lyme/zoonoses

what does it mean to say ixodids are exophilic?
they are ecologically independent of humans and their domestic environment
what are the two strategies that ticks use in finding hosts?
ambush, (passive waiting on vegetation for host) and hunter, (ticks directly attack host)
how far can ticks engorge?
ticks can increase their body weight by up to 120 fold
what is a caution in rx tx of borreliosis?
a jarisch-herxheimer reaction where a massive amount of bacteria die at once, releasing their endotoxins. this can cause a throbbing headache, diffuse, abdominal pain, fever, hepato-splenomegaly, pancytopenia, worsening rigors and HTN
what is the major phenotypic switch in borrelia borgdorferi from tick to human?
expression of OspA to OspC
what does borrelia borgdorferi express on its surface in persistent infections?
vlse – an antigenic switching protein that helps evade the immune system
is bell’s palsy associated with any other diseases besides lyme?
sarcoidosis, guillain-barre syndrome and HIV can also be associated with lyme
when does arthritis manifest itself in the course of lyme disease?
late
what are the different presentations of erythema migrans?
a large bulls-eye or a disseminated rash more related to the immune sytem. can present as a burning rash with flu-like symptoms
what is lyme disease confirmed by?
ELISA and western blot
where is the risk of lone star ticks tranmitting STARI, (southern tick associated rash illness) greater vs lyme risk?
roughly the policially “red states”. lyme disease is seen more in the “blue states”
why is it hard to develop immunity to borriela borgdoferi?
OpsC, which is expressed on transmission to humans, is highly variable
do boriella borgdorferi have flagella?
yes, they are along the length of the organism and help it move in highly viscous media
what is the “grace period” for b. borgdorferi to come out of the tick and into the human?
48 hrs
what is the hallmark of early-localized lyme disease? other symptoms?
a flat, non-tender, expanding bright red bulls-eye. other symptoms include fever, arthralgia, myalgia, malaise, fatigue, and lymphadenopathy
what is seen in late persistent lyme disease?
after >8 wks, oligoarticular (migratory/episodic) arthritis is seen along with encepthalopathy w/memory deficit, irritability, somnolence, and neuropathy with distal paresthesias and radiculoneritis
if untreated, what can lyme disease result in neurologically?
15% may experience: aseptic lymphocytic meningitis, cranial nerve VII palsy.
Headache, fatigue, vertigo, confusion, and impaired cognition, sleep, hearing,
memory and vision may be observed. Neuroborreliosis has been at the center of a perfect medical-sociologic storm.
if untreated, what can lyme disease result in in the heart?
5% may experience A.V. conduction block, bundle branch block. Symptoms are palpitations, syncope, dizziness, dyspnea and chest pain.
if untreated, what can lyme disease result musculoskeletally?
60% of pts experience migratory polyarthritis, monoarticular (knee) with painful, swollen and stiff joints.
if untreated, what can lyme disease result neuropsychiatrically?
school-age children are often
misdiagnosed as learning, behavioral, or attention deficit disorders.
what are surveillance criteria for erythema migrans rashes?
Rash must exceed >5cm in diam
It should show expansion (peripheral migration of organisms)
It should persist for >1 week.
is previous exposure to boriella borgdorferi enough to grant future immunity?
previous infection is not necessarily protective against future infections.
are the ELISA or western blot tests useful in assessing tx success or following up?
no
what is lack of reponse to antibiotic tx viewed as with lyme disease?
justification for more antibiotics
what is chronic lyme disease/post LD syndrome?
after appropriate rx, a small number of patients continue to have subjective symptoms, like musculoskeletal pain, neurocognitive difficulties or fatigue
what are public health measures for lyme disease control?
vector control, altering the landscape or wildlife population, tick checks – looking for “new freckles” that are moving. an attached tick, which is
not engorged, is very unlikely to have transmitted LD.
what is an uncommon presentation of lyme disease? where is it commonly seen?
acrodermatitis chronicum atrophicans, a widespread atrophy of the skin. involvement of the peripheral nervous system is often observed, specifically polyneuropathy. it is commonly seen in europe
is IgM helpful in diagnosis of lyme disease?
no
does STARI present with a similar rash to lyme?
yes
what is the most fatal tick borne infection in america?
rocky mtn spotten fever
what is the tx for rocky mtn spotten fever?
doxycyline, even if pt is young or pregnant -> lifethreatening
where does the rash for rocky mtn spotted fever begin?
wrists, ankles, then they move to palms, soles, and trunk
does rock mtn spotted fever cause gangrene?
yes, it is a particularly bad sign if this is seen on the scrotum
what happens if rocky mtn spotted fever becomes systemic?
