pandemic

Rest is best

Your Health
DR GITA MATHAI

It is the wrong time of year for “flu” (influenza), but the World Health Organization (WHO) has issued a warning that we are on the verge of a swine flu pandemic. This is serious news indeed because the WHO does not like to cause unnecessary panic. Its gradation of influenza varies from phase 1 where the infection is present and circulating only in animals like birds and pigs, to phase 6, the highest level,where the virus has spread to another geographic region and its transmission is increased and sustained. With the scare posed at phase 5 — where a pandemic is imminent — its fears seem justified as the H1N1 virus that causes swine flu has been identified in Mexico, the US, Canada, the Netherlands, Israel, the UK, Denmark, Germany and Spain.

Influenza pandemics occur with devastating regularity. The first wave of Spanish flu occurred in 1918, affected 50 per cent of the world’s population and killed 50 million people. Asian flu in 1957 killed one million and Hong Kong flu in 1968 another one million. The seasonal flu epidemics kill around half a million people a year. In contrast, only 25 million deaths are attributable to HIV and AIDS worldwide.

Flu starts like a common cold, with symptoms like fatigue, fever, headache, runny nose, watery red eyes and muscle pains that set in one or two days after contact with another infected individual. It spreads from one person to another by direct transmission. As an infected person coughs, sneezes or spits, the virus particles are transmitted in the air. The inhaled droplet particles are 0.5 to 5 µm in diameter. A single particle can cause an infection. Each cough or sneeze expels 40,000 droplets into the environment. These can also get deposited on surfaces, contaminating walls, doors, paper, coins and other surfaces. They can be transmitted through unwashed hands from one person to another. High ambient temperatures and ultraviolet radiation kill the viruses rapidly in 5-15 minutes. However, if the virus is expelled enveloped in mucous discharge, it can survive for up to 48 hours. Crowding, with close contact, lack of ventilation and low temperatures in winter facilitate the spread of influenza.

Flu is usually a mild disease from which patients recover spontaneously. Serious illness, complications like secondary bacterial pneumonia and death can occur in the very young and the elderly (extremes of life), pregnant women, those with HIV or heart disease, and in smokers.

The diagnosis is mainly clinical, based on the characteristic signs and symptoms during an epidemic. Rapid diagnostic tests and viral cultures are available and can confirm the diagnosis with an accuracy of 75-90 per cent.

The virus causing influenza is a RNA virus — a virus that has ribonucleic acid as its genetic material — with five genera (family subdivisions). The commonest disease causing ones belong to A, B and C. They are given names like H1N1, H5N1, depending on the human antibody response. These viruses live in birds and animals like pigs. They can suddenly mutate and become virulent enough to cause disease in humans. Since the human population hasn’t been exposed to this new form of the virus, it doesn’t have any immunity. The disease then spreads rapidly in the susceptible population, causing a pandemic.

Outbreaks of influenza usually occur in winter. Since winter occurs at different times in the northern and southern hemispheres, there are two major epidemics a year. In addition, in the tropics an epidemic also occurs during the rainy season. These are the times when usually there is less sunlight and people tend to crowd together indoors. Air travel among regions and hemispheres has blurred these typical occurrences.

To contain an epidemic

Wash your hands with soap after visiting a sick person. Wash your hands several times a day, especially after handling money.

Clean surfaces like door knobs with a disinfectant.

Use a face mask.

Cover the face while coughing or sneezing.

Avoid spitting.

Immunisation is available against the influenza virus. The WHO tries to predict the strain that is likely to cause an infection that year and passes on this information to the pharmaceutical companies. They then have around six months to develop the vaccine. It is 75 per cent effective in preventing influenza.

In people who develop it after immunisation, the disease is less severe and runs a shorter course with reduced complications. The injectable vaccine is available in India. It is recommended for the young, the elderly, the diabetics and those with heart disease. A nasal spray vaccine is available in other countries.

If you are unfortunate enough to contract flu, stay at home and rest. Recovery will be faster and you will not be spreading the virus to the general public. Take paracetamol for the fever, aches and pains. Generally aspirin and other salicylic acid preparations should be avoided. Though they are generally safe medication, they can cause dreaded complications if given with flu. Specific antiviral medication like oseltamivir (Tamiflu) can be taken under medical supervision for prophylaxis and also to reduce the duration and severity of the illness.

Dr Gita Mathai is a paediatrician with a family practice at Vellore. Questions on health issues may be emailed to her at yourhealthgm@yahoo.co.in
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