How does it present?

• Fever, cough, sore throat, runny nose, muscle aches, headaches, fatigue, diarrhea (in children especially)

Who cares…I got my vaccine! Does the vaccine work this year?

• There has been some antigenic drift this year in the influenza A (H3N2) type virus.
• 52% are anti-genically different than the H3N2 vaccine virus.
• So the vaccine is less effective this year but it can give some cross-protection (in addition to protection against the other strains used in the vaccine)
• CDC recommends still getting the vaccine  (http://www.cdc.gov/flu/protect/vaccine/vaccines.htm)
• 91% of samples reported to the CDC have been influenza A this year

Can I test for this?

• Rapid influenza diagnostic tests check for antigen detection
• Pooled sensitivity of 62%; specificity of 98%
• False negatives are common
• Good technique during sample collection is important

The CDC is recommending treatment...wait I thought we were done with Tamiflu?

• Benefits: shortens the duration of symptoms (day or less), reduces the risk of complications, reduces the risk of death among hospitalized patients
• Risks: side effects (see below)
• A recent Cochrane review revealed that treatment did not really help reduce complications and most of the data on anti-viral agents is biased (Roche funded) and hotly debated

Who is at risk/who deserves consideration for treatment?

• Hospitalized patients with influenza 
• Old people (>65)
• Children
• Pregnant women
• Chronic medical conditions (asthma, COPD, diabetes, or heart disease)
• American Indians and Alaskan natives
• Chronic immunosuppression
• Institutional outbreaks (nursing homes, correctional facilities)

Pearls of treatment

• Treat as early as possible (<48hours from symptom onset)
• 5 days of treatment; twice daily dosing. Wt based for children. Renally dosed.
• Oseltamivir: used for more severe influenza cases
• Zanamivir: 7 years or older; IV Zanamivir is currently in Phase III clinical trials

What are the side effects of anti-viral agents?

• Don’t use zanamivir in patients w/ pulmonary disease
• Transient neuropsychiatric events for oseltamivir
• Nausea, vomiting, diarrhea are common both both

 

References

http://www.cdc.gov/flu/index.htm

Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children.