arthropod-borne virus Flashcards
acronym for arthropod-borne virus.
Arbovirus
___ known arboviruses, __pathogenic to human and___to animals
500
100
50
arthropods
mosquito,ticks,ffly,mites
aedes mosquito (near water) what disease?
dengue and yellow fever
culex mosquito (forest) what disease?
st louis encephalitis
primary infection in what cells
macrophage/monocytes
secondary viremia affects
brain,liver,vasculature,skin
3 families of arthropod
bunya
toga
flavi
family:
flavivirus
genus:
flavivirus\
what diseases?
St. Louis encephalitis virus, Yellow fever virus,
dengue virus, West Nile virus
fam:
Toga
genus:
alpha
Eastern equine encephalitis virus, Western
equine encephalitis virus, Chikungunya virus
fam & genus:
bunya
California encephalitis virus
Bunyaviridae
4 virus
California encephalitis virus
• Rift valley fever virus
• Sandfly fever virus
• Hantavirus – no arthropod vector
Bunyaviridae
morphology
- (-) ssRNA
- 3 segments
- Helical symmetry
- All are arthropod-borne except Hantavirus
Bunyaviridae
clinical findings
Fever • Encephalitis • Hemorrhagic fever + renal syndrome (Europe and Asia) • Hemorrhagic fevers o Hantavirus o Sandfly/Rift valley fever virus o Crimean-Congo hemorrhagic fever • Hantavirus pulmonary syndrome - Fever, muscle aches, cough, N/V, pulmonary edema leading to respiratory failure -80% mortality
bunya tx
ribavirin
bunya target organs
cns liver lungs vasculature endothelium
California encephalitis virus
TRANSMISSION: • MORTALITY: • INCUBATION: • DIAGNOSIS: • CLINICAL MANIFESTATION:
culex mosquito, forests of North America
< 1%
3-7 days
RT-PCR in lung tissue
o Prodrome: fever, chills, nausea, vomiting, headache, lethargy,
abdominal pain (1-4 days)
o Fever, drowsiness, lack of mental alertness/orientation, seizures (50%
of children), focal neurologic findings, coma (10%)
hanta virus aka
Sin Nombre virus.
Korean hemorrhagic fever
Hantavirus pulmonary syndrome
hantavirus transmission:
mortality:
inhalation of infected rodent urine/feces
up to 50%
Togaviridae
alphavirus:
Western Equine encephalitis (WEE) from:
culex tarsalis mosquito
Togaviridae
alphavirus:
Eastern Equine encephalitis (EEE) from
aedes, culex
Togaviridae
alphavirus:
Venezuelan Equine encephalitis (VEE) from
Aedes, Psorophora, Culex
Togaviridae
rubivirus
no insect vector
Togaviridae
alphavirus:
morphology
- (+) ssRNA
- Non-segmented
- Icosahedral symmetry
- Replicates in the cytoplasm
- Enveloped
- Vector: insect for WEE, EEE, VEE
- MOT: respiratory secretions, transplacental
Togaviridae
alphavirus:
clin findings
- Headache and fever
- Altered loss of consciousness
- Focal neurologic deficits
- rubella
Togaviridae
alphavirus:
lab dx
• Culture – can be grown in both vertebrate and mosquito cell lines but
difficult to isolation
• Cytopathologic studies
• Immunofluorescence
• Reverse transcriptase-PCR
• Serology – hemagglutination inhibition, ELISA, latex agglutination
o Presence of specific IgM or 4-fold rise in titer between acute and
convalescent sera indicate a recent infection
Togaviridae
alphavirus:
prevention/tx
• MMR vaccine
o Live attenuated
o 3 doses
Togaviridae
Alphavirus
-Chikungunya virus
morphology
- (+) ssRNA
- Non-segmented
- Icosahedral symmetry
- Replicates in the cytoplasm
- Enveloped
Togaviridae
Alphavirus
-Chikungunya virus
vector
aedes aegypti, aedes albopictus, culex fatigans
Togaviridae
Alphavirus
-Chikungunya virus
clin findings
- Benign dengue-like syndrome
* Fever, arthralgia, maculopapular rash, leukopenia
Togaviridae
Alphavirus
-Chikungunya virus
prevention/tx
- Supportive
- Antipyretics
- Bed rest
chikungunya meaning
Swahili for “that which bends up”
Togaviridae
Alphavirus
-Chikungunya virus
dx
sero,pcr,viral culture
Togaviridae
Rubivirus
-Rubella
- aka
- a _____ disease
- transmission
- peak incidence
- IP
German measles, 3-day measles
mild
oral droplet and transplacental
5-14 years
14-21days
Togaviridae
Rubivirus
-Rubella
clinical manifestation:
• Rash occurs__ days after exposure
• Prodrome: mild catarrhal symptoms (young children have prodromal
symptoms)
• 2/3: subclinical
• In adolescents and adults: eye pain, sore throat, headache
• Most characteristic sign: (4)
• _____ evident 24 hours before the rash and remain for 1
week or more
• _____: discrete rose spots on the soft palate (_____) à
