Information about Haemophilus influenzae type b

For US Health Care Professionals Only

Merck Vaccines

Haemophilus influenzae
type b (Hib)

Hepatitis A

Hepatitis B

Human Papillomavirus (HPV)

Measles

Mumps

Pneumococcal Disease

Rotavirus Gastroenteritis

Disease Overview

	What invasive disease is caused by Haemophilus influenzae type b?
	The most common types of invasive disease caused by Hib are meningitis, epiglottitis, pneumonia, arthritis, and cellulitis.¹ Other, less common types of infection caused by Hib include osteomyelitis (bone infection) and pericarditis (infection of the sac covering the heart).¹

	What is the microbiology of Haemophilus influenzae type b?
	Hib is an encapsulated strain of bacteria that colonizes the human nose and throat. The bacteria may spread throughout the body through the bloodstream, and may become life threatening.² A polysaccharide, polyribosylribitol phosphate, or PRP, composes the outer layer of the Hib bacterium, and is an important determinant in the disease virulence.¹

	How is Haemophilus influenzae type b transmitted?
	Hib bacteria are thought to be spread primarily through contact with respiratory droplets expelled from an infected person. Although the contagious potential of Hib is thought to be limited, close contact with case-patients (eg, childcare, household, or institutional setting) can also lead to disease transmission.¹

	What is the pathology of Haemophilus influenzae type b?
	The bacteria enters through the nasopharynx, where it begins to colonize. The bacteria may remain there for several months without symptoms.¹ In some people, the bacteria causes invasive Hib disease.

	What are the clinical manifestations and symptoms associated with Haemophilus influenzae type b?
	The most common clinical manifestion of serious Hib disease is meningitis. Prior to widespread vaccine use, approximately 50% to 65% of all meningitis cases were attributed to the Hib strain.¹ Meningitis often presents with high fever, headache, and stiff neck. Less frequently, hearing impairment or other neurologic sequelae can result.^1,2

Disease Information

DISCLAIMER: By clicking on the links below, you will be directed away from MerckVaccines.com to another Web site. Merck does not review or control the content of sites to which the below hyperlinks connect; therefore, these hyperlinks do not constitute an endorsement by Merck.

CDC Information

AAP Information

CDC=Centers for Disease Control and Prevention.
Hib=Haemophilus influenzae type b.
AAP=American Academy of Pediatrics.

VACC-1018076-0000 02/12

haemophilus-influenzae-type-b-hib_Disease

Centers for Disease Control and Prevention (CDC). Haemophilus influenzae type b. In: Atkinson W, Wolfe S, McIntyre J, eds. Epidemiology and Prevention of Vaccine-Preventable Diseases. 12th ed. Washington, DC: Public Health Foundation; 2011: 87–101.

View all references

World Health Organization (WHO). Introduction of Haemophilus influenzae type b Vaccine Into Immunization Programs: Management Guidelines, Including Information for Health Workers and Parents. Geneva, Switzerland: World Health Organization; 2000.

View all references

Hib_ToolTipContent

From:

To: