Protothecosis infection on a human elbow with a close-up view of Prototheca wickerhamii green algae, the causative agent of the disease, computer illustration. Prototheca wickerhamii species, and can cause skin lesions, ulcers, and other symptoms. Prototheca is a type of green alga. The infection can affect humans, animals, and plants, and is usually acquired through contact with contaminated soil or water. Symptoms of Protothecosis can vary depending on the severity of the infection and the area of the body affected. In the case of a hand infection, symptoms may include skin lesions, ulcers, pain, swelling, and redness. Treatment typically involves antifungal medication and surgical removal of the infected tissue. However, Protothecosis can be difficult to treat, and recurrence is common.