Flu Season – Molecular Infectious Disease Testing
Flu is a contagious respiratory illness cause by influenza viruses that infect the throat, nose, and sometimes lungs. It can cause illness and sometimes death. Getting vaccinated is the best way to prevent catching flu .
There are four types of seasonal flu, A, B, C, and D. Types A and B cause seasonal epidemics of disease. Illnesses range from severe to mild and can even result in death in high risk groups. High risk groups include, pregnant women, children under 5 years of age, the elderly, and people with chronic or immunosuppressive medical conditions .
Symptoms of Flu 
• Sudden fever (temperature above 38C)
• Feeling tired
• Sore throat
• Loss of appetite
• Chesty cough
A test to detect Influenza viruses can be used to determine whether a patient has the flu. A swab is taken from either the nose or back of the throat and sent for testing. Molecular assays can be used to detect genetic material of the virus . Molecular methods play an important role in the diagnosis and surveillance of influenza viruses. Molecular diagnostics allow timely and accurate detection of influenza and are already implemented in many laboratories. The combination of automated purification of nucleic acids with real-time PCR should enable even more rapid identification of viral pathogens such as influenza viruses in clinical material .
The spread of Flu
Flu season begins as early as October, reaches its peak in February, and ends in March. In the southern hemisphere, flu season falls between June and September. Wherever it’s cold, it’s flu season. This can be seen in Figure A below, which shows google searches for the term ‘flu’ for the last five years for USA (northern hemisphere) and Australia (southern hemisphere). It is obvious that flu is prevalent at different times in the northern and southern hemisphere.
However, it’s a common misconception that flu is caused by the cold. There are many theories as to why the flu season comes in winter :
1. People spend more time indoors, with windows closed, not getting fresh air.
2. A lack of Vitamin D and melatonin from reduced sunlight, weakening the immune system.
3. Influenza virus thrives in the cold, dry air of winter
Of course, there have been attempts to test these theories, but animals do not contract the virus like humans, so testing is difficult. A researcher named Peter Palese decided to test theory 3 after finding an old medical journal article that reported guinea pigs are infected and spread the flu like humans.
Figure A. Google Searches for ‘Flu’ in USA and Australia for the last 5 years 
Having set up cages with varying temperatures and relative humidity, he observed how they affected the spread of the flu virus. He found Influenza spread more effectively in cold, dry air .
A theory about why this is the case is associated with how the virus moves through the air. When someone breaths out, they release little virus-containing droplets in to the air. The droplet then begins to evaporate. A lower relative humidity means there is less water in the air, meaning there is more room in the air for additional moisture, allowing the droplets to evaporate. A higher humidity means the droplet can’t evaporate because there isn’t as much room for more moisture, and the virus is not suspended into the air .
Whatever the case, the fact remains: when winter comes around, the flu will follow.
You can avoid catching the flu by getting the flu shot, investing in a humidifier, keeping your hands clean, and limiting contact with those who are already ill. Immunity gained from vaccination decreases over time, so annual vaccination is recommended. Vaccines are most effective when they closely match viruses in circulation. The constantly evolving nature of Influenza viruses requires the WHO Global Surveillance and Response System to monitor influenza viruses around the world and update vaccinations accordingly.
Personal protective measures can be taken in addition to vaccination :
• Properly washing and drying the hands
• Covering the mouth and nose when coughing and sneezing
• Self-isolation when showing symptoms of influenza
• Avoiding contact with sick people
• Avoiding touching the eyes, nose, and mouth
How Randox can Help
Randox offers molecular controls, calibrators, and EQA programmes for respiratory infection testing, which includes Influenza A and B, Adenovirus, Rhinovirus, and others.
Want to know more?
Contact us or visit our Qnostics page to learn more.
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