Influenza: Difference between revisions

Revision as of 22:38, 11 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)

Risk Factors for Complications

<5yr (esp <2yr) OR >65yr
Chronic illnesses (asthma, cardiovascular (except HTN), renal, hepatic, SCD, DM)
Immunosuppression
Pregnant or within 2wk after delivery
Morbidly obese (BMI >40)
Residents of nursing homes / chronic care facilities

Clinical Features

Constitutional
- Fever
- Headache
- Myalgia
- Malaise
Respiratory
- Non-productive cough
- Sore throat
- Rhinorrhea

Complications

Pneumonia
1. Primary influenza PNA
  1. Most severe and least common type of PNA
  2. Rare in otherwise healthy adults
  3. Consider in pts w/ persistent and worsening symptoms (esp high fever, SOB, cyanosis)
  4. CXR shows b/l opacities w/ or w/o superimposed consolidation
2. Secondary bacterial PNA

Source

UpToDate

Authors:

@@ Line 1: / Line 1: @@
 ==Background==
-#3 types, 2 of which cause dz in humans
+*Transmission
-##type A- most common and causes world pandemics- also found in pigs, horses, seals, whales and birds
+**Occurs in 6ft radius around infected pt who is sneezing and/or coughing
-##type B- only found in humans- causes regional epidemics, not global
+**Viral shedding lasts ~5d (starts 24-48hr before onset of symptoms)
-##type C- no human dz
+***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)
+===Risk Factors for Complications===
+#<5yr (esp <2yr) OR >65yr
+#Chronic illnesses (asthma, cardiovascular (except HTN), renal, hepatic, SCD, DM)
+#Immunosuppression
+#Pregnant or within 2wk after delivery
+#Morbidly obese (BMI >40)
+#Residents of nursing homes / chronic care facilities
-===Epidemiology===
+==Clinical Features==
-#transmitted by resp secretions or hand to hand. Infection limited to resp epithelium and ciliated columnar cells involved initially. Viremia rare.
+*Constitutional
-#symptoms start within 18 hrs, pt contagious for 2- 5 days. Usually involve sudden onset fever, malaise, headache. Later get sore throat, myalgia, cough and sputum. Cough can last for 2 wks. Can have vomiting and diarrhea in kids or even present as croup, bronchiolitis or febrile seizures.
+**Fever
+**Headache
+**Myalgia
+**Malaise
+*Respiratory
+**Non-productive cough
+**Sore throat
+**Rhinorrhea
-==Treatment==
+==Complications==
-#generally supportive but can use antivirals
+#Pneumonia
-##Amantadine- reduces fever and symptoms by 1- 2d. Targets M2 membrane protein of influ A. Has neurologic side effects (lightheadedness, nervous, confusion, insomnia) and resistance developing and not useful against Type B.
+##Primary influenza PNA
-##Flumadine- like amantadine but fewer side effects. Not for kids
+###Most severe and least common type of PNA
-##Neuraminidase Inhibitors- Relenza and Tamiflu. Inhibition of neuraminidase activity prevents spread and aborts infection. Works with all strains. Limited resistance.
+###Rare in otherwise healthy adults
-##Relenza- decreases symptoms by 1.5- 2.5 days. Use if age 7 or older and within 48 hrs of sxs.
+###Consider in pts w/ persistent and worsening symptoms (esp high fever, SOB, cyanosis)
-##Tamiflu- reduces duration of dz by 1.5 days but better yet, reduces by 50% sequela like otitis media, sinusitis, bronchitis, pneumonia
+###CXR shows b/l opacities w/ or w/o superimposed consolidation
+##Secondary bacterial PNA
+###
-==Complications==
-#post influenza asthenia- elderly can have malaise and lassitude requiring prolonged convelescence.
-#viral pneumonia-
-#secondary bacterial pneumonia- seen during recovery phase- staph, strep, hemophilus
-#myositis- calf muscle pain with elevated CPK seen in kids with influ B
-#Reyes Syndrome- fatty liver degeneration seen in viral syndrome tx?ed with ASA. Get liver failure, hepatic encephalopathy and brain edema
-#can also see encephalitis, Guillain Barre, transverse myelitis, myocarditis, pericarditis
 ==Source ==
-/06 MISTRY
+UpToDate
 [[Category:ID]]