B3-027 Vector-Bourne Infections Flashcards
__________ contributes to changes in vector distribution and local risk
climate change
arboviruses: flaviviridae
yellow fever, dengue, west nile
arboviruses: togaviridae
chikungunya virus
arboviruses are transmitted through
arthropod bite
non-neuroinvasive symptoms of arbovirus
GI symptoms, rash
neuroinvasive symptoms of arboviruses
meningitis or encephalitis
flavivirus binds to
non-specific heparin sulfate or to specific receptors via E protein
+ssRNA flaviviruses use ______________ for protein translation and processing in the ER
host and viral proteases
flaviviruses replicate in the
cytoplasm
flavivirus particles mature in the
trans-golgi
Yellow Fever Virus has _______ antigenic type[s]
a single
YFV endemic areas
Sub-saharan Africa
Central and South America
YF testing is done at
CDC
YF vaccine is
live attenuated
causes a robust innate immune response
IgM and IgG from the YF vaccine can
persist for years
**note patient immunization status when interpreting serology
WNV testing is done at
State PH lab or CDC
treatment for WNV
supportive therapy
prevention of WNV
anti-mosquito measures
dengue virus has [#] different serotypes
4
DENV 1-4
DENV viral entry is facilitated through
host receptor DC-SIGN or Fc receptors
DENV surface proteins
E, prM, and M
NS1 is a virulence factor of
DENV
NS1 causes
thrombocytopenia, hemorrhage, inhibition of complement
anti-body dependent enhancement occurs
upon secondary infection with DENV serotype
anti-body dependent enhancement causes
vascular damage, shock, hemorrhage (GI and skin)
dengue case definition
febrile person with travel history or residence in endemic area +
> 2: nausea, vomiting, rash, aches, pains, a positive tourniquet test, leukopenia
severe dengue case definition
plasma leakage
bleeding
organ impairment
altered consciousness
heart impairment
Trioplex rRT-PCR can be used to diagnose
dengue, chikungunya, zika
dengue can be diagnosed in the acute phase using
DENV-1-4 rRT-PCR
Trioplex
NS1 antigen test
dengue can be diagnosed in the acute and convalescent stage using
serology
IgM: 3d-3m p.i.
the vaccine for dengue is
a live attenuated tetravalent vaccine
the vaccine for dengue is only administered
to non naive people living in endemic areas
symptoms of chikungunya
acute high fever with severe and debilitating polyarthralgia
chickungunya virus is a _______virus spread by ________
togavirus; aedes mosquitos
rocky mountain spotted fever is caused by
rickettsia rickettsii
epidemic typhus is caused
rickettsia prowazekii
human monocytic ehrlichiosis is caused by
ehrlichia caffeensis
human granulocytic anaplasmosis
anaplasma phagocytophilum
small pleomorphic bacteria
rickettsia
obligate intracellular of mammalian cells; grow in cytoplasm
rickettsia
best stain for rickettsia
giemsa
RMSF has a _________ mortality
severe, 5-10%
rickettsia reservoir
rodents
rickettsia rickettsii vector
ticks (dermacentor)
R. prowazekii vector
body louse
R. prowazekii cause epidemics following
war, natural disasters, and in refugees
R. prowazekii is also found in
flying squirrels and squirrel fleas
RMSF classic triad
fever
rash
headache
RMSF fever starts _________ after tick bite
7 days
RMSF rash appears ________ after fever and spreads _______
3-5 days; centripetally
rash spreads centrifugally; on palms and soles
RMSF
rash spread centrifugally; spares face, palms and soles
R. prowazekii
mild recrudescence of latent typhus infection
anamnesic IgG response
Brill Zinsser disease caused by R. prowazekii
rickettsia multiplies in the vascular endothelial cells causing
vasculitis, most prominent in the skin
rickettsia treatment
Doxy immediately based on presumptive diagnosis
rickettsia diagnosis
serology
IFA on two paired samples
PCR
IHC
virulence factors rickettsia
phospholipase A: escape from phagosome
actin based motility
inhibition of apoptosis
obligate intracellular
replicate in phagosome of monocyte (morulae)
ehrlichia/anaplasma
resovoir for ehrlichia chaffeensis
deer/dog
reservoir for anaplasma phagocytophilium
rodent
HME/HGA are clinically
indistinguishable
HME/HGA symptoms
fever, headache, myalgia
no rash = “Spotless, Spotted Fever)
virulence factors ehrlichia/anaplasma
reduction in host cell apoptosis: promotes intracellular survival
upregulation og TfR: iron acquisition
diagnosis of ehrlichia/anaplasma
gold standard: blood culture in cell lines
IFA
morulae in Giemsa
PCR
ehrlichia/anaplasma treatment
tetracycline/doxy
even in children and pregnant women
do not delay treatment, treat for suspicion
borrelia burgdorferi
babesia microti
francisella tularensis
can exist as
co-infections with other tick-bourne pathogens transmitted from the same tick
Coxiella burnetti is caused by
dead end zoonosis
** not vector bourne
acute onset of atypical pneumonia
coxiella burnetti
chronic infection can lead to subacute endocarditis
coxiella burnetti
multiplication in fused phagolysosomes
coxiella burnetti
**need acidic pH
Q fever virulence factors
upregulation of TfR
antigenic phase variation
**highly infections in phase 1