BROWARD COUNTY HEALTH DEPARTMENT

 

  HOT TOPICS

 

The Facts on Influenza (“the Flu”)

 

 

What is influenza?  Influenza is a disease caused by a virus that attacks the respiratory system (nose, throat, lungs, and airways).  Commonly known as “the flu,” influenza may be caused by any of 3 types of an RNA orthomyxovirus.  Types A and B cause most human illness.  Influenza A subtypes mutate frequently and are responsible for widespread epidemics or pandemics.  The 6th leading cause of death in the United States, influenza and pneumonia, cause more than 40,000 deaths each year.

Text Box: Influenza pandemics (worldwide epidemics) arise at regular intervals. The earliest recognized pandemic occurred in 1580. There have been 31 more pandemics since then. When steamship travel was the most rapid form of international transportation, the “Spanish influenza” pandemic of 1918-1919 circled the globe. In less than 5 months, 21 million people were killed.

Who gets influenza?  All children and adults are equally susceptible.  Frequent mutations of Influenza A enable it to infect everyone because antibodies from prior infections do not protect against mutant forms of the virus.  The disease appears in the Northern hemisphere from October through April, and in the Southern hemisphere from May through September.  Pigs and birds are susceptible and serve as silent reservoirs for the virus when it is not causing the disease among humans.

 

How is the disease spread?  Airborne spread is frequent among crowded populations in enclosed spaces such as school buses, shopping malls, and airports.  The disease also may be spread via direct contact with an infected person.  Persons infected with influenza may spread the virus for 5 to 7 days after symptoms first appear.

 

What are the symptoms of influenza?  The usual symptoms are fever, weakness, headache, muscle aches, runny nose, sore throat, and cough.  Recovery within 2-7 days is common, but complications such as pneumonia and death may occur, particularly in the elderly and those who have a chronic illness such as heart failure, asthma, or emphysema.

 

When do symptoms appear?  Usually within 1 to 3 days after exposure to the virus.

 

How is influenza diagnosed?  Most cases are identified as “influenza-like illness” from the symptoms.  A direct antigen test is used for rapid diagnosis of Influenza A.  Antibody levels in 2 blood specimens obtained while the person is ill and soon after recovery also confirm the diagnosis.  The virus may be cultured from the nose or throat within 3 days after onset.  The Centers for Disease Control and Prevention (CDC) maintain a surveillance system of “sentinel physicians” who submit culture specimens for virus identification and report cases of influenza-like illness weekly.

 

What is the treatment?  Supportive care (bed rest, fluids, medications for aches, cough, and fever) is sufficient for most uncomplicated cases.  Antibiotics are useful only if pneumonia develops.  Two antiviral drugs, amantadine and rimantadine, interfere with Influenza A virus replication, but must be started within 48 hours of the onset of symptoms to be effective.  Both are 70% to 90% effective in preventing Influenza A illness.  They are not effective against Influenza B.  A new antiviral nasal spray (Relenza) has been developed which has been found to be effective against A and B influenza.

 

How can influenza be prevented?  Influenza vaccine should be given in October or early November before influenza outbreaks begin.  Anyone who wants to prevent the illness should receive the vaccine, but it is mandatory for elderly persons and those with underlying health problems.  Each year, the vaccine is updated to guard against the 3 most common strains of influenza circulating worldwide.  For maximum protection, the vaccine should be taken every year.

 

For further information, contact the Broward County Health Department at 467-4865.

 

         2421A SW 6th Ave., Ft. Lauderdale, FL  33315           Nov 1999