Found the following link on the BBC website, and was pleased that we are actively screening people for contagious diseases before considering giving them a visa. Among all the negatives about our immagration policy it's good to see there are some sensable polices being brought into effect 
http://news.bbc.co.uk/1/hi/world/africa/6320015.stm
http://news.bbc.co.uk/1/hi/world/africa/6320015.stm