repiratory viruses Flashcards
REspiratory viruses and their transmission
Respiratory transmission–> replication in upper respiratory tract–> upper and sometimes lower respiratory infections and diseases
Rhinovirus, enteroviruses, coronavirus, parainfluenza virus, REspiratory syncytial virus, metapneumovirus, influenza virus, adenovirus
could get in the blood–> viremia –> target organs (enteroviruses, measels virus, adenovirus)
Rhinovirus
Has lots of genetic variation leading to Antigenic Diversity
Humans only natural host, grows better at 33 degrees tahn 37 degrees, Transmission by respiratory secretions, directly from person to person, via fomites, prevention and control (no antivirals or vaccines, hand washing, disinfectants)
Causes Common cold, small portion of the nose and upper RT membrane (mild damage)
Mainly due to bodys response to infection, mostly self limited, asthma and COPD, otitis media sinusitis and chronic bronchitis causes complications
Enteroviruses
Some enteroviruses are transmitted mainly via respiratory route (enterovirus D68 and C), Colds and flu–> common cold symptoms, fever and headache
Complications: serious respiratory disease, systemic disease, no vaccine or antiviral therapy available
Acute flaccid myelitis
Weakness, loss of muscle tone, facial droop, difficulty swallowing slurred speech, paralysis
Coronaviruses
Cause common colds (second most pravelent cause), watery eyes, sneezing, nasal congestion, sore throat, fever, chills headache, aches and cough
Disease limited to upper RT, infect epithelial cells, no vaccine available,
Recently indentified coronaviruses that cause severe respiratory illness
Middle east respiratory syndrome MERSCoV
infects from bats and camels, statues of MERS-CoV, doesnt pass from person to person very readily
Nosocomial transmission in dubai hospitals, acute renal failure, lower respiratory tract specimans with high viral loads
Parainfluenza virus
aka croup, seal like cough, lower respiratory complications in infants and young children, croup
No vaccine available, types 1 and 2 common cause of croup, type 3 rSV, type 4 mild disease
Respiratory syncytial virus
Localized infection of RT no systemic spread
Blockage of narrow airways of infants (virus induced CPE includes syncytia, induction of inflammatory cytokines, infects everyone by age 2, outbreaks in the winter, can get reinfected
Bronchilitis, pneumonia in children and old eople with disease
Febrile rhinitis and pharyngitis- children
Common cold- everyone
Treatment: otherwise healthy infant, treatment is supportive, oxygen, IV fluids, nebulized cold stream
Premature or immunocompromised infants-
Prevention and control: no vaccine currently apporoved, many in clinical trials
Metapneumovirus: a lesser RSF in lower respiratory tract, no vaccine
Influenza virus
Genetic variation- anti genic differences, animal hosts other than human are important in the epidemiology of human infections
Basics of pathogenesis, prevention and control vaccine available antivirals available
Antigenic shift- new subtype (years), Antigenic drift- small mutation (months to one year)
Avian influenza viruses and human infections
Influenza- pathogenesis (viremia, not a major in pathogenesis, acute respiratory disease,
Flue clinical features:
normal self limited 3-7 days, more sever in the young and old
Secondary bacterial infections are the major cause of death (Streptococcus pneumoniae, staphylococcus aureus, h flu, rare complications (myostis and cardiac involvement, Guillain Barre syndrome, encephalitis, reye syndrome
Prevention and control : chemically inactivated- mixture of prevalent antigenic types (hemagglutinin and neruamindase), Attenuated infectious viruses (intranasal administration), quadrivalent vaccine available 2013
Antiviral therapy (amantadine and rimantadine- inhibit uncoating by blocking M2 protein (currently not used due to high degree of antiviral resistance), zanamivir and oseltamivir, neuraminidase inhibitors (inhibits the releast of progeny virus), Baloxavir marboxil capsnatching
Adenovirus
cause a wide spectrum of diseases, pharyngitis, conjunctivits, GI infections, hemorrhagic cystitis
can cause destructive productive infection, persistent infection with virus shedding, or latent infections
Acute respiratory disease, sometimes serious pneumonia,
