high angle view of a sick young man in bed blowing his nose with a tissue

The influenza virus, otherwise known simply as the flu, is an infectious disease that has mammals and birds as its hosts. Influenza is caused by RNA viruses within the family called Orthomyxoviridae. Influenza affects nearly 5 million people every year, killing about 500,000 yearly, with those numbers shooting up to the millions during periods of pandemics. The virus has often, over time, developed into newer, more complex strains such as the avian flu, and the swine flu (a hybrid flu virus from genes of the pig and bird). Records of the influenza date as far back as 2,400 years, when symptoms in humans were documented by Hippocrates. It is also believed that by the 1400′s the influenza virus spread to North America from Europe upon the arrival of explorers like Christopher Columbus; with the virus likely being responsible for wiping out the entire population of the indigenous peoples of the Antilles in 1493. Additionally, the most fatal and well-known of flu epidemics was the pandemic called the Spanish flu outbreak, lasting from 1918 to 1919, with a death rate reaching almost one-hundred million humans.


There are three ways that the influenza virus can be spread. The first way is when the virus is directly transmitted, often when a person who has the flu sneezes influenza laden mucus directly into either the nose, eyes, or mouth of another person who does not have the virus. The second way is when the virus goes airborne via an infected person sneezing, spitting, or coughing, with an uninfected person then breathing in the small microscopic droplets, or aerosols, of fluid released by the infected person. These droplets can travel quite a distance, up to three feet. The third mode of transmission is the surface to surface mode. Thus, for example, if you already have the virus, and then sneeze or cough either onto a surface or onto your hand and then touch a surface with your hand, an uninfected person  can then pass by and, by touching that same surface, transmit the virus to their body by touching their nose or mouth or eyes with their newly infected hand. Also, one additional mode for the influenza virus to be passed on is through hand-shaking. Thus if an infected person shakes the hand of an uninfected person, the virus can then easily be passed on.


Once a person has been infected with the influenza virus, it can take up to two days before the person begins to show signs. However, once signs do appear, they often have a sudden and rapid onset. At first, the person may begin to feel very lethargic with little energy. Also, feelings of being chilled (with accompanying shivering and shaking) will begin, and then a fever can ensue with a spike in body temperature often rising to 103 degrees Fahrenheit. From there, the person may experience further symptoms such as congestion of the sinus cavities, coughing, headaches, and runny nose. Experiencing bodily aches is also common, and will quite often be localized in the joints and the throat. There may also be a red discoloring in the face as well as on the nose and the throat. In some cases, what is called a Petechia rash may break out on the skin, characterized by purple-reddish spots, and is due to severe fits of either coughing or vomiting. Additionally, vomiting, abdominal cramps and diarrhea can be seen in children with influenza, but is quite rare in adults. However, if an adult contracts the bird flu (H5N1 strain of influenza), diarrhea can occur. Finally, sometimes influenza can cause further secondary complications such as a bacterial infection like pneumonia, with the predominant sign here being difficulty breathing.


When it comes to keeping the influenza virus at a minimum, either for symptom relief for those who have the virus or else outright prevention, there are a number of avenues to consider. For example, vaccination is often used as the best defense, especially for populations who are most at risk such as kids, the elderly, those in the health-care field, as well as people who already are suffering from a disease such as asthma or heart disease. The flu vaccine is highly recommended by both the Center for Disease Control and the World Health Organization. Another preventive measure is good personal hygiene to counteract the spread of infection. So, for instance, avoid touching your face (especially the nose, mouth, and eyes). Also, practice frequent hand washing, either using soap and water or else  hand sanitizer. Another sensible measure is to simply cover your mouth when you sneeze or cough. Avoiding people who are sick or areas where the sick are, and of course staying out of public areas if you yourself are sick, can also help in reducing the spread of infection to yourself and others. On the side of medications, acetaminophen and ibuprofen can help in symptom relief. Antiviral drugs are also available. Two types of these drugs are Neuraminidase inhibitors and M2 inhibitors. Both drugs work by preventing the flu virus from entering cells, and should be used as soon as flu symptoms are experienced.