1.   Cryptosporidium, found in the feces of infected humans and animals, enters the water supply mainly through agricultural runoff and sewage leaks.

2.   East African tsetse flies acquire trypanosomes from the blood of infected animals, typically savanna-dwelling bushbucks, or infected humans.

3.   For decades, the fresh tissues of infected humans were the only good source of the microbe.

4.   Found in the feces of infected humans and animals, it typically enters the water supply through agricultural runoff or sewage leaks.

5.   H. pylori has probably infected humans and their predecessors for millions of years.

6.   Infected humans can transmit the AIDS virus for a decade with no adverse medical symptoms to tip them off.

7.   West African tsetses tend to acquire the parasite by feeding off infected humans.

8.   Cholera is caused by a bacteria in the feces of infected humans.

9.   Infected humans can spread the disease by blood, saliva or droplets from sneezing.

10.   Infected humans show symptoms including high fever, exhaustion, aching body and coughing.