Lyme Disease
how can tick bites be prevented on pets?
Check your pets for ticks daily, especially after they spend time outdoors. If you find a tick on your dog, remove it right away. Ask your veterinarian to conduct a tick check at each exam. Talk to your veterinarian about tickborne diseases in your area. Reduce tick habitat in your yard. Talk with your veterinarian about using tick preventives on your pet.
what is infection like in the Western and Southeat US?
Colorado = infected nonpathogenic species --> no human infection southeastern US = the tick feeds on lizards, which are resistant to B. burgdorferi infection because of complement-mediated killing of the spirochete - rare in SE not much disease
how can tick bites be prevented in one's yard?
Create a tick-safe zone through landscaping Apply Pesticides Outdoors to Control Ticks: acaricides = tick pesticides
how can tick bites be prevented on people?
Avoid Direct Contact with Ticks Repel Ticks with DEET (skin) or Permethrin (clothing and gear) Find and Remove Ticks from Your Body
what does persistent infection look like in Europe/Asia?
B. afzelii may persist in the skin for decades, resulting in acrodermatitis chronica atrophicans, a skin condition that occurs primarily on sun-exposed surfaces of distal extremities in elderly women
what is the most arthritogenic (causing most arthritis) type of Lyme disease? what % of untreated patients experience this?
B. burgdorferi (US type) persistent infection: about 60% of untreated patients with this infection experience intermittent attacks of arthritis, primarily of the large joints, especially the knee.
what is the most neurotropic type of Lyme disease?
B. garinii persistent infection = May cause a wide range of neurologic abnormalities, including borrelial encephalomyelitis
what are the 3 species of borrelia that cause Lyme disease? where do they cause Lyme?
Borrelia burgdorferi - sole cause in US & most pathogenic strain (also found in Europe but not primary cause of disease) Borrelia afzelii - cause of disease in Europe and Asia (not found in US) Borrelia garinii - cause of disease in Europe and Asia (not found in US) other species nonpathogenic
what are the 3 stages of infection?
Stage 1: localized infection of the skin Stage 2: disseminated infection (days or weeks after infection) Stage 3: persistent infection (months to years after infection - includes arthritis and neurological symptoms) variable outcomes to infection - some develop arthritis need treatment - some can clear without but most won't disseminates widely in body can be asymptomatic (rare)
what was the first symptoms discovered in Lyme disease?
arthritis
how long must the tick be attached for greatest risk of infection? how else can infection be prevented? how long is treatment?
at least 24 hours (needs 24-72) if removed before that, no infection usually engorged tick = a single, 200-mg dose of doxycycline prevents the infection Treatment is recommended for 10 to 20 days
what type of disease is Lyme Disease? where was it first recognized/identified as an emerging disease? how?
bacterial disease Lyme, CT = first identified - outbreak of juvenile arthritis in this area only (1976)
what bacterium causes Lyme in the US? what are some features of this bacteria?
borrelia burgdorferi vigorously motile weak gram negative cork-screw shape Borrelia does have an outer membrane that contains an LPS-like substance, an inner membrane, and a periplasmic space which contains a layer of peptidoglycan
what is the most common feature of infection?
bulls eye pattern (70-80% of infections) after 3-32 day incubation period
how can the Lyme bacteria survive the immune response? what is needed to control Lyme infection?
by changing or minimizing antigenic expression of surface proteins and by inhibiting certain critical host immune responses control - need BOTH innate and adapted immune system
how is post-Lyme disease syndrome treated?
follow the guidelines for treating chronic fatigue syndrome or fibromyalgia
what is infection like in the Northeast US?
high rates of infection among rodents and nymphal ticks many new cases of human Lyme disease during the late spring and early summer months (highest infection times)
how is Lyme arthritis treated? what if it persists?
Lyme arthritis may be treated with either oral or intravenous therapy, but oral therapy is easier to administer, is associated with fewer side effects, and is considerably less expensive If patients with Lyme arthritis have persistent joint inflammation after 2 months of oral antibiotics or 1 month of intravenous antibiotics and the results of PCR testing are negative, they are given standard antirheumatic treatment
does Lyme disease or the flu kill more people?
Lyme disease
what is the most commonly reported arthropod-borne illness in the US and Europe?
Lyme disease
what is persistent infection of Lyme? what are the symptoms?
Lyme disease agents may still survive in localized niches for several years minimal/absent symptoms each of the three pathogenic species may spread to the joints, nervous system, or other skin sites
are humans part of the natural zoonotic cycle of Lyme disease?
