Dr.R.SOMASEKAR.MOB:9444115222/9566217123Mail:drsomas1960@gmail.com

Influenza H1N1

The term “swine flu” is no longer in use

• On Apr. 30, 2009, WHO, United Nations Food and Agriculture Organization (UNFAO) and World Organization for Animal Health reached an agreement to replace “swine flu” with influenza A (H1N1)

Influenza Virus

Type A virus Type B virus Type C virus

Infects humans, birds, pigs and horses Infects only humans Infects humans, pigs and

dogs

Causes human epidemic disease almost every

year

Causes human epidemic disease almost every

year

Does not cause epidemics

Causes pandemic Does not cause pandemic

Does not cause pandemic

1. Wright PF. Influenza viruses (Chapter 250). In: Nelson’s Text Book of Pediatrics, 19th edn. Elsevier, 2011, pp. 1121 1125; 2. Seasonal influenza and influenza A(H1N1). Available at: http://www.who.int/ith/diseases/si_iAh1n1/en/index.html. Accessed on: May 15, 2013. 3. Seasonal Flu. Available at: http://www.cdc.gov/flu/about/viruses/types.htm. Accessed on: May 15, 2013.

Influenza Virus Structure

According to two surface antigens, two subtypes of influenza A are:

1. Hemagglutinin (HA) 17 different subtypes H1 H2 H3 human subtypes

2. Neuraminidase (NA) 10 different subtypes N1 N2 human subtypes

Seasonal Influenza (Flu). Available at: http://www.cdc.gov/flu/about/viruses/types.htm. Accessed on: May 15, 2013.

Two currently circulating subtypes of type A viruses are:

(1) Influenza A (H1N1) (2) Influenza A (H3N2)

Communicability

• From 1 day before to 7 days after the onset of symptoms.

• If illness persist for more than 7 days, chances of communicability may persist till resolution of illness.

• Children may spread the virus for a longer period.

BRAUNWALD E. Toux et hemoptysie. Harrison Médecine interne. 1995 ; 1:171-174

Sneezing Coughing Talking

When coughing, the air is expelled at close to the speed of sound!

BRAUNWALD E. Toux et hemoptysie. Harrison Médecine interne. 1995 ; 1:171-174

Sneezing Coughing Talking Fomites

When coughing, the air is expelled at close to the speed of sound!

Influenza transmission

Incubation period

• 1-7 days.

Clinical features • Important clinical features of H1N1 influenza

include 1. Fever2. Upper respiratory symptoms such as

a) cough, b) running nose c) sore throat.

3. Head ache, 4. Body ache, 5. Fatigue 6. Diarrhoea and vomiting

Influenza vs. common cold

Symptoms Influenza Cold

Fever Usually high, lasts 3-4 days Unusual

Headache Yes Unusual

Fatigue/ weakness Can last up to 2-3 weeks Mild

Pains, aches Usual and often severe Slight

Exhaustion Early and sometimes severe Never

Stuffy nose Sometimes Common

Sore throat Sometimes Common

Cough Yes Unusual

Chest discomfort Common and sometimes severe Mild to moderate

Complications Bronchitis, pneumonia; in severe cases life-threatening Sinus congestion

Symptoms Influenza Cold

Fever Usually high, lasts 3-4 days UnusualSeasonal Influenza (Flu). Available at: http://www.cdc.gov/flu/about/qa/coldflu.htm. Accessed on: June 13, 2013.

Complications

At higher risk

1. Individuals at extremes of age 2. Individuals with preexisting medical

conditions are at higher risk of complications and exacerbation of the underlying conditions

• Respiratory1. Sinusitis, 2. Otitis media, 3. Croup, 4. Pneumonia (primary viral pneumonia and

secondary bacterial pneumonia (especially group A streptococcal pneumonia and staphylococcus aureus pneumonia).

