Cyclosporiasis is already killing people who drink municipal Tap water with compromised immune systems every day here in the U.S.

Older people and people who are HIV or people who have AIDS all have compromised immune systems so drinking tap water anywhere in cities around the U.S. could prove fatal this time of year (summer or fall) because of Cyclosporiasis in most municipal water systems nationwide this time of year.

So, if you have a compromised immune system you cannot drink tap water in any city anywhere and be sure you are safe to drink this without a reverse osmosis tippet in the kitchen to filter out the Cyclosporiasis or by boiling the water you drink for 5 minutes.

In India and Nepal we boiled water whenever we could in 1985 and 1986. However, the feces in the dust of the roads in Kathmandu gave us giardia (4 out of the 5 of us anyway). So, you can get I KNOW from personal experience giardia just from Feces in the dust of cattle or deer for example. However, it is true that American Giardia is often not as bad as Asian Species of Giardia which is a protozoa parasite similar to Cyclosporiasis.

Then to get rid of the Asian Version of Giardia it took us 6 months and we were all skinny as a rail during this time after we returned to the U.S. Around April of 1986. 

So, I haven't had Cyclosporiasis but I have had giardia along with 4 out of 5 of us traveling from december until April in India, Nepal, Thailand and Japan. But, likely we got in in Kathmandu from feces in the dust there. This is the most likely culprit.

However, Kathmandu is paved over mostly now (the roads) so there isn't as much feces in the dust likely as before. when I was there in some neighborhoods in Kathmandu there were open sewers of water running down trenches with little children playing in the water with Sticks and sailboats made of wood.

Because most people at that time had no education whatsoever (about 50% of the people couldn't read or write any language at all so no way for them to be informed about health at that time.