well did you know this?

Not at all

Perfectly

Why do we not feel tick bites?

The tick secretes a local anesthetic

How well did you know this?

Not at all

Perfectly

True or False:

Transmission of Lyme disease occurs in the first 24 hrs

False, the transmission is not thought to occur during the first ~24 hours following bite

How well did you know this?

Not at all

Perfectly

What stage of ticks normally transmit disease?

Nymphs

How well did you know this?

Not at all

Perfectly

What should you not do when removing ticks?

Do not squish the tick body
Do not burn the tick off
Do not apply petroleum jelly

How well did you know this?

Not at all

Perfectly

What must Borrelia burgdorferi do to propagate through it’s life cycle?

Cause disseminated and persistent infection to propagate through it’s life cycle

How well did you know this?

Not at all

Perfectly

What is the central event in the development of Lyme Disease?

Hematogenous dissemination

How well did you know this?

Not at all

Perfectly

What is the migration of Borrelia burgdorferi in the skin known as?

Erythema migans lesion
* “Bulls eye rash”

How well did you know this?

Not at all

Perfectly

How do compounds in tick saliva inhibit dendritic cells?

(4 points)

Decreased phagocytosis
Decreased maturation
Decreased inflammatory mediators
Decreased antigen presentation

How well did you know this?

Not at all

Perfectly

How do Borrelia burgdorferi move?

Moves in a corkscrew like manner due to periplasmic flagella (axial filaments)

What are axial filaments?

Periplasmic flagella * Axial filaments * Promotes movement through extracellular matrix of host tissues and invasion of vasculature

What is unusual about the Borrelia burgdorferi outer membrane?

* No LPS * Many surface expressed lipoproteins that can act as adhesins

Why does Borrelia burgdorferi express so many lipoproteins?

To escape from the blood flow, so that it can invade the endothelium

What is unusual about Borrelia burgdorferi genetic structure?

* 'Linear' chromosomes * Multiple plasmids, some circular and some linear

# True or False: Plasmids vary from strain to strain in Borrelia burgdorferi

True

What are plasmids needed for in Borrelia burgdorferi?

Infection * Have limited metabolic capability

What are the 4 stages of Lyme Disease?

1. Early (Localized) Stage 2. Early Disseminated Stage 3. Late Disseminated Stage 4. Post-treatment Lyme Disease syndrome

# Signs/Symptoms: Early (Localized) Stage

* Bulls eye rash (~25% of patients do not have a rash) * Flu-like symptoms (fever, chills, fatigue, body aches)

When does the Early (Localized) Stage of Lyme disease occur?

~1-2 weeks after tick bite

# Signs/Symptoms: Early Disseminated Stage

* Multiple rashes * Pain and swelling of large joints * Heart palpitations * Meningitis (severe headaches, neck stiffness) * Bell's (facial) palsy

# Define: Heart Palpitations

Interference with heart electrical signals

# Define: Bell's (facial) palsy

Loss of muscle tone on one or both sides of the face

What mechanism does Borrelia burgdorferi use to traverse the BBB?

Paracellular travel

How long does it take for the Early Disseminated Stage to occur?

Days to weeks

# Signs/Symptoms: Late Disseminated Stage

* Serious long-term disability * Muscle pain * Arthritis * Severe pain and swelling in large joints * Neurological problems (shooting pains, numbness, tingling in hands and feet, memory)

Approximately what percentage of patients develop neurological problems in the Late Disseminated Stage?

~5%

How long does it take for the Late Disseminated Stage to occur?

Months to years

# Signs/Symptoms: Post-treatment Lyme disease syndrome

* Fatigue * Muscle and joint pain * Cognitive defects * Sleep disturbances

How well do antibiotics work in the Late Disseminated stage?

Work slowly

Approximately what percentage of individuals develop Post-treatment Lyme disease syndrome?

10-20%

What is the cause of Post-treatment Lyme disease syndrome?

Unknown * May involve an autoimmune response * Possibly persistent infection

How long does it take most patients to recover from post-treatment Lyme disease syndrome?

After a few months * Long-term antibiotics are not thought to help

What is the distribution of ticks continuing to spread?

* Migratory birds * Warmer climates

Prevention of Lyme Disease

* Avoid low lying brush, long grass, wooded areas endemic with Lyme disease * Stay on paths * Wear long pants + shirts * Light colored clothing * Repellants (containing DEET) * Check for ticks and remove them

Diagnosis of Lyme Disease

* Symptoms * Tick bite history * Anti-B. burgdorferi antibody tests * Submit tick for testing

Why is the anti-B. burgdorferi antibody test controversial?

False negatives often due occurs (early testing and genetic diversity of B. burgdorferi causes this) * Sensitivity is not very good

Treatment for Lyme Disease

* Watch for signs and symptoms * Antibiotic treatment (2-4 week course)

What can happen in Lyme disease without treatment?

1. Joint issues 2. Heart issues 3. Nervous system issues

What is "Chronic Lyme Disease"?

Very controversial 1. Chronic infection by B. burgdorferi 2. Diagnosed without evidence of prior Lyme Disease

What are signs/symptoms of "Chronic Lyme Disease"?

* Fatigue * Headaches * Sleep disturbances * Cognitive dysfunction * Neurological problems

What treatment was found to be not helpful for "Chronic Lyme Disease"?

Long-term antimicrobial therapy

LYMErix

Outer memberane protein vaccine for Lyme disease

How effective is LYMErix in humans?

75% effective

Why was the vaccine pulled from the markey (LYMErix)?

'Lack of demand' * Lawsuits and claims that vaccine caused arthritis (no evidence)

Is the LYMErix vaccine recommended?

"Should be considered" for those in high risk areas

What is the LYMErix vaccine approved for only?

Dogs