Lyme Disease: Borrelia burgdorferi

how to test for Lyme's (3)

ELISA --> detects antibodies to B. burgdorferi (needs another test to diagnose because can provide false positive) Western blot test (used to confirm when positive ELISA) --> detects antibodies to several proteins of B. burgdorferi (in dogs can differentiate vaccinated from infected animals!) Polymerase chain reaction (PCR) --> detect bacterial DNA in fluid drawn from an infected joint

what is the most common symptom of Lyme's disease?

Erythema migrans --> Bull's eye circular skin rash most common but not all people get this

symptoms of lyme's disease

Fatigue Chills and fever Headache Muscle and joint pain Swollen lymph nodes Bull's eye circular skin rash (Erythema migrans)

what cells are usually invaded during Intracellular invasion

Fibroblasts, lymphocytes, macrophages, neuronal and glial cells Grows in these cells (many of which are involved in immune response)

mechanisms of bacterial persistence (5)

Growth in sites inaccessible to the immune system or antibiotics (brain/CNS) Intracellular invasion Altered morphological forms (cysts, granules) Antigenic variation (vary surface proteins or OspC sequences) Immune suppression

know this graph!!

Hatch spring of 1st year Summer of first year --> Larvae feed on small animals (mouse); tick becomes infected with bacteria Fall/winter of 1st year -->Larvae form is dormant in environment Spring of 2nd year --> Go into nymph form: Aggressive stage of tick --> Bites another host and transmit bacteria (Dog, human, deer, etc) Fall of 2nd year --> Mate and female tick drops off the deer in spring and lays egg and cycle starts again

what else can the bacteria infect if left untreated? is there always permanent damage?

In addition to joint damage, the bacteria can affect the dog's heart muscle and nerve tissue. If the disease is diagnosed in time, treatment can cure the dog before permanent joint or nerve damage occurs

what does the inflammatory response do that usually helps decrease iron to kill bacterium?

Inflammatory response induces production of *ferritin* --> way to sequester iron and limit bacteria cell growth will not affect B. burgdorferi growth

what occurs during immune suppression (2)?

Inhibits complement --> No good complement mediated lysis response Induces anti-inflammatory cytokines

what occurs during early infection of Lyme's?

Localized infection localized inflammatory response (rash) bacteria grows locally and then disseminates throughout the bloodstream (heart, joints, neuro infections)

how is the bacteria transmitted? what occurs if untreated?

An infected tick can transmit the spirochete to the humans and animals it bites Untreated, the bacterium travels through the bloodstream, establishes itself in various body tissues, and can cause a number of symptoms, some of which are severe

what antigen causes Lyme's disease?

Borrelia burgdorferi bacteria!!

control of Lyme's?

Use of flea/tick/mosquito medications like Frontline Plus or K9Advantix Control of deer populations has proven effective It is still imperative to routinely examine dogs and pick off ticks

are the spirochetes gram - or gram + ?

are not classified as either Gram-positive or Gram-negative

why can Lyme disease show up all year long?

because dogs can harbor the bacteria in their tissues a long time before the disease is evident

where are the endoflagella contained?

between a semi rigid peptidoglycan helix and a multi-layer, flexible outer membrane sheath they wiggle in the sheath to move the bacterium unique cell wall structure!!

how does B. burgdorferi avoid immune response (2)

flagella inside sheath and hidden inflamm response producing ferritin has no effect of growth on lyme disease

B. burgdorferi is microaerophilic. what does this mean?

grows in presence of oxygen but grows slowly (12-18 hour generation time)

are B. burgdorferi obligate anaerobes?

Not obligate anaerobic but prefers not oxygen

______________ is how lyme presents in dogs!!!!

lameness In over 75% of affected dogs the worst limp will be in one front leg; close observation, though, reveals multiple joint tenderness

most common symptoms of dogs with lyme's?

lameness in the hind legs

are chancres (rashes) seen in infected dogs?

no

do flea/tick/mosquito medications kill 100% of ticks?

no also only kill the tick after it climbs onto the dog

can humans contact Lyme's from wild or domestic animals?

no must go through tick vector

are symptoms of Lyme's disease specific?

no nonspecific and are often found in other conditions, such as viral infections, various joint disorders, muscle pain (fibromyalgia), chronic fatigue syndrome, and even depression What's more, the ticks that transmit Lyme disease also can spread other diseases at the same time

can PCR detect infection of B. burgdorferi in urine? blood? when is this test commonly used (2)?

