1. INFLUENZA Causes of influenza: Influenza viruses A, and B RSV and adenovirus Mycoplasma pneumoniae Chlamydia species.

3. Influenza viruses: @ Influenza virus is the main human pathogen of the Orthomyxoviruses family. @ It has an enveloped, helical capsid and a linear, single, stranded RNA. @ Spherical in shape, with capsid projecting spikes

5. Classification of influenza virus: @ Classified into 3 types A, B or C: @ A – causes epidemic influenza in Man and influenza in birds, pigs, and horses. @ B – causes mild winter influenza. @ C – not sure to cause influenza in Man. * Influenza A viruses are subdivided into 9 H subtypes and 13 N subtypes.

7. Antigenic Structure: @ S or soluble antigen, found inside the core of virus @ H or haemagglutinin antigen in the envelope projecting spikes @ N or neuraminidase antigen in the envelope projecting spikes

9. Antigenic Variations: Called antigenic drift and antigenic shift. Antigenic Drift: @ Occurs in both influenza A and B @ The antigenic drift is due to mutation of the virus genes @ This is due to production of new strains each year. @ This leads to epidemics only inside countries.

11. Antigenic Shift: @ Occurs only in influenza A viruses @ It is due to the production of new subtypes every 20 years causing pandemics all over the world. @ In 1957: Asian pandemic. @ In 1968: Hong Kong pandemic.

13. Symptoms: @ Fever and headache @ Productive cough @ Runny nose @ Muscle aches @ Watery and painful eyes @ Difficulty in breathing through nose

15. Complications of influenza: @ Viral pneumonia: by influenza virus @ Bacterial pneumonia: by Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus. @ Myocarditis. @ Encephalitis.

17. Lab. Diagnosis of Influenza: @ Nasopharyngeal swab or throat swab in a viral transport medium for culture @ Isolation in monkey kidney cell culture @ Serology using ELISA and CFT. @ Sputum collected for both bacterial and viral culture @ Blood culture to diagnose bacteremia @ Bronchoalveolar lavage to identify influenza by immunofluorescence

19. Vaccination against influenza: @ By giving an inactivated vaccine. @The vaccine contains: * Influenza A, subtypes: H1N1 and H3N2 * Influenza B. @ Vaccine is given IM & it is 70% effective @ It is effective for only one year because antigens change from year to year.

21. @ Vaccination is given to people with:  Asthma  Chronic heart disease  Chronic renal failure  Diabetes mellitus  Immunosuppression.  Old people above 70 years.