virology II Flashcards
(35 cards)
ORF virus
causes localized skin infections
parapox virus
usually infects sheep/goats and their handlers
localized to a few lesions on hands and arms
lesions are PAINFUL and take weeks to heal but are self-resolving
no treatment available
vaccine for animals has been approved
what viruses cause skin lesions and systemic infection but don’t have infectious particles in the lesions?
herpes 6/7, measles, rubella, parvovirus B19
parvovirus: characteristics of the family (type, characteristics). where do they replicate? relevant human pathogen?
small ssDNA virus
non-enveloped icsohedral capsid
no DNA pol- only replicate in actively dividing cells. B19 is human pathogen
Parvovirus B19: disease
biphasic childhood disease
early phase: flu-like illness 1 wk post infection
Later phase: (17 days post infection) rash- aka erythema infectiosum, fifth disease, or slapped cheek disease. lasts 2-4 days. may be accompanied by arthritis
parvovirus B19 transmission and complications
transmission: resp. and oral secretions; placental
complications: bone marrow is a major site for replication due to affinity for P antigen. can disrupt RBC production. anemic persons may get APLASTIC CRISIS. treat with blood transfusion.
may also cause spontaneous abortion or hydrops fetalis (edema in fetal subcutaneous tissue). babies that come to term with B19 infection have no lasting complications.
what viruses spread systemically and cause skin lesions with infectious virus?
HSV, VZV, coxackie, echoviruses, orthopoxviruses (cariolla, vaccinia, cowpox, monkeypox)
cowsakie and echoviruses
skin rashes, enanthems. not severe. aka hand foot and mouth disease. may also cause CNS infections
orthopoxvirus
enveloped dsDNA viruses
replicate in the CYTOPLASM
variola, monkeypox, cowpox, vaccinia
variola:
causes smallpox
highly contagious and often fatal (30%)
four clinical subtypes: ordinary (90%), modified (in previously infected ppl), flat, and hemorrhagic
enveloped dsDNA virus
transmission and acute infection with variola
transmission: person to person via droplets and/or contact with bodily fluids, lesions, scabs, clothing, air. 5-10 virus particles can cause infection.
acute infection: incubation of 3-17 days.
prodrom with fever and malais 2-4 days before rash
rash leaves scars
cause of death: secondary infections? bacterial sepsis? pneumonia? nephritis? encephalitis?
what is the historical vs. the current smallpox vaccine?
historical dryvax was a live vaccinia virus cultured from calf lymph. new vaccine will be ACAM2000, which is grown in culture. MVA, which was created by many passages in chicken embryo fibroblasts, may be even safer- no replication in human cells.
What five features can be used to distinguish smallpox from chickenpox? what are the differences?
incubation, prodrome, location of lesions, and scabs.
incubation is 7-17 days for sp, 17-21 for cp
smallpox has a prodrome before rash
smallpox has uniform lesions most numerous on face, arms, and legs; palms and soles too
chickenpox has non-uniform lesions on body, not palms and soles
scabs for 10-14 days post rash for small pox, and 4-7 days post rash for chickenpox
smallpox vaccine: contraindications and complications
contraindications: immunocompromised person, person with eczema
complications: eczema vaccinatum- virus spreads from vaccination spot across the body. high mortality
generalized caccinia: vaccinial lesions anywhere on the body 4 days or more post vaccination. cause by viral spread through the blood. usually self-limiting but can be severe in immunocompromised people
progressive vaccinia: vaccination site doesn’t heal. may be fatal and due to immune deficiencies
post-vaccinal encephalitis: not due to direct infection of CNS
myocarditis/pericarditis
monkeypox virus
resembles smallpox. endemic in rodents in Africa. outbreaks in US from pet importation. doesn’t spread easily from human to human.
characteristics of flaviviruses and alpha viruses
enveloped positive ssRNA viruses
important flaviviruses
yellow fever, west nile, dengue, japanese encephalitis, St. louis encephalitis
most important cause of encephalitis worldwide
japanese enchephalitis
dengue virus disease
transmitted by mosquites, though humans serve as a reservoir
classic dengue: flu symptoms that are followed by severe pain in muscles and jts. often see a maculopapular rash.
Dengue hemorrhagic fever: 10% fatality rate. hemorrhage into GI tract and skin. occurs in 2nd exposures to dengue. (4 viral serotypes- infection with one serotyp generates abs that protect against that type but enhance the ability of other serotypes to infect monocytes via Fc receptors. monocyte infection leads to cytokine release leading to vascular damage, shock and hemorrhage
pos sense ssRNA virus; enveloped
yellow fever- virus characteristics and clinical stuff
ssRNA pos sense enveloped
severe liver damage, coagulopathy and upper GI tract hemorrhage. signficant fatality. live attenuated vaccine available but no treatment.
fecal/oral viruses: envelope or no?
all viruses transmitted by the fecal oral route have no envelope
Rotavirus: charachteristics
segmented dsRNA viruses
common cause of GI distress in kids
incubation 1-2 days. vomiting and diarrhea for 4-7 days. infected cells in the intestine are killed- villous atrophy. fluid and electrolyte loss with watery diarrhea.
rotavirus vaccines
2 live attenuated viruses possible
Rotarix is monovalent vaccine
TotaTeq is a live oral pentavalent vaccine.
norovirus- characteristics, disease
GI distress in adults pos ssRNA no envelope common in group settings (cruises) low infectious dose, shedding of virus post-recovery, resistance of virus to chlorination vomiting and diarrhea 24-48 hrs
hepatitis A: type, mode of infection, incubation
ssRNA non-enveloped
fecal oral rout
2-4 wks
esp. common in developing countries. disease milder in kids
