New Influenza A (H1N1)

Earlier called – Swine Flu

India: 13th August 2009

Information source : WHO Websites

Influenza: A Viral infection

Acute respiratory infection caused by Influenza virus – Three types A, B and C

Currently viruses circulating in human population – Influenza A (H3N2), A (H1N1) and B Strains

All known pandemics (global outbreaks) were caused by Influenza A

Animal influenza viruses may affect humans in special circumstances – Bird Flu: A (H5N1)

Influenza Virus

Continues to evolve Two distinct surface antigens H – Total 16 (1 to 16) N – Total 9 (1 to 9)

Antigen H (Haemagglutinin) initiates infection following attachment of virus to susceptible cells

Antigen N (Neuraminidase) responsible for release of virus from the infected cell

Antigenic changes less in B while C appears stable

Virus Reservoirs

Major reservoir in wide variety of birds and animals including swine, horses, dogs, cats, domestic poultry

Evidence is available that animal reservoirs provide new strains by recombination between influenza viruses of man, animals and birds

Influenza in Past

1918 – A (H1N1) Spanish Flu : > 20 million deaths

1957 – A (H2N2) Asian Flu : > 2 million deaths

1968 – A (H3N2) Hong Kong Flu : > 2 million deaths Antigenic shift only in H antigen

2003 – Avian Influenza / Bird Flu A (H5N1) First human case in 1997 Human – to – Human transmission relatively inefficient and

not sustained

Novel Influenza A (H1N1) 2009 Virus New strain of A (H1N1) Not previously detected in swine or humans Unusual mix of genetic segments including of swine,

avian and human influenza viruses Originated from pigs and at some point of time

transmitted to humans Cases began to appear from 17th March’09 in

Mexico with human – to – human transmission No cases in swine population and no infections from

pork. Pigs are responsible only for mutation of virus.

Global Scenario when 1 case in India

Pandemic Phases

Preventive Behaviors Wash your hands. Get plenty of sleep. Be physically active. Manage your stress. Drink plenty of fluids. Eat nutritious food. Avoid touching your

eyes, nose or mouth. Avoid close contact with

people who are sick. Avoid crowding.

CASE DEFINITIONSuspected case : A person with acute febrile respiratory illness   (fever ≥ 38 0 C) with onset

within 7 days of close contact with a person who is a confirmed case of novel influenza A (H1N1) virus infection, or

within 7 days of travel to community where there are one or more confirmed novel influenza A(H1N1) cases, or

resides in a community where there are one or more confirmed novel influenza cases.

Probable case : A person with an acute febrile respiratory illness who is positive for influenza A, but unsubtypable for H1 and H3

by influenza RT-PCR or reagents used to detect seasonal influenza virus infection, or

who is positive for influenza A by an influenza rapid test or an influenza immunofluorescence 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.

Confirmed Case of A(H1N1)

A person with an acute febrile respiratory illness with laboratory confirmed novel 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

Clinical Features

Ranging from non-febrile, mild upper respiratory tract illness to severe or fatal pneumonia

The most common symptoms include cough, fever, sore throat, malaise and headache

Some cases have experienced gastrointestinal symptoms (nausea, vomiting and/or diarrhoea)

Secondary bacterial infections may occur Rarely rhabdomyolysis with renal failure, myocarditis Worsening of underlying conditions like asthma and

cardiovascular disease

Diagnosis

Confirmatory diagnostic tests of nasal or throat swab can be done by specialized Laboratories.

Reverse transcriptase polymerase chain reaction (RTPCR) will provide the most timely and sensitive evidence of infection

Clinical diagnosis based on the acute onset of fever and cough can be increasingly predictive as the prevalence of infections increase

Specialized Labs in India

Treatment Considerations

Most cases of new influenza A (H1N1) virus infection have had uncomplicated illness of limited duration.

Hospitalization is being done more for isolation and for observation and treatment of seriously ill patients

Supportive care includes antipyretics, such as Paracetamol for fever or pain.

Fluid rehydration to be provided as needed. Salicylates (such as aspirin) should not be used in

children and young adults because of the risk of Reye’s syndrome.

Infection control at Individual level Respiratory Hygiene / Cough Etiquette

Cover the nose/mouth with a handkerchief/ tissue paper when coughing or sneezing

Use tissues to contain respiratory secretions and dispose of them in the nearest waste receptacle after use

Hand hygiene Hand washing with non-antimicrobial soap and water,

alcohol-based hand rub, or antiseptic hand wash after having contact with respiratory secretions and contaminated objects /materials

Use of mask Three layered surgical mask For cases and immediate family and social contacts.

USE OF MASK Any person who is in close contact with someone who has

influenza-like symptoms is at risk of being exposed to potentially infective respiratory droplets.

Correct use of mask place mask carefully to cover mouth and nose and tie securely

to minimise any gaps between the face and the mask while in use, avoid touching the mask and whenever you touch a

used mask (when removing or washing), clean hands by washing with soap and water or using an alcohol-based hand rub

replace masks with a new clean, dry mask as soon as they become damp/humid

do not re-use single-use masks. Discard single-use masks after each use and dispose of them immediately upon removing.

Using a mask incorrectly however, may actually increase the risk of transmission, rather than reduce it.