5. Bronchiolitis, 6. Status asthamaticus, 7. ARDS

Cardio vascular1. Myocarditis, 2. Pericarditis,

Musculo skeletal• Myositis, • Rhabdomyolysis,

Neurological• Encephalitis, • Seizures,

Multi organ dysfunction• Toxic shock syndrome • Renal ,hepatic other systems involvement

Guidelines on categorization of Influenza A H1N1 cases

Category- A

• Mild fever plus cough / sore throat with or without body ache, headache, diarrhoea and vomiting will be categorized as Category-A.

1. Do not require oseltamivir 2. Symptomatic treatment. 3. No testing for H1N1 is required.

What to do for the pts in Cat-A

1. Monitored for their progress and reassessed at 24 to 48 hours

2. Patients should a) confine themselves at home and b) avoid mixing up with public and high risk

members in the family.

Category-B

Category-B (i)

1. In addition to all the signs and symptoms mentioned under Category-A,

2. if the patient has high grade fever and severe sore throat,

Category-B (ii)

• In addition to all the signs and symptoms mentioned under Category-A,

• individuals having one or more of the following high risk conditions

1. Children with mild illness but with predisposing risk Factors.

2. Pregnant women;3. Persons aged 65 years or older;4. Patients with lung diseases, 5. Heart disease,6. Liver disease, 7. Kidney disease, 8. Blood disorders, 9. Diabetes, 10. Neurological disorders, 11. Cancer 12. HIV/AIDS;13. Patients on long term cortisone therapy.

What to do for the pts in Cat-B(both i and ii)

1. Shall be treated with Oseltamivir;2. No tests for H1N1 is required for Category-B

(i) and (ii).3. All patients of Category-B (i) and (ii) should

confine themselves at home and avoid mixing with public and high risk members in the family

Category-C

• In addition to the above signs and symptoms of Category-A and B, if the patient has one or more of the following:

1. Breathlessness,2. Chest pain, 3. Drowsiness, 4. Fall in blood pressure,5. Sputum mixed with blood, 6. Bluish discolouration of nails;

7. Children with influenza like illness who had a severe disease as manifested by the red flag signs (Somnolence, high and persistent fever, inability to feed well, convulsions, shortness of breath, difficulty in breathing, etc).

8. Worsening of underlying chronic conditions.

What to do for the pts in Cat-C

• All these patients require1. Testing, 2. Immediate hospitalization 3. Treatment.

Laboratory Tests and Special Tests

Diagnosis

• Respiratory specimen would generally need to be collected within the first 4 to 5 days of illness

Viral transport medium

Nasopharyngeal swab

LAB INVESTIGATIONS

• VIRUS ANTIGEN DETECTIONImmunofluorescence Reverse transcriptase –PCR(most sensitive)• VIRUS ISOLATIONPossible in first 2-3 days of illness• Immunofluorescence

SEROLOGY• COMPLIMENT FIXATION TESTSComplex, so rarely usedUsed to detect RNP antigen of influenza virus A,B,C &

V antigen for demo of strain specific antibodies

Haematological

• WBC count–usually normal• Secondary infections, the white blood cell

count increases

Biochemical

• Hypokalemia may occur.• Creatine kinase (CK), aspartate

aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase occasionally increase.

Radiological

• X-ray chest • CT-chest• Relevant other radiological investigations

based on complications

Other investigations

• Pulmonary Function Tests and Blood Gas Analysis

• Relevant Investigations if complicated

Clinical Course

• For most patients with Influenza A (H1N1), recovery usually can be achieved within a week after treatment.

• And for some patients, the clinical course may be longer.

Mortality

• Cause of death is commonly severe secondary complications.

• The period from the onset of symptoms to death is averagely 9 days,

• Mortality rate is lower than those of – Bird flu – Severe acute respiratory syndrome (SARS).

Treatment

1. General Treatment2. Supportive Treatment

Infrastructure / manpower / material support

• Isolation facilities: if dedicated isolation room is not available then patients can be cohorted in a well ventilated isolation ward with beds kept one metre apart.

• Manpower: Dedicated doctors, nurses and paramedical workers.

