parasites and population

[Becky Self]

Please excuse the intrusion on this newsgroup if this is not the right
place to ask the question, but I'm not sure where else to go....

I've heard that the parasites in the human population is on the rise.  Can
anyone (with some credentials to back them up) give me some statistics on
the percentage of the population in the United States who have parasites. 
And how about the world population in general?

I appreciate it.  Thank you.

--Becky
lbself at worldnet.att.net