Influenza H1n1 Pandemic

Human Influenza H1N1 Pandemic

Dr J Kishore MBBS, MD, PGCHFWM, PGDEE, MSc., MNAMS, FIPHA

Professor, Community Medicine, MAMC, New Delhi

What’s Influenza? An acute RTI, caused by Influenza virus, characterized by sudden onset of:

• • • • • •

Fever/ chills Headache, myalgia Sore throat Cough Coryza Prostration

•

Range of symptoms differs by age – Vomiting & diarrhea in children/ elderly – Fever alone in infants – May be atypical in elderly

• Serious complications can occur among high-risk groups

Fever Running Nose, Sore Throat

Coughing

Lack of Appetite, Headache

Nausea, Vomiting

Diarrhea

Influenza Virus: 3 Types RNA virus (8-12 micron) Antigenically distinct No cross-immunity Type A A Type

Type B B

Causes significant Causes significant disease: epidemics; disease: milder pandemics epidemics

Type C Does not cause significant disease

Infects both humans Limited to humans Limited to humans and other species ! Frequent antigenic Infrequent antigenic Antigenically stable variations variations

Influenza A: Important Feature 2 surface antigens:

• Haemagglutinin (HA)

Influenza Virus

– Initiates infection following attachment of virus to susceptible cells

• Neuraminidase (NA)

– Release of virus from infected cell

• 16 ‘H’ antigens (1-16) • 9 ‘N’ antigens (1-9) • Different combinations

HA

NA

Influenza A: Antigenic Variations Antigenic drift: gradual antigenic change over a period; • Involves ‘point mutations’ in genes owing to selection pressure by immunity in host population • Responsible for frequent influenza epidemics; necessitates reformulations of influenza vaccines.

Antigenic shift: sudden complete or major change; • Results from genetic recombination of human with animal/ avian virus; • Leads to a novel subtype different from both parent viruses; • If ‘novel subtype’ has sufficient genes from HI viruses which make it readily transmissible from person to person, it may cause pandemics; • Evidence suggests HI viruses responsible for last 3 pandemics contained gene segments closely related to avian influenza viruses.

Species Infected by Influenza A Subtypes N1 N2

H1 H2 H3 H4

N3

H5 H6 H7 H8

N5 N6 N7 N8 N9

H9 H10 H11 H12 H13 H14 H15,16

N4

?

All 16 H subtypes infect birds; most widespread epidemics & all pandemics: H1N1, H2N2, H3N2

Influenza Terminology - 1

• Seasonal influenza • Avian Influenza • Pandemic Influenza

Influenza Terminology - 2 Seasonal influenza: influenza

• occurs every year with gradual variations in • •

previous year’s virus surface proteins (antigenic drift); may give rise to epidemics every 2-3 years. spreads around the world in seasonal epidemics, affecting 10 - 20% of total population in general and >50% on close community; annual epidemics thought to result in 3-5 million cases of severe illness and 2.5 - 5 lakh deaths

Avian Influenza Pandemic Influenza

Influenza Terminology - 3 Seasonal influenza

Avian Influenza: Influenza

• Primarily a disease of birds due to large group of different influenza viruses; • Rarely jumps species and infects humans; • An influenza pandemic happens when a new •

subtype emerges that has not previously circulated in humans and is adapted to human to human transmission. Ultimately, is the source of new viruses in humans causing pandemics.

Pandemic Influenza

Influenza Terminology - 4 Seasonal influenza Avian Influenza

Pandemic Influenza: Influenza

• a worldwide surge in cases caused by the

introduction of a new type A surface protein (antigenic shift).

Influenza Pandemics so far

1918: “Spanish Flu”

1957: “Asian Flu”

1968: “Hong Kong Flu”

50 million deaths

1- 4 million deaths

1- 4 million deaths

A(H1N1)

A(H2N2)

A(H3N2)

2004- 09:Current outbreak

421 cases,257 deaths Azerbaijan, China, Cambodia, Djibouti, Egypt, Indonesia, Iraq, Lao’s PDR, Myanmar, Nigeria, Pakistan, Thailand, Turkey, Vietnam & B’desh ; till Apr. 2009

A(H5N1)

Pre-requisites to Start Influenza Pandemics (i)

Emergence of a novel virus to which all are susceptible (ii) New virus is able to replicate and cause disease in humans (iii) New virus is transmitted efficiently from human-to-human.

All criteria met

two or more countries in one WHO region

• Highly contagious acute respiratory disease of pigs, caused by one of several swine influenza A viruses: – Morbidity tends to be high – Low mortality (1-4%)

• Although swine influenza viruses (SIV) are normally species specific, sometimes cross species barrier to cause disease in humans

Swine influenza – Present virus • Sometimes pigs can be infected with more than one virus type at a time, which can allow the genes from these viruses to mix • This can result in an influenza virus containing genes from a number of sources, called a "reassortant" virus • The present virus: H1N1 virus with re-assorted segments from: – – – –

American swine, Eurasian swine, Avian and Human virus

• Influenza A/H1N1 virus characterized in this outbreak has not been previously detected in pigs/humans.

