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FunMed PBL > PBL 7 > Flashcards

PBL 7 Flashcards

1
Q

what is myalgia

A

Pain in a muscle/ group of muscles

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2
Q

what is pyrexia

A

Fever

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3
Q

What is Rhinitis

A

= inflammation of the mucous membrane of the nose caused by a viral infection or an allergic reaction. It leads to a stuffy nose, runny nose and sneezing

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4
Q

what virus family does influenza belong to

A

Orthomyxoviridae family

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5
Q

What are the type of influenza

A

Type A - birds, humans, mammals
Type B - humans only
Type C - humans only pigs and dogs
type D - cattle and pigs

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6
Q

what is the genome of Type A and B made out of

A

8 RNA segments

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7
Q

What is the genome of type C made out of

A

7 RNA segments

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8
Q

describe type A

A
  • most common and causes most severe illness
  • has glycoproteins haemagglutinin and neuraminidase glycoproteins in the protective envelope surface (this subdivided into types of influenza A)
  • glycoproteins can vary in structure so are identified by a number
  • H3N2 and H1N1 are the most common type A subtypes to infect humans and infect some animals
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9
Q

describe type B

A
  • less common and doesn’t mutate as often
  • limited number of H and N glycoproteins on its surface
  • only infects humans
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10
Q

describe type C

A
  • least common and least likely to mutate
  • only has 1 species
  • Presence of haemagglutinin-esterase fusion protein on surface used to enter and exit cells
  • Causes mild disease in children
    Can infect humans and pigs and dogs
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11
Q

what is genetic drift in type A

A

Virus can mutate its H and N glycoproteins during replication
Daughter viruses are different from each other and parent virus
Over time, accumulation of such changes => infection in an individual immune to previous strains
This is why people are infected year after year

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12
Q

what is antigenic drift in type A

A

Virus circulating in animal population suddenly mutates, enabling human infection
Occurs when animal host cell is infected by 2 similar flu viruses, e.g. one infecting animals and the other humans
Viral genome is in segments of RNA  reassortment of segments  new viruses contain a mixture of RNA segments
The viruses now produced have completely new H and/or N glycoproteins

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13
Q

why does genetic drift occur in type A

A

Genetic drift can occur because over time, the H and N glycoproteins of the virus become completely different to the virus that was protected against via the flu vaccine

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14
Q

what does antigenic shift lead to in type A

A

Antigenic shift leads to the production of viruses that can now infect humans with completely new glycoproteins. The population is obviously not protected against this new strain thus leading to the rapid spread through a population  PANDEMICS

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15
Q

how is the flu transmitted

A

Airborne/ droplet infection – infected individual sneezes/ coughs
Touching a contaminated surface
Window for transmission:
1 day before symptom onset  5-7 days after symptom onset
The time from when a person is infected with flu to when symptoms begin is about 2 days

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16
Q

describe the pathophysiology of the virus

A
  • Virus uses haemagglutinin to bind to sialic acid sugars on the surface of epithelial cells in URT
  • Endocytosis of virus and release of –ve sense RNA
  • RNA polymerase converts –ve sense RNA  +ve sense mRNA
  • mRNA transcribed into proteins and assembled into new viruses
  • Viruses leave cell via exocytosis using neuraminidase which cleaves sialic acid sugars from membrane
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17
Q

How does the virus infect the body

A
  1. Exposure to virus via water droplets in the air
  2. Virus infects epithelial cells in the URT – does so via binding of haemagglutinin to sialic acid (sialic acid is found on almost all human cells, incl. RBCs)
  3. Virus is then taken into the cell via receptor mediated endocytosis and is kept in an endosome
  4. H+ ions enter the endosome => fusion of viral envelope with endosomal membrane => release of viral contents into the cytoplasm
  5. Influenza A has an M2 ion channel that allows H+ ions to enter virus and facilitate this fusion
  6. -ve sense ss RNA enters nucleus but must be converted to +ve sense RNA to make proteins (for which there is no human enzyme)
  7. Thus, viral RNA-dependent RNA polymerase is used (travels to host nucleus with RNA)
  8. +ve sense RNA  proteins  new virions assembled  bud off cell membrane
  9. Haemagglutinin binds to sialic acid again therefore preventing virus release
  10. Neuraminidase cleaves sialic acid => virus release
18
Q

What are the signs and symptoms of influenza

A

Occur 1-4 days post infection
Fever, headache, runny nose, cough, sore throat, (vomiting, diarrhoea)
Resolve after 1 week
Complications, e.g. sinusitis, pneumonia, acute otitis media (ear infection) and bronchiolitis can occur
- Flu can make chronic medical conditions worse
- E.g. asthmatics may experience asthma attacks

19
Q

what are the risk factors that can cause flu

A

Extremes of age
<6 months
>65 years old
Pregnancy
People living in nursing homes and other long-term care facilities
Chronic health conditions, e.g. heart disease, asthma, diabetes

20
Q

How do you diagnose flu

A

Rapid influenza diagnostic tests

Detect presence of virus from nasal secretions in minutes

Can be unreliable

Detects type, but not specific strain

Viral culture
- Grow virus to identify it

PCR
- Detects very small amounts of viral RNA

21
Q

what is more reliable in the diagnosis of flu

A

Viral culture
- Grow virus to identify it

PCR
- Detects very small amounts of viral RNA

22
Q

How do you treat influenza

A

Antivirals are Reserved for high risk groups/ severe illness
Neuraminidase inhibitors – prevent release of viruses from host cell
M2 proton channel inhibitors – contain adamantane which prevents virus replication inside host cell
(Virus M2 gene mutates frequently => resistance to M2 proton channel inhibitors)

