Vaccine-preventable diseases
Haemophilus influenzae type b (Hib) infections |
What is it?
Haemophilus influenzae type b infections are widespread throughout the world. Hib infections may develop under various forms but meningitis is the most frequent one. Hib infections occur in children under the age of 5 years, and mostly during the first year of life.
Symptoms
Following colonization of the pharynx, the bacterium may enter the bloodstream, and subsequently spread to reach various target organs resulting in different clinical forms of Hib disease:meningitis, pneumonia, epiglottitis, arthritis, cellulitis, osteomyelitis.
Hib meningitis is often fatal (in 5 to 40% of cases depending on the country) and may lead to neurological sequelae such as deafness, motor deficit, or mental retardation. (3)
Medical management relies on intensive care and appropriate antibiotic therapy.
Epidemiology and vaccination
Hib infections are strictly human. Children infect each other through saliva droplets or by playing with contaminated toys.
Worldwide, Hib infections account for 3 million cases of severe illness, and 400,000 to 700,000 deaths annually, with a peak of incidence among infants of age 4 to 18 months. (4)
The Hib vaccine is usually administered along with the other vaccines included in the childhood vaccination schedule. This vaccine has led to a rapid decline in the number of cases in industrialized countries, but its use is unfortunately not widespread in developing countries.
References:
3 - WHO. Introduction of Haemophilus influenzae type b vaccine into immunization programmes. WHO/V and B/00.05
4 - Peltola H. Worldwide Haemophilus influenzae type b disease at the beginning of the 21st century: global analysis of the disease burden 25 years after the use of the polysaccharide vaccine and a decade after the advent of conjugates. Clinical Microbiology Reviews, Apr. 2000.p.302-317
