My brother who suffers from multiple sclerosis (among other things) and lives in an institution to be nursed and generally looked after, went on a pilgrimage to Lourdes with a score of other patients and the necessary helpers. As seems customary, they brought back several bottles of publicly available spring waters collected over there.
I'm not sure those would qualify as holy waters but they definitely are regarded by some as something special that could work wonders of miraculous healing. Nevertheless, several of these pilgrims already became sick during their return trip home.
After arriving home they distributed some of those bottles of Lourdes water to other patients who couldn't make the trip themselves and it so happened that some of these ingested all this non purified water within a few days. Eventually, as a result of all this a lot of them (54 patients and 30 staff) got ill, several of them very much so and a few (4) even died from it. Cruel joke, isn't it.
Later on it was revealed that just at the time of their visit the spring waters probably were contaminated by some sort of Norovirus, possibly due to the overcrowding (ca. 7 - 8 million visitors in 2008) because of the Jubilee year: the 150Th anniversary of the apparitions.
My brother, by the way, just got a mild fever and speedily recovered after only a few days of discomfort. He was and continues to be in robust health, relatively speaking of course. ;)
Sources:
_http://www.omroepbrabant.nl/?news/107118792/Vier+doden+door+buikgriepvirus+bij+GGZ+Etten-Leur.aspx (in Dutch)
_http://en.wikipedia.org/wiki/Norovirus
_http://en.wikipedia.org/wiki/Lourdes