Hemophilus influenzae infection is a bacterial infection occurring mainly in children. It is vaccine preventable. It causes life-threatening meningitis, pneumonia, and epiglottitis.
CASES/YEAR
35,390 (US); 1,200,000 (Global)
OTHER NAMES
Haemophilus meningitis; H. influenzae serotype b (Hib) infection;
INCUBATION
Probably 2-4 days; [CCDM]
INITIAL SYMPTOMS
Meningitis: stiff neck, headache, vomiting, seizures, and lethargy; Pneumonia: cough, rales, infiltrates; Epiglottitis: sore throat, difficulty swallowing, drooling, and airway obstruction;
PRECAUTIONS
Meningitis, Epiglottitis & Pneumonia in children: Droplet until 24 hours after initiation of effective therapy; Pneumonia in adults: Standard
COMMENTS
In the USA prior to the use of the Hib vaccine, H. influenzae was one of the major causes of meningitis, and it also caused epiglottitis and bacteremia. In developing countries, Hib is a major cause of pneumonia (estimated 480,000 pneumonia deaths/year in children <5 years). Hib meningitis has a mortality rate of about 5%. "As of the late 1990s, with widespread vaccine use in early childhood, Hib meningitis has virtually disappeared in industrialized countries and in developing countries that have introduced Hib vaccine." [CCDM, p. 409-10] The bacteria can also cause epiglottitis, pneumonia, septic arthritis, otitis media, conjunctivitis, and endocarditis. [Merck Manual, p. 1585] H. influenzae type B can cause facial cellulitis in unimmunized children. [ID, p. 1158] May cause septic arthritis in children aged two and younger; Also causes septic arthritis in adults; [PPID, p. 2747] Type b strains cause meningitis and other invasive disease in unimmunized children. Nontypable strains (no capsule) cause otitis media in children and chronic bronchitis, puerperal sepsis, and sinusitis in adults. [Harrison ID, p. 485t]
DIAGNOSTIC
Gram stain and culture; Antigen detection (CSF, serum, and urine) not recommended because rarely contributes to clinical management; [Wallach, p. 1139] Antigen detection test positive in 80-90% of cases of Hemophilus meningitis; [ABX Guide]
SIGNS & SYMPTOMS
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>fever
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E dysphagia
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E pharyngitis
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G nausea, vomiting
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H leukocytosis
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H lymphadenopathy
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N headache
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N lethargy
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N seizure
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N stiff neck
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O conjunctivitis, acute
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R cough
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R dyspnea
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R sputum production
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S cellulitis or rash, circinate
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S papules or plaques
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X lung infiltrates
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X pleural effusions
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*arthritis
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*endocarditis
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*epididymo-orchitis
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*meningitis
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*osteomyelitis
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*paralysis
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*pericarditis
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*pneumonia
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*sepsis
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*stupor, coma
ENTRY
Inhalation, Skin or Mucous Membranes (Includes Conjunctiva)
RISK FACTORS
- AIDS patients
- Asplenic patients
- Cancer patients
- Fail to complete immunizations
- Travel to endemic area
REFERENCES FOR CASES/YEAR
1. (US) Published in MMWR 2011 = 3539; Use correction factor of 10 for reported diseases: 3539 X 10 = 35,390;
2. (Global) Before immunizations, >40 cases/100,000 of invasive disease in children <5 years in US; Now <40 cases/year reported; "However, the majority of the world's children remain unimmunized." [Harrison ID, p. 484-5] Guesstimate: Assume 1/2 of population (3 trillion or 30,000 X 100,000) not immunized; Calculate: 40 X 30,000 = 1,200,000;