coalesce à red blush extend over the face
• _____: erythematous, maculopapular and discrete
• Starts centrally and spreads centrifugally
• 2nd day: pinpoint appearance on the trunk
• 3rd day: eruption clears
• Rash is pruritic particularly in adults
• Pharyngeal mucosa and conjunctiva slightly inflames
• No photophobia
• Temperature elevation not marked (low-grade fever x 1-3 days)
17
retro-auricular, post-cervical and postoccipital
lymphadenopathy
Lymphadenopathy
Enanthem
Forchheimer spots
Exanthem
Togaviridae
Rubivirus
-Rubella
Complications:
• Joint involvement
o ___ & ___ are the most common complications in
adolescents and adults
o Polyarthritis with arthralgia, swelling, tenderness with effusion x 2
weeks
o Small joints of the hands
o____ are affected 4-5 times more frequently than ____
• Thrombocytopenia
o Rare complication
o Occurring in 1 on 3000 cases
• Neurologic
o Encephalitis is a rare complication and occurs with greater
frequency in children
o Occurs in 1 per 6000 cases
o Observed 2-4 days after the onset of the rash
• Mild hepatitis
o Rarely reported complication of rubella
Arthralgia and arthritis
Females,males
Togaviridae
Rubivirus
-Rubella
tx:\_\_\_\_ prevention: • MMR vaccine o \_\_\_months o 2nd dose: \_\_\_\_years o Females should be advised not to become pregnant 3 months after receiving rubella vaccine
Supportive
12-15
4-6 years
Togaviridae:
Congenital rubella syndrome
classic triad:
Sensorineural hearing loss
Ocular abnormalities
Sensorineural hearing loss
Togaviridae:
Congenital rubella syndrome
§ Most common manifestation of congenital rubella syndrome
§ Occurs in approximately 58% of patients
Sensorineural hearing loss
Togaviridae:
Congenital rubella syndrome
§ Cataract, infantile glaucoma, and pigmentary retinopathy
§ Occurs in approximately 43% of children
Ocular abnormalities
Togaviridae:
Congenital rubella syndrome
§ Patent ductus arteriosus (PDA) and pulmonary artery stenosis
§ Present in 50% of infants infected in the first 2 months of
gestation
Sensorineural hearing loss
Flaviviridae
2 virus
• Hepatitis C virus • Arboviruses: o Dengue virus o St. Louis encephalitis virus o Yellow fever virus o West Nile virus o Zika virus
Flaviviridae
morphology
• (+) ssRNA • Non-segmented • Icosahedral symmetry • Replicates in the cytoplasm • Enveloped • Vector is mosquito o Aedes – Yellow fever, Dengue fever o Culex – St. Louis, Japanese, West Nile encephalitis
Flaviviridae clin findings: yellow fever (3) dengue/breakbone fever (2) st louis japanese, west nile encephalitis (2)
hepatitis, fever, backache
painful fever, DHF
encephalitis, fever
Flaviviridae
prevention/tx:__
mosquito control
Flaviviridae
dx:
___
repeated infection,high risk of ___
viral culture/sero
DHF
Flaviviridae Dengue Fever -how many serotypes? -acute febrile illness syndrome -caused by arbovirus
4- DEN-1 to DEN 4
Flaviviridae
Dengue Fever
Most common insect-borne viral disease in the world. t/f
t
Flaviviridae
Dengue Fever
transmission
Bite of female mosquito (aedes aegypti, aedes albopictus)
recognized by white markings on its legs and a
marking in the form of a lyre on the upper surface of its thorax
Aedes aegypti
Flaviviridae
Dengue Fever
clinical findings
• Fever
• Maculopapular rash
• Myalgia/Arthralgia – “breakbone fever”
•Leukopenia/Thrombocytopenia/Inc hematocrit
• Lymphadenopathy
• Hemorrhagic shock is due to cross reacting antibody during the 2nd
infection
Flaviviridae
Dengue Fever
diseases(2)
- Dengue fever (breakbone fever)
- Dengue hemorrhagic fever, under this is hemorrhagic shick syndrome
Influenza-like syndrome characterized by biphasic fever,
myalgia, arthralgia, rash, leukopenia and lymphadenopathy
Dengue fever (breakbone fever)
Severe, often fatal, febrile disease characterized by capillary
permeability, abnormalities of hemostatic and protein-losing
shock syndrome
Dengue hemorrhagic fever
_____is due to the production of large
of cross-reacting antibody at the time of a second dengue
infection (antibody-dependent enhancement)
Hemorrhagic shock syndrome
course of dengue illness:
While the exact reason for the severity is still unknown, studies have
linked the severity to _____. This
theory was first described in 1964, when it was observed that serious
dengue infection was linked to secondary infection.