How swine flu spread to human

Re-assortment and Direct Transmission Human to human spread

Non-human virus

Human virus

Reassortant virus

Pigs not involved in transmission

Cases started around 18th March And in short interval reached to epidemic form

Evolution of Swine Influenza Pandemic 18th March 2009

Evolution of Swine Influenza Pandemic 13th April 2009

Evolution of Swine Influenza Pandemic

22 May India-1

28 June India 89

50

0

DEATHS 6/19/2009

6/12/2009

6/5/2009

5/29/2009

5/22/2009

5/15/2009

CASES

5/8/2009

0

6/19/2009

6/12/2009

6/5/2009

5/29/2009

5/22/2009

5/15/2009

5/8/2009

5/1/2009

10000

5/1/2009

60000

50000

40000

30000 Series1

20000

250

200

150

100 Series1

New Cases reported since last reporting period 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 6/19/2009

6/12/2009

6/5/2009

5/29/2009

5/22/2009

5/15/2009

5/8/2009

5/1/2009

Series1

Public Health Concern • Number of affected countries with Influenza H1N1 increasing • Number of human cases of influenza H1N1 increasing • The majority of the human population has no immunity • Potential to further mutate to a lethal novel influenza virus

WHO Alert • Current situation constitutes a PHEIC (public health emergency of international concern). • WHO has declared H1N1 Pandemic, i.e, Phase 6 implying widespread human transmission. • Containment of the outbreak is not feasible. • The current focus should be on mitigation measures. • Not to close borders and not to restrict international travel ???

Disease Transmission • H-2-H transmission mainly occurs through direct droplet transmission (usually within 6 feet). • Same way as seasonal flu - mainly through coughing or sneezing • People may be infected by touching something with flu viruses on it and then touching their mouth, nose or eyes (moist mucous membranes) before washing their hands. • Infected people can infect others beginning 1 day before and up to 7 or more days after symptoms develop.

Symptoms and signs of H1N1 in humans? • Similar symptoms as of human seasonal influenza. • Fever (≥ 38 º C), AND • cough and sore throat • Body aches, headache, chills, and fatigue or lack of appetite. • Some people with H1N1 have reported runny nose, nausea, vomiting, and diarrhea.

Case Definition: Influenza A (H1N1) virus infection • Suspected case is defined as a person with acute febrile respiratory illness (fever ≥ 380C) with onset: • within 7 days of close contact with a person who is a confirmed case of swine influenza A (H1N1) virus infection, or • within 7 days of travel to community where there are one or more confirmed swine influenza A(H1N1) cases, or • resides in a community where there are one or more confirmed swine influenza cases.

Case Definition: Influenza A (H1N1) virus infection Probable case: defined as a person with an acute febrile respiratory illness who is: • positive for influenza A, but unsubtypable for H1 by influenza RT-PCR or reagents used to detect seasonal influenza virus infection, or • positive for influenza A by an influenza rapid test or an influenza immuno-fluorescence assay (IFA) plus meets criteria for a suspected case • individual with a clinically compatible illness who died of an unexplained acute respiratory illness who is considered to be epidemiologically linked to a probable or confirmed case.

Case Definition: Influenza A (H1N1) virus infection Confirmed case: defined as a person with: • An acute febrile respiratory illness with laboratory confirmed swine influenza A (H1N1) virus infection at WHO approved laboratories by one or more of the following tests: – Real Time PCR – viral culture – Four-fold rise in swine influenza A (H1N1) virus specific neutralizing antibodies.

• If swine flu is suspected, clinicians should obtain a Nasopharyngeal or throat swab for swine influenza testing and place it in a refrigerator (not a freezer) but transport within 24 hours if not then store at –70 degree C. – Once collected, the clinician should contact their state or local health department to facilitate transport and timely diagnosis at a state public health laboratory

he guiding principles of treatment are: arly implementation of infection control precautions o minimize nosocomical / household spread of disease. rompt treatment to prevent severe illness & death. arly identification and follow up of persons at risk. nfrastructure / manpower / material support

nfrastructure & Manpower solation facilities: if dedicated isolation room is not available then

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.

Steps of Hand Washing Technique

Clinical Management Pharmaceutical Interventions Viruses so far characterized have been sensitive to oseltamivir & zanamivir; resistant to amantadine & rimantadine •Treatment: • Oseltamivir 75 mg twice daily for 5 days

•Chemoprophylaxis: – Close contacts of a confirmed case – Health care personnel coming in contact with confirmed case – Oseltamivir 75 mg once daily for 10 days

•Vaccine: Not available as of now; 4-6 mths later

Oseltamivir – Recommended doses Body weight

Recommended Dose

< 15 kg (< 33 lb)

30 mg

> 15 kg – 23 kg (> 33 lb – 51 lb) > 23 kg – 40 kg (> 51 lb – 88 lb) > 40 kg (> 88 lb)

45 mg 60 mg 75 mg

Supportive Therapy •

Fluid

•

Parentral nutrition.