it can cause acute respiratory distress syndrome
what is the causative organism of rocky mtn spotten fever? vector?
rickettsia rickettsii, ticks are the vector
what is the difference between anaplasmosis and ehrlichiosis?
ehrlichiosis and anaplasmosis are two closely related tickborne, (ixodes scapularis, amblyoma americanum) diseases, caused by different bacteria. anaplasmosis affects granulocytes, ehrlichiosis affects monocytes
what is diagnosis and tx for anaplasmosis?
morula, (intracellular inclusions) visible under a microscope and PCR is diagnostic for anaplasmosis. doxycyline is the tx
what is babesiosis similar to? is it tick borne? what is diagnostic for babesiosis? who is more at risk for this disease?
the relapsing fever it causes can resemble malaria. it is tick borne. the maltese cross, (intraerythrocytic tetrads/rings), is diagnostic for babesiosis as well as howell-jolly bodies (histopathological findings of basophilic nuclear remnants). orange-colored urine is another tip. asplenic pts are more at risk for hemolytic anemia associated with this disease
what can babesiosis be treated by?
clindamycin or quinine
how does babesiosis affect the eyes?
it causes icteric skin and sclera
can babesiosis be transmitted through the placenta of pregnant women?
yes, this can lead to congenital babesiosis, with hyperbilirubinemia
what causes “rat bite fever”? what is it treated with?
streptobacillus moniliformis, which can cause arthralgia, blisters. it is treated with PCN
what is the bacteria what can infect in relation to dog or cat bites? how does it gram stain?
pasteurella multocida, which gram stains gram negative
what is another organism associated with dog bites?
capnocytophaga canimorsus (gram -)
what is the difference between human and dog bites?
Human bite marks – superficial abrasions or contusions (incisors have rectangular marks and canines leave triangular marks). dog’s canines leave deep puctures, with tissue tearing
what are zoonotic infections? do they include malaria?
diseases transmitted among vertebrate animals, therefore malaria is not included
bacillus anthracis would be harmless except for which of its products that can be made “weapons grade”? how is it made into a bioweapon?
its spores which, if treated with silica (removes static charge) become unclumped and able to be inhaled
how does bacillus anthracis appear? gram stain? are they easily grown?
bacillus anthracis are gram + rods,
arranged like box-cars or bamboo shaped.
they are easily grown on regular media in about 18 hrs
what are the 3 types of anthrax?
inhalation (most used type in bioterrorism), GI and cutaneous
what are the virulence factors for Bacillus anthracis?
protective antigen (key player -> used in vaccine), edema factor, lethal factor and capsule
what can a cutaneous anthrax infection appear as? why?
a spider bite, due to similar diffuse edema of sub cuteanous tissue
what is anthrax eschar? what usually surround it?
the dry scab which forms at site of cutaneous infection, which is usually surrounded by vesicles and indurated plaque
what characterizes cutaneous anthrax?
brawny/gelatinous edema
what characterizes brown recluse spider bites?
“red, white and blue” sign: concentric zones of erythema, ischemia and cyanosis
why does cutaneous anthrax still evolve even after antibiotic tx?
b/c the tissue damage is toxin mediated
do anthrax spores cause disease?
no, the vegetative form must grow and produce toxin
what antibiotics should be used to treat environmental vs weapons-grade anthrax?
IV PCN should treat environmental anthrax, while weapons grade anthrax should be treated with broad spectrum antibiotics, (such as doxycycline or quinolones)
what can happen with a disseminated anthrax infection, (bacteria found in blood/CSF)?
mental changes, cardinal’s cap: congested leptomenges, frontal/parietal hematoma
can anthrax spores come on african drums?
yes
what are the early symptoms of anthrax infection?
fever, myalgia, fatigue, chills, cough
what are the later symptoms of anthrax infection?
meningitis, stridor, pleural effusions, widened mediastinum, hemmorrhagic mediastinitis, distress, septic shock, cyanosis, chest pain, dyspepnea, nausea, bloody diarrhea, abdominal pain, myalgia, painless necrotic ulcers with black base, (from direct dermal contact)
what might mediastinal widening on a xray/CT scan be indicative of?
anthrax infection
is there an anthrax vaccine?
yes, (6 shots and a yearly booster)
what are the vectors for plague?
fleas carried by rodents
can anthrax or plague be transmitted person to person?
anthrax can’t, plague can
what is a bubo? what is a precaution related to them?
very painful lymphdenopathy caused by the plague, transmitted by fleas. aspirate from bubos can be transmittable to physicians who stand directly in front of them
what is pneumonic plague?
