H. influenzae meningitis is caused by Haemophilus influenzae type b bacteria. This illness is not the same as the flu (influenza), which is caused by a virus.
Before the Hib vaccine, H. influenzae was the leading cause of bacterial meningitis in children under age 5. Since the vaccine became available in the United States, this type of meningitis occurs much less often in children.
H. influenzae meningitis may occur after an upper respiratory infection. The infection usually spreads from the lungs and airways to the blood, then the brain area.
Risk factors include:
Meningitis is an infection of the membranes covering the brain and spinal cord. This covering is called the meninges.
Bacteria are one type of germ that can cause meningitis. Haemophilus influenzae type b is one kind of bacteria that causes meningitis.
Exams and Tests
The health care provider will perform a physical exam. Questions will focus on symptoms and possible exposure to someone who might have the same symptoms, such as a stiff neck and fever.
If the doctor thinks meningitis is possible, a lumbar puncture (spinal tap) is done to take a sample of spinal fluid (cerebrospinal fluid, or CSF) for testing.
Other tests that may be done include:
This is a dangerous infection and it can be deadly. The sooner it is treated, the better the chance for recovery. Young children and adults over age 50 have the highest risk for death.
Long-term complications may include:
Infants and young children can be protected with the Hib vaccine.
Close contacts in the same household, school, or day care center should be watched for early signs of the disease as soon as the first person is diagnosed. All unvaccinated family members and close contacts of this person should begin antibiotic treatment as soon as possible to prevent spread of the infection. Ask your provider about antibiotics during the first visit.
Always use good hygiene habits, such as washing hands before and after changing a diaper, and after using the bathroom.
Symptoms usually come on quickly, and may include:
- Fever and chills
- Mental status changes
- Nausea and vomiting
- Sensitivity to light (photophobia)
- Severe headache
- Stiff neck (meningismus)
Other symptoms that can occur include:
- Bulging fontanelles in infants
- Decreased consciousness
- Poor feeding and irritability in children
- Rapid breathing
- Unusual posture, with the head and neck arched backwards
Antibiotics will be given as soon as possible. Ceftriaxone is one of the most commonly used antibiotics. Ampicillin may sometimes be used.
Corticosteroids may be used to fight inflammation, especially in children.
Unvaccinated people who are in close contact with someone who has H. influenzae meningitis should be given antibiotics to prevent infection. Such people include:
- Household members
- Roommates in dormitories
- Those who come into close contact with an infected person
When to Contact a Medical Professional
Call the local emergency number (such as 911) or go to an emergency room if you suspect meningitis in a young child who has the following symptoms:
- Feeding problems
- High-pitched cry
- Persistent, unexplained fever
Call the local emergency number if you develop any of the serious symptoms listed above. Meningitis can quickly become a life-threatening illness.
Nath A. Meningitis: bacterial, viral, and other. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 412.
Tunkel AR, Van de Beek D, Scheld WM. Acute meningitis. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 89.