Flashcards in Viral Skin Infection - Diebel Deck (20)
What units is the capsid made of in the virion?
Describe the 3 classes of DNA viruses in the Baltimore classification system:
Class 1 - dsDNA, Classic semi-conservative
Class 2 - ssDNA, Semiconservative, discard the (-) strand
Class 7 - dsDNA, transcription followed by reverse transcription
Describe the 4 classes of RNA viruses in the Baltimore Classification System:
Class 3 - dsRNA, transcibe (-) strand
Class 4 - ssRNA(+), used directly as mRNA
Class 5 - ssRNA(-), makes ssRNA(+)
Class 6 - ssRNA(+), makes ssRNA(+) by reverse transcription and a double stranded intermediate
Basic description of HPV:
Human Papilloma Virus
Site: epithelial cells/mucous membranes (Warts on genitalia and hands) can lead to cancer
non-enveloped, circular genome, dsDNA
Viral proteins block Rb and p53
Basic description of poxviruses:
various rashes - severe ones include multiple organs
-autoinoculation (one lesion spreads to other parts of the body via scratching)
-limited to the epidermis, no dormant state (trunk and anogenital regions)
often seen in AIDS patients
-Presentation: pearly skin papules and nodules forms craters
-Pathology: (1) Inhalation: upper respiratory epithelium, enters the bloodstream establishing primary viremia. Infects organs, back into blood (secondary) (2) Skin infection and replication within epidermis, macules on head spread to extremities, macules become vesicles, crusts form -detection = serology Treatment = vaccination
-presentation: exanthemous disease causing denuded lesions.
-Pathology: Zoonotic, direct contact with infected sheep or fomites carrying virus.
-Local, purulent-appearing papule.
-Diagnosis: history/clinical presentation.
-Treatment: topical cidofovir
What are the important herperviruses we need to know?
Herpes Simplex Virus 1
Herpes Simplex Virus 2
Epstein Barr Virus
Basic Description of Varicella Zoster:
varicella Zoster (chickenpox) or
Herpes Zoster (shingles).
-Pathology: Contracted from respiratory secretions or contact with ruptured vesicles
-2 week incubation.
-“dew on a rose petal”
-resolves within 2 weeks
-Latent infection of the dorsal root ganglion. Stress or immunocompromised individuals can lead to viral reactivation
-rash appears over the sensory dermatome
-Treatment: supportive, acyclovir (severe), live-attenuated VZV vaccine
Basic Description of Herpes Simplex Virus 1:
-sporadic encephalitis (adults).
-Clinical presentation: Gingivostomatitis, -keratoconjunctivitis, cold sores (labialis). -Pathology: Humans are the only reservoir for this virus, transmitted via saliva—mucous membranes. -The primary infection resolves after 2-3 weeks.
The virus enters sensory ganglion cell bodies to establish latent infection.
Basic Description of Herpes Simplex Virus 2:
-Clinical presentation: genital herpes or neonatal herpes.
-Pathology: Human reservoir, transmission via sexual contact. Mucous membranes, asymptomatic, vesicular lesions in the genital area. -Possible transmission to unborn child.
Diagnosis: detection of virus (PCR), Tzanck. Treatment: acyclovir.
Prevention: cesarean section in infected mothers.
Basic Description of Roseolovirus:
Clinical presentation: exanthema subitum, sudden high fever. reactivation can occur in organ transplant patients leading to enchepalitis, bone marrow suppression.
Pathology: Children: 3mo-3yrs, aerosol transmission
Diagnosis: clinical presentation.
Basic Description of Epstein Barr Virus:
-patients with infectious mononucleosis are at risk for splenic rupture.
Clinical presentation: “kissing disease”. Pathology: transmitted by saliva and respiratory secretions. Infects the oropharynx epithelium. Infects B cells—transformed and multiply—lymph nodes and spleen enlarged due to immune response.
Diagnosis: monospot test- heterophil antibody, anti-EBV IgM (acute), IgG (past)
Viruses are sometimes boring... Can you think of anything exciting about the parvovirus?
in immunodeficiency patients parvovirus infection can lead to chronic severe anemia
Clinical presentation: erythema infectiosum (5th Disease)
5th disease is pretty exciting! Right?
Referring to herpes viruses again, what do the alpha beta and gamma mean?
Herpes viruses infect you for life and often hide in areas until a reactivation event
Alpha – in nerve cells
Beta - Bone marrow
Gamma – in b cells
What are two important examples of flaviviruses?
Describe Dengue fever - real simple-like:
Clinical presentation- “breakbone fever” (flu-like with severe joint and muscle pain).
Pathology: mosquito bite
First - Infects macrophages causing acute inflammation pyrogens and pain mediators released
Second - antibodies from 1st increase and cross-react to form immune complexes and a type III hypersensitivity reaction→ hemorrhage and shock.
Treatment: prevention against mosquito bites
West Nile Virus, what is it's deal?
-most infections asymptomatic
-Can have fever, fatigue, headache, myalgia, anorexia, eye pain, nausea, vomiting, diarrhea, rash.
-West Nile encephalitis- neuroinvasive disease causing encephalitis (elderly) or meningitis (children). May progress to coma or death.
Pathology: Mosquito - Spreads to human host and replicates in the skin Langerhans cells → regional lymph nodes -→viremia and infects multiple organs (CNS).
Treatment: prevention/ supportive.
Let's say you have a young patient that didn't get vaccinated because the child's parents love Jenny McCarthy....
The child has had flu symptoms for a couple days along with some small white pustular lesions on the buccal mucosa inside her mouth
The parents bring her in today because she has a red maculopapular rash.
What is your diagnosis?
Tell the parents they need to get her an MMR and help them realize they could have infected a lot of people for being so inconsiderate of their child and others.
How would you know if a child has Rubella?
Clinical presentation: fever followed by descending rash.
Pathology: aerosol transmission, infects nasopharynx,replicates in lymph nodes.
Antibody mediated reaction leads to maculopapular rash
no MMR? that's a good clue
Basic description of Coxsackievirus A&B?
Hand-foot-mouth disease: vesicles in young children.
A: herpangia-HFM = an infection of the throat which causes red-ringed blisters and ulcers on the tonsils and soft palate, the fleshy back portion of the roof of the mouth.
B: pleurodynia, myocarditis, A&B aseptic meningitis, paralysis, upper respiratory tract infection.
Pathology: summer/fall, aerosols or fecal-oral route. Travels in the GI tract and infects mucosal epithelial cells. Viremia, lyse skin and mucosal epithelium. (B: travels to heart)
Treatment: anti-inflammatory agents. No antivirals/vaccines available