Haemophilus influenzae bacteria can cause invasive disease: infection of parts of the body that are normally germ-free, such as the blood. CDC tracks invasive disease through two surveillance systems. It does not track non-invasive infections such as ear infections.
Image from CDC's page on H. influenzae surveillance.
Two ways of watching
| System | How it works |
|---|---|
| National Notifiable Diseases Surveillance System (NNDSS) | Invasive H. influenzae disease is nationally notifiable; CDC receives reports every week |
| Active Bacterial Core surveillance (ABCs) | Collects information from laboratories in 10 areas of the country, as part of CDC's Emerging Infections Program. Its data feed projected national incidence estimates, explorable in CDC's Bact Facts Interactive tool |
CDC also runs enhanced surveillance of disease in children, reporting case counts and rates by serotype and age, vaccination history, deaths, clinical syndromes and daycare attendance. Cases are defined by the Council of State and Territorial Epidemiologists' case definition, last revised in 2015.
What vaccination changed
The picture changed once the United States began using Hib vaccines — for children in 1987 and for infants in 1990. Since then, annual rates of invasive disease in children under 5 have shifted:
| Type | Trend |
|---|---|
| Type b (Hib) | Down 99% |
| Non-b types (mainly a and f) | Increasing |
| Nontypeable | Increasing |
CDC's national incidence estimates run from 1989, with detail by serotype and age for 2020–2024.
Sources
Based on "Haemophilus influenzae Disease Surveillance and Trends," Centers for Disease Control and Prevention; a work of the United States government in the public domain.
Licence: CC0 1.0 (public domain) · Adapted from www.cdc.gov
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