Other methods
Rest and sleep
Keep warm
Take paracetamol or ibuprofen to lower your temperature and treat aches and pains
Drink plenty of water toavoid dehydration

23
Q

What vaccines do you use in the flu

A
  1. Trivalent inactivated influenza vaccine (killed virus injected into muscles)
  2. Live attenuated influenza vaccine (weakened virus sprayed into the nose)
  • Both vaccines are trivalent
  • Contain a mixture of the 3 strains that are predicted to dominate the coming season
  • Prediction is based on what strains typically dominate year after year, e.g. H1N1, H3N2, influenza B and also which strains are circulating during the winter season in the other hemisphere
24
Q

What preventative methods can you use to stop you from getting the flu

A

Preventative actions, e.g. stay away from infected people, covering coughs/sneezes, frequent handwashing

25
Q

Why can you still catch the flu after you have had the flu jab

A

Antibodies that provide protection develop in the body about 2 weeks after vaccination therefore if exposed to virus immediately after jab, you can still catch the flu

26
Q

describe symptoms that can develop with the flu jab

A
  • The most commonSEare soreness, redness, and tenderness or swelling where the shot was given

Low-grade fever, headache and muscle aches also may occur

More severe SE incl. allergic reaction (esp. if allergic to egg proteins) and Guillain-Barre syndrome (autoimmune disorder of the peripheral nervous syndrome)

27
Q

what does the flu jab do

A
  • reduces the risk of contracting viral infection by Half
28
Q

what are the factors that determine whether the flu jab is effective or not

A

Individual characteristics (high risk => increased likelihood of becoming infected despite vaccination)

Vaccine must match the circulating virus stain of the season

Herd immunity = vaccinating most of the population protects those that were unable to get vaccination, e.g. in the immunocompromised, pregnant and babies <6 mths

29
Q

What is the difference between cold and flu

A 
Cold 
- Sneezing
• Rhinitis
• Cough/coryza
• Sore throat
- common 
flu 
Sudden onset
• Fever, chills, shivering
• Headache
• Myalgia
• Cough
• Rarely more than once per year, usually less frequent
• Infectious from 24hrs pre symptoms to 5-7 days after illness starts
30
Q

Mesningitis symptoms

A

Symptoms incl. stiff neck, severe headache, fever, confusion N+V, discomfort from bright lights, seizures, rash

31
Q

what is meningitis

A

inflammation of the meninges covering the brain and spinal cord

32
Q

what can cause meningitis

A

Bacteria such as Haemophilus influenza type B are found in the nose and throat and are usually harmless. However, in people with weakened immune systems, such as those recovering from a cold or the flu, the bacteria can sometimes spread to the brain and cause meningitis

33
Q

whats the difference between bacterial meningitis and viral meningitis

A

Bacterial meningitis symptoms come on quickly, usually over a period of hours. With viral meningitis, symptoms might appear over several days

34
Q

what is a fever

A
  • Not clearly defined
  • Depends on age and site at which it is recorded
  • Possible sites: oral, rectal, tympanic, forehead
  • Tympanic and rectal closest to core temperature
  • > 38oC fever in baby or young child
  • Older child or adult >37.2 -37.5oC
35
Q

what are the viruses that infect the upper tract

A
  • rhinovirus
  • parainfluenza
  • herpesvirus
  • adenovirus
  • bocavirus
  • influenza virus
36
Q

What are the viruses that infect the lower repsiratory tract

A
  • influenza
  • parainfluenza
  • respiratory syntactical
  • adenovirus
  • bocavrisu
37
Q

what is freshers flu

A
  • a term used in UK, affects students after arrival at university
38
Q

What does the freshers flu involve a combination of

A
  • upper respiratory tract infection, exposure to novel viruses • excess alcohol,
  • lack of sleep,
  • Homesickness,
  • Adjustment to living independently
39
Q

what are the pandemic flu causes

A
  • Spanish flu 1918 H1N1 INFLUENZ A 20-50 million deaths
  • swine flu 2009 H1N1
  • Avian flu 2014 H5N1
40
Q

what are the anti - influenza drugs

A

Oseltamivir (Tamiflu)
• Oral preparation
• Side-effects include (slight increase in risk of)
GI disturbance and neuropsychiatric symptoms
• Zanamivir (Relenza)
• Inhaled, fewer systemic side-effects but cannot be used in patients with asthma or COPD (risk of bronchospasm)
• Both neuraminasase inhibitors
• Modest benefits with both, shortened duration of illness

41
Q

what are the types of influenza vaccines

A
  • Adjuvanted trivalent flu vaccine (aTIV) - This is licensed for people aged 65 years and over and is the vaccine recommended by the Joint Committee on Vaccination and Immunisations (JCVI) for this age group.
  • Quadrivalent vaccine (QIV) - This is recommended for children aged from 6 months to 2 years and in adults from 18 years to less than 65 years of age who are at increased risk from flu because of a long term health condition.
  • Live attenuated influenza vaccine (LAIV) - This is a nasal spray and is licensed for children and young people from 2 years old to less than18 years of age. The age groups targeted in England for this vaccine in 2018/19 are two and three year olds (through their GP surgery) and school aged children in reception class through to Year 5 (through schools).

FunMed PBL (7 decks)

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