It is also known as H1N1 viral influenza A or simply as H1N1 Influenza.
The last big pandemic was in 2009. Nowadays it occurs off and on in India and other countries mainly during flu season.
Fever usually more than 100o F is common. It is accompanied by a sore throat, running nose, cough, headache and muscle pains. Shivering may occur as do vomiting and loose motions.
Individuals both very young and very old as well as pregnant women are at high risk of complications. Similarly, those with other debilitating conditions: malignancy, asthma, smokers, HIV +ve patients and those who have low immunity due to various drugs and disease may develop severe complications.
About 10 % persons may have no symptoms. Fever may not occur in some cases.
The complications may occur in about 20 % cases. These are in the form of failure of gas exchange by lungs, low BP, altered level or lack of consciousness, fits, liver and kidney failure etc.
The diagnosis is made by both nasopharynx and throat (combined) real time reverse transcriptase (rt RTPCR) which is nearly always positive. Chest X Rays can show pneumonia.
In some cases, superadded bacterial infections occur a few days later and complicate the illness.
Treatment and prevention
Treatment with antiviral drugs reduces complications. The drugs used are Oseltamivir and Zanamivir. The doses are different for children. These drugs are also used for prevention of infection after and before contact with swine flu patients.
The spread is by droplets (during coughing and sneezing ) and close contact. Patients should be diagnosed early to prevent the spread of the disease.