Influenza is a highly infectious viral illness caused by influenza virus. It is a single stranded, helically shaped, RNA virus of the orthomyxovirus family. Basic antigen types A, B, and C are determined by the nuclear material. Type A influenza has subtypes that are determined by the surface antigens hemagglutinin (H) and neuraminidase (N). Three types of hemagglutinin in humans (H1, H2, and H3) have a role in virus attachment to cells. Two types of neuraminidase (N1 and N2) have a role in virus penetration into the cells.
Signs and Symptoms
- Fever or feeling feverish/chills
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- It is believed that flu viruses spread mainly by droplet made when people with flu cough, sneeze or talk.
- These droplets can land in the mouths or noses of people who are nearby.
- Less often, a person might also get flu by touching a surface or object that has flu virus on it and then touching their own mouth, eyes or possibly their nose.
- Respiratory transmission of virus.
- Replication in respiratory epithelium with subsequent destruction of cells.
- Viremia rarely documented.
- Virus shed in respiratory secretions for 5-10 days.
- It is very difficult to distinguish the flu from other viral or bacterial causes of respiratory illnesses on the basis of symptoms alone.
- A number of flu tests are available to detect influenza viruses. The most common are called “rapid influenza diagnostic tests.”
Prevention and Treatment
- The first and most important step in preventing flu is to get a flu vaccination each year.
- Antiviral drugs are prescription medicines that fight the flu in the body.
- The FDA-approved influenza antiviral drugs are: Oseltamivir, Zanamivir, and Peramivir.