Afraid I don't know what a furphy is, but one link (http://sti.bmjjournals.com/cgi/repnt/79/1/65.pdf) was a typo as far as I can tell (compare with the corrected South Korea URL: http://sti.bmjjournals.com/cgi/reprint/79/1/65.pdf  two characters are missing). Either way, the links were wrong. I'll try to remember where I've seen the Mexico data.