Giardiasis is an infection caused by a tiny parasite called Giardia lamblia. This parasite often spreads through contaminated water, food, or surfaces, especially in places with poor sanitation. When someone ingests the parasite, it can lead to symptoms like diarrhea, stomach cramps, and nausea. Most people recover from Giardiasis without treatment, but it can be more serious for young children or those with weakened immune systems. To prevent infection, it's important to drink clean water, wash hands regularly, and avoid consuming food that may be contaminated.