Influenza: Difference between revisions
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==Background== | ==Background== | ||
*Transmission | *Human Influenza type A and B cause majority of infections. Type A has more severe disease course. | ||
===Transmission=== | |||
*Occurs in 6ft radius around infected patient 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, patients with chronic illnesses | ||
** | **Shedding from asymptomatic individuals does not contribute significantly to transmission | ||
** | *Use of either N95 or plain surgical mask by healthcare professionals caring for patients with proven influenza helps to decrease rates of provider contraction of influenza.<ref>SURGICAL MASK VS. N95 RESPIRATOR FOR PREVENTING INFLUENZA AMONG HEALTH CARE WORKERS Loeb, M., et al, JAMA 302(17):1865, November 4, 2009</ref> | ||
===Risk Factors (for complicated course)=== | |||
*Age <2 years or >65 years | |||
*[[Pregnancy]] through 2 weeks after delivery | |||
*Chronic pulmonary (including [[asthma]]), cardiovascular (except hypertension), renal, hepatic, hematological (including sickle cell disease), neurologic, neuromuscular, or metabolic disorders (including diabetes mellitus) | |||
*Immunosuppression, including that caused by medications or by HIV | |||
*Persons younger than 19 years of age who are receiving long-term aspirin therapy | |||
*American Indians and Alaska Natives | |||
*Morbid obesity | |||
*Patients in nursing homes or chronic-care facilities | |||
===Vaccination Status=== | |||
*A history of influenza vaccination does not rule out influenza in an ill patient with clinical signs and symptoms compatible with influenza. | |||
*Therefore, vaccination status should not impede the initiation of prompt antiviral treatment. | |||
==Clinical Features== | ==Clinical Features== | ||
Line 13: | Line 27: | ||
**[[Fever]] | **[[Fever]] | ||
**[[Headache]] | **[[Headache]] | ||
** | **[[Myalgia]]s | ||
**Malaise | **Malaise | ||
*Respiratory | *Respiratory | ||
**Non-productive cough | **Non-productive [[cough]] | ||
**[[Sore throat]] | **[[Sore throat]] | ||
**Rhinorrhea | **[[Rhinorrhea]] | ||
==Diagnosis== | ===Cough and Fever=== | ||
''Odds that acute cough and fever are due to flu during flu season:''<ref>[http://www.cdc.gov/flu/professionals/acip/clinical.htm CDC Clinical Flu]</ref> | |||
*Adolescents ≥ 12 yo - 79-88% | |||
*Children 5-12 yo - 71-83% | |||
*Children < 5 yo - 64% | |||
*Adults - unreliable predictors especially when older than 60 yo | |||
===Convalescence=== | |||
*Most gradually improve over 2-5d, although may last for one week or more | |||
*Some have persistent weakness lasting several weeks (postinfluenza asthenia) | |||
==Differential Diagnosis== | |||
{{ILI DDX}} | |||
{{Acute Fever DDX}} | |||
==Evaluation== | |||
===Workup=== | |||
*Influenza PCR preferred for inpatients (sensitivity >95%) | *Influenza PCR preferred for inpatients (sensitivity >95%) | ||
*RSV/Flu/metapneumovirus test low sensitivity for adults (48-60%) and children (62-72%), with turnaround time <24 hours | *RSV/Flu/metapneumovirus test low sensitivity for adults (48-60%) and children (62-72%), with turnaround time <24 hours | ||
Line 26: | Line 57: | ||
*Rapid tests specific but not sensitive (cannot be used to rule-out) | *Rapid tests specific but not sensitive (cannot be used to rule-out) | ||
== | ===Diagnosis=== | ||
===Outpatients=== | ====Outpatients==== | ||
*Risk factors: | *Risk factors: | ||
**Yes | **Yes | ||
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***Do NOT send Point of Care influenza test. | ***Do NOT send Point of Care influenza test. | ||
***Do NOT send diagnostic test for influenza. | ***Do NOT send diagnostic test for influenza. | ||
***May consider treating with anti-influenza antivirals | ***May consider treating with anti-influenza antivirals if symptoms <48 hours | ||
= | ====Admitted Patients==== | ||
===Admitted Patients=== | |||
*Do not send Point of Care influenza test | *Do not send Point of Care influenza test | ||
*Send diagnostic test for influenza | *Send diagnostic test for influenza | ||
**Influenza PCR preferred for inpatients | **Influenza PCR preferred for inpatients | ||
*Empirically treat for influenza using antivirals | *Empirically treat for influenza using antivirals | ||