• Equipment: Portable X Ray machine, ventilators, large oxygen cylinders, pulse oxymeter

• Supplies: Adequate quantities of PPE, disinfectants and medications (Oseltamivir, antibiotics and other medicines)

Standard Operating Procedures • Reinforce standard infection control precautions

i.e. all those entering the room must use high efficiency masks, gowns, goggles, gloves, cap and shoe cover.

• Restrict number of visitors and provide them with PPE.

• Provide antiviral prophylaxis to health care personnel managing the case and ask them to monitor their own health twice a day.

• Dispose waste properly by placing it in sealed impermeable bags labeled as Bio- Hazard.

Oseltamivir(Tamiflu)

• Oseltamivir is the recommended drug both for prophylaxis and treatment.

Dose for treatment is as follows:

• By Weight: • ‐ For weight <15kg 30 mg BD for 5 days • ‐ 15-23kg 45 mg BD for 5 days • ‐ 24-<40kg 60 mg BD for 5 days • ‐ >40kg 75 mg BD for 5 days

Adverse reactions

• Oseltamivir is generally well tolerated, – Gastrointestinal side effects (transient nausea,

vomiting) may increase with increasing doses, particularly above 300 mg/day.

– Bronchitis, insomnia and vertigo. – Angina, pseudo membranous colitis and

peritonsillar abscess have also been reported. – Anaphylaxis and skin rashes

Supportive therapy

1. IV Fluids. 2. Parentral nutrition. 3. Oxygen therapy/ ventilatory support. 4. Antibiotics for secondary infection. 5. Vasopressors for shock.

• Paracetamol or ibuprofen is prescribed for fever, myalgia and headache.

• Patient is advised to drink plenty of fluids. • Smokers should avoid smoking. • For sore throat, short course of topical

decongestants, saline nasal drops, throat lozenges and steam inhalation may be beneficial.

• Salicylate / aspirin is strictly contra-indicated in any influenza patient due to its potential to cause Reye’s syndrome.

Constant monitoring of suspected cases

• The suspected cases would be constantly monitored for clinical / radiological evidence of lower respiratory tract infection and for hypoxia (respiratory rate, oxygen saturation, level of consciousness).

Oxygen therapy

• Patients with signs of 1. Tachypnea, 2. Dyspnea, 3. Respiratory distress Oxygen saturation less than 90 per cent

should be supplemented with oxygen therapy.

Types of oxygen devices

• Depend on the severity of hypoxic conditions which can be started from

1. oxygen cannula, 2. simple mask, 3. partial re-breathing mask (mask with reservoir

bag)4. non re-breathing mask. 5. In children, oxygen hood or head boxes can be

used.

Mechanical ventilation

1. Severe pneumonia 2. Acute respiratory failure (spo2 < 90% and

pao2 <60 mm hg with oxygen therapy)

• Invasive mechanical ventilation is preferred choice.

• Non invasive ventilation is an option when mechanical ventilation is not available.

High dose vs. Low dose corticosteroids

• High dose corticosteroids in particular have no evidence of benefit and there is potential for harm.

• Low dose corticosteroids (Hydrocortisone 200-400 mg/ day) may be useful in persisting septic shock (SBP < 90).

Antibiotic therapy

1. Suspected case not having pneumonia do not require antibiotic therapy.

2. Patient on mechanical ventilation should be administered antibiotics prophylactically to prevent hospital associated infections.

Discharge Policy

• A treated and recovered patient, even though testing positive, has very little possibility of infecting others.

Following recommendations are made

• Patients who responded to treatment after two to three days and become totally asymptomatic should be discharged after 5 days of treatment. There is no need for a repeat test.

• Patients who continue to have symptoms of fever, sore throat etc. even on the 5th day should continue treatment for 5 more days.

• If the patient become asymptomatic during the course of treatment there is no need to test further.

• For patients who 1. Continue to be symptomatic even after 10 days of

treatment or 2. Those cases with respiratory distress and in whom

secondary infection is taken care of, and if patient continue to shed virus,

• Then resistance of the patients to anti viral would be tested.

• The dose of anti viral may be adjusted on case to case basis.

Chemoprophylaxis

• (i) Chemoprophylaxis for health care workers at high risk.

