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What Is the History of Haemophilus Influenzae?

Once the leading cause of bacterial meningitis in children in the United States, Haemophilus influenzae was discovered in the 19th century. The history of this bacterium began with a case of mistaken identity.

  1. The Facts

    • Haemophilus influenzae is a bacterium that is found around the world. It is only found in humans, not in any other species of animal. It typically affects children, causing infection in the eyes, ears and sinuses. It can also lead to pneumonia. A more serious strain of the disease called Haemophilus influenzae type B can lead to meningitis and even cause deadly swelling of the throat. The history of Haemophilus influenzae begins with its discovery in the 19th century.

    Isolation

    • Haemophilus influenzae was first isolated in 1890 by Richard Pfeiffer. He believed it was the cause of an influenza pandemic that was then in progress and named the bacterium to reflect that belief. Haemophilus influenzae is often a secondary invader during pandemics because weakened immune systems are less able to resist it. It was subsequently found in patients during later influenza epidemics.

    Before Vaccines

    • History shows that Haemophilus influenzae type B was the leading cause of bacterial meningitis in children in the United States in the mid-1980s and earlier. It caused between 12,000 and 20,000 cases a year, leading to about 500 deaths each year. Doctors treated children infected with Haemophilus influenzae with antibiotics and while survival rates were good for a child who had been diagnosed early, 30 percent of children who developed meningitis and then recovered experienced lingering neurological effects.

    After Vaccines

    • Effective vaccines for Haemophilus influenzae and Haemophilus influenzae type B were developed in the 1980s and have been widely available in the United States since 1987. This radically changed the outlook for what had historically been a wide spread health problem. Ten years later, vaccinations had reduced the occurrence of Haemophilus influenzae in the United States by 95 percent. In 1996 and 1997, only 144 cases of Haemophilus influenzae were reported. It is now found chiefly in children who have not been immunized and those who are members of particularly at-risk populations.

    Chromosome Imaging

    • In 1995, Haemophilus influenzae's entire chromosome was sequenced. It was the first free-living organism to have its chromosome completely mapped. Researchers are studying the structures and processes of Haemophilus influenzae's construction. Some of what they have learned is now being used in fields like biotechnology and DNA cloning.

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