**Most effective when administered when symptoms of influenza have occurred for < 48 hours | **Most effective when administered when symptoms of influenza have occurred for < 48 hours | ||
Line 56: | Line 80: | ||
*Droplet precautions (see below) | *Droplet precautions (see below) | ||
=== | ==Management== | ||
* | ===[[Isolation Precautions]]=== | ||
** | *Droplet precautions | ||
**If the patient is in an area in which they are in contact with other patients or need to be transported and thus may come in close contact (<3 feet) with staff, visitors, or other patients, the patient needs to wear a surgical mask (or N-95 respirator, if not available). | |||
===Antiviral Treatment=== | |||
''Despite questions on efficacy and safety, CDC still recommends treatment for all hospitalized patients and outpatients at risk for complications<ref>Fiore AE, et al. Antiviral Agents for the Treatment and Chemoprophylaxis of Influenza: Recommendations of the Advisory Committee on Immunization Practices (ACIP). CDC. Recommendations and Reports. January 21, 2011. 60(RR01);1-24.</ref>'' | |||
{| class="wikitable" | {| class="wikitable" | ||
| align="center" style="background:#f0f0f0;"|'''Antiviral Agent''' | | align="center" style="background:#f0f0f0;"|'''Antiviral Agent''' | ||
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| align="center" style="background:#f0f0f0;"|'''Adverse Events''' | | align="center" style="background:#f0f0f0;"|'''Adverse Events''' | ||
|- | |- | ||
| Oseltamivir (Tamiflu®) | | [[Oseltamivir]] (Tamiflu®) | ||
|| | || | ||
*Treatment: any age | *Treatment: any age | ||
Line 78: | Line 101: | ||
*Adverse events: nausea, vomiting. Sporadic, transient neuropsychiatric events (self-injury or delirium) mainly reported among Japanese adolescents and adults. | *Adverse events: nausea, vomiting. Sporadic, transient neuropsychiatric events (self-injury or delirium) mainly reported among Japanese adolescents and adults. | ||
|- | |- | ||
| Zanamivir (Relenza®) | | [[Zanamivir]] (Relenza®) | ||
|| | || | ||
*Treatment: >7 yrs | *Treatment: >7 yrs | ||
Line 86: | Line 109: | ||
*Allergic reactions: oropharyngeal or facial edema. | *Allergic reactions: oropharyngeal or facial edema. | ||
*Adverse events: diarrhea, nausea, sinusitis, nasal signs and symptoms, bronchitis, cough, headache, dizziness, and ear, nose and throat infections. | *Adverse events: diarrhea, nausea, sinusitis, nasal signs and symptoms, bronchitis, cough, headache, dizziness, and ear, nose and throat infections. | ||
|- | |||
|[[Baloxavir marboxil]] (Xofluza®) | |||
|| | |||
*Treatment: >12 years | |||
*Prophylaxis: not yet approved for this indication | |||
||children less than 12 or weighing less than 40kg, pregnancy, breastfeeding | |||
|| | |||
*Adverse Events: diarrhea, bronchitis, nausea, common cold symptoms (nasopharyngitis) and headache | |||
*Allergic reactions: oropharyngeal or facial edema | |||
|} | |} | ||
===[[ | ===[[Oseltamivir]] (Tamiflu)=== | ||
* | ''Shorten duration of illness by 16.8 hrs while NNTH (number needed to harm) was 28 in regards to causing nausea/vomiting, headache and renal and psych syndromes<ref>Jefferson T, et al. Oseltamivir for influenza in adults and children: systematic review of clinical study reports and summary of regulatory comments. BMJ. 2014; 348:g2545.</ref>'' | ||
** | *Greatest benefit if within 48hrs of symptom onset<ref>CDC Guidelines. 2015-2016. http://www.cdc.gov/flu/professionals/antivirals/summary-clinicians.htm</ref> | ||
**However, may be beneficial up to 4-5 days, including in pregnant patients | |||
**Early treatment of hospitalized patients can reduce death | |||
====Dosing==== | |||
*'''Age <1 year:''' 3mg/kg PO BID x 5 days | |||
*'''<15kg:''' 30mg PO BID x 5 days | |||
*'''15-23kg:''' 45mg PO BID x 5 days | |||
*'''24-40kg:''' 60mg PO BID x5d | |||
*'''Adult:''' 75mg PO BID x 5 days | |||
===[[Zanamivir]] (Relenza)=== | |||
''Relatively contraindicated in patients with [[asthma]], [[COPD]], or [[pregnancy]]. Shorten duration of illness by 14.4 hrs with no reduction in flu-related complications<ref>Heneghan CJ, et al. Zanamivir for influenza in adults and children: systematic review of clinical study reports. BMJ. 2014; 348:g2547.</ref>'' | |||
====Dosing==== | |||
*'''Age >7yo:''' 10mg (2 inhalations) BID x 5d | |||
