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Haemophilus influenzae

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What is Haemophilus influenzae?

Haemophilus influenzae is a bacteria that is commonly found in the nose and throat of children and adults. A particular type, Haemophilus influenzae serotype B (Hib), can invade and cause infections. H. influenzae may cause a variety of diseases, including meningitis (inflammation of the coverings of the spinal column and brain), blood stream infections, pneumonia, arthritis, and epiglottitis. Although it was once the most common cause of bacterial infections in children, due to widespread use of Hib vaccine few cases are reported each year. Despite its name, this bacterium has nothing to do with the influenza viruses.

Who gets H. influenzae infection?

Unvaccinated household and daycare contacts of people with known H. influenzae infection are at greatest risk. Hib infection is most common in children three months to three years of age. It is unusual in persons over the age of five. The elderly and adults with underlying disease are at greatest risk of non-serotype B disease.

How is H. influenzae spread?

H. influenzae may be spread through contact with mucus or droplets from the nose and throat of an infected person

What are the symptoms of H. influenzae infection?

Symptoms of meningitis may include fever, vomiting, listlessness, and a stiff neck or back. Other symptoms depend upon the part of the body affected.

How soon after exposure do symptoms appear?

Symptoms generally appear in less than 10 days after exposure, commonly within 2 to 4 days.

When and for how long is a person able to spread H. influenzae?

The contagious period varies and, unless treated, may last for as long as the organism is in the nose and throat, even after symptoms have disappeared. A person can no longer spread H. influenzae after taking the proper antibiotics for 1 to 2 days.

Does past infection with H. influenzae make a person immune?

No. Children who have had H. influenzae infection can get it again.

What is the treatment for H. influenzae infection?

Specific antibiotics are generally used to treat serious infections.

Should people who have been in contact with someone diagnosed with H. influenzae infection be treated?

Preventive treatment is only recommended in specific situations. For example, treatment with an antibiotic is recommended for household members when there is at least one unvaccinated child under four years of age in the home. In certain situations, preventive treatment will be recommended in childcare centers. Casual contact such as occurs in classrooms or office settings is not usually significant enough for preventive treatment to be needed.

What can be done to prevent the spread of H. influenzae?

Hib vaccines are available. All children should be vaccinated against Hib beginning at approximately two months of age. Contact your physician or local health department for further information about vaccination.

Last Updated: 07-30-2011

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