Common Viral Pathogens Flashcards
1
Q
Virus vs. Bacteria
A
- Viruses require host cells in order to replicated
- Bacteria are living vs. Virus=infectious particle
- viral infection=virus has replicated with host
2
Q
Common laboratory tests looking for actual virus
A
- culture w/in tissue
- assay to look for antigens
- PCR to amplify portion of viral genome
3
Q
Common laboratory test looking for host immune response to virus
A
- ELISA (Enzyme-Linked Immmunosorbent Assay)
- add host serum to viral antigen
- add tagged/immunofluorescent Ab to visualize host Ab
4
Q
8 herpes viruses which infect humans
A
- HHV-1: Herpes Simplex Virus-1 (HSV-1)
- HHV-2: HSV-2
- HHV-3: Varicella Zoster Virus (VZV)
- HHV-4: Epstein Barr Virus (EBV)
- HHV-5: Cytomegalovirus (CMV)
- HHV-6: Roseola (HHV-6a, HHV-6b)
- HHV-7: Roseola
- HHV-8: HHV-8
5
Q
Clinical manifestations of HSV-1/HSV-2
A
- oral and genital herpes; HSV-1 mostly orofacial lesions and HSV-2 mostly genital lesions
- incubation: ~4 days
- transmission: direct shedding into mucosal surface
- primary infection: usually asymptomatic, but may sometimes produce rash
- reactivated infection: can be symptomatic, but usually less symptomatic than primary infection
6
Q
HSV diagnosis
A
- usually clinical but may use:
- Tzanck smear
- HSV culture
- Direct Fluorescent Antigen stain
- PCR of lesions
7
Q
HSV treatment
A
- severe HSV (in neonate/immunocompromised or encephalitis)–> IV acyclovir
- oral antiviral therapy
8
Q
VZV clinical syndromes
A
-2 main syndromes: chicken pox and shingles
9
Q
Clinical manifestations of primary VZV infection
A
- primary VZV=varicella=chickenpox
- highly contagious
- incubation 10-21 days
- fever, malaise, headache
- itchy, vesicular rash develops starting at trunk and spreading to limbs
10
Q
Pathogenesis of primary VZV infection
A
- entry via respiratory tract
- spreads to regional lymph nodes and replicates for 2-4 days –> primary viremia
- replicates in liver, spleen, etc. –> secondary viremia
- secondary viremia spreads virus to skin 14-16 days after exposure –> rash
11
Q
Prevention of HSV-1/HSV-2
A
- no vaccine
- hand hygiene/physical barriers
- avoid contact
- prevent reinfection w/lower doses of acyclovir on daily basis
12
Q
Primary VZV infection treatment
A
- usually self-limited and requires no treatment
- treatment accelerates resolution/decreases symptoms
- treatment necessary for immunocompromised patients
13
Q
VZV varicella prevention/prophylaxis
A
- varicella vaccine: live-attenuated vaccine=2 doses @ 12-15mo. and 4-6 yrs.
- Varicella-zoster immune globulin (Varizig): reduces severity in high-risk pts w/in 4 days of exposure (=pooled Abs from people w/high VZV Ab titers)
14
Q
Pathogenesis of VZV latency and reactivation
A
- VZV remains latent in cranial, dorsal root, or trigeminal ganglia
- no asymptomatic viral shedding
- dermatomal rash along sensory nerve from ganglion
15
Q
VZV reactivation infection clinical manifestations
A
- VZV reactivation=zoster=Shingles
- pain where vesicles will erupt several days later
- lesions erupt over single dermatome
- lesions itchy w/pain; 2 weeks before crust over
