Spirochaetes: Borrelia

Question 1

Borrelia is a gram _____ bacteria

Answer 1

Negative

Longer and wider than treponemes

Linear chromosome

Question 2

Which species of Borrelia causes Lyme disease?

Answer 2

B. burgdorferi

[also B. garnerii and B. afzelii - mentions that these have been ID in the US causing Lyme disease in humans, dogs and horses]

Question 3

True/False. Borrelia is microaerophilic and an obligate pathogen.

Answer 3

True

Microaerophilic - need oxygen because they cannot ferment or respire anaerobically. However, they are poisoned by high concentrations of oxygen.

Question 4

Which species of Borrelia causes avian borreliosis?

Answer 4

B. anerina

Question 5

Which species of Borrelia causes relapsing fever?

Answer 5

B. reccurentis

[Antigenic vairation occurs post-infection at days 4, 7, 14, 21 and 28 and at 7 and 12 months due to selective pressure of antibodies for OSP (outer surface proteins)]

Question 6

How is Borrelia transmitted?

Answer 6

Arthropod vector - ticks

Question 7

What is the main virulence factor for Borrelia?

Answer 7

Antigenic variation - major outer surface lipoproteins

[can change based on where its growing - tick or human etc]

Question 8

Which OSP of B. burgdorferi changes its variation in the midgut of ticks and in culture?

Answer 8

OSP C changes to OSP A

Question 9

Which OSP of B. burgdorferi changes its variation in the salivary gland of ticks?

Answer 9

OSP A changes OSP C

Question 10

Which species of ticks transmit B. hermsii? What disese does it cause? Does the blood require a high number or low number of orangisms for infection?

Answer 10

Ornithodoros hermsi (soft tick, fast feeder)

Relapsing fever (also B. recurrentis)

High density in blood for infection

Question 11

Which OSP of B. burgdorferi is present in mammals early in infection?

Answer 11

OSP C

Question 12

Which species of ticks transmits B. Burgdorferi? What disease does it transmit? Does the blood require a high number or low number of orangisms for infection?

Answer 12

Ixodes scapularis and Ixodes pacificus (hard tick, slow feeder)

Lyme’s disease

Low denisty in blood for infection

Question 13

Which tick species transmits Lymes disease in the western US?

Answer 13

Ixodes pacificus

Question 14

Which tick species transmits Lyme’s disease in the eastern US?

Answer 14

Ixodes scapularis

Question 15

Which species of ticks maintains a sylvatic infection in the southeast US?

Answer 15

Ixodes affinis

Ixodes minor

Question 16

Where do the spirochetes of B. burgdorferi multiply in the highest numbers?

Answer 16

Spirochetes multiply to highest numbers in the skin

[then disseminate via the bloodstream]

Question 17

Which organs are infected in an animal infected with Lyme’s disease?

Answer 17

Organisms spread throughout blood to joints, brain, nerves, eyes, heart, liver and kidney

Question 18

How long would expect recovery from Lymes disease to take? How would you treat it?

Answer 18

Disease is caused by acute infection; however, full recovery may take months or years after infection resolves due to residual damaging effects of infection

No need for more than a single course of antimicrobial treatment

Question 19

Which seasons would you expect to see an increased amount of Lymes disease cases?

Answer 19

Spring and summer

Question 20

What clinical signs would you expect to see in a dog infected with B. Burgdorferi?

Answer 20

Canine lyme disease

Clinical signs: fever, acute arthritis, arthraglia and lamness

(sometimes accompanied by anorexia, lethargy and depression)

[CNS involvment, heart and renal lesions, and uveitis are less frequently reported and not reproduced experimentally in dogs]

Question 21

Is it difficult to directly detect B. burgdorferi microscopically and on culture? What kind of biopsy would you want to use for the most successful chance of culture?

Answer 21

Yes it is difficult due to small numbers of organism

Greater probability of successful culture from skin biopsy

Question 22

What technique can you use to distinguish between natural exposure to B. burgdorferi and vaccination?

Answer 22

Western blotting

Question 23

What is the presumptive diagnosis of Lymes disease based on?

Answer 23

Evidence of exposure to B. burgdorferi

Clinical signs consistent with disease

Consideration of other differentials

Response to treatment

Question 24

What types of serology tests are you gonna use to diagnose Lymes?

Answer 24

Detection of antibody

Two tiered testing: SNAP test (EIA) plus western blot

SNAP test for point of care testing

Quantitative C6 ELISA - monitor therapy

For dogs and horses: multiplex assay

Question 25

How would you treat a dog that had clinical signs of Lymes disease, but tested negative?

Answer 25

Don’t treat

Evaluate for underlying disease and retest

Question 26

How would you treat a dog that was healthy, but tested positives for lymes disease?

Answer 26

Infection is likely (not 100%) subclinical

Treatment preferred in endemic areas (doxycycline)

Treatment in non-endemic areas not pursued

Question 27

Does the Lyme disease vaccine prevent infection?

Answer 27

No. Reduces incidence of disease in endemic region by ~3%.

Vaccines cause production of OSP A antibodies which will neutralize the organism in the midguy of the tick after a blood meal. OSP A cannot convert to OSP C.