Human blood protozoa infections cause oxidative stresses from the parasites,
host's defense systems, and administered drugs. Oxidative stress is an important tool to
eliminate parasites from the host's body. However, the host's cells, tissues, and even
organs would be damaged along with parasites. Many pathologies such as cerebral
malaria, and renal or hepatic failures are a result of the unbalanced oxidative condition.
Many medicinal plant extracts show both anti-protozoa and antioxidant activities
simultaneously. Therefore, the administration of medicinal plant extracts in
combination with chemical drugs should be beneficial for patients with blood-protozoa
infection, by both eradicating the parasites and alleviating the oxidative stress. In
addition, the combination might also help prevent parasite resistance to chemical drugs
as the extract and chemical drugs aim at different targets simultaneously. In this
chapter, the properties and benefits of medicinal plant extracts are discussed