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Diseases & Topics

Haemophilus influenzae Infection

Haemophilus influenzae is a type of bacteria that lives in the upper respiratory tract (nose, mouth and throat). These bacteria can cause a variety of infections, from mild (such as ear or sinus infections) to severe (such as meningitis and pneumonia).

Haemophilus influenzae can be divided into types (types a - f and non-typeable) based on specialized laboratory tests. Of these, Haemophilus influenzae type b, or "Hib" is the most dangerous. Before Hib vaccines were widely available, Hib was one of the leading causes of meningitis in children. Hib meningitis can lead to long-term health problems such as brain damage, hearing loss and even death, especially in infants and young children.

Because young children have routinely received Hib vaccine in the United States since 1990, the incidence of Hib disease in infants and young children has decreased by 99 percent, to less than 1 case per 100,000 children under 5 years of age. Hib disease in the U.S. now occurs primarily in under-immunized children and among infants too young to have completed the primary immunization series. However, in countries where vaccination is not widely available, Hib remains a major cause of childhood respiratory tract infections.

Haemophilus influenzae infections are spread through coughing and sneezing or otherwise coming in contact with respiratory droplets from an infected person. It is important for young children to get vaccinated against Hib.

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