II. Definitions
-
Influenza-Like Illness (ILI)
- Documented fever >37.8 C. or (>100 F) and-or
- Cough and Sore Throat
- Absence of another cause
III. Epidemiology
- Reported April 12, 2009 in Veracruz, Mexico and WHO declared pandemic by April 27, 2009
- Widespread Influenza in United States in September, 2009
- Peak this early is unprecedented (previously outbreaks started in October and November)
- Global pandemic declared over as of August 2010
- United States H1N1 outcomes
- Cases: 61 million infected
- Hospitalizations: 274,000
- Deaths: 12,470
IV. Pathophysiology
- Chimera of swine flu, avian flu, and human flu
- Transmission through respiratory droplets (coughing, sneezing, or contaminated fomites)
V. Labs
- Standard rapid Influenza A and B testing only has 70% Test Sensitivity at best
- Treat outpatient cases empirically without testing
- Hospitalized case testing
- Test with Rapid Influenza Testing and
- Viral culture and
- Send sample to Department of Public Health (process varies by state)
VI. Management
- Indications to use specific agents (e.g. Tamiflu) as soon as possible (do not wait for labs)
- All patients hospitalized for Influenza-like illness
- Patients at high risk of complication from Influenza-like illness
- Prophlyaxis for patients at high risk of complication with close exposure to contact with H1N1
- Use treatment protocol instead of prophylaxis if exposure was >48 hours ago
- Do not give prophylaxis to healthy patients without risk
- Treatment and prophylaxis may be started by phone for patients who meet criteria
- Quarantine
- Stay home for 7 days from onset or at least 24 after last fever, significant symptoms
VII. Prevention
- H1N1 Immunization
- Prevent transmission
- Isolate patient early in triage process and have them wear mask
- Modified Droplet Precautions
- Healthcare workers wear mask with shield, gloves, gown
- N95 required only for aerosol generating procedure (e.g. intubation), but not nebulizer
- Pregnant healthcare workers should not take care of H1N1 patients
- Patients should still be considered infectious even after completing Antiviral Agents (i.e Tamiflu)
VIII. Prognosis: Risks of mortality
- Highest risk ages
- Under age 5 years (especially under age 1 years)
- Age 45-54 years old
- Pregnant women (highest risk in third trimester)
- Corticosteroid use has been associated with a higher mortality risk
IX. References
- Kline (2009) UMN CME Internal Medicine Review, Minneapolis