ticks and bugs and stuffs Flashcards
pathogen, vector, and host of lyme disease?
pathogen: borrelia burgdorferi (gram negative spirochete)
vector: ixodes scapularis (blacklegged deer ticks)
host: white tailed deer
during which life cycle phase do ticks typically bite and infect humans with lyme?
nymphal stage!
how long must a ticks bloodmeal be in order to infect a human? what must occur?
24-48 hours to get the bacterium from the gut to the mouth, there must be OSPa to OSPc conversion because A is not infectious but C is!
what does a tick secrete when it bites us?
an anesthetic and anticoagulant
hinders pain and clotting so we can’t detect it when it happens!
what is the first stage of a lyme disease infection?
erythema migrans (80 percent); bullseye rash that shows up 7-10 days post bite and is sometimes associated with viral-like syndrome (headaches, fever, malaise)
what is the second stage of a lyme infection?
early disseminated (1-2 weeks)
- arthralgias
- multiple erythema migrans
- CN 7 palsy, radiculoneuritis, neuropathy
- AV BLOCK!
what does late disease (over 6 months) of lymes disease consist of?
persistent arthritis (usually knee), neurological issues (peripheral axonal neuropathy, mild encephalopathy, encephalomyelitis)
how do we diagnose lyme disease?
often clinically
ELISA followed by western blot if ELISA positive
PCR can be done in research labs
treatment of lyme disease?
doxycycline in adults; amoxicillin DOC in children 9 years and younger
when would we consider treating lyme with IV ceftriaxone?
complete heart block, CNS diseases
what is post-lyme syndrome?
prior LD with stabilization post RX; persistence of fatigue, MSK pain, cognitive complaints past 6 months
what are the four conditions in which prophylaxis with doxycycline is indicated for lyme?
1) tick has been identified as engorged deer tick attached over 36 hours
2) exposure occurred in an area where there is a high rate of infected ticks
3) prophylaxis can be started within 72 hours
4) doxy treatment is not contraindicated
**even if prophylaxis used, monitor symptoms for 30 days
do we continue to treat people with post-lyme syndrome with ABX?
NO!
pathogen and vector for rocky mountain spotted fever?
pathogen: rickettsia rickettsi (spirochete bacteria)
vector: dermacentor (hard or dog) ticks
which of our tick disease is potentially fatal but easily curable? how do we treat it?
rocky mountain spotted fever, treat with doxycycline (even in children)
what type of acquisition accounts for the majority of rocky mountain spotted fever cases?
peridomestic acquisition
who is most likely to acquire RMSF?
MALE CHILDREN
early symptoms vs. late symptoms of RMSF?
early: high fever, headache, myalgia, GI symptoms
late: RASH, photophobia, confusion, ataxia, seizures, JAUNDICE, thrombocytopenia, hyponatremia
how does the rash of RMSF present?
red maculopapular rash FIRST on wrists/ankles/forearms that spreads centrally to the trunk
petechiae after day 6
face usually spared!
long term sequelae of RMSF?
CNS deficits, amputations
why is diagnosis of RMSF difficult?
85% of patients lack diagnostic titers in first week of illness
need to test acute and convalescent samples (2-4 weeks apart) via indirect immunofluorescence; a four-fold rise in titers is confirmatory
pathogen, vector, and reservoir for anaplasmosis?
pathogen: BACTERIAL infection (caused by rickettsial agent anaplasma phagocytophilum)
vector: ixodes scapularis (black legged tick)
reservoir: HGA: deer & white footed mouse
what is the pathogenesis of anaplasmosis?
infects WBC and granulocytes over 24-48 hours
you will see granulocytes on peripheral blood smear
where is ehrlichiosis most common? what tick is responsible for infecting humans?
south!
lonestar tick
what is STARI? how does it present?
southern tick associated rash illness
cause is unknown; transmitted by lonestar tick
get similar rash as lyme but NO arthritic, neurologic, or chronic symptoms
what disease is considered our “summer flu”? how does it present?
anaplasmosis
fever, chills, severe headache, malaise, myalgia, arthralgia
some cough, GI upset, stiff neck
what laboratory findings are associated with anaplasmosis?
mild anemia
thrombocytopenia
leukopenia with a left shift
mild elevation of LFT
how do we diagnose anaplasmosis?