plague which has infected the lungs, highly transmittable. associated with bacteremia/fever
where does plaque bacteria like to localize? why?
plaque bacteria like to localize in peripheral tissue, they prefer lower temperatures
what is the name for the bacteria that causes the plague? what stain is diagnostic for it? what is its morphology?
yersinia pestis which the wayson stain is diagnostic for. Y. pestis is a rod-shaped facultative anaerobe with bipolar staining (giving it a safety pin appearance)
has quarantine been used for plaque prevention through history?
yes there wasa 40-day quarantine on plague-infected ships coming into venice, there are also biblical accounts
what is a symptom of tularemia? diganosis? treatment?
tularemia pts present with lymphadenopathy, (supre/infra clavicular), and oozing green pus. the bacteria are gram negative and are detected via serology. the treatment is streptomycin
what are ways of recieving a tularemia infection?
tick and deer fly bites, skin contact with infected animals (particularly rabbits), ingestion of contaminated water, or inhalation of contaminated dusts or aerosols.
what is the baceria causing tularemia? is it virulent?
francisella tularensis, which is highly virulent -> potential bioweapon
what can francisella tularensis be confused with?
haemophilus spp
can eating medium roasted rabbit cause tularemia?
yes
what do hamsters infected with tularemia die of?
“wet tail disease”
can sniffing the agar upon which francisella tularensis is growing cause tularemia?
yes
what does the typhoidal form of tularemia present as?
the typhoidal form presents as
non-specific pleuro-pneumonitis
what is brucellosis, (malta fever), caused by? how is it transmitted? how is it diagnosed? what is tx?
brucella causes a painful, lingering disease with pyrexia, anemia, and joint involvement. it is transmitted by direct contact, inhalation of aerosol, and consumption of **non-pasturized dairy products. it is diagnosed via serology and is treated with doxycycline and rifampin
what causes Q fever? what biosafety level is it? how is it transmitted?
coxiellea burnetii, it is BSL 3 (pretty deadly, 4 is the highest). it originated in australia, and can be transmitted through contact with animals or aerosolized as a bioweapon
what is the clinical triad of Q fever? how is it diagnosed?
fever, hepatitis, and atypical pneumonia. it is diagnosed by antibody detection in an immunofluorescence assay. it is treated by doxycycline.
can Q fever affect the heart?
yes, q fever can cause cx-negative endocarditis
what is diagnostic for Q fever?
a doughnut-shaped granuloma and serology positive for coxiellea burnetii
what is bacillary angiomatosis? what organisms cause it? what patients might you see this with more commonly?
knots of capillaries in various organs caused by intraerythrocytic bacteria such as babesia, malaria and bartonella. this is seen in HIV pts.
how is bacillary angiomatosis caused by bacteria?
extremely fastidious, tiny gram-neg bacilli infecting small blood vessels to proliferate in the skin and in visceral organs in an immunocomp. host
what is the identifying stain for bartonella? what is this bacteria associated with?
warthin-starry stain. bartonella is associated with bacillary angiomatosis
where does Bartonella henselae come from?
flea-infected cats
where does Bartonella quintana come from?
human body louse
are Bartonella intraerythrocytic?
yes
what are symptoms of pts with bacillary angiomatosis?
Patients are almost invariably
febrile with fatigue and anaemia.
do many dogs and cats have antibodies against bartonella?
yes
what is the tx for bacillary angiomatosis?
erythromycin or doxycycline
what are peliosis in relation to bacillary angiomatosis?
large blood-filled spaces
what are some symptoms of Bartonella henselae infection? what is diagnostic?
worsening headache, unilateral decreased visual acuity. retinoscopy revealing : optic disk elevation,
edema, lipid exudates forming a
macular star, choroiditis, Bartonella henselae antibodies are diagnostic. treatment is prednisone/azithromycin
what is a possible dx for a pt who is HIV positive, lice infested, with purplish lesions?
bartonella infection
can bartonella cause glomerulonephritis and endocarditis?
yes
what is cat scratch fever? what is a common diagnostic?
baronella henslae infections usually seen in immune-compromised hosts. lymphadenopathy is often seen with this.
what is leprospirosis?
a disease caused by leptospira. symptoms include fever, headache, chills, nausea and vomiting, eye inflammation, and muscle aches. in more severe cases, the illness can result in liver damage and jaundice (yellowing of the skin and whites of the eyes), kidney failure, and internal bleeding. it is a biphasic disease
when is leptospirosis seen often in human? where does it come from?
after heavy rains/floods. it comes from rodent urine
how are leptospirosis, lyme disease, and syphillis related?
they are all caused by spirochetes
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