antibody-dependent enhancement (ADE)
After a primary infection with one dengue virus serotype, the immune
system produces antibodies that bind and neutralize secondary
infection with the same serotype, however, a secondary heterotypic
infection may lead to enhance severity. t/f
t
The antibodies produced from the primary infection have the ability to
bind to the virus but lack the ability to neutralize.t/f
t
Flaviviridae
Dengue Fever
lab dx:
___: to detect gene product (NS1 glycoprotein) from day ___
until day __ from the onset of fever
• ____: to detect dengue viral genes (RNA) in acute phase serum
samples which coincide with the onset of viremia
• ___: marker of recent infection
• ___: marker of past infection; a fourfold increase confirms the
diagnosis
• ____: characteristic findings are thrombocytopenia with
leukopenia. A hematocrit level increase >20% is a sign of
hemoconcentration and precedes shock
NS1 antigen 1 6 RT-PCR Dengue IgM Dengue IgG CBC-PC
Flaviviridae
Dengue Fever
prevention
• Insecticides
• Draining stagnant water
• Mosquito repellent
• Dengue vaccine
o Dengvaxia (CYD-TDV)
§ First licensed in Mexico on December 2015 for use in
individuals 9-45 y/o living in endemic areas
§ Live recombinant tetravalent dengue vaccine
§ Given as a 3-dose series on a 0/6/12-month schedule
Flaviviridae
Japanese Encephalitis Virus
- how many serotype?
- vector
- ___important source of viral amplification (some birds)
- dead end host
- prevalent among rural areas
1
culex mosquito
pigs
man
Flaviviridae
Japanese Encephalitis Virus
clin findings
- Fever
- Rash
- Myalgia/Arthralgia
- Leukopenia/Thrombocytopenia
- Lymphadenopathy
Flaviviridae
Japanese Encephalitis Virus
complications
- Aseptic meningitis or encephalitis
- Fever, headache, nausea
- Confusion, motor abnormalities
- Seizures, respiratory failure
Flaviviridae
Japanese Encephalitis Virus
dx
• (+) Serum JE-specific IgM (ELISA)
• (+) CSF IgM JE-specific (ELISA)
• Four-fold increase in titer between acute and convalescent-phase
serum by hemeagglutination inhibition (HAI)
Flaviviridae
Japanese Encephalitis Virus
prevention
Japanese encephalitis virus vaccines
Flaviviridae
Japanese Encephalitis Virus
tx
- Supportive, CFR 10-35%
* Remember: immunity is permanent after single infection
Togaviridae
West Nile Virus
transmission
- Bite of culex mosquito
- Reservoir: wild birds
- Humans are the dead-end hosts.
Most common cause of neuro-invasive arboviral disease
west nile virus
Togaviridae
West Nile Virus
most important clinical picture:
encephalitis with or without signs of
meningitis (typically in >60 years of age)
Togaviridae
West Nile Virus
Asymptomatic in 80%; fever and headache in 20%; encephalitis in 1%
t/f
t
Togaviridae
West Nile Virus
lab dx
viral isol
pcr
Togaviridae
West Nile Virus
tx
no antiviral therapy
Togaviridae
Yellow fever virus
reservoir
monkey/human
Togaviridae
Yellow fever virus
diseases
• Characterized by___&___
• Severe, life threatening disease that begins with sudden onset of fever,
headache, myalgias, and photophobia
• After this prodrome, the symptoms progress to involve the liver, kidneys,
and heart
• Prostration and shock occur, accompanied by ___ with ___
jaundice and fever
UGIT hemorrhage with
hematemesis (“black vomit”)
Togaviridae
Yellow fever virus
lab dx
May see councilman bodies or apoptotic bodies (eosinophilic
apoptotic globules) on liver biopsy
Togaviridae
Yellow fever virus
prevention
- Mosquito control
* Vaccine containing live, attenuated yellow fever virus
Togaviridae
Hepa C virus
transmission
parenteral, sexual, perinatal
Togaviridae
Hepa C virus
PHASES OF ACUTE HEPATITIS:
o ____ – fever, malaise, anorexia
o _____ – nausea, vomiting, abdominal pain, fever, chills
o___ – jaundice, dark urine, increase in liver enzymes
Prodromal
Preicteric
Icteric
