Swine Flu (Basics)
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Transcript Swine Flu (Basics)
web site: www.drsarma.in
Dr. R V S N Sarma., MD., MSc. (Canada),
Consultant Physician & Chest Specialist
Land line: 044 3760 9993 Mobile 91 9380521221
email: [email protected]
What Should be Our Approach?
Essential – Positive – Constructive Approach
Adequate awareness in general public – adopting the
preventive measures
Comprehensive knowledge for the healthcare providers
Appropriate planning and responsibility of all involved
Unwarranted – Misleading – Dangerous – Negative
Fear, minute to minute monitoring of deaths, rumors
Media hype , Anxiety about infection and death by this flu
Panic, mania of mask use by one and all, and worry
Types of Human Flu (Influenza)
Influenza A
Common, More Severe, Several Sub-types
Epidemics, Pandemics, Mortality, High
Mutagenicity
Influenza B
Less Severe, Less Frequent, No Sub types, Faithfully
Human
Influenza C
Mild, Rare, No Sub types, Non fatal, Mild Illness in
Children
Common Cold – Coryza Virus – It is not ‘Flu’
Influenza A Virus Types
Neuraminidase (N)
For Detachment
Hemagglutinin (H)
for Attachment
Orthomyxoviridae Family
Single stranded RNA virus
High mutagenicity, 8 proteins
H Ag types are 16
N Ag types are 09
So, 16 x 9 = 144 types possible
But only 3 types infect Humans
H1N1, H2N2 and H3N2
Avian Flu Virus is H5N1
‘Swine Flu’ Virus H1N1
Misnomer
Present Pandemic – (H1N1)v
Seasonal v/s Pandemic Flu
Influenza Pandemics
Name of the
Pandemic
Year
Deaths
Subtyp
e
Pandemic
Severity
Index
Asiatic (Russian) Flu
1889 - 1890
I Million ? H2N2
NA
Spanish Flu 1918
Pandemic
1918 - 1920
50
Million
H1N1
5
Asian Flu
1957 - 1958
4 Million
H2N2
2
Hong Kong Flu
1968 - 1969
2 Million
H3N3
2
2009 Flu Pandemic
2009 –
Present
1,500
H1N1v
About 1.5
Seasonal Influenza
Every Year
500, 000
H1N1
NA
Global Picture of the Pandemic
Cumulative Confirmed Cases In
India
Natural History of H1N1v
Mortality Rate =
15/1,00,000 =
0.015%
Exposed
Infected
1,00,000
50,000
Clinical Cases
10,000
Hospital
CFR = 15/10,000
or 0.15%
Death
1,000
15
Symptoms of H1N1 Pandemic Flu
Very Similar to the Seasonal Flu and Not like Common
Cold
Moderate to high fever
aches, muscle and joint pains
chills and fatigue
sore throat, head ache
cough
sneezing and running nose
shortness of breath, chest pain on breathing
diarrheas and vomiting (possible), loss of appetite
When to Suspect H1N1 ?
Onset of acute febrile respiratory illness within 7
days of close contact with a person who has a
confirmed case of H1N1 influenza A virus
infection, or
Onset of acute febrile respiratory illness within 7
days of travel to a community (within the United
States or internationally) where one or more
H1N1 influenza A cases have been confirmed, or
Acute febrile respiratory illness in a person who
resides in a community where at least one H1N1
influenza case has been confirmed.
Fever or H/o Fever
87%
Head ache
41%
Myalgia
38%
Arthralgia
23%
Diarrhea
12%
Dry cough
49%
Vomiting
16%
Productive cough
17%
Nausea
17%
Sore throat
49%
Conjunctivitis
7%
Running nose
33%
Nose bleed
2%
Sneezing
21%
Altered Sensorium
0.5%
Shortness of Breath
10%
Others
22%
Seasonal v/s Pandemic Influenza
Age and Gender Distribution
Global Experience of the
Pandemic
Secondary attack rate in household contacts: 12 %.
Overall proportion of hospitalizations: 8 %.