no to both only fluid from joints It's used for people who may have chronic Lyme arthritis It may also be used to detect persistent infection in the cerebrospinal fluid of people who have nervous system symptoms

is there a vaccine for Lyme's?

only for dogs --> considered a core vaccine in endemic areas no human vaccine

what occurs if Lyme is left untreated?

severe symptoms! arthritis (brief bouts, usually in large joints, especially knees) --> dogs get this too neurological abnormalities heart palpitations

what do over 90% of canine patients have signs of (3)?

signs of limping (usually one foreleg) lymph node swelling in the affected limb a mild temperature of 103 degrees

what type of bacterium is Borrelia burgdorferi?

spirochete

what occurs when Borrelia burgdorferi is Gram-stained?

stain like a weak Gram-negative

what antibiotic is used to treat Lyme's disease? do dogs respond well?

tetracycline antibiotic Over ninety percent of dogs treated within the first week of obvious signs of Lyme Disease will respond rapidly to treatment The earlier the antibiotic is started in the course of the disease, the better the patient's chances of a complete recovery

what occurs when the tick begins to take a blood meal in turns of Osp?

the spirochete must prepare to enter the warm-blooded vertebrate host so it *upregulates OspC and down regulates Osp A and B* - this process can take up to 24 hours

what does the endoflagella allow for the bacterium?

this allows the spirochetes to hide their flagella, which are normally antigenic, from the host immune defenses flagella = PAMP

what is the cork-screw movement an adaptation to?

to viscous environments, such as aquatic sediments, biofilms, mucosal tissues and the intestinal tracts of animals

Lyme disease in dogs has been reported in every state (T/F)

true

Once the dog starts to be affected by the bacteria, Lyme Disease can progress within two or three days from a mild discomfort to the stage where a dog will be in such joint and muscle pain it will refuse to move (T/F)

true can progress very fast

how do spirochetes move?

unique mode of motility by means of *axial filaments (endoflagella)* do not extend into the environment

is Lyme disease found in the US?

yes 100% prevelance in NE/mid atlantic/upper midwest No lyme in san diego/texas Heartworm: -100% = Southeast US -Minimal in NE

can B. burgdorferi survive without iron?

yes avoids the problem many pathogenic bacteria face in acquiring iron

does disease reoccurrence occur in Lyme's? if so, how?

yes may be caused by a second, distinct infection OR it could be a flare-up of the original episode (because the Borrelia organism replicates quite slowly and could still be somewhere in the body --> Joints not easily accessible to circulatory system so if not all bacteria eliminated, infection will return) Rare complications = heart, kidney, brain

once in the mammalian host, only the protein ______ is expressed on the spirochete

OspC

what is the nickname for Lyme's disease? why?

"The Great Imitator" because it has often been mistakenly diagnosed when another disorder is present, such as an autoimmune disease, lymph tissue cancer, Blastomycosis, or septicemia

what does Borrelia burgdorferi outer membrane contain like most spirochetes? what type of cell wall does it have (gram - or gram +)?

*LPS-like substance* an inner membrane a periplasmic space which contains a layer of peptidoglycan it has a Gram-negative bacterial type cell wall, despite its staining characteristics

what is an Osp? what do they play a role in?

*outer surface protein* found on the outer membrane of Borrelia burgdorferi (Osp A through OspF) play a role in virulence

how long is the life cycle of borrelia burgdorferi?

2 year cycle

when do symptoms appear in lyme's disease in humans?

3-30 days after the tick bite Some symptoms may not appear until weeks after a tick bite

what occurs to 5% of dogs after treatment?

5% will have some type of relapse of signs such as cardiac or neurological difficulties even after treatment Some will experience chronic, lifelong joint pain from the damage caused by the bacteria and its direct and indirect stress to joint tissues.

___% of deer are carrying the disease

50%

In endemic areas ___% of dogs are exposed but only ___% exhibit clinical signs

75% exposed 5% exhibit signs Lots of subclinical lyme disease in dogs

When the filaments rotate within this space, the spirochetes move in a ___________________

cork-screw fashion

what are Spheroplasts

cysts, granules Form these in certain parts of life cycle not susceptible to antibiotics!! part of Altered morphological forms

main vector of Lyme's disease

deer ticks (black-legged ticks) Ixodes scapularis only three species carry the disease organism

it is uncommon for an owner to have to carry a sick dog into the animal hospital

false it is not uncommon for an owner to have to carry a sick dog into the animal hospital because of the quick disease progression

B. burgdorferi was the fifth bacterial genome to be sequenced

false third