In a very rare homepage update Google UK is putting their great weight in to supporting World Tuberculosis Day.
The text, which sits below the search box, reads "Tuberculosis is a global threat. Get tested and treated." The link takes you to this support page which supports World Tuberculosis Day while putting nearly as much effort into explaining how other causes could win Google's support.
It may just be a time zone issue - it's not yet World Tuberculosis Day in the States at the time of posting - but despite calling this a global threat Google.com does not yet carry the same message. Neither does Google Germany, France or Spain... so this is likely to be a local decision from the UK team.