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H1N1 Flu or Influenza

01) What is influenza?
02) Cause /VIRUS
03) Symptoms /Clinical Features
04) Influenza diagnosis/Laboratory Investigation
05) Complications
06) How do you get it /Transmission?
07) Survival of the virus in the environment
08) Individual Prophylaxis
09) Precautions for the Doctor
10) Treatment
11) Prevention?

What is influenza?

Influenza or Flu - an acute viral infection of the respiratory tract which is known to be transmitted from man to man can spread rapidly if preventive measures are not undertaken.

Cause / VIRUS

Influenza, an infectious viral disease, is cause by a group of viruses called Orthomyxoviridae. This group contains three distinct droops called Influenza A, Influenza B and influenza C. Of these the first virus that is Influenza A is the virus that is known to cause pandemics from 1890 onwards. In fact the world has seen epidemics and the last one documented is in 1977 leading to increased hospitalization and deaths. The pandemics are caused by this virus acquiring a new set of genes from animal or bird influenza viruses. This acquisition of genes creates a new strain which rapidly spreads through the community because immunity (resistance) is not there in population. Avian (bird) Influenza scares in South East Asia was caused by the bird Influenza virus spreading to humans.

The present outbreak is said to be caused by a pig influenza virus, changing itself by mixing itself with the human and avian influenza viruses. This is called reassortment and is possible due to the fact that the virus RNA genetic material is present in fragments and is capable of mixing itself by taking up fragments from different group of virus and emerging as a new strain. The initial name given to this was the Swine Influenza Virus but it is redesignated as the deadly H1N1 Influenza, A virus by the World Health Organization which has put the risk of a pandemic occurring to Phase 5 which is just one level below the full scale pandemic alert. The saving grace has been that this virus seems not to be such a killer, due to some deficiencies in the attack rate. In fact the H1N1 virus has been known to decimate more than 50 million worldwide in the outbreak of 1918. This is the fear that has made healthcare workers, veterinary doctors and administrators to scramble to contain the infection. In the west free flow of information has brought new cases to light and in contrast we have severe measures applied in Hong Kong where a whole hotel guests are kept under observation by legislation. This is because Asia has seen severe infections in the SARS outbreak.

Symptoms /Clinical Features:
Clinically a person infected with the virus comes over with

  • Fever which can be high on the level of 38 to 41 degrees centigrade that is 99 to 104 degrees Fahrenheit. This fever comes all of a sudden and usually persists for a few days and then subsides.-
  • Along with this the person gets cough with or without production of sputum.-
  • Severe body pain.
  • Sore throat.
  • Running nose

These symptoms may be present together or may be present as a single symptom making diagnosis confusing

Added to this we have to remember that the disease has an incubation period, that it takes anywhere between 2 to 7 days before an exposed person becomes symptomatic. This effectively means that a person is just like you or me and can carry the virus through the checks done at airports and go through to spread the virus in the community when he or she comes down with the infection. In fact these symptoms complex makes it similar to common cold which is the usual disease that it is confused with

Influenza diagnosis / Laboratory Investigation:

Currently laboratory tests are only available in select centers like the National institute of Communicable diseases (NICD) or National Institute of Virology (NIV) which is making diagnosis difficult. In fact the easy availability of the following tests would make containment of the disease easier and should be taken up on a war footing.

A Nasal swab, nasopharyngeal washing, throat swab etc should be taken and transported to the laboratory. A blood sample is also taken and only serves to retrospectively diagnosis infection by looking at antibodies. This may be negative early in the infection. This makes it necessary for us to take another blood specimen 2 weeks later to confirm that a person is or not exposed to the virus.

The tests done are

  • Antigen detection: detects the H: hem agglutinin antigen and N: Neuraminidase antigen and the results can be available in a few minutes. This is very efficient to identify the virus infection in the field. The drawback is it is only 60 to 70 present sensitive.
  • Virus culture available in most laboratories having a virology laboratory but is time consuming and laborious and is not done routinely.
  • PCR or Polymerase chain reaction is the test that is finding acceptance as a tooled which can identify the disease but is equipment intensive and costly. More over it is highly sensitive, so if laboratory practices are not correct it could lead to erroneous results.


In few people severe complications like Influenza pneumonia (primary) may be encountered, which is life threatening. This is caused by the virus and can be dangerous if not treated immediately in a hospital. The viral infection destroys the respiratory tract lining and there in can allow bacterial infections. A secondary bacterial pneumonia may need antibiotic treatment in a hospital.

The disease is severe in children, old aged persons and in people with cardiac and respiratory problems. A person who has asthma or /respiratory infection would have a more severe episode. Pregnant women seem to have more severe clinical features.

