Cold or flu – do you know the difference?

By Dr. Dineshani Hettiarachchi Sirisena

“Is there a flu going around?” is a common question most medical professionals get asked.

The flu (also known as seasonal influenza) is an acute viral infection caused by viruses that circulate worldwide. To get a clinician’s perspective on this cyclical occurrence, we spoke to Dr. Priyankara Jayawardana, a Consultant Physician at the National Hospital of Sri Lanka (NHSL).

What are the currently circulating strains?

Influenza A (H1N1, H3N2, etc.) and B are the viruses currently circulating causing human infection.

When should we expect an outbreak?

Influenza occurs throughout the year with two peaks, as below:
· May/June/July
· November/December/January

How do you get infected with the virus?

· Droplets from an infected patient can make contact with you if you’re within the proximity of one metre
· By direct contact with an infected person or contact with contaminated fomites
· Patients are at the risk of infecting others from one day before their symptoms appear up to five to seven days after becoming sick. Children may be at risk of passing the virus for longer
· Patients are no longer infectious 24 hours after the resolution of the fever, provided they have received 72 hours of anti-influenza medication, or seven days have elapsed since the onset of respiratory symptoms

Since the initial presentation of the influenza infection can mimic the common cold, one must watch out for the sudden onset of high fever, a cough, headache, muscle and joint pain, a sore throat, and runny nose, as these are some cardinal features.

Most people recover from the fever and other symptoms within a week without requiring medical attention. However, influenza can cause severe illness or death, especially in people with high risk. Hence, those at high risk should seek medical care without delay to avoid complications.

Who is at high risk?

· Children younger than two years of age, adults aged 65 years or older
· All pregnant ladies
· Adults and children who have serious long-term health conditions such as;

o Respiratory diseases (such as asthma, chronic obstructive pulmonary disease [COPD], or bronchitis)
o Heart diseases (such as heart failure)
o Kidney diseases
o Liver diseases (such as hepatitis)
o Neurological conditions (such as Parkinson’s disease or motor neurone disease)
o Diabetes
o Spleen problems (such as sickle cell disease)
o A weakened immune system as a result of conditions such as HIV and AIDS, or medication such as steroid tablets or chemotherapy.

Dr. Jayawardana further emphasised that high risk patients need not wait for lab reports to start treatment, especially during an epidemic, and all pregnant women presenting symptoms of influenza should be referred to a hospital with specialist care. Patients consulting general practitioners and who may require laboratory investigations and/or antiviral treatment should also be directed to a hospital where these facilities are available.

How can we avoid contracting the virus?

· Wash hands with soap and water frequently.
· Use alcohol-based hand rubs if available and if hands are not visibly dirty.
· Cover mouth and nose when coughing or sneezing, with a tissue, handkerchief, or the inner surface of the forearm when tissue/handkerchief is not available.
· Dispose the tissues and masks in no-touch receptacles.
· Cleaning and disinfection of the environment and equipment

(Source: Epidemiology unit, Ministry of Health)

When asked about the influenza vaccine, Dr. Jayawardana recommends all high-risk patients get vaccinated and stated that there are no major vaccine-related side effects. However, he said it’s better to avoid getting vaccinated in the first trimester of pregnancy.

Influenza vaccine

· Takes two weeks to develop immunity
· Current vaccine covers influenza A including H1N1 and influenza B
· It’s a killed intramuscular type vaccine
· Has to be taken once a year

In most countries, the mainstay of seasonal influenza prevention and control is the vaccination. Influenza vaccines reduce the infection rate and influenza-related complications and deaths in some populations.
However, in stark contrast to other viruses like measles, where one acquires lifelong immunity following a single exposure, individuals are repeatedly exposed to influenza viruses throughout their lifetime without developing broad and durable protection against the infection. Hence, adequate precautions should be taken during an outbreak to prevent getting infected.

Precautions to be taken during an outbreak

· Don’t spread or get infected – avoid crowds, rest, wear a face mask
· Keep clean – wash hands, clean frequently touched surfaces with disinfectants
· Stay fit and healthy – drink plenty of fluids, keep moving, get enough sleep, and eat your greens
Influenza, by and large, has caused severe worldwide pandemics of varying degrees of mortality, the most devastating of which occurred in 1918 and resulted in an estimated 50-100 million deaths worldwide.
We have come a long way since then. Tremendous scientific advances give us hope that we will soon celebrate the development of a universal vaccine to rid our lives of this persistent and elusive pathogen.

Further reading: Immunity to influenza – The Journal of Immunology