Here's an interesting link to a posting about filters on the CDC site:

http://www.cdc.gov/ncidod/dpd/parasites/cryptosporidiosis/factsht_crypto_prevent_water.htm

In the posting it says:
Filters labeled only with these words may NOT be designed to remove crypto

One of the items listed is:
Ultraviolet light

Am I reading that correctly? UV does not kill cryptosporidium? Crypto is relatively rare in the contiguous states, Canada, and Alaska, but not necessarily elsewhere. If I'm reading this correctly, a Steripen would be a poor choice for international travel.

Steripen's website says:
SteriPEN™ is the only portable water purifier that uses ultraviolet (UV) light to destroy waterborne microbes. Whether your source is a woodland brook or an overseas hotel tap, SteriPEN purifies clear water by destroying viruses, bacteria and protozoa—including Giardia and Cryptosporidium —- in seconds. Carry a SteriPEN to disinfect water wherever you travel, hike, camp or trek. It’s the fastest route to pure, safe drinking water anywhere.

Somebody's got to be off here.