I think in the past I came across the idea that "leprosy" in the Bible might not actually be the leprosy that we know today. Indeed, there is work by Biblical scholars and others to back up my memory. This article by Cochrane (not Archie), material from Cornell, and an article from the Jewish Encyclopedia. There is also Encyclopedia Judaica, made available online by the Bureau of Jewish Education in Indiana (search for "leprosy").
A PubMed search for leprosy AND bible finds 54 items, the oldest 1873 and the most recent October 2013.
Patient.co.uk has information (for professionals). Public Health England has advice, with statistics. Leprosy is rare in the UK, although it is a notifiable disease. Between 2001 and 2010 there were 129 cases. No case has definitely been acquired indigeneously since 1925. However, globally, (figures from that same document) there were 244796 cases in 2009, over half of them in the South East Asia region of WHO. Numbers of cases have been falling year on year since 2003, and in 1985 there were around 5 million. There is a figure of "prevalence" for 2008 nearby, which is lower than the number of new cases detected, so I am not sure what this figure is, but whatever it is, the fall is striking.
The same statistics, but containing 2010 and 2011 are in this WHO Weekly Epidemiological Record. This also includes figures for the number of new cases, by country.
So, back to "leprosy" in the Bible.
It's certainly interesting to explore whether "leprosy" in the Bible was leprosy as we know it, and if it was not, what it was. It is also important to think about how it was regarded in the Bible (Jewish and Christian) and how Jesus regarded people with it, whatever it might have been.
Mark 1:40 has resonance today. A longstanding friend of ours, Stephen Haward, wrote a Sunday School syllabus for the United Church of Zambia called Believing and Belonging, and uses the story to address the topic of HIV. What do the stories talk about for me? What is leprosy for the UK?
In closing, have a look at the work of the Leprosy Mission, a Christian organisation working with people affected by leprosy. There is still discrimination against people with leprosy, and they have a programme of advocacy. Their "Don't call me a leper" campaign addresses discrimination and stigma in the UK by campaigning for the word "leper" to be lost from current usage. Have a look too at their information about leprosy.