Haemophilus Influenzae (Including Hib)

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Organism, Causative Agent, or Etiologic Agent 
Invasive Haemophilus influenzae disease can be caused by six identifiable types of H. influenzae bacteria (types a through f) or non-typeable H. influenzae bacteria. H. influenzae, type b (Hib) usually causes the most severe disease and is the only type that is vaccine-preventable. All cases of invasive H. influenzae disease are reportable in Texas.  

Transmission 
Direct contact with respiratory droplets from a carrier or case-patient. 

Symptoms 
The most common and severe manifestation of invasive H. influenzae disease is meningitis (inflammation and swelling in the coverings of the brain and spinal cord). Symptoms of meningitis include fever, weakness, vomiting, and a stiff neck. Hib and other types of H. influenzae can also cause infection of the lungs, blood, joints, bones, throat, and covering of the heart. Symptoms depend on the part of the body affected. 

Incubation Period 
The incubation period is hard to define because most people who get H. influenzae infections are asymptomatically colonized. Those who become ill following exposure to a case usually do so within 10 days, although the risk may be slightly elevated for up to 60 days.  

Communicability 
A person is contagious as long as the organism is present in discharges from the nose or throat. Communicability ends within 24 hours of initiation of appropriate chemoprophylaxis. Note that treatment of invasive disease does not necessarily eradicate the organism from the nose/throat. Those exposed more than seven days before the onset of illness are not at significantly increased risk. Hib cases are probably most infectious during the three days before the onset of symptoms. 

Prevention 
Invasive Hib disease is preventable by giving the Hib vaccine to kids 2-18 months of age. Hib and other types of H. influenzae can be preventable by maintaining respiratory isolation for patients and applying good hand-washing technique. 

School Exclusion Policy 
Keep children with bacterial meningitis, like that caused by H. influenzae, out of school or childcare until they have written permission from a healthcare provider and until they are fever-free for 24 hours without the use of fever suppressing medications. See rules for exclusion of sick children from school and childcare in the Texas Administrative Code, 25 Tex. Admin. Code §97.7. 

Haemophilus influenzae Invasive Disease Incidence Rates per County by Year (jpeg image) 

Haemophilus influenzae Invasive Disease Cases and Incidence Rates* in Texas, 2010-2019   

*Incidence rates calculated per 100,000 population. Population data are projected population from Texas Demographic Center’s Texas Populations Projections Program; 2019 population projections were updated July 18, 2019, and 2018 & earlier population projections were from the prior version.  

**Case Counts Haemophilus Influenzae type b only 2006-2015; all serotypes reported 2016-2019. Data Source: Texas NEDSS Finalized Data File, 2010-2019, Texas Notifiable Conditions.     

Haemophilus influenzae Invasive Disease Cases and Incidence Rates by Age Group in Texas, 2018-2019  

Haemophilus influenzae Invasive Disease Cases and Incidence Rates by Age Group in Texas, 2007-2017 

Haemophilus influenzae Invasive Disease Cases and Incidence Rates by Most Populous Counties in Texas, 2018-2019 

Haemophilus influenzae Invasive Disease Cases and Incidence Rates by County in Texas, 2006-2017 

Recent Texas Trends 
Haemophilus influenzae (all serotypes) have been steadily increasing between 2016 to 2018 from 317 to 464 cases respectively. In 2019, cases dropped to 452. Before 2016, only invasive disease caused by H. influenzae type b (Hib) was reportable. Hib disease is rare in Texas. Since 2000, there have been an average of 9 (range of 2-15) Hib cases reported each year in Texas with 5 reported in 2018 and 9 in 2019. The majority of Haemophilus influenzae cases reported were the non-typeable strain also seen at the national level.  Most cases of Haemophilus influenzae occur in older adults with other underlying that make them susceptible to Haemophilus influenzae. 

For more data about this condition, view our Infectious Disease Annual Reports or submit a Data Request.  

• CDC Pink Book Haemophilus influenzae Vaccine 

• Center for Disease Control and Prevention’s (CDC) Haemophilus influenzae Vaccine Chapter within the Pink Book  

• For Healthcare Professionals 

• Haemophilus influenzae Vaccine information for healthcare professionals on the CDC website 

• For the Public 

• Haemophilus influenzae Vaccine information for the public FAQs on the CDC website  

• ACIP Recommendations 

• Most recent articles and recommendations for Haemophilus influenzae vaccination from the Advisory Committee on Immunization Practices.