Overall case fatality: 0.15 % or 1.5 per every 1000 cases
Most cases (58 %) highest incidence in 5–24 years age
group,
Second highest incidence in children < 5 years
Most hospitalizations (34 %) in 5–24 years age group,
Highest age-specific hospitalization rate in children < 5
years
Most deaths in 5–24 years age group
The old are generally spared > 65
The Current H1N1 Virus
Cocktail mix of Porcine, Avian and Human Influenza A Virus
Direct
Fine droplets expelled during coughing and sneezing
Expectorated sputum and the dried secretion
Indirect
All items that have been in contact with a patient
(Fomite)
Incubation Period (IP)
3 to 7 days – from the day of symptoms – Median 2-3
days
Transmission
Transmission
Transmission
The Aaa-chooh – (Sneezing)
High Risk Groups for H1N1
Diabetes
Pregnancy
Neuromuscular disorder
Chronic cardio-vascular disease (excluding hypertension)
Seizure disorder and other neurodegenerative disease
Chronic renal disease stages III and IV
Cancer and immuno suppression
Obesity
More deaths in people <18 years of age
Diagnostic Testing
rRT-PCR Swine Flu assay– reverse transcriptase real time PCR
Highly specific test, 24 to 48 hours, costly Rs. 4,000, detects viral
multiplication, can identify the novel H1N1 correctly
Confirmatory test, sensitivity is also quite high 85%, Quantitative
RIDT (Rapid Influenza Diagnostic Test) – Not Recommended
point of care, 1 hour, less cost (Rs 700), card test, detects viral
protein
Sensitivity low 10 to 70% - A negative result can’t exclude Influenza
Can not distinguish between Influenza B or A or A sub types
Specificity – 80% - can confirm Influenza infection – not the type
If positive – needs a confirmatory test to identify the type
Testing Facilities in Chennai
Government
King Institute, Guindy
Private
Bharat Scans, Royapettah
Hi-Tech Diagnostic Center, T. Nagar
Diagnostic Services, T.Nagar
Lister Metropolis
Sri Rama Chandra University
General Hygiene
1. Cover the mouth whenever you cough, then wash hands
2. Cover the nose every time you sneeze, then wash hands
3. Wipe with disposable tissue paper, throw into a garbage
can covered with a lid and then wash hands
4. Do spit in a disposable tissue paper, throw into a garbage
can covered with a lid and then wash hands
5. Hand hygiene, is essential and imperative, either washing
with soap or by clean by rubbing alcohol based sanitizer. It
must be done carefully and repeated as often as possible
6. Use of surgical mask and personal protection equipment
(PPE)
Face Masks, N95 Respirators
General Treatment
Treatment is largely supportive
Bed rest; Patient should stay at home for 7 days
Increased fluid consumption; Cough suppressants
and
Cough Etiquette, Hand washing
Antipyretics and analgesics (Paracetamol, NSAIDs)
Avoid close contact with sick person
May require intravenous hydration & supportive
measures
Home Isolation; One designated person to take
care
Categories of H1N1 (Govt. India)
1.
Category A: Common fever with cough and throat pain body
pain and headache, diarrhea and vomiting. No need to test for
A(H1N1). No Tamiflu. Under constant supervision for a three
days. Cough etiquette.
2. Category B: High fever and severe throat infection. Children < 5
years, pregnant women, Adults 65 + age and with complications
of the kidneys, heart and lungs, diabetics and HIV. Give Tamiflu,
but no test for A (H1N1). Home isolation.
3.
Category C: Same as Category B, but have breathlessness,
chest pain, fainting spells, low blood pressure, blood in the
phlegm, cyanosis, not taking feeds, altered sensorium. They
need A (H1N1) test and be given Tamiflu and need
hospitalization.
Categories of H1N1 cases as per
Govt. India
A (90%)
B (8%)
• Home
• No NAI
• No Test
• Home
• NAI
• No Test
C (2%)
• Hosp
• NAI
• Test
Oseltamivir (Tamiflu)
It is a neuraminidase inhibitor (NAI), decreases the
release of viruses from infected cells and, thus, viral
spread.
