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 five years, and mostly during the first year of life.
Symptoms of Haemophilus influenzae type b infections
- 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.(1)
- Medical management relies on intensive care and appropriate antibiotic therapy.
Epidemiology and vaccination against Haemophilus influenzae type b infections
- Hib infections are strictly human. Children infect each other through saliva droplets or by playing with contaminated toys.
- Before the large introduction of vaccination programs worldwide, Hib infections accounted for three million cases of severe illness, and 400,000 deaths annually, with a peak of incidence among infants of age 4 to 18 months.(2) As of March 2012, the WHO estimates that globally 199,000 HIV negative child deaths under five years of age occurred during 2008 due to Hib (Haemophilus influenzae type b).(3)
- Hib vaccination is usually administered along with the other vaccines included in the childhood vaccination schedule. It has led to a dramatic decrease in the number of cases following the introduction in the vaccination programs.
1 - WHO. Introduction of Haemophilus influenzae type b vaccine into immunization programmes. 2000. Accessed January 2018. http://archives.who.int/vaccines-documents/DocsPDF99/www9940.pdf
2 - 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, April 2000, 302-317. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC100154/pdf/cm000302.pdf
3 - WHO. Estimated Hib and pneumococcal deaths for children under 5 years of age, 2008. Updated December 2013, accessed January 2018. http://www.who.int/immunization/monitoring_surveillance/burden/estimates/Pneumo_hib/en