County of Los Angeles
Department of Public Health
Acute Communicable Disease Control
313 N. Figueroa Street, Room 212
Los Angeles, CA 90012
Phone: (213) 240-7941
Fax: (213) 482-4856
E-Mail:acdc2@ph.lacounty.gov
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Acute Communicable Disease Control
Haemophilus Influenzae Invasive Disease
Haemophilus influenzae is a Gram-negative coccobacillus that can cause both invasive
and noninvasive disease. H. influenzae invasive disease includes meningitis, sepsis,
pneumonia, cellulitis, and septic arthritis. Currently, the disease primarily affects
infants and the elderly, as well as immunocompromised individuals and those who have
abnormal splenic function. H. influenzae can be transmitted by respiratory secretions
of individuals colonized in the oropharynx with the organism. There are six
encapsulated, typeable strains (a–f) and unencapsulated, nontypeable strains of H.
influenzae. Prior to the introduction of the H. influenzae type b (Hib) conjugate
vaccine in 1990, most cases of invasive disease in children were caused by type
b. H. influenzae type b is the only serotype that is vaccinepreventable and for
which chemoprophylaxis is effective.
Haemophilus influenzae is a Gram-negative coccobacillus that can cause both invasive
and noninvasive disease. H. influenzae invasive disease includes meningitis, sepsis,
pneumonia, cellulitis, and septic arthritis. Currently, the disease primarily affects
infants and the elderly, as well as immunocompromised individuals and those who have
abnormal splenic function. H. influenzae can be transmitted by respiratory secretions
of individuals colonized in the oropharynx with the organism. There are six
encapsulated, typeable strains (a–f) and unencapsulated, nontypeable strains of H.
influenzae. Prior to the introduction of the H. influenzae type b (Hib) conjugate
vaccine in 1990, most cases of invasive disease in children were caused by type
b. H. influenzae type b is the only serotype that is vaccinepreventable and for
which chemoprophylaxis is effective.
