Haemophilus influenzae Disease: Infections, Spread and Prevention

Computer-generated image of Haemophilus influenzae*. Image from CDC's page.*

The main points

• Haemophilus influenzae bacteria can cause many kinds of infection, some mild and some serious.
• Despite the name, H. influenzae does not cause the flu.
• Vaccines prevent infection from one type, H. influenzae type b (Hib).

Infections it causes

Serious — the most common:

• pneumonia (a lung infection);
• bloodstream infection;
• meningitis (swelling of the lining of the brain and spinal cord);
• epiglottitis (swelling of the throat);
• cellulitis (a skin infection);
• infectious arthritis (swelling of a joint).

Mild: a common cause of ear infections in children and bronchitis (chest cold) in adults.

Symptoms depend on the part of the body infected. Serious infections can cause long-term health problems and death. More on symptoms and complications.

The bacteria and their types

H. influenzae live in people's nose and throat, usually harmlessly, but can move elsewhere in the body and cause infection. There are 6 types, named a through f; the best known is type b (Hib). Some have no type and are called nontypeable.

Who's at risk: people of certain ages and racial or ethnic groups, and people with some medical conditions — see the risk factors.

How it spreads

• Through coughs and sneezes, which release small respiratory droplets others breathe in.
• Most often from people who aren't sick but carry the bacteria in their nose and throat.
• To people with close or lengthy contact with someone who has the disease.

Prevention

• You can get H. influenzae disease — Hib included — more than once. Healthy habits help: wash your hands often and avoid close contact with people who are sick.
• Vaccination is the best protection against Hib, though it doesn't prevent other types. CDC recommends Hib vaccine for all children younger than 5. More on Hib vaccination and vaccine schedules for parents.
• Close contacts of someone with Hib disease sometimes need preventive antibiotics; a health care provider or health department usually decides who.

Diagnosis and treatment

• Providers usually diagnose it with one or more lab tests, most often on a sample of blood or spinal fluid.
• It is treated with antibiotics. People with serious infections may need hospital care, including breathing support, medicine for low blood pressure, and wound care for damaged skin.

Sources

Based on "About Haemophilus influenzae Disease," Centers for Disease Control and Prevention; a work of the United States government in the public domain. Its stock photograph is not reproduced.