The influenza virus has -

Influenza virus  Belong to orthomyxoviridae → Envelope, RNA virus  Contain single stranded RNA which is segmented → 8 pieces  There are three viral subtypes 1. Type A → Causes all pandemics and most of the epidemics 2 Type B → Can cause epidemics 3. Type C → Causes endemic infection  Three types of influenza viruses are circulating in world →A(H1N1), A(H3N2) and B  A new type has been recognized →A (H5N1)  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 viremia  Complications Pneumonia → M.C. by str. pneumoniae Worsening of COPD Encephalitis Reye’s Syndrome→ with type B virus GB. Syndrome GI 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.