Influenza is an acute respiratory illness caused by influenza A or B viruses

-Transmission occurs primarily by droplet nuclei

-The incubation period is 1–4 days

-The average duration of influenza virus shedding in immunocompetent patients: 5 days 

Symptoms & Signs

-Sudden onset of fever, rhinorrhea, chills, pharyngitis, hoarseness, nonproductive cough,malaise, myalgias, enlargement of cervical lymph nodes, tracheal tenderness 

-The major complication of influenza is pneumonia (most common is  Pneumococcal pneumonia, most serious is staphylococcal pneumonia

Diagnosis

The best specimens for diagnostic testing: nasopharyngeal swabs and nasal aspirate or lavage fluid 

RT-PCR, rapid molecular assays, antigen detection assays, viral culture 

Treatment 

Treatment is supportive

Antiviral therapy: Oseltamivir, inhaled zanamivir (it can cause bronchospasm),peramivir, baloxavir 

Prevention

Annual administration of influenza vaccine is the most effective measure for preventing influenza and its complications.