Influenza Flashcards
What type of virus is influenza?
RNA
What family does influenza come from?
Orthomyxoviridae family
How many main groups of influenza are there?
3 (A,B and C)
Who does each influenza group affect?
A - Humans, mammals and birds
B and C - only humans
What are the surface proteins found in influenza?
Haemagglutinin
Neuraminidase
What is antigenic drift?
Changes the antigenic properties so eventually the immune system will not combat the virus as well
Causes worse than normal epidemics and vaccine mismatch
What is antigenic shift?
Abrupt major change in virus resulting in new H/N combinations
Enables flu strain to jump from one animal species to another
Combine to form a new subtype
What is seasonal flu?
Occurs every winter
Affects 10-15% population
Usually unpleasant but not life threatening
What is pandemic flu?
Occurs sporadically
Affects 25%+ population
More serious, more complications
How is avian flu spread?
Direct contact with infected birds, dead or alive
What is the incubation period for flu?
2-4 days average
What are the clinical features of flu?
Abrupt fever of 41c which lasts 3 days Cough Sore throat Rhinorrhoea Myalgia Malaise Headache Nausea Vomiting Diarrhoea
How long does the flu virus survive?
24-48 hours on non-porous surfaces
8-12 hours on porous surfaces
What are the high risk groups for contracting flu?
Chronic respiratory disease Chronic heart, neurological, renal and liver disease Diabetes Immunosuppression Morbid obesity (BMI>40) Pregnancy
What are common complications of flu?
Acute bronchitis
Secondary bacterial pneumonia
What are uncommon complications of flu?
Primary viral pneumonia
Myocarditis/pericarditis
Transverse myeltiis/ Guillian-Barre
Myositis and myoglobinuria
What are the symptoms of encephalitis lethargica?
Fever Headache Lethargy Sleep reversal External ophthalmoplegia
What investigations should be done for flu/encephalitis lathergica?
Viral nose and throat swabs CXR Blood culture Pulse oximetry Respiratory rate U&Es, creatinine and FBC CRP
What should be used to assess the severity of secondary bacterial pneumonia?
CURB65
What is CURB65?
Confusion Urea >7mmol/L Respiratory rate >30/min Blood pressure (diastolic <60 systolic <90) >65 years old
What antiviral therapy can be used for flu?
Oseltamivir
Zanamivir
Peramivir
Favipiravir
What are the side effects of oseltamivir?
Nausea Vomiting Abdominal pain Diarrhoea Headache Hallucinations Insomnia
What are the side effects of zanamivir?
Occasional bronchospasm (rare)
What kind of drugs are oseltamivir and zanamivir?
Neuraminidase inhibitors