How do you get / Transmission?

When an infected person coughs or sneezes (and does not cover his/her mouth) the viruses fly into the air along with mucus, saliva and other secretions. It takes a while for these microscopic particles to settle, so for several minutes, they are airborne. Another person can become infected by inhaling the airborne particles or touching a surface that has been contaminated with them. It is for this reason health authorities ask people not to go to matches, cinema and malls etc where large number of people congregates. If a person is infected he or she should take care to keep a handkerchief to the mouth and nose while sneezing and coughing. Wearing of a surgical mask not certified like the N95 mask is not useful.

The virus must enter the respiratory system, before an infection can occur. Influenza viruses cannot enter the body through the skin

Survival of the virus in the environment:

  • The virus survives on hard surfaces like table tops, plastic surfaces and other areas where direct sunlight or high temperature is not seen for 72 hours. This is a long time for another person to be infected from this.
  • In fact it is seen that for 12 hours the virus can be transmitted from this surface to the hand. On the hand the virus survives for over 3 hours.
  • In clothing the virus survives for 24 hours and can be transferred from one surface to the other for over 12 hours. In addition the soiled handkerchief can hold huge amounts of the virus.
  • All virus dies on drying or washing with detergents.
  • All skin surfaces are cleaned using an alcohol hand rub available from drug stores, this kills the virus.
  • Any contaminated surface and clothes should be washed with detergent and a hot wash cycle.

Individual Prophylaxis:

  • Please use a tissue or wipe to sneeze into and drop into a plastic bag kept next to the individual. This can be discarded into the regular waste.
  • Ensure that all contact is kept to a minimum.
  • Ensure that all vessels and other personal belongings are washed with detergent.
  • Wash hands with alcohol rubs or gels.
  • Keep away from greeting a person by kissing on the hand or cheek. It could transmit the infection.
  • Indian way of greeting like Namestae is great to keep the virus at bay.

Precautions for the Doctor:

  • Wear gloves for examination of a suspected case.
  • Wear a mask if you are within three feet of the individual
  • All interventions like bronchoscopy and aspiration needs a respirator
  • The room should have a separate air conditioner and should have a exhaust fitted with HEPA filter.
  • The isolation room should have a air lock and negative pressure so no air comes and contaminates the other areas of the hospital.
  • Keep one person in one room.
  • Keep all necessary instruments for the care in the same room
  • Allow access only to the essential personnel only.
  • Use of personal protective equipment like visors and other goggles and apron should be one use only and should be discarded after use.
  • Discard all material inside the room itself and rub hands with alcohol after discarding gloves.
  • Use surface disinfectants in the room at least once a day.
  • Final fumigation with H2O2 hydrogen peroxide vapor could be used to disinfect the room and is safe for adjacent room occupants.


  • Most of the cases of Influenza need only symptomatic treatment like Paracetamol for fever and some cough suppressant.
  • Usually the person clears the infection within 5 to 7 days.
  • For severe conditions drugs like Tamiflu are available which can be used for chemoprophylaxis or prevention when a person is exposed to the virus. This has to be administered with caution and has to be done by a medical practitioner as these drugs have side effects and should be only taken in extreme
  • cases in patients having risk factors.
  • There are other drugs available and used by Doctors on case to case basis.
  • Please do not self medicate.

Please ensure that you give correct details of the travel to Influenza reporting countries and keep your health care doctor advised of any symptoms resembling the flu at all times. If you come down with symptoms keep yourself at home and ask for advice and help. Your doctor has to take the help of the medical authorities and public health department.

They would require the help of tracing your contacts so that can confine them and see that the infection does not spread. In fact the advantage that we have is that most of our country is dry in the following months and have a high temperature which may be imical to the virus transmission. With the advent of monsoon and the cooling down of temperature and increased humidity would make the transmission of the virus more possible. Please also take that time off to ensure that this virus is kept at bay by following the instructions of the health care authorities.


  • Prevent exposure by asking the infected person to stay and work from home.
  • Prepare all meat products and cook them properly before eating, meat and poultry products do not transmit the infection per say.
  • Vaccines are available but the present outbreak is caused by a new variant of the Influenza virus which is a reasserted mixture of swine, avian and human strains. A new vaccine is being prepared and would be available after 6 months. The old vaccine is available and is said to be cross protective.
  • Drink sufficient water.
  • If you are traveling please ensure that you have Paracetamol and this should be only used for the fever and body pain.
    * Aspirin should not be taken as it causes a serious complication called Reyes syndrome.
  • Do not travel unnecessarily to countries reporting Influenza outbreak.




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