After swimming at an indoor water park at Hotel A in Warren County, Ohio during December 27-29, 2010, several guests presented with diarrheal illness about a week after their stay. The affected guests had symptoms of watery diarrhea, lack of appetite, stomach cramps, fever, nausea and vomiting. What is the likely causative agent?

The correct answer is cryptosporidium.

Explanation:

Cryptosporidium is a parasite that thrives in recreational water parks, swimming pools, streams, and lakes. The infection caused by cryptosporidium is known as cryptosporidiosis, which results when the parasite invades the body of a human being and enters into the small intestine and gets itself attached to its walls.  

In healthy individuals, the infection by the parasite leads to watery diarrhea that can even become lethal when left untreated. Some of the other signs of the infection are lack of appetite, dehydration, stomach pain, weight loss, vomiting, and fever. Thus, in the given case, the guest is suffering from cryptosporidiosis.  

the answer is sex-linked recessive.