Week 12 - Topic 1: Upper Respiratory Tract Infections Flashcards
How do URTIs happent?
Viruses attach to receptors in the cells of mucous membranes (eyes, nose, pharynx, throat, lungs)
Name some URTI
Chronic/acute sinusitis Acute rhinitis (allergic or viral) Laryngitis Pharyngitis Tonsilitis Acute tracheobronchitis
Why do URTI often cause ear infections?
Because the auditory channel (eustachian tube) is connected to the pharynx, so viruses will travel from the URT to the middle ear to cause otitis media
What defense mechanism against microorganisms does the lacrimal apparatus have?
Tears: washing action + lysozymes + secretatory IgA
Why can URTI cause eye infections?
Viruses can travel from the URT to the eyes through the nasolacrimal duct. They can also block the lacrimal gland ducts from producing tears (defense mechanism)
What URT virus causes what kind of eye infection?
Adenovirus and pinkeye (conjuctivitis)
Why do people with respiratory illnesses, such as COPD, have a higher chance of infection?
They have difficulty getting rid of secretions = “clogged” lungs = microorganisms remain stuck in lungs = higher risk of pneumonia and infections
What delimitates the lower respiratory tract?
From the trachea to the lungs (alveoli)
What are 4 natural first line defences against respiratory infections?
1) Ciliated cells in bronchi to push viruses out
2) Coughing reflex
3) Exhaling contaminants out (air movement)
4) Macrophages in alveoli
What can interfere with out natural host defences against URTI?
- Smoking
- Alcohol
- Being immunocompromised (loss of function in macrophages)
What are the 3 portal of entries for microorganisms in the respiratory tract?
1) Inoculation of conjunctiva or nasal passages
2) Aspiration of mouth flora or food (through choking)
3) Inhalation of small aerosolized droplets <3 um diameter
What is so dangerous about small aerosolized droplets?
They are small enough to bypass cilia and enter the lungs
How do you prevent inoculation of conjuctiva and nasal passages?
Do not touch your face
What is an endemic?
Disease that perpetually exists in a particular region/population
Ex: TB in certain areas
What is an outbreak?
The occurrence of cases of disease in excess of what would normally be expected in a defined community
Excess = more than 3 cases
What is an epidemic?
When it spreads to several communities at about the same time
What is a pandemic?
When it spreads throughout the world, over several countries/continents –> usually occurs URTI
What are 3 normal flora that cause infections in the nares?
1) Haemophilus influenzae
2) Moraxella catarrhalis
3) Staph aureus
What are the 3 normal flora that cause infections in the pharynx?
1) Staph spp.
2) Strep pneumoniae
3) Strep pyognes (Group A) –> only some people are carriers
**all gram + cocci
What are the 7 normal flora that cause infections in the eye?
Gram + cocci:
1) Staph aureus
2) Staph epidermidis
3) Strep spp
Gram + bacilli:
4) Corynebacterium spp
5) Propionibacterium acnes
Gram - cocci:
6) Moraxella
7) Neisseria spp
True or False: Most infections are spread through contact + droplet.
True
How does conjunctivitis usually happen?
Self inoculation by touching the mucous membranes of the eyes
How do you prevent conjunctivitis (3)?
1) Hand hygiene
2) Environmental cleaning of high touch surfaces
3) High level disinfection of instruments that touch eyes (ex: eye pressure inducer at optometry clinics)
What mode of transmission is conjunctivitis?
Contract droplet
What PPE do you need for contact droplet?
1) Gown
2) Mask
3) Face shield
4) Gloves
What commonly causes sinusitis (3 bacteria)?
1) Strep pneumoniae
2) Haemophilus influenzae
3) Moxarella catarrhalis
True or False: Infections that cause sinusitis are not transmissible.
True
What bacteria causes pharyngitis?
beta-hemolytic strep pyogenes (Group A)
What bacteria causes epiglottitis?
Haemophilus influenzae type B
What mode of transmission is pharyngitis?
Droplet
What mode of transmission is epiglottitis?
Droplet
What PPE do you need for droplet precautions?
1) Mask
2) Face shield
What are symptoms of Group A Strep infection?
Sandpaper rash with tiny bumps
Skin peeling
Raw red sore throat
Fever, malaise, headache
The toxins in Group A Strep trigger which disease?
Scarlet fever
If untreated, what does Group A Strep infection evolve into?
Rheumatic fever (pain in heart and joints)
How does a Group A Strep infection evolve?
Respiratory droplets enter the body = pharyngitis (red pharynx, swollen lymph nodes, tonsils abscess, fever) = laryngitis if spread to trachea = bronchitis if spread to bronchi = scarlet fever (rash) from erythrogenic toxins = rheumatic fever
How long are Strep pyogenes people infectious for?