If masks are to be used, this measure should be combined with other general measures to help prevent the human-to-human

transmission of influenza, Training on the correct use of masks and consideration of cultural and personal values.

Seriously Ill Patients

Signs of clinical deterioration Chest pain Difficulty in breathing Coughing up coloured sputum Altered level of consciousness and confusion

Immediate hospitalization required Take into account other associated illness

such as immune-compromising conditions, pre-existing chronic lung or cardiovascular disease, diabetes etc.

Oxygen therapy

In seriously ill patients oxygen saturation should be monitored by pulse oximetry and supplemental oxygen should be provided to correct hypoxemia.

The WHO recommendations for pneumonia is to maintain oxygen saturations above 90%; however, this threshold may be increased to 92–95% in some clinical situations, for example during pregnancy.

Populations at altitude will require different thresholds for diagnosing hypoxemia but will also have increased susceptibility to severe hypoxemia in the presence of pneumonia or ARDS.

Use of Antibiotics

Antibiotic chemoprophylaxis should not be used.

Antibiotics should be used only if secondary bacterial infections occur. The microbiological test results, wherever possible, should be used to guide antibiotic usage.

Several patients in Mexico have developed ventilator-associated pneumonia or hospital-acquired pneumonia caused by typical nosocomial pathogens.

ANTIVIRAL THERAPY The new influenza A (H1N1) viruses currently susceptible to the

neuraminidase inhibitors (NAIs) Oseltamivir and Zanamivir Early administration of NAIs

may reduce severity and duration of illness may also contribute to prevent progression to severe disease and

death Antiviral therapy will be beneficial specially for

pregnant patients, in whom administration of antiviral medicines should be carefully evaluated taking possible benefits and risks into consideration

patients with progressing lower respiratory disease or pneumonia patients with underlying medical conditions.

If used, antiviral treatment should ideally be started early, but it may also be used at any stage of active disease when ongoing viral replication is anticipated as it is possible that the virus may replicate for a prolonged period of time in some patients as a result of the lack of pre-existing protective immunity

Oseltamivir : Drug of choice

Age Group : Above 1 Year Dosage by 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

For infants: < 3 months 12 mg BD for 5 days 3-5 months 20 mg BD for 5 days 6-11 months 25 mg BD for 5 days It is also available as syrup (12mg per ml

) If needed dose & duration can be

modified as per clinical condition.

Capsules of 75 mg each

Store at room temperature

Generally well tolerated

Side effects occur especially at

higher dosages

Only 6 resistant cases reported

so far of which 5 responded to

Zanamivir

Vaccine for new virus Making vaccine ready to immunize people generally takes five to

six months after first identification (April 2009) of the virus. The very first doses of influenza A (H1N1) vaccine usable to

immunize people, from one or more manufacturers, are expected as early as September 2009.

Most of these vaccines will be produced using chicken eggs, while a few manufacturers are using cell culture technology for vaccine production.

When vaccine first becomes available, it is anticipated that the demand will be greater than the supply. This gap will narrow as more vaccine becomes available over time.

Three vaccine manufacturers in India have shown interest Serum Institute of India Panacea Biotech Bharat Biotech

Mild Illness ! Why one should worry ? A new virus will affect large number of people

as there is no immunity. Need to identify seriously ill patients early to

prevent deaths. Virus has a high potential for mutation and

may develop into more lethal strain over the time.

Surveillance and preparedness needed. Social and Economic impacts to occur.

Expected Social Impact

Rapid global spread of illness All are susceptible as none are immune Illness occurring in waves of variable period Work absenteeism Travel restrictions Event cancellations Institutional closures Vaccine not likely to be available in first wave

Travel during pandemic

It is safe to travel. Limiting travel and imposing travel restrictions would have very

little effect on stopping the virus from spreading, but would be highly disruptive to the community.

Although identifying signs and symptoms of influenza in travellers can help track the path of the outbreak, it will not reduce the spread of influenza, as the virus can be transmitted from person to person before the onset of symptoms.

WHO do not believe that entry and exit screenings would work to reduce the spread of this disease.

People who are ill should delay travel plans. Returning travellers who become ill should contact their health

care provider. Travellers can protect themselves and others by following simple

prevention practices that apply while travelling and in daily life.

School Closure : CDC Guidelines Schools should try to stay open. Decision-making up to local

communities. Weight the very real harm of school closings against the potential harms

of increased flu spread. Advice students

To stay home when sick, longer if needed. Wash hands. Observe cough / sneeze etiquette

Separate ill students and staff. Routine cleaning to be maintained. Closure of the school to be considered

If there is excessive absenteeism among students or staff. If large numbers of kids are ill and being sent home during the day. If the school isn't able to keep sick people out. If the flu becomes severe. For other reasons that "decrease the ability to maintain school functioning.“ Closed schools should also cancel school-related mass gatherings. School should remain closed for five to seven calendar days and then

consider whether to reopen.

Conclusion

Rapid spread as no immunity. Mild illness in majority. Remain cautious and prepared. Not to panic. Flexibility in implementing control strategy. Focus on evidence based practical and

acceptable measures. Vaccine will be soon available. Watch for further mutation in virus is needed.