Entamoeba Encystation: New Targets to Prevent the Transmission of Amebiasis

Amebiasis is caused by Entamoeba histolytica infection and can produce a broad range of clinical signs, from asymptomatic cases to patients with obvious symptoms.The current epidemiological and clinical statuses of amebiasis make it a serious public health problem worldwide.The Entamoeba life cycle consists of the trophozoite, the causative agent for amebiasis, and the cyst, the form responsible for transmission.These two stages are connected by "encystation" and "excystation."Hence, developing novel strategies to control encystation and excystation will potentially lead to new measures to block the transmission of amebiasis by interrupting the life cycle of the causative agent.Here, we highlight studies investigating encystation using inhibitory chemicals and categorize them based on the molecules inhibited.We also present a perspective on new strategies to prevent the transmission of amebiasis. Entamoeba histolytica Infection and Amebiasis: Behavior of the Causative Agent and the Parasite Life CycleAmebiasis is caused by Entamoeba histolytica infection, a protozoan parasite belonging to the phylum Amoebozoa.Infected individuals show a wide range of clinical signs and can be asymptomatic or have obvious symptoms, such as diarrhea, dysentery, fever, and abdominal pains owing to invasive infection.As a consequence of the invasive infection, various extraintestinal manifestations may also arise: for example, amebic liver, lung, or brain abscesses.Worldwide, 35-50 million symptomatic cases occur annually, leading to approximately 55,000 deaths [1].However, only a few drugs are available, and no effective vaccines exist [2,3].Furthermore, because of the high occurrence of asymptomatic infections, amebiasis morbidity is thought to be much higher than estimates that are only based on the number of reported symptomatic cases.These clinical and epidemiological statuses make amebiasis a serious public health problem worldwide [4].E. histolytica infection usually occurs by oral ingestion of cysts, the dormant form of the parasite (Fig 1) [5].The cysts, particularly in endemic regions, can be found in various materials or on surfaces (including human hands) that have been contaminated with feces.This can directly or indirectly lead to oral intake.Because the cysts are resistant to severe environments