2-3 weeks
When do Strep pyogenes people stop being contagious?
24h after beginning antibiotic treatment
What causes Hand Foot and Mouth disease (3)?
Enterovirus, coxsackieviruses, echoviruses
What virus is part of the enterovirus genus but does not cause Hand Foot Mouth disease?
Poliovirus
How does enteroviruses enter, replicate in and leave the body?
- Entry via aerosol or ingestion
- Replication in the oropharynx
- Replication in the GI tract
- Circulation in the bloodstream (viremia)
- Possible secondary viremia in different target tissue
- Excreted in the feces
What viruses can cause meningitis?
- Echo
- Polio
- Coxsackievirus
What viruses can cause encephalitis and paralysis?
- Polio
- Coxsackievirus
What mode of transmission is enterovirus group infections?
Contact and droplet
How is are enteroviruses transmitted?
Close mucous to mucous + feces
Why is Hand Foot and Mouth Disease so common in kids?
Daycares deal a lot with feces containing diapers that transmit the virus.
What is the manifestation of Hand Foot and Mouth Disease?
Sores/rashes on the soles of feet, palms of hands, in and around the mouth
What are the 8 types of human herpesvirus?
1) Herpes simplex virus type 1
2) Type 2
3) Varicella-zoster virus
4) Epstein-Barr virus
5) Cytomegalovirus
6) Human herpesvirus 6
7) 7
8) Kaposi sarcoma-associated herpesvirus
What does HSV type 1 and 2 cause?
Genital herpes, mouth sores
What does the Epstein-Barr virus cause (3)?
Infectious mononucleosis
Hepatitis
Encephalitis
What does cytomegalovirus cause (2)?
CMV mononucleosis
Congenital disease
What does human herpesvirus 6 and 7 cause?
Roseola infantum
What types of patients usually have Kaposi sarcoma-associated herpesvirus?
AIDS patients
How is herpesvirus transmitted?
Close mucous to mucous contact
What is the mode of transmission of roseola?
Droplet
What are the symptoms of roseola?
Red ish patchy rashes that come and go
Toddler is perfectly healthy
What mode of transmission is Bordetella pertussis?
Droplet
When are pertussis people infectious?
After the incubation period (5-10 days, max 3 weeks)
When is the paroxysmal stage of pertussis and what happens?
When: 1-6 weeks after incubation
What: whooping cough
What causes croup?
Parainfluenza 1,2,3
What are the sx of croup?
Starts with a cold
Ends with a harsh barking cough (like a seal) + high pitched stridor
What causing the stridor and barking cough in croup?
Swelling and narrowing of the trachea, larynx, and bronchi
What causes mumps?
Viral: Paramyxovirus of the rubulavirus family
What are the symptoms of mumps?
Swollen salivary parotid glands = puffy cheeks and swollen jaw
What mode of transmission is mumps?
Droplet
What 7 viruses cause the common cold?
1) Rhinovirus
2) Coronavirus
3) Adenovirus
4) Human metapneumovirus (hMPV)
5) Parainfluenza
6) Respiratory Syncytial virus (esp children)
7) Enterovirus
What mode of transmission is the common cold?
Contact + droplet
Your friend has the common cold and just sneezed. Being a fan of your IPC class, you want to count the viral load in his secretion. How much do you find?
100,000 virions/ml of resp secretions
What were the two outbreaks associated with coronavirus prior to 2019?
2002: SARS-CoV
2012: MERS-CoV
What helped contain the spread of MERS-CoV
Early recognition + initiation of contact precautions
What are the sx of measles (including the 3 Cs)?
- High fever 40°C
- 3 Cs: conjunctivitis, cough, coryza
- Koplik rash spots on mucous membranes
- Photophobia, perioribital edema
What is coryza?
Runny nose and eyes
When are measles people contagious?
4 days before and 4 days after the onset of rash
True or False: Viruses spread more easily in warmer temperatures. Explain.
False in cold T°
The lowered humidity allows the virus to live longer in droplets and to attach more easily to dried out nasal passages + people do more crowded indoor activities
When is viral load highest for someone (2)?
During febrile period
When they have pneumonia
They shed a lot more
What groups of people shed for longer periods of time?
Children (14 days vs 7 for adults) Immunocompormised people (several months)
Which 2 viruses circulate throughout the year?
Adenovirus and parainfluenza
Which 2 viruses are mostly present during winter months?
Coronavirus and
Respiratory syncytial virus
What causes whooping cough?
Bordetella pertussis
bacteria
