Viral (V-Z) Flashcards
what is the virus causing chickenpox?
varicella-zoster virus (VZV)
Herpesviridae family
how does VZV get transmitted?
-respiratory route - inhalation of aerosols -from vesicular fluid of skin lesions
-direct contact
-enters through the upper respiratory tract or the conjunctiva
-utero infection also can occur due to transplacental passage of the virus during maternal varicella infection
-herpes zoster rash cause varicella, not herpes zoster, in susceptible people
how contagious is VZV?
what is contagious period for VZV?
-highly contagious, secondary attack 85%
-herpes zoster is 20% as infectious as varicella
-1-2 days before the onset of rash and ends when all lesions are crusted, typically 4-7 days after onset of rash
-herpes zoster: while they have active, vesicular lesions (7-10 days)
which part of the body does chickenpox rash first appear?
chesk, back and face
-then spread over the entire body in 3 successive waves and resolve by crusting
what is the chicken pox complication?
cerebellar ataxis, encephalitis, hemorrhgic conditions, pneumonia, secondary bacterial infections of skin lesions (bacteremia or sepsis)
rare death (1 in 40,000 varicella cases)
what is modified varicella?
varicella in vaccinated people - mild, <50 lesions, low or no fever, shorter duration for rash, fewer vesicles and predominance of maculopapular lesions
which testings are available for chickenpox diagnosis?
- nucleic acid amplification testing: specimen from skin lesions, PCR testing or direct flourescent antibody
- serologic testing: varicella IgG titers, to confirm disease but less reliable than PCR or direct fluorescent antibody methods for virus identification; IgM not recommended
how to treat chickenpox?
antiviral not recommended routinelyly for healthy children with varicella
-acyclovir oral
-acyclovir IV for immunocompromised
-initiate tx within 24 hours to maximize efficacy
-no aspirin or aspirin-containing products and ibuprofen
what is the VZV vaccine and dose?
1 - 12 yr: 2 doses more than 3 months apart (typical schedule: 12-15 month & 4-6 years)
13 yr and up: 2 doses 4 weeks or more apart
no recommendation for vaccine for infants aged < 12 months before international travel
what is vaccine efficacy of VZV?
80% after 1 dose;
92-95% after 2 doses
what is postexposure prophylaxis of VZV in unvaccinated people?
-vaccine ASAP - within 5 days after exposure
-immune globulin (VariZIG): immunocompromised, pregnant without evidence of immunity, some neonates and infants; ASAP but as late as 10 days is still ok.
-intravenous immunoglubulin (IVIG) 400mg/kg if VariZIG not available
-oral acyclovir 80mg/kg/day in 4 divided doses for 7 days upto max of 800mg qid, beginning 7-10 days after exposure
what are the 3 virus families and 1 order virus that cause viral hemorrhagic fever diseases (VHF)?
Arenaviridae
Filoviridae
Flaviviridae
order Bunyavirales
what viruses are Arenaviridae (arenaviruses) that cause viral hemorrhagic fever disease?
Chapare
Guanarito
Junin
Lassa
Lujo viruses
lymphocytic choriomeningitis virus (LCMV)
Machupo and Sabia varuses
what viruses are filoviridae (filoviruses) that cause viral hemorrhagic fever diseases?
Ebola, Marbur, Reston viruses
what viruses are Flaviviridae (flaviviruses) that cause viral hemorrhagic fever diseases?
Alkhurma, Kyasanur Forest disease
Omsk kemorrhagic fever
Dengue
Yellow fever viruses
what viruses in the order Bunyavirales that cause viral hemorrhagic fever diseases?
Arenaviridae family viruses
Crimean-Congo hemorrhagic fever virus
hantaviruses
rift valley fever virus
what are the viruses of VHF viruses that can be transmitted person to person?
arenaviruses, CCHF virus, filoviruses - direct physical contact of unprotected skin or mucous membranes and the blood
how long can Ebola virus and Marburg virus can persist in body fluids?
upto 21 days~ 33 days~ 2-3 months
what are the viruses of VHF viruses that can be transmitted through arthropd vectors?
some bunyaviruses (RVF virus) and flaviviruses (dengue and yellow fever) -mosquitoes
some bunyaviruses (CCHF virus) and flaviviruses (Alkhurma, Kyasanur Forest disease and Omsk viruses) - tick bite or crushing infected ticks
what are the viruses of VHF viruses that can be transmitted through bats?
filoviruses - Ebola, Marburg viruses
Natural reservoir for Marburg virus is the Egyptian fruit bat (Rousettus aegyptiacus)
what are the viruses of VHF viruses that can be transmitted through livestock?
some bunyaviruses (CCHF and RVF viruses) and flaviviruses (Alkhurma virus) can be transmitted during slaughter of infected animals or from the consumption of raw meat or unpasteurized milk of an infected animal
what are the viruses of VHF viruses that can be transmitted through rodents and insectivores?
Arenaviruses and some bunyaviruses (hantaviruses)
how are arenaviruses categorized?
Old world arenaviruses -
Lassa virus (Lassa fever),
Lujo virus,
LCMV (lymphocytic choriomeningitis virus)
New world arenaviruses -
Chapare virus
Guanarito (Venezuelan hemorrhagic fever)
Junin (Argentine hemorrhagic fever)
Machupo (Bolivian hemorrhagic fever)
Sabia (Brazilian hemorrhagic fever)
what are the Old World rats and mice family?
Muridae, subfamily Murinae
what are the New World rats and mice family?
family Muridae, subfamily Sigmodontinae
where is Crimean-Congo Hemorrhagic Fever (CCHF) endemic to?
Africa (including South Africa)
Eurasia (the Balkans, Middle East, Russia, Western China)
highly endemic to Afghanistan, Iran, Pakistan, Turkey
which tick is responsible for CCHF (Crimean-Congo Hemorrhagic Fever)?
genus Hyalomma - primarily associated with livestock but will also bite humans
how does CCHF virus get transmitted to humans?
tick bite;
fresh carcasses of infected animals, usually domestic livestock;
human-to-human through droplets or direct contact