'Influential' is the disease more commonly know as the 'flu.
Be careful you don't catch the latest strain of 'flu bird', as recently publicised by Bush. If you do happen to catch a 'flu bird, the symptoms are being able to go out less with your friends, watch less sport, drink less alcohol, and your porn consumption and/or strip club attendance will probably shrink to nothing.
Go to your lifestyle doctor immediately if this happens.