Hemophilus influenzae organisms, the most common of which is type b (HiB), are among the many strains of bacteria that can grow in the respiratory tract without causing problems. Sometimes, however, they spread beyond control in the throat or middle ear or gain access to the bloodstream and other parts of the body, causing severe illnesses.
WHY SHOULD PARENTS BE CONCERNED ABOUT HIB?
HiB causes severe infections, including epiglottitis (inflammation of the tissue flap that keeps food out of the windpipe) and meningitis, which can lead to permanent neurological problems, including deafness and mental retardation. Because HiB infections are so serious, a vaccine has been developed to prevent HiB disease. Since the introduction of the vaccine, there have been many fewer cases of HiB infection.
HOW DO HIB INFECTIONS DEVELOP?
It depends on the site of the infection. Hemophilus bacteria can be responsible for middle ear infections, severe skin infections (known as cellulitis), bone infections (known as osteomyelitis) and joint infections (known as septic arthritis). HiB also can infiltrate the lungs, causing pneumonia, or the sinus cavities in the skull, causing sinusitis. The most feared HiB infections, however, are epiglottitis and meningitis.
In many cases, the mechanism by which HiB infection develops is poorly understood. Studies have shown that a high proportion of children harbor the bacteria in their throats at one time or another, so presence of the organism does not necessarily lead to illness.
Doctors believe HiB meningitis usually begins with an upper respiratory tract infection from which the bacteria enter the bloodstream and travel to the membranes surrounding the brain. This original infection, however, may not cause symptoms. Epiglottitis most commonly strikes children who show no other signs of infection, although in about one-fourth of cases there is a history of a preceding cold or sore throat. For unknown reasons, HiB epiglottitis rarely leads to meningitis or joint infection, even though the organisms are detectable in the bloodstream when the epiglottitis leads to HiB pneumonia or infection of the lymph nodes in the neck.
WHEN SHOULD I SUSPECT THAT MY CHILD HAS AN HIB INFECTION?
The symptoms vary according to the site of the infection, but fever, change in mood and weakness are virtually always part of the picture. A child with meningitis may be irritable, vomit and have a stiff neck. Infants with meningitis tend to be particularly irritable, especially in response to motion and other ordinarily soothing actions. Epiglottitis, which generally strikes children between the ages of three and seven, comes on suddenly and is marked by a severely high fever, inability to speak, drooling, and difficulty breathing and swallowing. Affected children commonly sit up and lean forward with their mouths open and tongue protruding. This is an emergency and the child should be taken to the hospital immediately. A middle ear infection caused by HiB has the same symptoms as other middle ear infections—pain, fever, and a feeling of fullness in the ear. HiB skin infections are most likely to appear on the face, causing pain, swelling and red or purplish discoloration. Bone or joint infections, which typically affect the legs, cause fever, pain and difficulty standing and walking.
CAN MY CHILD BE PROTECTED AGAINST HIB INFECTIONS?
Yes. Immunization has been available since the mid-1980s. As of 1992, the American Academy of Pediatrics recommended use of one of two available vaccines that produce immunity in infants. (Earlier HiB vaccines were not effective in babies under 18 months of age—the age group in which the majority of serious infections occur.) One of the recommended vaccines, known as the HbOC vaccine, is given at ages two, four and six months of age, followed by a final dose at 12 to 15 months. The other, known as the PRP-OMP vaccine, is given at two, four and 12 to 15 months.
As with any immunizations, protection against HiB is greatly improved by vaccine but is not 100 percent guaranteed. Therefore, if your child has been immunized, but develops symptoms of cellulitis, meningitis or epiglottitis, you should still seek prompt medical attention to obtain proper antibiotic treatment for the infection.
PREVENTING HIB INFECTIONS
• Make sure your child is fully immunized against HiB bacteria. Under current recommendations, one shot will not do it if the infant is less than 15 months of age. Your baby needs at least three or four injections to be protected completely.
• Regularly clean and disinfect toys shared by large groups of children.
GETTING HELP
Call your doctor if your child:
• Has not been immunized against HiB
• Has any signs and symptoms of infection, including fever, localized pain and swelling or a stiff neck
