Dr Antonis Pantazis, from the Heart Hospital in London, talks about the virus, what cardiomyopathy patients can do to help avoid it, and what to do if they have symptoms
Viruses are microscopic agents that often cause infectious diseases. Different sub-types of viral infections are affecting significant numbers of people on a yearly basis. Occasionally, they affect larger than usual numbers of people in a given period and then we call it an epidemic. There are circumstances that make it easier for a virus to spread to larger numbers of people and among different population groups.
These circumstances can be cold or humid weather, crowded places and bad hygiene. Also, there are occasionally new types of virus that are different from those of previous years and people are not immune to them. When an epidemic extends worldwide, it is called a pandemic.
History
A group of the viral sub-types can cause the influenza (or flu) that affects birds and mammals. Flu, like many other viral infections, can occur at the usual rate of prevalence in the population but may potentially present with an epidemic or pandemic. Epidemics are not unusual and yearly influenza epidemics are estimated to affect five to 15 per cent of the global population. Although most cases are mild, some are severe and around 250,000–500,000 deaths will occur worldwide each year. Three influenza pandemics occurred in the 20th Century: the Spanish flu in 1918, Asian flu in 1957 and Hong Kong flu in 1968. These killed tens of millions of people.
Each of these pandemics was caused by the appearance of a new type of virus in humans. Often these new strains appear when an existing flu virus spreads to humans from other animal species, or when an existing human strain picks up new genes from a virus that usually infects birds or pigs.
In April 2009 a novel flu strain that combined genes from human, pig, and bird flu emerged in Mexico. It was initially called swine flu and is now also known as influenza A (H1N1). The World Health Organisation officially declared the outbreak to be a pandemic in June. This was an indication of spread, not severity.
Transmission
Typically, flu is transmitted through the air by coughs or sneezes, producing droplets containing the virus. It can also be transmitted by saliva, nasal secretions, faeces and blood. Infection can also occur through contact with these body fluids or through contact with contaminated surfaces.
Airborne transmission is thought to cause most infections. Influenza viruses can be inactivated by sunlight, disinfectants and detergents. As the virus can be inactivated by soap, frequent hand washing reduces the risk of infection.
Those with other health problems
It is almost self evident that those who already suffer from another health problem are more likely to suffer complications from the virus. These complications can be more serious. For example, if a person is troubled by chronic disease of the lungs, he or she is at higher risk of developing a viral pneumonia and be more severely affected. Conditions suppressing the immune system of the body can also increase the vulnerability and susceptibility of individuals.
The heart is the pump that maintains the circulation of blood around the body. Any dysfunction may affect other organs in a temporary or in an irreversible way.
A cardiac disease will not directly make someone vulnerable to a viral infection but will influence the patient’s risks and clinical course to the extent that it affects other organs such as the lungs, kidneys and liver. Therefore, if a heart condition is very stable and causes no disruption to the function of other organs, then no significant risk should exist in the case of a viral infection.
Clinical presentation
Flu symptoms are non-specific and can be caused by many other viruses too. The most common symptoms are chills, fever, sore throat, muscle pains, severe headache, coughing, weakness and sleepiness, vomiting or diarrhoea and general discomfort. During the course of the viral illness, a number of organs can be affected, often in a reversible way.
What appears to be frequent in swine flu, compared to other viral diseases, is the prevalence of severe infection of the lungs (pneumonia). This complication is probably responsible for the greater number of hospital admission and deaths. Although a number of deaths may be inevitable and would occur with any other flu, it is reassuring so far that the overall number of fatal cases appears to be low. Also, the total number of people affected by the flu is unknown as mild cases may remain undiagnosed. If we knew the overall incidence of the disease, the percentage of deaths might be even lower. The exact circumstances of the deaths is not known. Some may have had no or limited access to medical services or been severely ill from other diseases.
In some cases patients with cardiomyopathy can become severely affected by the flu virus. The risk depends more on their heart function. Those patients with significant heart dysfunction who are very symptomatic and breathless beforehand are apparently at higher risk. The degree of limitations the patient is experiencing is a very important prognostic factor for complications. Therefore, patients with cardiomyopathy should inform their doctor if they have flu symptoms. It is likely that little intervention will be required other than hydration, rest and temperature management. Patients can probably remain at home if they are stable, but should contact their doctor again if their condition worsens or is not improving after five to seven days.
Treatment
The treatment in most cases involves managing symptoms and supporting the body’s functions until recovery from the virus is complete. The medication used against swine flu — Tamiflu (oseltamivir phosphate) — must be used with caution as in any other health condition.
Although the medication has been tested and considered to be safe and effective, there are various side effects and possible interactions with other drugs. It is also expected that new side effects and interactions will be seen with wider use of the drug. The medical community is also learning by observing and analysing the reported successes and failures.
The World Health Organisation and local authorities in all countries have systems in place to pick up adverse reactions immediately and use information coming in from all over the world. This learning process has been used with all diseases and treatments in the past and will continue to be so. A vaccine is also anticipated once its efficacy and safety are validated. Generally speaking, clinical decisions are based on a risk versus benefit evaluation. So when the risk of a condition appears to be very high but the associated medication or vaccine offer high efficacy but relatively low risk, then they can been used with caution. Medication that patients were on before being affected by the flu should not be discontinued or changed except on doctor’s advice.
So in practical terms every flu outbreak is a “new” disease and although knowledge from previous outbreaks is extremely useful, there is always a degree of uncertainty.
Fortunately, the process of studying a new pandemic is quite fast today, thanks to communication and IT advances. Patients should follow the recommendations for basic hygiene to minimise the risk of catching the virus. Washing hands and avoiding unnecessary visits to places where there is a higher risk of coming into contact with the virus is advisable and common sense.
When a patient with cardiomyopathy has symptoms suggestive of flu, they should contact their doctor and fully report the symptoms. Depending on their cardiac health, appropriate action may vary from surveillance to hospital admission.
Even if surveillance is initially indicated, any worsening of the symptoms should raise a new alarm. Suffering from a flu infection is a dynamic and evolving situation. Therefore, constantly updating the physician responsible for your care is essential.
Dedicated to Damian McLoughlin, who died age 20 of cardiomyopathy. This site is supported by Damian's family and friends.
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