Which disease is primarily transmitted through contaminated water?

Giardiasis and schistosomiasis are both diseases primarily transmitted through contaminated water, making the combined option a correct choice.

Giardiasis, caused by the protozoan parasite Giardia lamblia, is often contracted through drinking water that has been contaminated with feces containing the cysts of the parasite. This can occur in conditions where water sanitation is poor, and it is commonly associated with outbreaks in areas lacking adequate water treatment.

Schistosomiasis, on the other hand, is caused by trematode flatworms of the genus Schistosoma. The transmission occurs when people come into contact with water that contains the larval forms (cercariae) of the parasite, which are released from infected freshwater snails. This disease is prevalent in areas with freshwater bodies and poor sanitation and is particularly linked to agricultural and recreational activities in contaminated water.

While ascariasis, caused by the roundworm Ascaris lumbricoides, is primarily transmitted through fecal-oral contact, especially via contaminated food and hands, it does not have the same direct relationship with water sources as the other two. Thus, selecting both Giardiasis and Schistosomiasis accurately reflects the diseases that are primarily transmitted through contaminated water, confirming the correctness of