Influenza (seasonal and avian)

Differences between seasonal and avian influenza

There are many different influenza (flu) viruses, and they often circulate at the same time. Seasonal influenza refers to different flu viruses that circulate together among humans in the same cyclical or seasonal pattern each year. Though the viruses which cause seasonal influenza are circulating all the time, different regions tend to be most affected at different times, year after year, based on global position. For instance, seasonal influenza in the northern hemisphere usually peaks between October and March, while the southern hemisphere peak is usually April to September.  

Avian influenza, or "bird flu", is a virus that affects birds. Very rarely, an avian flu virus will infect a person who has very close contact with birds. Usually, humans cannot spread avian flu from one person to another. However, there is a small chance the virus can adapt in such a way that it becomes easy for people to spread the virus from person to person. This is dangerous because people would not have any immunity to this virus as they have never been exposed to it before. It could spread quickly and the whole population would be vulnerable to getting sick.

Transmission: Seasonal influenza - Airborne or droplet-borne, direct contact; Avian influenza – Direct or indirect contact with mucous membranes (for example, the eyes, nose or mouth)

** Seasonal influenza **

• When infected people cough, sneeze, blow their nose or spit, they spread small particles or droplets through the air, which are then breathed in by other people
• Direct or indirect contact (for example, through kissing, sharing cups or eating utensils) with infected saliva or nose mucous

** Avian influenza **

• Direct or indirect contact with an infected bird or contaminated items from the bird’s environment, such as feathers or eggs 
  • For example, if a person touches an infected bird and then touches their own nose, mouth or eyes, the virus can spread to the person
• Though it is not common, there is the chance the virus could mutate once a human has been affected. If this happens, human-to-human transmission (same as seasonal influenza transmission) is possible.

Most vulnerable to severe consequences

• Children under five years old
• Elderly
• People with weakened immune systems or other respiratory problems are at highest risk of severe illness

Most vulnerable to contracting the disease

• Displaced populations and others who live in overcrowded environments

Symptoms

• Cough and runny nose (cough may be dry or may cough up mucous or phlegm)
• Difficulty breathing
• Sore throat
• Muscle aches 
• Fever (sometimes)
• Headache (sometimes)
• Tiredness (sometimes)