2 Viral And Chlamydial Respiratory Infections Flashcards
Infections of the nasal cavity and pharynx are generally referred to as…
Upper respiratory tract infections (URI)
Acute respiratory diseases are more severe in…
Children
Hallmark signs of a URI
Nasal discharge/obstruction
Sneezing, cough, malaise, throat discomfort
2-4 days incubation
Fever, or other indications of a constitutional infection are uncommon in these cases - typically benign, transitory, and self-limited
Most common etiologic cause of acute respiratory diseases?
Viral infections
Most common viral causes of URI
RHINOVIRUSES - 25-50%
Coronaviruses - 10%
Adenoviruses (and other unknown viruses) - 30-40%
Rhinoviruses are better transmitted by _____ than by ______
By touch than by cough
Don’t shake hands!!!
Wash hands, clean toys at daycare
Why did the FDA say not to use Zicam anymore (2009)?
Intranasal zinc remedy, can lead to permanent loss of sense of smell
Treatment for URIs
Supportive, symptomatic relief only
Abx will not alter course of disease with these agents and it is best to avoid prescribing them in these cases
__________ infections are predictably hyperendemic in winter months
Rhinovirus
The greatest incidence of rhinovirus infections is in …
Children and young adults
Are colds caused by exposure to cold temps?
No, you idiot
Experimental data suggests that simple exposure to cold temps does not DIRECTLY induce disease
How is rhinovirus transmitted?
By aerosol and fomites and direct contact
Hands are a major vector
Treatment of Rhinovirus
Primarily symptomatic relief
B/c hands are the major vector, hand washing and disinfection of objects are best means of control
Don’t use Zicam. Just don’t. You’ll lose your sense of smell
Possible pharmacological treatment for rhinovirus
Picovir (Pleconaril) - inhibits virus infective process by binding in rhinovirus virion canyon
Not yet approved for mass use in US
But many viruses cause colds and are not susceptible to pleconaril, so limited usefulness
Skeletal muscle weakness/paralysis syndrome similar to poliomyelitis, non-polio enters viruses and West Nile virus
Acute Flaccid Myelitis (viral etiology suspected, not yet proven)
What are the three types of influenza?
A, B, and C, defined by nucleocapsid proteins
Influenza type that is most problematic
Type A
Type B also causes epidemics and type C is the least pathogenic
How are different subtypes of influenza categorized/labeled?
Based on envelope proteins
H hemagglutinin (viral attachment)
N neuraminidase (viral penetration and release from infected cells)
Nomenclature: Type / Location / Year / Isolation # / Antigenic type
Ex: “A/HongKong/68/H2N1”, “A/Spanish/18/HswN1”
Clinical manifestations of influenza
Short incubation (1-2 days)
Very abrupt onset of symptoms
Respiratory tract entry
SSx - FEVER, aches, chills, cough, sometimes severe
Persists for about 1 week, with long convalescence (1-2 weeks)
Viral destruction of respiratory tract ciliated epithelium (mucociliary escalators system) sets stage for complication
In flu patients, return of fever after it went away usually indicates…
Possible secondary pneumonia (most common way it kills)
Pulmonary complications of influenza
Primary influenza viral PNA
Secondary bacterial PNA
• Strep pneumo
•Staph aureus
• H flu type B (if unvaccinated)
Two other categories of non-pulmonary complications of influenza
Reye’s syndrome
• Associated with many viral infections
• Acute, sometimes catastrophic systemic disorder —> edematous encephalitis and fatty alteration of liver
Guillain-Barré syndrome
• Demyelination disease, insult unclear
• Associated with 1976 swine flue vaccine
Reye’s syndrome is primarily observed in …
Children aged 6 months - 15 years with influenza
What is important to keep in mind with regards to Guillain-Barre and the flu vaccine?
Influenza vaccination may induce GBS but bear in mind the estimated risk is 10x higher after a natural infection with the virus
How do you diagnose influenza
Clinical findings are diagnostic in epidemic situations but lab confirmation is available via direct viral isolation from throat nasopharyngeal swabs
Rapid antigen detection kits are now available in-office (but lots of false negatives, esp early in course of disease)
Treatment for influenza
Typically supportive, symptomatic relief
Amantadine/Rimantadine - effective against the type A viruses only by stopping uncoating/penetration but no longer used (resistance)
Osetamivir and Zanamivir - neuraminidase inhibitors, stop viruses from releasing/spreading
NEW in 2018 - Xofluza - inhibits viral cap-dependent endonuclease
Why does the CDC issue specific advice on meds each season?
Emergence of resistance is a constant concern for all anti-influenza agents and the situation is very fluid
Multivalent vaccines are made available each season around October for ….
Influenza
Formulation changes each year and you need a new one every flu season
The trivalent vaccines contain the two type A and one type B viruses predicted most likely to be dominant that season (quadrivalent is two As and two Bs and is now more common)
The flu shot is a ________ vaccine while FluMist (intranasal) is __________
Shot = inactivated FluMist = live attenuated
How to vaccinate kids against influenza
Children under 9 without history of prior influenza infection require two administrations of vaccine to attain max degree of protection
Type of influenza vaccine developed to primarily target elderly patients (age 65+)
High potency and adjuvanted flu vaccine
What is the intruder all flu vaccine
Used in patients 18-64, much smaller needle used to inject antigen under skin
Most common adverse event with the flu vaccine is …
Pain at the site of injection
Almost all vaccines are produced in embryonated chicken eggs so concerns over allergies and meeting demand for vaccine in timely fashion
Influenza vaccine target groups
Persons ≥65
Residents of nursing homes or other care/housing facilities
Adults and children with chronic pulmonary or CV disorders
Children with asthma
Debilitating chronic disease or immunosuppression
DM
CKD
Hemoglobinemias
Pediatric patients on long term aspiring therapy (Reyes)
Health care workers
What allows type A influenza viruses to create novel forms that cause pandemics?
Segmented genome
The two basic types of influenza virus antigenic variations:
Antigenic drift
Antigenic shift
Point mutations of the H or N genes in influenza that usually cause comparatively minor genetic variations but are recognized to be of major importance to flu epidemiology
Antigenic drift
The result of exchange of genomic segments of the influenza virus —> major variations in the virus
Antigenic shift
Recombination involving entire genome segments encoding H and/or N
Over 80% of last year’s flu deaths were in what group?
Patients >65 years of age
What is the typical flu season?
December - March/April
The 2009 H1N1 was unique - emerged early, before the vaccine was ready
Obligate intracellular parasites that are something in between a true bacteria and a virus
Chlamydiae
They are biochemically restricted, energy parasites (remove ATP from host since they have no means of synthesizing it themselves)
Infant pneumonia with onset ~3 weeks after birth is usually caused by …
Chlamydia trachomatis
Rhinitis —> cough
Risk factor = infected mother (child aspirated agent during birth)
Chlamydia trachomatis infection is associated with what syndrome?
Reiter’s syndrome
Microbe associated with atherosclerosis
Chlamydophila pneumoniae
Widely distributed species, cause of bronchitis, pneumonia, and sinusitis
