Influenza

Influenza, commonly known as the flu, is an infectious disease that affects mammals and birds. There are many types and strains of flu, each adapted to different types of hosts.

Symptoms
In humans, common symptoms of the disease are chills, fever, pharyngitis, muscle pains, severe headache, coughing, weakness and general discomfort. In more serious cases, influenza causes pneumonia, which can be fatal, particularly in young children and the elderly. Although it is often confused with the common cold, influenza is a much more severe disease and is caused by a different type of virus.

Types of influenza

There are several types of Influenza.

• Influenza A - Mainly in birds, but can transmit to humans (see below)
• Influenza B - Exclusively affects humans, immunity is usually acquired at an early age.
• Influenza C - Influenza C virus infects humans and pigs and can cause severe illness and local epidemics. However, influenza C is less common than the other types and usually seems to cause mild disease in children
• Isavirus - "Infectious salmon anemia" is a viral disease of Atlantic Salmon that affects fish farms in Canada, Norway, Scotland and Chile, causing severe losses to infected farm
• Thogotovirus - A genus in the virus family Orthomyxoviridae, usually transmitted by ticks. THOV is known to infect humans in natural settings. DHOV is able to infect humans, causing a febrile illness and encephalitis.