Influenza is a common, contagious respiratory illness caused by a group of viruses known as influenza viruses. It can cause mild (usually)to severe illness, and at times can lead to death. The best way to prevent influenza is to get vaccinated. Influenza can occur and spread worldwide (pandemic)

How does one contract flu?

The flu virus is spread by the respiratory route. When a patient with flu sneezes, coughs or even talks, droplets of respiratory secretions are released in the air. These also carry the flu virus and can be inhaled by other people. The flu virus then settles in the respiratory tract and given the right conditions could cause infuenza infection. Much less common route of transmission is by touch. When a person comes in contact with a surface on which droplets of respiratory secretions of a patient infected with flu have been deposited. He or she may then carry this infected material in contact with the upper respiratory tract.

A person can infect others from one day before getting symptoms to five days after getting sick.

What are the symptoms that a patient with flu experiences?

After a person contracts infection it takes around two days for the symptoms to manifest themselves. The most common symptoms are:

• Fever – Usually high (however, it is important to emphasize that some patients will not have fever).
• Cough that is usually dry
• Sore throat
• Runny nose
• Headache
• Myalgia (muscle pain)
• Arthralgia (joint pain)
• Malaise – feeling of being unwell
• Vomiting and diarrhea – especially in children

What is the subsequent course?

In most people, the symptoms subside within a week and do not require medical attention. However people with risk factors can progress to a significant illness that may lead to considerable morbidity and rarely even mortality. Persistence of symptoms like weakness and easy fatigability (post-influenza asthenia) may last for several weeks in older children. One needs to be very careful if:

• Extremes of age: Adults who are > 65 years of age and Children who are < 5 years of age and especially if they are < 2 years.
• Pregnant women.
• People suffering from underlying medical conditions:
  • Asthma – even if they are well controlled with medications
  • Pre-existing chronic lung diseases like chronic obstructive pulmonary disease or cystic fibrosis
  • Heart disease – congenital heart disease, congestive heart failure and coronary artery disease
  • Diabetes and other endocrine disorders
  • Pre-existing liver disease
  • Pre-existing kidney disease
  • Children who have inherited disorders of metabolism
  • Immunodeficient – either due to disease (like HIV) or drugs (steroids) or malignancy
  • < 19 years and on chronic aspirin therapy
  • People who are morbidly obese (BMI > 40)

What can one do to prevent the spread of flu and protect oneself against flu?

• General health and hygiene measures.
• Vaccinating oneself against flu by taking flu shots once a year.
• Any person suffering from flu like illness should stay at home until 24 hours after their fever has resolved without taking fever medications.
• Pre-exposure prophylaxis (This is usually indicated for high-risk groups who cannot be vaccinated for some reason).
• Post-exposure prophylaxis (Again indicated in high risk groups who have been exposed to a patient suffering from flu and who either cannot be vaccinated or who have been vaccinated < 2 weeks before exposure).

How do you diagnose flu?

In most cases, flu is diagnosed by the typical symptoms that the patient experiences. In most people we do not order specific tests to diagnose flu, preferring to prescribe standard treatment. However there are timeswhen the symptoms may not match up to the typical presentation and then the tests may be ordered. Tests are also ordered when flu is suspected in pregnant women and in any person whose immunoligical status is compromised.

The most common tests used to diagnose flu are the rapid tests that can diagnose the illness in about 30 minutes. However these tests have a wide variability in their ability to give an accurate diagnosis depending on number of factors like which viruses are causing this particular attack of flu etc. More specific tests are only done in special labs and involve taking a swab from the back of the throat or nose and then sending it to special labs (in our country, the National Institute of Virology, Pune is the standard lab).

2 thoughts on “Influenza”

1. Pingback: Swine Flu Resurfaces | Nathani Clinic
2. Pingback: Correct sneezing and coughing techniques | Nathani Clinic