*'''Prophylaxis:''' 10mg (2 inhalations) once daily x 7 days | |||
**Not for age < 5yo | |||
===Baloxavir marboxil (Xofluza)=== | |||
''Only approved for patients >12 years old and >40kg in weight, no current safety data exists for pregnancy and breastfeeding.<ref>https://www.cdc.gov/flu/treatment/baloxavir-marboxil.htm</ref> More expensive but one time dosing. Genentech, its creator, states a recent phase III trial has shown it to be effective for prophylaxis but not currently FDA indicated for this.<ref>https://www.gene.com/download/pdf/xofluza_prescribing.pdf</ref> | |||
====Dosing==== | |||
*'''Weight between 40-80kg:''' 40mg PO once (20 mg tab x2) | |||
*'''Weight >80kg:''' 80mg PO once (40mg tab x2) | |||
*'''Prophlyaxis:''' not yet approved for this indication by CDC or FDA | |||
===NOT Indicated=== | |||
*Amantadine and other M2 viral proton channel blockers are '''no longer indicated for influenza treatment''' due to nearly 100% resistance | |||
==Disposition== | |||
==Complications== | ==Complications== | ||
*[[Pneumonia]] | |||
**Primary influenza pneumonia | |||
***Most severe and least common type of pneumonia | |||
***Rare in otherwise healthy adults | |||
***Consider in patients with persistent and worsening symptoms (esp high fever, shortness of breath, cyanosis) | |||
***[[CXR]] shows bilateral opacities with or with out superimposed consolidation | |||
**Secondary bacterial pneumonia | |||
***Exacerbation of fever and respiratory symptoms after initial improvement | |||
****Higher fever, productive cough, radiographic evidence of infiltrates | |||
***Microbiology | |||
****[[Pneumococcus]] and [[S. aureus]] (including [[MRSA]]) most common (35% and 28%, respectively)<ref>Klein EY, Monteforte B, Gupta A, et al. The frequency of influenza and bacterial coinfection: a systematic review and meta-analysis. Influenza Other Respir Viruses. 2016;10(5):394-403. doi:10.1111/irv.12398</ref> | |||
*****[[MRSA]] associated with necrotizing cavitary infections with high mortality rate in previously healthy young people<ref>Centers for Disease Control and Prevention (CDC). Severe methicillin-resistant Staphylococcus aureus community-acquired pneumonia associated with influenza--Louisiana and Georgia, December 2006-January 2007. MMWR Morb Mortal Wkly Rep. 2007;56(14):325-329.</ref><ref>Hageman JC, Uyeki TM, Francis JS, et al. Severe community-acquired pneumonia due to Staphylococcus aureus, 2003-04 influenza season. Emerg Infect Dis. 2006;12(6):894-899. doi:10.3201/eid1206.051141</ref> | |||
*[[Otitis Media]] | |||
**More common in children | |||
*[[Myositis]] and [[rhabdomyolysis]] | |||
**More common in children | |||
**Extreme tenderness of affected muscles (most commonly in the legs) | |||
*[[Pericarditis]]/[[myocarditis]] | |||
**Rare complication | |||
==See Also== | ==See Also== | ||
*[[H1N1 (Swine) Flu]] | *[[H1N1 (Swine) Flu]] | ||
*[[Pandemic]] | |||
== | ==References== | ||
<references/> | <references/> | ||
[[Category:ID]] | [[Category:ID]] |
Latest revision as of 21:51, 1 February 2021
Background
- Human Influenza type A and B cause majority of infections. Type A has more severe disease course.
Transmission
- Occurs in 6ft radius around infected patient 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, patients with chronic illnesses
- Shedding from asymptomatic individuals does not contribute significantly to transmission
- Use of either N95 or plain surgical mask by healthcare professionals caring for patients with proven influenza helps to decrease rates of provider contraction of influenza.[1]
Risk Factors (for complicated course)
- Age <2 years or >65 years
- Pregnancy through 2 weeks after delivery
- Chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, hematological (including sickle cell disease), neurologic, neuromuscular, or metabolic disorders (including diabetes mellitus)
- Immunosuppression, including that caused by medications or by HIV
- Persons younger than 19 years of age who are receiving long-term aspirin therapy
- American Indians and Alaska Natives
- Morbid obesity
- Patients in nursing homes or chronic-care facilities
Vaccination Status
- A history of influenza vaccination does not rule out influenza in an ill patient with clinical signs and symptoms compatible with influenza.