• The treating physicians and other paramedical personnel at the isolation facility would be put on chemoprophylaxis.

? Is there any vaccines

►Two vaccines are available a) Given by intranasal route. b) Given by injection.

Indications

• H1N1 influenza virus injectable vaccine is for use in adults and children who are at least 6 months old.

Influenza Vaccine: Types

• Virus strains in each year’s influenza vaccine. – Influenza A (H1N1) strain– Influenza A (H3N2) strain– Influenza B strain

• The flu vaccine does not protect against the influenza C virus.

Seasonal Influenza (Flu). Available at: http://www.cdc.gov/flu/about/viruses/types.htm. Accessed on: May 15, 2013.

• The injectable H1N1 influenza virus vaccine is a "killed virus" vaccine.

• H1N1 influenza virus vaccine is also available in a nasal spray form, which is a "live virus" vaccine.

Efficacy of TIV [Vaxigrip]

Population Efficacy

Healthy subjects 70-90 %

Renal failure (chronic) 66 %

Renal transplant 18-93 %

Hemodialysis 25-100 %

Bone marrow transplant 24-71 %

Cancer 18-60 %

HIV infection 15-80 % Vaxigrip Product Monograph 2005

Influenza Vaccination Schedule

Age Vaccine Dose Initial Vaccination Subsequent

Vaccination

635 months 0.25 mL 2 doses1 month apart

Single annual dose as soon as new vaccine is

released38 years 0.5 mL 2 doses

1 month apart

≥9 years 0.5 mL 1 Dose

Individual vaccines. In: Yewale V, Choudhury P, Thacker N (eds). IAP Guide Book on Immunization. IAP Committee on Immunization. 20092011. Mumbai, 2011, pp. 51144.

Influenza Vaccine: Side-Effects

• Mild fever and rash• Injection site reactions • Influenza vaccines and Gullian-Barré Syndrome

(GBS)– Equivocal risk– <1 case per million people vaccinated– Avoid in patients with history of GBS

• Caution in patients with the history of egg allergyIndividual vaccines. In: Yewale V, Choudhury P, Thacker N (eds). IAP Guide Book on Immunization. IAP Committee on

Immunization. 20092011. Mumbai, 2011, pp. 51144.

Less serious side effects

• Last for a day or two after you receive this vaccine and may include:

• Runny or stuffy nose;• Low fever;• Sore throat;• Loss of appetite;• Headache, tired feeling; or• Muscle pain.

Contraindications

• Guillain-barré syndrome (especially if you had it within 6 weeks after having a flu vaccine);

• Weak immune system caused by disease, bone marrow transplant, or by using certain medicines or receiving cancer treatments; or

• Neurologic disorder or disease affecting the brain (or if this was a reaction to a previous vaccine).

• This vaccine should not be given to a child younger than 6 months old.

To Conclude• Mimics other respiratory viral diseases early in the

course of illness.• High index of suspicion is needed• CAT-C requires Testing and treatment with Tamiflu• CAT-B needs to be treated by Tamiflu,no test• CAT-A needs no antiviral treatment and no test• Patient positive,should be isolated and treated with

full protective methods• Vaccine approximately protective for 1 year is

available in both killed and live formulations.

Cough etiquette

• Respiratory etiquette– Cover nose / mouth when

coughing or sneezing

• Hand washing!

PERSONAL PROTECTIVE EQUIPMENT

• Masks (N-95)

• Gloves

• Protective eye wear (goggles)

• Hair covers

• Boot or shoe covers

• Protective clothing (gown or apron)

What is PPE for medical providers regarding droplet precautions?

• Wear a fit-tested N95 respirator, disposable gloves, gown, & eye protection (face shield or goggles)

• Place a surgical mask on the patient & utilize devices to reduce secretion distribution

• Before & after contact with respiratory infected people: – clean hands thoroughly with soap & water or an alcohol-

based hand gel.

What is good hand hygiene?

• Washing hand for more than 15 seconds with soap & water or apply an alcohol-based cleanser rubbing hands until dry

Precautions

Isolation ward in ICH&HC

Vigilant monitoringLimited action

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