•

Oxygen therapy/ ventilatory support.

•

Antibiotics for secondary infection.

•

Vasopressors for shock.

•

Paracetamol or ibuprofen is prescribed for fever, myalgia and headache. Patient is advised to drink plenty of fluids. 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 (Reye’s syndrome).

•

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).

- Maintain airway, breathing and circulation (ABC);

- Maintain hydration, electrolyte balance and nutrition. - If the laboratory reports are negative, the patient would be discharged after giving full course of oseltamivir. -Immunomodulating drugs has not been found to be beneficial in treatment of ARDS or sepsis associated multi organ failure. - Low dose corticosteroids (Hydrocortisone 200-400 mg/ day) may be useful in persisting septic shock (SBP < 90). - No antibiotics if no pneumonia. - Antibacterial agents should be administered, if required, as per locally accepted clinical practice guidelines. Patient on mechanical ventilation should be administered antibiotics prophylactically to prevent hospital associated infections.

Types of protective masks •

Surgical masks – Easily available and commonly used for routine surgical and examination procedures

•

High-filtration respiratory mask – Special microstructure filter disc to flush out particles bigger than 0.3 micron. These masks are further classified: • oil proof • oil resistant • not resistant to oil – The more a mask is resistant to oil, the better it is – The masks have numbers beside them that indicate their filtration efficiency. For example, a N95 mask has 95% efficiency in filtering out particles greater than 0.3 micron under normal rate of respiration.

•

The next generation of masks use Nano-technology which are capable of blocking particles as small as 0.027 micron.

Non-Pharmacological Measures

Complete Personal Protective Equipment for Infectious diseases

Non-Pharmacological Measures

Respiratory etiquettes

Non-Pharmacological Measures

Keeping distance

Frequent Hand wash

Isolation and Home quarantine Self Monitoring of fever

•Community measures •Social distancing measures (at onset of outbreak) •Avoiding crowded places •Border/ Port / airport Control •Infection control practices •Risk communication

Actions taken by Ministry of Health • CoS, Inter Ministerial Task Force ( IMTF) and Joint Monitoring Group (JMG) monitoring the situation. • Enhanced surveillance at all International Airports to detect entry of disease into India at the earliest and contain the same. • Travel advisory issued to defer non-essential travel to the affected countries. • Tracking of persons travelled to India from affected countries.

Actions taken by Ministry of Health • States alerted to heighten the level of preparedness and action. • IDSP focal points in States to look for and report clusters of ILI and that of pneumonia • Central and State RRTs alerted to investigate and manage outbreaks. • Identified labs at NICD, Delhi and NIV, Pune beside all regional centers BSL2 Laboratories to test clinical samples of the novel virus.

Actions taken by Ministry of Health-3 • Guidance issued to States on clinical management, infection control practices, laboratory support. • Guidelines also available on MOHFW web site. • Supply of Oseltamivir to states reporting cases. • Supply of PPE to states reporting cases and other potential states. • Medical supplies are decentralized • IEC activities initiated in print and visual media. • 24X7 Control room • Daily press briefing by identified authority.

Actions by State Governments •Travel advisory issued by Central Government be reemphasized. •Assist MOHFW in tracking of persons travelled to India from affected countries. •Websites: • www.mohfw.nic.in • www.nicd.nic.in

Actions by State Governments • IEC activities has been initiated using print and visual media. • Messages suggesting Do’s & Dont’s to be reemphasised • Nodal person for media briefing to be identified and communicated to MOHFW. He should be in constant touch with Director (M&C), 99999-96104. • Press briefing by designated authority only.

Dos and Don’t: Educating the Public • Covering nose and mouth with a tissue when coughing or sneezing – Dispose the tissue in the trash after use. • Handwashing with soap and water – Especially after coughing or sneezing. • Cleaning hands with alcohol-based hand cleaners • Avoiding close contact with sick people • Avoiding touching eyes, nose or mouth with unwashed hands • If sick with influenza, staying home from work or school and limit contact with others to keep from infecting them • Staying away: from poultry. Keep them secure in cages. Keep children out of reach. Wash hands if in contact with poultry or poultry products. • Remain healthy by adequate sleep and balanced diet

References • CDC USA website • Ministry of Health & Family Welfare, Govt. of India, • National Institute of Communicable Diseases, Government of India • WHO website • Kishore J A Dictionary of Public Health (2nd Ed). New Delhi: Century Publications 2007