- Therefore, vaccination status should not impede the initiation of prompt antiviral treatment.
Clinical Features
- Constitutional
- Respiratory
- Non-productive cough
- Sore throat
- Rhinorrhea
Cough and Fever
Odds that acute cough and fever are due to flu during flu season:[2]
- Adolescents ≥ 12 yo - 79-88%
- Children 5-12 yo - 71-83%
- Children < 5 yo - 64%
- Adults - unreliable predictors especially when older than 60 yo
Convalescence
- Most gradually improve over 2-5d, although may last for one week or more
- Some have persistent weakness lasting several weeks (postinfluenza asthenia)
Differential Diagnosis
Influenza-Like Illness
- Influenza
- Parainfluenza
- URI
- Pneumonia
- Sinusitis
- Toxic exposure
- Pyelonephritis
- Bronchitis
- Coronavirus
Fever
Infectious
- Critical
- Sepsis
- PNA with respiratory failure
- Peritonitis
- Meningitis
- Cavernous Sinus Thrombosis
- Necrotizing Fasciitis
- Emergent
- PNA
- Peritonsillar Abscess
- Retropharyngeal Abscess
- Epiglottitis
- Endocarditis
- Pericarditis
- Appendicitis
- Cholecystitis
- Diverticulitis
- Intra-abdominal abscess
- Pyelonephritis
- Tubo-ovarian abscess
- Encephalitis
- Brain abscess
- Cellulitis
- Abscess
- Malaria
- Non-emergent
Non-infectious
- Critical
- Emergent
- CHF
- Dehydration
- Recent Seizure
- Sickle Cell Dz
- Transplant rejection
- Pancreatitis
- DVT
- Serotonin Syndrome
- Non-emergent
- Drug fever (except as in NMS and Serotonin Syndrome)
- Malignancy
- Gout
- Sarcoidosis
- Crohn's Disease
- Postmyocardiotomy syndrome
- Sweet's syndrome
Evaluation
Workup
- Influenza PCR preferred for inpatients (sensitivity >95%)
- RSV/Flu/metapneumovirus test low sensitivity for adults (48-60%) and children (62-72%), with turnaround time <24 hours
- The Viral Respiratory Panel (influenza, RSV, adenovirus, parainfluenzavirus) discouraged (sensitive 70-90%) with 3-5 days turnaround
- Rapid tests specific but not sensitive (cannot be used to rule-out)
Diagnosis
Outpatients
- Risk factors:
- Yes
- Do NOT send Point of Care influenza test
- Do NOT send diagnostic test for influenza
- Empirically treat for influenza using antivirals if symptoms for <48 hours
- No
- Do NOT send Point of Care influenza test.
- Do NOT send diagnostic test for influenza.
- May consider treating with anti-influenza antivirals if symptoms <48 hours
- Yes
Admitted Patients
- Do not send Point of Care influenza test
- Send diagnostic test for influenza
- Influenza PCR preferred for inpatients
- Empirically treat for influenza using antivirals
- Most effective when administered when symptoms of influenza have occurred for < 48 hours
- May be benefit when initiated in severely ill inpatients with 48 hours to 5 days of symptoms
- No evidence of benefit after 5 days of symptoms
- Treat empirically promptly with oseltamavir unless there is an alternative diagnosis
- Droplet precautions (see below)
Management
Isolation Precautions
- Droplet precautions
- If the patient is in an area in which they are in contact with other patients or need to be transported and thus may come in close contact (<3 feet) with staff, visitors, or other patients, the patient needs to wear a surgical mask (or N-95 respirator, if not available).
