Viruses Flashcards
What are the common portals of entry for viruses
- respiratory tract
- GI tract
- GU tract
- placental
- eye
- skin
- transplanted organs/blood
What are the periods of infection from a virus
- incubation period (communicable toward the end)
- prodromal period (communicable)
- illness period (communicable)
- convalescent period (communicable at the beginning)
Describe zoonosis
- when an infectious disease jumps from a vertebrate animal to a human
- can spread through direct contact or through indirect contact
- covid, avian flu, ebola, etc
What are the types of viral hosts
- maintenance host: symbiosis (mosquito vector)
- link host
- amplifier host: high replication, ideally asymptomatic
What is responsible for the variability in symptoms between different people to the same virus
- different biomedical profile/immunity
- genetics & prior exposures
- difference in severity of current exposure
Describe how to diagnose a viral infection
- viral culture gold standard
- direct detection (cytopathology, electron microscopy, PCR, immunoassay)
- serology (IgG & IgM levels to check Abs)
What is the primary treatment for viral infection
- prevention (vaccines, hygiene, isolation)
- supportive care (treat sxs)
- antivirals (inhibit replication)
- immunomodulators (boost immune system)
- interferons (cytokines inhibit replication)
- virucidal agents (kill inactive virus)
Why is it hard to treat viruses (RNA viruses specifically)
- RNA viruses have high mutation rates with replication compared to DNA viruses
- Recombination: viruses can swap genetic material
- much more diverse than bacteria
- use the hosts building blocks (also hiding inside host cells)
- robust capsid
- ability to become resistant to meds that previously worked d/t mutations & recombinations
- antivirals are expensive $$$
List some viruses in the Herpesviridae family
- HSV 1 & 2
- varicella zoster
- EBV
- cytomegalovirus
- Human herpesvirus 6 & 7
- Kaposi’s sarcoma associated herpesvirus
What is the etiology of cytomegalovirus
DNA Virus
CMV: seroprevalence 40-100% of adults worldwide
- diverse spectrum of illness depending on immune status
- produces acute primary infection & latent infection (reactivation can occur any time)
Transmission through close contact, sexual, blood exposure
Describe the clinical presentation of CMV
Primary: resembles mononucleosis, significant protracted fever, fatigue
Colitis, hepatitis, encephalitis, GBS, retinitis
CMV Mono: fever predominates, less so of the LAD & tonsillitis, exudates, splenomegaly
Describe the diagnostic testing for CMV
Lymphocytosis, atypical lymphocytes
Describe the etiology of influenza
RNA virus
Seasonal epidemics
A & B cause global pandemics
Primary transition thru resp droplets, close contact, contact with contaminated surfaces
Describe the clinical presentation of influenza
Incubation 1-4 days
Sxs vary with each strain: abrupt onset fever, nonproductive cough, myalgia, sore throat, nausea, congestion, HA
Vomiting & diarrhea not common in adults
Complications: pneumonia, MI, carditis, encephalitis, GBS, myositis
Describe the diagnostic testing for influenza
Labs normal on uncomplicated flu
Confirmatory testing (rule out covid) - PCR
Describe the treatment for influenza
Oseltamivir (Tamiflu) bid x5 days shortens duration of symptoms by 1 day, reduces viral shedding, reduces severity of sxs