Report Immediately by Phone
Also known as: Hib disease, H. flu, spinal meningitis, Haemophilus
Hospital: Report immediately by phone, follow up required
Infection Control Practitioner: Report immediately by phone, follow up required
Lab Report /Isolate submission requirements: Isolates from invasive sites, should be submitted to University Hygienic Laboratory (UHL), all labs for serotyping.
Lab: Report positive isolates immediately by phone
Physician: Report immediately by phone
Local Public Health Agency: Report immediately by phone, follow up required
Iowa Department of Public Health
Disease Reporting Hotline: (800) 362-2736
Secure Fax: (515) 281-5698
Haemophilus influenzae disease is caused by small gram-negative coccobacilli that may be either encapsulated (types a-f) or unencapsulated (nontypeable). Type b (Hib) is the only kind for which there is a vaccine and for which control measures are considered necessary. It is the only type that is reportable.
B. Clinical Description
Symptoms: Invasive disease may produce various clinical syndromes, including meningitis, bacteremia or sepsis, epiglottitis, pneumonia, septic arthritis, osteomyelitis, pericarditis, empyema, and abscesses. In contrast, mucosal infections such as bronchitis, sinusitis, and otitis, which can be caused by Hib, are considered noninvasive disease
Onset: Onset will depend on the site of infection. With meningitis sudden onset of high fever, vomiting, lethargy, and meningeal irritation consisting of bulging fontanelle in infants or stiff neck in older children can occur.
Humans are the only known host.
D. Modes of Transmission
Haemophilus influenzae type b is transmitted person-to-person by droplet or direct contact with nasopharyngeal secretions of an infected person. The most common portal of entry is the nasopharynx. Newborns can become infected by inhaling amniotic fluid or genital tract secretions containing the organism.
E. Incubation Period
The incubation period is unknown but probably short, 2 - 4 days.
F. Period of Communicability or Infectious Period
- If not on antibiotic therapy - as long as organisms are present in the upper respiratory tract, which may be for a prolonged period even without symptoms.
- If on antibiotic therapy - noncommunicable within 24-48 hours after starting effective antibiotic therapy.
The contagious potential of invasive Hib disease is considered to be limited. However, certain circumstances, particularly close contact with a case (e.g., in a household, child care center, or institutional setting), can lead to outbreaks of Hib or direct secondary transmission of the disease. Asymptomatic carriage is known to occur.
Hib occurs worldwide. Invasive Hib is most prevalent among children 2 months to 3 years old and is unusual in healthy individuals over the age of 5 years (though can occur in adults with chronic conditions such as chronic obstructive pulmonary disease). In the United States, peak incidence is in children 6 - 12 months of age. Secondary cases may occur in households, child care centers, and other institutional settings.
Before the widespread use of Hib conjugate vaccines, Haemophilus influenzae type b (Hib) was a leading cause of bacterial meningitis in the United States among children less than 5 years old and a major cause of other life-threatening invasive bacterial diseases in this age group. Meningitis occurred in approximately two-thirds of children with invasive Hib disease, resulting in hearing impairment or severe permanent neurologic sequelae (mental retardation, seizure disorder, cognitive and developmental delays,) and paralysis in 15-30% of survivors. Approximately 5% of all cases were fatal. Invasive Hib disease now occurs in unvaccinated or under vaccinated children and adults. Type f is the most common other serotype causing invasive infections in the U.S. Iowa had approximately 64 cases of Hib per year prior to the vaccine. In the last 10 years Iowa has averaged 0.7 cases per year in persons less than 5 years of age.
Invasive disease has been more frequent in boys, African Americans, Alaskan Eskimos, Apache and Navajo Indians, child-care center attendees, children living in overcrowded conditions, and children who were not breastfed. Unimmunized children, particularly those younger than 4 years old, in prolonged close contact (such as in a household setting) with a child with invasive Hib disease, are at increased risk for invasive Hib disease. Other factors predisposing to invasive disease include sickle cell disease, asplenia, HIV infection, certain immunodeficiency syndromes, and malignant neoplasms.
H. Bioterrorism Potential
I. Additional Information
The Council of State and Territorial Epidemiologists (CSTE) surveillance case definitions for Haemophilus influenza type b can be found at:
CSTE case definitions should not affect the investigation or reporting of a case that fulfills the criteria in this chapter. (CSTE case definitions are used by the state health department and the CDC to maintain univorm standrads for national reporting.)
Positive antigen test results from urine or serum samples are unreliable for diagnosis of H. influenzae disease, but may help determine need for control measures while waiting for definitive laboratory results.
American Academy of Pediatrics. Red Book 2009: Report of the Committee on Infectious Disease, 28th Edition. Illinois, American Academy of Pediatrics, 2009.
CDC. Progress toward elimination of Haemophilus influenzae type b disease among infants and childrenUnited States, 19871995. MMWR. 1996; 45:901906.
CDC. Haemophilus website available at: www.cdc.gov/hi-disease/index.html
CDC. Updated Recommendations for Use of Haemophilus influenzae Type b (Hib) Vaccine: Reinstatement of the Booster Dose at Ages 12--15 Months. MMWR. 2009; 58(24);673-674
CDC. Manual for the Surveillance of Vaccine-Preventable Disease., Available at: www.cdc.gov/vaccines/pubs/surv-manual/index.html
Heymann, D.L., ed. Control of Communicable Diseases Manual, 20th Edition. Washington, DC, American Public Health Association, 2015.