Influenza is an infectious disease caused by an attack of a specific type of virus of the Orthomyxoviridae Family, which itself encompasses a half-dozen genera of viruses. In humans, influenza's symptoms may include runny nose, elevated body temperature (fever), a persistent cough, headache, and a general feeling of weakness or soreness. At present, most influenza attacks are curable in those communities which have basic access to modern primary healthcare. Attacks generally last less than a week, though symptoms may lead to various types of potentially deadly complications, including viral and bacterial pneumonia, asthma, and even heart failure.
The virus is transmitted through the air, being exposed to the external environment by the carriage of particulate matter from the infected person via cough or sneezing. Propagation may also happen by physically touching an infected surface, such as touching the body or belongings of a person. Certain strands can also be spread between different human and animal species.
Globally, the flu has been found to spread most rapidly in burst amid seasonal outbreaks. In the Temperate regions and the Upper Tropics, such outbreaks typically occur in winter, with proportionally higher infection rates in cases of higher humidity in the atmosphere. Closer to the equator, outbreaks may occur any time of the year. There, the outbreaks are connected more with humidity level than temperature. Each year, 3 to 5 million people are severely infected by influenza worldwide, and death estimates vary between 250,000 to 500,000 cases per year. Calculating influenza mortality is complicated, as influenza infections occur in the wake of various other kind of complications. Old people die more commonly from influenza complications, as they are typically more often suffering with some other diseases to begin with that lowers their resilience, especially those of the heart or lungs.
Previously, there have been global mass outbreaks of influenza which have been termed as 'pandemics' of the disease. The 1918 Flu Pandemic of the H1N1 strain of influenza, which was referred to as the "Spanish flu", actually swept many parts of the world and killed between 50 and 100 million people. The outreach reached virtually all inhabited corners of the earth, everywhere from European population centers to some of the most remote Pacific Islands.
Regular washing of the hands and other exposed body parts with soap is generally recommended in environments known to have the active influenza virus. Vaccinations are available for certain influenza viral stains as well. Updated Influenza vaccinations are generally recommended to be received yearly, as the virus is a rapidly evolving one, and vaccines made for another year may not be effective later on.
Influenza attacks are generally treated with antiviral drugs containing neuraminidase inhibitors and M2 Protein inhibitors. However, with influenza being a common ailment that occurs across all age groups and regions, patients are generally advised to take rest, avoid going out, and not continue consuming alcohol and tobacco products, which may worsen their situation. Paracetamol drugs are widely used as a common medication in case of mild attacks. Recently, a virulent stain of influenza virus had emerged, classified as the H5N1 variety, which in mass media became popularly known as "bird flu" or "avian influenza". For this particular strain that caused a recent outbreak, medication is now still in the research and development stages. Indeed, Paracetamol is not deemed effective in treating H5N1 infection. The drug Oseltamivir is generally used in its treatment instead, though large scale effectiveness studies are yet to confirm the utility of this drug, although in preliminary studies it had been observed to inhibit infections within patients' bodies.