Pathogenesis (disease development)
The unencapsulated form of Haemophilus influenzae colonizes the mucosa (mucous membrane) of the nasopharynx (nasopharyngeal cavity) and represents part of the normal flora of humans.
The capsule is an important pathogenicity factor: encapsulated H. influenzae is obligate pathogen (pathogen that also infects a healthy, immunocompetent host).Encapsulated strains can often be detected in children, which is why severe illness after infection with Haemophilus influenzae occurs especially in the age group between six months and five years.In adults, infections with Haemophilus influenzae tend to occur as a complication of other underlying diseases. In this case, unknown strains can also be identified as the causative agent.
Etiology (Causes)
Behavioral causes
- Droplet infection
- Contact infection
Causes due to disease
- In adults, weakness of the immune system may favor infection with Haemophilus influenzae