Antiviral Treatment
Despite questions on efficacy and safety, CDC still recommends treatment for all hospitalized patients and outpatients at risk for complications[3]
Antiviral Agent | Recommended For | Not Recommended With | Adverse Events |
Oseltamivir (Tamiflu®) |
|
N/A |
|
Zanamivir (Relenza®) |
|
Underlying respiratory disease (e.g., asthma, COPD) |
|
Baloxavir marboxil (Xofluza®) |
|
children less than 12 or weighing less than 40kg, pregnancy, breastfeeding |
|
Oseltamivir (Tamiflu)
Shorten duration of illness by 16.8 hrs while NNTH (number needed to harm) was 28 in regards to causing nausea/vomiting, headache and renal and psych syndromes[4]
- Greatest benefit if within 48hrs of symptom onset[5]
- However, may be beneficial up to 4-5 days, including in pregnant patients
- Early treatment of hospitalized patients can reduce death
Dosing
- Age <1 year: 3mg/kg PO BID x 5 days
- <15kg: 30mg PO BID x 5 days
- 15-23kg: 45mg PO BID x 5 days
- 24-40kg: 60mg PO BID x5d
- Adult: 75mg PO BID x 5 days
Zanamivir (Relenza)
Relatively contraindicated in patients with asthma, COPD, or pregnancy. Shorten duration of illness by 14.4 hrs with no reduction in flu-related complications[6]
Dosing
- Age >7yo: 10mg (2 inhalations) BID x 5d
- Prophylaxis: 10mg (2 inhalations) once daily x 7 days
- Not for age < 5yo
Baloxavir marboxil (Xofluza)
Only approved for patients >12 years old and >40kg in weight, no current safety data exists for pregnancy and breastfeeding.[7] More expensive but one time dosing. Genentech, its creator, states a recent phase III trial has shown it to be effective for prophylaxis but not currently FDA indicated for this.[8]
Dosing
- Weight between 40-80kg: 40mg PO once (20 mg tab x2)
- Weight >80kg: 80mg PO once (40mg tab x2)
- Prophlyaxis: not yet approved for this indication by CDC or FDA
NOT Indicated
- Amantadine and other M2 viral proton channel blockers are no longer indicated for influenza treatment due to nearly 100% resistance
Disposition
Complications
- Pneumonia
- Primary influenza pneumonia
- Most severe and least common type of pneumonia
- Rare in otherwise healthy adults
- Consider in patients with persistent and worsening symptoms (esp high fever, shortness of breath, cyanosis)
- CXR shows bilateral opacities with or with out superimposed consolidation
- Secondary bacterial pneumonia
- Exacerbation of fever and respiratory symptoms after initial improvement
- Higher fever, productive cough, radiographic evidence of infiltrates
- Microbiology
- Exacerbation of fever and respiratory symptoms after initial improvement
- Primary influenza pneumonia
- Otitis Media
- More common in children
- Myositis and rhabdomyolysis
- More common in children
- Extreme tenderness of affected muscles (most commonly in the legs)
- Pericarditis/myocarditis
- Rare complication
See Also
References
- ↑ SURGICAL MASK VS. N95 RESPIRATOR FOR PREVENTING INFLUENZA AMONG HEALTH CARE WORKERS Loeb, M., et al, JAMA 302(17):1865, November 4, 2009
- ↑ CDC Clinical Flu
- ↑ Fiore AE, et al. Antiviral Agents for the Treatment and Chemoprophylaxis of Influenza: Recommendations of the Advisory Committee on Immunization Practices (ACIP). CDC. Recommendations and Reports. January 21, 2011. 60(RR01);1-24.
- ↑ Jefferson T, et al. Oseltamivir for influenza in adults and children: systematic review of clinical study reports and summary of regulatory comments. BMJ. 2014; 348:g2545.
- ↑ CDC Guidelines. 2015-2016. http://www.cdc.gov/flu/professionals/antivirals/summary-clinicians.htm
- ↑ Heneghan CJ, et al. Zanamivir for influenza in adults and children: systematic review of clinical study reports. BMJ. 2014; 348:g2547.
- ↑ https://www.cdc.gov/flu/treatment/baloxavir-marboxil.htm
- ↑ https://www.gene.com/download/pdf/xofluza_prescribing.pdf
- ↑ Klein EY, Monteforte B, Gupta A, et al. The frequency of influenza and bacterial coinfection: a systematic review and meta-analysis. Influenza Other Respir Viruses. 2016;10(5):394-403. doi:10.1111/irv.12398
- ↑ Centers for Disease Control and Prevention (CDC). Severe methicillin-resistant Staphylococcus aureus community-acquired pneumonia associated with influenza--Louisiana and Georgia, December 2006-January 2007. MMWR Morb Mortal Wkly Rep. 2007;56(14):325-329.
- ↑ Hageman JC, Uyeki TM, Francis JS, et al. Severe community-acquired pneumonia due to Staphylococcus aureus, 2003-04 influenza season. Emerg Infect Dis. 2006;12(6):894-899. doi:10.3201/eid1206.051141