NO - we insert ourselves in the cycle
has there been a continuous increase or decrease in Lyme infections?
increase
what is infection-induced autoimmunity?
infection that causes autoimmune response
what is Lyme encephalopathy or polyneuropathy?
late neurologic syndrome manifested primarily by subtle cognitive disturbances, spinal radicular pain, or distal paresthesias very rare in US
for ages 5-10, are more boys or girls infected with Lyme? when are more females infected?
more boys infected up to age 70 past 70 = more females infected
what is the most common Lyme symptom? least common?
most common = erythema migrans least common = cardiac symptoms
in Post-infectious Syndromes, where is B. burgdorferi found?
no bacteria in body antibiotics have no effect on these patients symptoms from messed up immune system leads to prolonged antibiotic use
are whitetailed deer involved in the life cycle of Lyme disease?
no but they are the preferred host to adult bacterium critical for survival of ticks
in what areas of the US is Lyme disease seen most in?
north east (delmarva included) = most cases north/central = some cases not many cases in west has been moving throughout the years to more areas in US
control and prevention of Lyme disease?
prevention/education most important control of Lyme disease depends on public and physician education about personal protection measures, signs and symptoms of the disease, and appropriate antibiotic therapy (USE DEET!!!!!!) if the risk of the infection continues to increase or if public perceptions change = need vaccine again
what animals are involved in the life cycle of Lyme disease in the Northeast US?
reservoir = rodents high rates of infection in rodents between larval/nymphal ticks and certain rodents, particularly whitefooted mice and chipmunks
enzootic cycle of B. burgdorferi infection. when is the greatest risk of infection? in what stage is the disease harbored in?
risk of human infection greatest in late spring and summer (transition from biting small to large animals) harbor disease in larva stage - best transmission to humans adult tick = not much disease transmission (notice them easier bc bigger)
tick and host life cycle. what ticks bite small animals? large animals?
small animals = larva and nymphs large animals = nymph and adult
since surveillance of Lyme has started by the CDC, have reports increased or decreased?
steadily increasing reports
what time of year has the highest cases of lyme disease?
summer (june/july) cycles overlap - people outside a lot with ticks growing up
what other disease occurs around the same time as Lyme disease and can get misdiagnosed?
the flu - most cases of flu-like illness during summer are not caused by B. burgdorferi infection but If a patient from a highly endemic area has a fever-associated illness with headache and joint or muscle pain, without respiratory or gastrointestinal symptoms, antibiotic treatment is needed
what is infection like in the West Coast of the US? what is the life cycle? what is the main reservoir?
the frequency of Lyme disease is low main reservoir = wood rat (different ticks like this species) two intersecting cycles: one involving the dusky-footed wood rat and Ixodes spinipalpis ticks, which do not bite humans and which maintain the cycle in nature the other involving wood rats and I. pacificus ticks, which are less often infected but do bite humans not much of a concern
how does the bacteria evade early detection by the immune system? what is on the surface of bacteria in an unfed tick, fed/attached tick, or during persistent infection in a mammal?
unfed tick = bacteria has OspA on surface fed tick (attached) & early infection = bacteria changes to OspC to evade detection and get into cells persistant infection = VisE
what is a gram stain?
way to classify bacteria (gram negative or positive) gram negative = one layer of peptidoglycan gram positive = 4 layers of peptidoglycan
is prolonged antibiotic use harmful?
yes - causes autoimmune responses
has Lyme Disease been around before?
yes - found in ticks in museums reemerged in 1970s as human pathogen
if Lyme an endemic zoonosis?
yes - persists through the popluation
is there a Lyme vaccine for humans? what happened to it?
yes - use ospA protein limited use by physicians and people so took off the market in 2002 (due to low risk in some areas of US / high cost compared to antibiotic treatment) also need a booster every year for the vaccine there was a theoretical, though never proven, concern that in rare cases, vaccination might trigger autoimmune arthritis have a vaccine that we use for dogs
can reinfection occur in Lyme patients?
Reinfection may occur in patients who are treated with antibiotics early in the illness
what is Treatment-resistant Lyme arthritis?
10% of lyme arthritis persists months/years after antibiotics may have infection-induced autoimmunity!!
how did Lyme disease emerge?
cleared forests to build cities/farms etc deer and predators hunted to almost extinction people moved west and forests started to come back - Farmland reverted to woodland, deer proliferated, white-footed mice were plentiful, and the deer tick thrived. NO PREDATORS RETURNED fragmented forests aka suburbs (predators do not like so did not come back - deer okay with this) proliferation of reservoir (deer) and ticks no population control besides human hunting Soil moisture and land cover, as found near rivers and along the coast, were favorable for tick survival
what was the main driver of Lyme disease emergence?
deforestation and then reforestation (causing increased incidence)
what is needed to treat early onset? neurological symptoms?
early onset - oral antibiotics (better option) neurological = IV antibiotic