Must be administered within 48 hours of symptom onset
Reduces the length of illness by an average of 1.5 to 2.5
days
Duration of administration for treatment is 5 days
Post-exposure prophylaxis to be initiated within 7 days of
exposure and continued for at least 10 days
Available as 30-mg, 45-mg, and 75-mg oral capsules and as
a powder for suspension containing 12 mg/mL after
reconstitution
Oseltamivir (Tamiflu)
Adult Dose
Acute illness: 75 mg PO bid for 5 days
Prophylaxis: 75 mg PO once a day for 10 days
Pediatric dose
Acute illness in children aged <1 year
<3 months: 12 mg PO bid for 5 d; 3-5 months: 20 mg PO bid
for 5 d
6-11 months: 25 mg PO bid for 5 d
Acute illness and age >1 year
<15 kg: 30 mg PO bid for 5 d; 15-23 kg: 45 mg PO bid for 5 d
23-40 kg: 60 mg PO bid for 5 d; >40 kg: Administer as in
adults
Zanamivir (Relenza)
It is a neuraminidase inhibitor, decreases the release of viruses from
infected
cells and, thus, viral spread. Must be administered within 48 hours
Adult Dose
Treatment for acute illness: 10 mg inhaled orally bid for 5 days
Prophylaxis of household contact: 10 mg inhaled orally od for 10
d
Prophylaxis for community outbreak: 10 mg inhaled orally od for
28 d
Pediatric Dose
Treatment for acute illness
<7 years: Not established; >7 years: Administer as in adults
Both are ‘Pregnancy Category C’ – Not a contraindication – prefer
Zanamivir
Anti Viral Formulations
Management of Severe Disease
Most cases do not need Test, Tamiflu, Hospitalization
Supportive treatment and home isolation will suffice
Watch out for the high risk groups and Category B and C
Early administration of Tamiflu if indicated; Reduces viremia
Monitor O2 saturation and maintain 90-92% saturation - O2
Rx.
Antibiotics for secondary bacterial pneumonia – as per CAP
MRSA; Ventilator support in severely ill – VAP; Vasopressors
No role for corticosteroids except in shock; Risk is increased
ARDS – Lung protective mechanical ventilation
Executive Summary
1. Airborne transmission – No unusual routes – Food no
risk
2. Cumulative clinical attack rate – 20 to 30%
3. Over 90% of the illness is mild and self limiting
4. Highest affected will be children and young adults
5. Adults > 60 years seem to be least affected
6. High risk groups discussed must be watched for fatality
7. Hospitalization rates will be 1 to 2% of clinical cases
8. The term ‘swine flu’ is inaccurate & confusing– A H1N1v
2009
Executive Summary
9. Case Fatality Rate will be around 0.1 to 0.2% (1-2 per 1000)
10. Fatality will be more in children and very old and high risk
11. Hospitalizations are for high risk groups, people < 5, > 60 y
12. H1N1v is sensitive to Oseltamivir and Zanamivir – NAIs
13. Seasonal flu vaccine is ineffective; Vaccine in October
14. The virus can mutate at any time – Second wave aggressive
15. International co-operation and sharing of experience
16. All these rates & ratios are biased upwards – inapparent inf.
The Three Golden Principles
Cough Etiquette
Hand washing
Social Distancing
What We Know?
This Flu is like any other ARI
Cover your cough and sneeze
Frequent hand washing
Hand – face distancing
Social distancing
Fomite transmission – cell phones
Home isolation; Discuss the need for Test and Tamiflu
Only a small proportion need hospitalization
Flu death is very rare; No need to panic
What Should We do?
Remember is similar in most respects like any other ARI
Suspect the pandemic flu – particularly if temp is > 100
Look for signs of serious illness – SOB, chest pain, blood etc
Look for high risk profile, Be watchful about young kids
Categorize the patient as A, B or C and note the stage
Take appropriate action as per the category
Segregate patients at first contact in the waiting room
Give priority to those with ARI and reduce contact time
Protect yourself with mask while examining a suspect case
Top Resources Consulted
http://www.emedicinehealth.com/swine_flu/article_em.htm#hi
story
http://www.who.int/csr/disease/swineflu/en/index.html
http://www.who.int/csr/disease/avian_influenza/phase/en/
Journal of Applied Microbiology 91 (4): 572–579, 2001
http://knol.google.com/k/salim-djelouat/swine-flu-pandemic-
review
http://emedicine.medscape.com/article/1673658-overview
http://www.cdc.gov/h1n1flu/general_info.htm
http://www.cdc.gov/h1n1flu/
http://www.cdc.gov/h1n1flu/surveillanceqa.htm
http://www.cdc.gov/h1n1flu/masks.htm
Top Resources Consulted…
contd
http://www.cdc.gov/h1n1flu/guidance/rapid_testing.htm
http://www.cdc.gov/h1n1flu/recommendations.htm
http://www.ecdc.europa.eu/en/Pages/home.aspx
http://www.ecdc.europa.eu/en/healthtopics/PublishingImages/
World_Map
http://sis.nlm.nih.gov/enviro/swineflu.html#a3
New England Journal of Medicine: H1N1 Influenza Center
http://www.lancet.com/H1N1-flu
http://h1n1.nejm.org/?ssource=rthome
http://pandemicflu.bmj.com/
H1N1 Clinical Medical References & Guidelines @
MDConsult.com
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