Amebiasis

阿米巴病

Evidence-backed information EN 5/7 applicable sections · ZH 5/7 applicable sections Updated Oct 23, 2026

Amebiasis is a parasitic disease produced by Entamoeba histolytica and represents a major global cause of mortality among parasitic infections, ranking as the second or fourth leading parasitic killer worldwide ^[1]^[2]^[3]. Most infected persons harbor the organism without symptoms, but roughly one in ten develops invasive illness such as colitis or liver abscess ^[4]^[2]. The condition is endemic in developing countries and continues to pose a public-health challenge despite declining case reports in some regions ^[1]^[5]^[2].

Read the full clinical and epidemiological profile 6

Definition

Amebiasis is an enteropathic infection caused by the protozoan parasite Entamoeba histolytica, which can persist as a non-pathogenic colonic commensal or become invasive ^[1]^[4]^[2]. Recognition that morphologically similar organisms include the pathogen E. histolytica and the commensal E. dispar has reshaped understanding of the disease ^[3].

Clinical features

In the majority of infected individuals the parasite colonizes the large intestine asymptomatically and is self-limiting, whereas in others it breaches the mucosal barrier to produce acute diarrhea, dysentery, and amebic colitis ^[1]. Dissemination to soft organs can generate abscesses, with amebic liver abscesses being the most common extraintestinal manifestation, presenting with right-upper abdominal pain and fever ^[1]^[5]. Invasive trophozoites secrete proteinases, kill host cells on contact, and may travel via portal circulation to the liver, causing liquefactive necrosis ^[3].

Epidemiology

Amebiasis affects millions of people globally and causes about 70,000 deaths each year, with extraintestinal abscesses responsible for nearly 50,000 fatalities in 2010 ^[1]^[2]^[5]. It is endemic in developing countries and principally infects children there, while liver-abscess complications remain an important public-health problem in endemic areas despite recent declines ^[1]^[5]^[2]. The disease is the second leading cause of death from parasitic disease worldwide ^[3].

Transmission

The parasite is transmitted through contamination of food and water with infective stages ^[1]. After ingestion, E. histolytica may colonize the intestine asymptomatically or become virulent, and in invasive cases trophozoites can enter the circulation and seed the liver via portal blood flow ^[1]^[5]^[3].

Prevention

No vaccine for amebiasis has yet been approved for human use, though several candidate approaches are under study ^[1]. Control relies on improving water-purification systems and hygiene practices to reduce contamination and lower incidence ^[1]. Additional research strategies include probiotics, natural products, and enhanced sanitation alongside ongoing vaccine development ^[1]^[2].

References

1 Li J et al. Review of zoonotic amebiasis: Epidemiology, clinical signs, diagnosis, treatment, prevention and control. Res Vet Sci. 2021 May. PMID: 33676155. doi: 10.1016/j.rvsc.2021.02.021. PubMed: https://pubmed.ncbi.nlm.nih.gov/33676155/
2 Nagaraja S et al. Target identification and intervention strategies against amebiasis. Drug Resist Updat. 2019 May. PMID: 31112766. doi: 10.1016/j.drup.2019.04.003. PubMed: https://pubmed.ncbi.nlm.nih.gov/31112766/
3 Stanley SL Jr et al. Amoebiasis. Lancet. 2003 Mar 22. PMID: 12660071. doi: 10.1016/S0140-6736(03)12830-9. PubMed: https://pubmed.ncbi.nlm.nih.gov/12660071/
4 Guillén N et al. Pathogenicity and virulence of Entamoeba histolytica, the agent of amoebiasis. Virulence. 2023 Dec. PMID: 36519347. doi: 10.1080/21505594.2022.2158656. PubMed: https://pubmed.ncbi.nlm.nih.gov/36519347/
5 Usuda D et al. Amebic liver abscess by Entamoeba histolytica. World J Clin Cases. 2022 Dec 26. PMID: 36683647. doi: 10.12998/wjcc.v10.i36.13157. PubMed: https://pubmed.ncbi.nlm.nih.gov/36683647/