Biological contamination refers to the presence of harmful microorganisms, such as bacteria, viruses, fungi, or parasites, in food, water, or the environment. These contaminants can cause illness in humans and animals when ingested or contacted. Common sources include improperly handled food, contaminated water supplies, and unsanitary conditions. Preventing biological contamination involves proper hygiene practices, such as washing hands, cooking food to safe temperatures, and ensuring clean water sources. Organizations like the World Health Organization (WHO) provide guidelines to help reduce the risk of contamination and protect public health.