Influenza: Difference between revisions
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**Most pts gradually improve over 2-5d, although may last for one week or more | **Most pts gradually improve over 2-5d, although may last for one week or more | ||
**Some pts have persistent weakness lasting several weeks (postinfluenza asthenia) | **Some pts have persistent weakness lasting several weeks (postinfluenza asthenia) | ||
==Clinical Features== | ==Clinical Features== | ||
Line 35: | Line 28: | ||
###CXR shows b/l opacities w/ or w/o superimposed consolidation | ###CXR shows b/l opacities w/ or w/o superimposed consolidation | ||
##Secondary bacterial PNA | ##Secondary bacterial PNA | ||
### | ###Exacerbation of fever and respiratory symptoms after initial improvement | ||
####Higher fever, productive cough, radiographic evidence of infiltrates | |||
###Microbiology | |||
####Pneumococcus, S. aureus (including MRSA), H. flu | |||
#Myositis and rhabdo | |||
##More common in children | |||
##Extreme tenderness of affected muscles (most commonly in the legs) | |||
#Peri/myocarditis | |||
##Rare complication | |||
==Treatment== | |||
*Antiviral therapy | |||
**Efficacy | |||
***Can shorten duration of symptoms by 1-3d and reduces duration of viral shedding | |||
***Benefit greatest when started w/in first 24-30hr and in pts w/ fever at presentation | |||
****Little to no benefit when tx is started 2d or more after symptom onset | |||
****Do not wait for test results (if obtained) before beginning treatment | |||
***Controversial whether tx significantly prevents influenza-associated complications | |||
**Indications: | |||
***Illness requiring hospitalization | |||
***Severe, complicated, or progressive illness | |||
***High risk for complications: | |||
****Age <2yr OR age >65yr | |||
****Chronic illnesses: | |||
*****Pulmonary (including asthma), CV (except HTN), renal, hepatic, hematological, DM | |||
****Immunosuppression (meds and HIV) | |||
****Pregnant or within 2wk after delivery | |||
****Morbidly obese (BMI >40) | |||
****Pts age <19yr who are receiving long-term aspirin therapy | |||
****American Indians/Alaska Natives | |||
****Residents of nursing homes / chronic care facilities | |||
***Can consider in pts w/ mild illness who are otherwise healthy to reduce length of sx | |||
**Meds | |||
***Neuraminidase inhibitors | |||
****Oseltamivir 75mg PO BID x5d | |||
****Zanamivir 10mg (2 inhalations) BID x5d | |||
*****Relatively contraindicated in pts w/ asthma, COPD, or pregnancy | |||
***Adamantanes (amantadine, rimantadine) | |||
****Not recommended due to high rates of resistance | |||
*Abx | |||
**Only recommended for secondary bacterial PNA | |||
**Choice of meds should be guided by Gram stain sputum culture if possible | |||
**Empiric therapy: | |||
***CTX OR levofloxacin +/- vancomycin | |||
Revision as of 01:19, 12 October 2011
Background
- Transmission
- Occurs in 6ft radius around infected pt who is sneezing and/or coughing
- Viral shedding lasts ~5d (starts 24-48hr before onset of symptoms)
- Longer duration of shedding occurs in children, elderly, pts w/ chronic illnesses
- Shedding from asymptomatic individuals doesn't contribute significantly to transmission
- Convalescence
- Most pts gradually improve over 2-5d, although may last for one week or more
- Some pts have persistent weakness lasting several weeks (postinfluenza asthenia)
Clinical Features
- Constitutional
- Fever
- Headache
- Myalgia
- Malaise
- Respiratory
- Non-productive cough
- Sore throat
- Rhinorrhea
Complications
- Pneumonia
- Primary influenza PNA
- Most severe and least common type of PNA
- Rare in otherwise healthy adults
- Consider in pts w/ persistent and worsening symptoms (esp high fever, SOB, cyanosis)
- CXR shows b/l opacities w/ or w/o superimposed consolidation
- Secondary bacterial PNA
- Exacerbation of fever and respiratory symptoms after initial improvement
- Higher fever, productive cough, radiographic evidence of infiltrates
- Microbiology
- Pneumococcus, S. aureus (including MRSA), H. flu
- Exacerbation of fever and respiratory symptoms after initial improvement
- Primary influenza PNA
- Myositis and rhabdo
- More common in children
- Extreme tenderness of affected muscles (most commonly in the legs)
- Peri/myocarditis
- Rare complication
Treatment
- Antiviral therapy
- Efficacy
- Can shorten duration of symptoms by 1-3d and reduces duration of viral shedding
- Benefit greatest when started w/in first 24-30hr and in pts w/ fever at presentation
- Little to no benefit when tx is started 2d or more after symptom onset
- Do not wait for test results (if obtained) before beginning treatment
- Controversial whether tx significantly prevents influenza-associated complications
- Indications:
- Illness requiring hospitalization
- Severe, complicated, or progressive illness
- High risk for complications:
- Age <2yr OR age >65yr
- Chronic illnesses:
- Pulmonary (including asthma), CV (except HTN), renal, hepatic, hematological, DM
- Immunosuppression (meds and HIV)
- Pregnant or within 2wk after delivery
- Morbidly obese (BMI >40)
- Pts age <19yr who are receiving long-term aspirin therapy
- American Indians/Alaska Natives
- Residents of nursing homes / chronic care facilities
- Can consider in pts w/ mild illness who are otherwise healthy to reduce length of sx
- Meds
- Neuraminidase inhibitors
- Oseltamivir 75mg PO BID x5d
- Zanamivir 10mg (2 inhalations) BID x5d
- Relatively contraindicated in pts w/ asthma, COPD, or pregnancy
- Adamantanes (amantadine, rimantadine)
- Not recommended due to high rates of resistance
- Neuraminidase inhibitors
- Efficacy
- Abx
- Only recommended for secondary bacterial PNA
- Choice of meds should be guided by Gram stain sputum culture if possible
- Empiric therapy:
- CTX OR levofloxacin +/- vancomycin
Source
UpToDate