The epiglottis a cartilaginous structure located at the back of the throat, just beneath the tongue. This flap of tissue closes the top of the trachea on swallowing to prevent food from being inhaled, which can cause a person to cough or choke.

Epiglottitis refers to a condition where the epiglottis becomes inflamed and swollen, usually as a result of infection. The condition is more common among children than among adults, since their underdeveloped immune system means they are more vulnerable to infection.

Onset of symptoms is usually sudden and symptoms quickly worsen, although older children and adults may find symptoms take a few days to develop.

Symptoms include the following:

• Very sore throat
• Pain on swallowing
• Difficulty breathing
• Fever
• Irritability
• Drooling
• Hoarse voice

Causes

There are various causes of this condition including burns to the inside of the throat, injury to the throat and a number of infections, but the most common cause in children is Hemophilus influenza type b (Hib) infection. This is the bacteria that also causes blood infections (septicemia), meningitis and pneumonia. In adults, common causes are infection with Streptococcus pneumoniaeand the herpes simplex virus.

Infection with Hib

The Hib bacteria is spread in a similar way to the flu virus. The bacteria is contained in saliva and mucus, which are expelled into the air as droplets when an infected individual coughs or sneezes. Another person can become infected if they breath those droplets in. It is possible for Hib to be present in the nose and mouth without causing illness, but an infected person can still spread the bacteria to other people. The expelled droplets can also contaminate surfaces and objects, which may infect a person who touches them and then touches their mouth.

The most effective way to protect children against epiglottitis is to vaccinate them against Hib and ensure vaccinations are kept up to date. Nowadays, epiglottitis is rare in developed countries, since all children are routinely given the Hib vaccination.
Less common causes

Other less common causes of epiglottitis include the following:

• Infection with  the bacteria Streptococcus pneumoniae, which can also cause meningitis, pneumonia and septicemia.
• Infection with streptococcus A,B or C, which can also lead to septicemia and strep throat.
• Fungal infections, which are most likely to occur in immunocompromised individuals.
• Infection with a virus such as the herpes simplex virus or the virus that causes chickenpox.
• Injury to the throat caused by a blow or burning as a result of drinking very hot liquids or chemicals that can damage the throat.
• Smoking can also cause epiglottitis, especially if the substance inhaled is a drug such as cocaine or cannabis.