Haemophilus influenzae type B and Hib Vaccine Epidemiology and Prevention of VaccinePreventable Diseases

Note to presenters: Images of vaccine-preventable diseases are available from the Immunization Action Coalition website at http://www.vaccineinformation.org/photos/index.asp

National Immunization Program Centers for Disease Control and Prevention Revised January 2006

Haemophilus influenzae type b

• Severe bacterial infection,

particularly among infants

• During late 19th century believed to cause influenza

• Immunology and microbiology clarified in 1930s

Haemophilus influenzae type b Pathogenesis

• Organism colonizes nasopharynx • In some persons organism invades

bloodstream and cause infection at distant site

• Antecedent upper respiratory tract infection may be a contributing factor

Haemophilus influenzae

• Aerobic gram-negative bacteria • Polysaccharide capsule • Six different serotypes (a-f) of polysaccharide capsule

• 95% of invasive disease caused by type b

Haemophilus influenzae type b Clinical Features* Epiglottitis 17% Meningitis 50% Pneumonia 15%

Osteomyelitis 2% Arthritis 8% Cellulitis 6%

Bacteremia 2%

*prevaccination era

1

Haemophilus influenzae type b Meningitis

• Accounted for approximately

Haemophilus influenzae type b Medical Management

• Hospitalization required • Treatment with an effective 3rd

50%-65% of cases in the prevaccine era

generation cephalosporin, or chloramphenicol plus ampicillin

• Hearing impairment or neurologic sequelae in 15%-30%

• Case-fatality rate 2%-5% despite of effective antimicrobial therapy

• Ampicillin-resistant strains now common throughout the United States

Incidence*of Invasive Hib Disease, 1990-2004

Haemophilus influenzae type b Epidemiology Human • Reservoir

25

Asymptomatic carriers Respiratory droplets

• Temporal pattern

Peaks in Sept-Dec and March-May

• Communicability

15 10 5

Generally limited but higher in some circumstances

Haemophilus influenzae type b, 1986 Incidence* by Age Group

Incidence

Incidence

• Transmission

20

0 1990

1992

1994

1996

1998

2000

2002

2004

Year *Rate per 100,000 children 2 months

5

Haemophilus influenzae type b Vaccine Adverse Reactions

Haemophilus influenzae type b Vaccine

Contraindications and Precautions

• Swelling, redness, or pain in

• Severe allergic reaction to vaccine

• Systemic reactions infrequent • Serious adverse reactions rare

• Moderate or severe acute illness • Age