Treatment Methods of Traditional Chinese Medicines Against Intestinal Protozoan Infections

Abstract

Protozoa that parasitize the human intestine include Entamoeba histolytica, Blastocystis hominis, Trichomonas hominis, Cryptosporidium parvum, Giardia lamblia, Balantidium coli, Isospora, and other protozoa. Most intestinal protozoan infections can cause acute or chronic diarrhea in healthy individuals and may result in intractable, life-threatening illness in patients in immunosuppressive status. Collectively, they infect over one billion people each year. E. histolytica can invade the gut epithelium and subsequently other organs, where it forms abscesses. E. histolytica infection (amoebiasis) is the second leading cause of death from parasitic diseases. Cryptosporidium and Giardia are the most common parasitic causes of diarrheal illness worldwide, especially in the developed countries, where they were associated with waterborne outbreaks. In addition, Cryptosporidium, Entamoeba, and Isospora have been most frequently identified as the most commonly implicated pathogens which cause persistent diarrhea in patients with HIV, followed by Giardia and Strongyloides. Clinically, the nitroimidazoles class of agents including metronidazole, tinidazole, ornidazole, etc, is considered as the front line of defense against intestinal protozoan infections in the world. However, drug-resistant intestinal protozoa (such as E. histolytica and Giardia) have appeared in clinical and laboratory isolates regularly. Accordingly, resistant strains have been treated with longer repeat courses or higher doses of the original agent in clinic. Chinese medicine therapeutic approaches have been employed for intestinal disease caused by intestinal protozoa for a long time in China and Asian countries, with low side effects compared with western medicine. Several Chinese medicines including Radix Pulsatillae, Fructus Bruceae, Allium sativum, Radix Sophorae Flavescentis, Fructus cnidii, etc, are shown to be effective for anti-protozoa. This review presents the current advances in traditional Chinese medicines with a focus on effective treatment and control of intestinal protozoan infections.