Meningitis is an inflammation of covering of the brain. It can be caused by bacteria or viruses, and there is no single cause of the condition. Viral meningitis may resolve itself, but bacterial meningitis is almost always fatal when left untreated. Certain groups of people such as children and people with compromised immune systems are more susceptible to the various forms of meningitis.
Streptococcus pneumoniae is one of the bacteria that may cause meningitis. It is present all over the world and is responsible for life-threatening illnesses such as pneumonia as well as meningitis. Most infections and deaths from S. pneumoniae are in children under 5. Other people at higher-than-normal risk for infection include those living in close quarters with many other people such as in college dorms or prisons.
Hib stands for Haemophilus influenza type B. It is another type of bacteria that can cause meningitis and other illnesses, most often in small children. Hib is all around us because adults tend to have immunity. Infants receive immunity from their mothers, but at some point this immunity fades and they become susceptible to the bacterium. Most children develop natural immunity without becoming ill, but when illnesses do occur they can be severe and even life-threatening.
The pneumococcus vaccine is relatively new but extremely effective and safe. Since 2000, it has been a recommended basic vaccination for infants in the U.S. and other countries. Because there are now antibiotic-resistant strains of the bacteria present, vaccination is especially important to ensure that the most vulnerable remain safe.
The Hib vaccine has been available since 1985, with the version that was specially made to induce immunity in infants introduced in 1987. It is also a recommended core vaccine for all infants. Since almost all children will be exposed to Hib at some point and there is no way of knowing which children will become seriously ill, the vaccine is important for preventing potentially life-threatening illnesses.
Both the Hib and the pneumococcal vaccines are specially made to provoke an immune response from children under 2. Previous to these special formulas the vaccines were not effective in infants because their immune systems could not yet recognize the polysaccharide shell of the bacteria used to induce immunity in older children and adults. Newer vaccines couple the polysaccharide with a harmless piece of protein which enables the immune systems of infants to mount a response.
In the year 2000, S. pneumoniae and Hib combined caused some 735,000 deaths worldwide in HIV-negative children under 5. There were a total of 14.5 million cases of illness caused by the bacteria. Most cases occurred on the African continent and India, but there were also significant numbers found elsewhere in Asia and in South and Central America. The highest numbers of deaths were found in the areas of highest incidence.