PCR assay for DNA
four-fold rise in IgG antibody by IFA
immunochemistry staining of organism
treatment of anaplasmosis?
doxycycline
which of our tick infections is a parasitic infection?
babesiosis! caused by protozoa of the babesia genus
pathogen, vector, and reservoir for babesiosis?
pathogen: babesia microti
vector: ixodid tick
reservoir: ANIMALS! rodents and small animals
where does babesiosis primarily infect?
the red blood cells! causes hemolysis
considered the “american malaria”
where in the US is babesiosis most common?
northeast!
incubation period for babesiosis?
following tick bite: 1-3 weeks
following blood transfusion: 6-9 weeks
symptoms of babesiosis? what will PE look like?
fever, chills, myalgia, arthralgia, fatigue, NV
PE: splenomegaly, hepatomegaly, JAUNDICE
what are some risk factors of developing severe disease with babesiosis?
over 50 asplenia malignancy HIV immunosuppressives
is asymptomatic disease common in babesiosis? why is this nervewracking?
YES. this is how it is transmitted via infusion!
how does severe babesiosis present?
high-level parasitemia (over 10 percent)
significant hemolysis (plus DIC)
renal, hepatic, pulmonary compromise
how will labs look for someone with babesiosis?
anemia, thrombocytopenia, increased conjugated bilirubin
how do we diagnose babesiosis?
blood smear (intra-erythrocytic parasites)
PCR
serology for antibody testing
first line treatment for babesiosis?
clindamycin/quinine
OR
atovaquone/azithromycin
which tickborne disease is uncommon but has been found in every state besides hawaii?
tularemia
125 cases/year
what type of tickborne disease is tularemia?
bacterial disease (francisella tularensis)
gram-negative, non-motile, non-sporulating coccibacillus
how is tularemia transmitted?
via the american dog tick, lone star tick, and rocky mountain wood tick, deer fly bites, inhalation, ingestion, or skin contact with infected animals
what species does tularemia infect? who are the vectors?
small mammals (squirrels, rabbits, muskrats, etc.)
arthropod vectors (ticks, biting flies, mosquitoes)
which of our tickborne diseases kills less than 50 people a year worldwide?
tularemia
why is tularemia so concerning in terms of transmission?
it is HIGHLY infectious (inhalation of 10 bacteria can cause disease)
can tularemia be spread person to person?
NO!
just by arthropod intermediates or animal bites
what are the types of disease forms that tularemia can cause?
ulceroglandular (less than 5 percent mortality)
oculoglandular
typhoidal syndrome (30-60 percent mortality)
oropharyngeal
gastrointestinal
pneumonia
what is the gold standard for diagnosing tularemia?
PCR!
know there is a high risk to lab personnel with culture
treatment of tularemia?
streptomycin, gentamycin
ciprofloxacin
mortality=0 with treatment
what is the name for the group of acute infections caused by the athropod born spirochetes of the genus borrelia?
relapsing fevers
what are relapsing fevers characterized by?
infection by borrelia genus
recurrent cycles of febrile episodes, separated by asymptomatic intervals of apparent recovery
borrelia recurrentis causes what type of relapsing fever?
louse-borne relapsing fever!
case fatality is 10%
spread when uninfected human crushes infected louse and it enters abraded skin
invades bloodstream
bartonella quintana causes what type of relapsing fever?
trench fever! less serious (flu-like symptoms), rarely fatal
characteristic five-day fever
rickettsia prowazekii is responsible for causing what type of relapsing fever?
epidemic typhus!
significant contributor to worldwide mortality prior to ABX
which of our relapsing fevers is considered a category B bioterrorism agent?
epidemic typhus! caused by rickettsia prowazekii
which type of lice is the only lice that can transmit disease?
body lice!! pediculosis humanus
what is the pathogenesis of relapsing fever?
1) lice is crushed
2) incubation period 5-10 days
3) patient produces neutralizing antibodies (clear circulating strain in 3-5 days)
4) new antigenic variants appear (3-5 relapses may occur)
treatment of relapsing fever?
penicillins
tetracyclines
