Influenza A is caused by the influenza A virus and the symptoms are similar to those of seasonal flu, both of which are very contagious. However, it can cause higher fevers and more severe muscle pain, vomiting and diarrhoea.
It is a chronic, autoimmune disease, whose origin is unknown and has no cure. It is more prevalent in women of childbearing age, usually appearing after the age of 30. When it manifests itself, lupus can reach any organ.