According to the researchers on flu, the flu is caused by the flu viruses that can affect our aspiratory system. When we get infected, the flu virus will inhabit in ... ]]> Flu is a highly contagious disease, and there is a death rate of about 0.1% among those who catch flu. You may know the pandemic of 1918 flu, which caused 50 million people’s death. Sometimes, the flu is dreadful, like bird flu, so it is wise of us to know the causes of the flu. When we know the causes, we can have proper measures taken to prevent the flu from spreading wildly. This article is to help the readers to know the causes of the flu.

According to the researchers on flu, the flu is caused by the flu viruses that can affect our aspiratory system. When we get infected, the flu virus will inhabit in our eyes and respiratory system. A few days later, we will have runny nose, sore throat, and run a high fever. It is also possible that it can lead to pneumonia. What’s worse, we can pass the flu virus from person to person, and we can pass the flu to our pet animals, too. Ferrets, cats, dogs (particularly, greyhounds) can catch flu from us. Up to now, the researchers have found three types of flu viruses, namely, type A, type B, and type C. They are all responsible for the causes of the flu.

However, they are different. Type A is the one which causes epidemics around the world. The viruses of type A have different variants, and they change from time to time. Type A has two sub-branches of the variants. Either of the sub-branch variants can cause serious illness of flu, if there is no proper and timely treatment. In most of the death cases, people die from Type A flu viruses. They change constantly by mutation, and the constant changing can make the viruses easily invade the cells of our respiratory system. What’s worse, they can invade our immune system as well. Type B functions similar to Type A. However, Type B is milder, and it can only cause local outbreak of flu. Type C is the mildest among the three types, which could only cause very common cold symptoms.

How can we get hit with the flu then? The flu viruses are divided into types based on differences in two viral surface proteins, called the hemagglutinin (H) and the neuraminidase (N) respectively. They can have many combinations. The viruses can spread by droplets or direct contact. That is to say, the flu viruses spread and transit via airborne transmissions, and they can spread by handshakes or kisses or touching on the things with flu virus. It is well known that the flu virus can live for a period of time on objects which they drop on, such as tables, shelves, doorknobs, pens, keyboards, telephone