Can You Catch Schistosomiasis From Drinking Water?

You can get schistosomiasis from drinking contaminated water, but it happens differently than you might think. The primary way people catch schistosomiasis is when the parasite (in its infective stage, called a cercaria) penetrates the skin while a person is swimming, wading, or bathing in contaminated freshwater ^[1][2].

However, if you drink water drawn directly from a contaminated lake, river, or stream, you are still at risk. Rather than infecting you through your stomach or intestines, the parasites can actually penetrate the mucous membranes inside your lips, mouth, or throat as you swallow the water ^[3][4]. While this is not the most common way the disease spreads, it is a known risk of consuming untreated freshwater ^[3][4].

Are Tap Water and Ice Safe?

In areas where schistosomiasis is common, tap water is typically safe only if it comes from a treated municipal supply. Standard water treatment processes, such as chlorination, are effective at killing the parasites ^[5][6]. However, if the tap water is drawn straight from a local freshwater source without proper treatment, it could still contain infective parasites.

Keep in mind that freezing does not immediately kill all parasites. Ice made from untreated water carries the exact same risks as the water itself and should be avoided.

How to Make Drinking Water Safe

If you are traveling in an area where schistosomiasis is present and you are unsure about the safety of the water supply, it is essential to treat your water before drinking or using it to brush your teeth. You can protect yourself by:

• Boiling your water: Bringing water to a rolling boil for at least one minute is the most reliable way to kill the parasites and make the water safe to drink.
• Filtering your water: Using a high-quality water filter can physically remove the cercariae. Because the parasites are flexible and actively swimming, it is recommended to use microfiltration or ultrafiltration systems with a pore size of 1 to 10 microns to effectively block them ^[7][8].
• Chemical disinfection: Treating your water with proper amounts of chlorine or standard water purification tablets can kill the parasites if left to sit for the recommended contact time ^[6].
• Storing water: Storing water in a clean, sealed container for 48 to 72 hours will cause the parasites to die, as they cannot survive for long periods outside of a human or snail host ^[5].

Safe Water for Washing

If you must use potentially contaminated water for washing dishes or hands, boiling it first is the safest approach. If boiling is not an option, you can treat the water with soap to kill the parasites ^[9]. To do this correctly, add soap to your stored water container, stir, and wait 5 to 15 minutes before using that water to wash your hands or dishes ^[9].