Influenza pandemic is mainly caused by -

↵ Influenza Influenza is an acute respiratory tract infection caused by influenza virus. There are three viral subtypes Type A → Causes all Pandemics and most of the epidemics Type B → Can cause epidemics Type C → Causes endemic infection Three types of influenza viruses are circulating in world → A (H1N1), A (H3 N2) and B A New type has been recognized → A (H5 N1) Source of infection → case or subclinical case Mode of transmission → Droplet infection by respiratory route Incubation period →18-72 hours Clinical manifestations Most infections are subclinical fever, headache and myalgia Respiratory → coughing There is no virernia Complications Pneumonia → M.C. by str. pneumoniae Worsening of COPD Encephalitis Reye's Syndrome → with type B virus GB. Syndrome G I Symptoms (gastric flu) → type B virus Laboratory diagnosis Most commonly, the diagnosis is established by the use of rapid viral tests that detect viral nucleoprotein or neuraminidase   - Harrison - 1069 Best specimen is nasopharyngeal secretion.