Amebiasis

Amebiasis is an enteropathic disease caused by the protozoan parasite Entamoeba histolytica, characterized by infection of the large intestine that may remain asymptomatic or progress to invasive intestinal and extraintestinal manifestations ^[1][5]. The parasite exists in two life cycle stages: the invasive trophozoite form and the environmentally stable cyst form ^[1].

Clinical presentation ranges from asymptomatic colonization to symptomatic intestinal and extraintestinal disease ^[3][4]. Intestinal amebiasis presents with acute diarrhea, dysentery, and amebic colitis ^[1][2]. Extraintestinal manifestations include amebic liver abscesses, characterized by upper-right abdominal pain and fever, occurring in approximately 9% of cases ^[2]. Pathogenesis involves trophozoites secreting proteinases that dissolve host tissues, killing host cells on contact, and engulfing red blood cells, enabling invasion of the intestinal mucosa and potential dissemination through portal circulation to the liver ^[4].

Amebiasis is an endemic parasitic disease in developing countries, affecting millions of people worldwide ^[5][3]. It ranks as the second leading cause of death from parasitic disease, responsible for approximately 70,000 deaths annually ^[3][4]. The infection predominantly affects children, though all age groups in endemic areas are at risk ^[1]. Approximately 90% of infected individuals remain asymptomatic, while 10% develop symptomatic invasive disease ^[5][3]. Amebic liver abscesses caused approximately 50,000 fatalities globally in 2010 ^[2].

Transmission occurs through the fecal-oral route via ingestion of E. histolytica cysts from contaminated food and water ^[1][4]. The cysts are environmentally stable and can contaminate water sources, food supplies, and surfaces in areas with inadequate sanitation ^[1]. Poor hygiene practices and insufficient water purification systems facilitate transmission in endemic regions ^[1].

Prevention focuses on improving water purification systems and sanitation infrastructure in endemic areas, along with promoting hygiene practices such as proper handwashing and safe food preparation ^[1][5]. No amebiasis vaccine has been approved for human use, though research into vaccine development continues ^[1][5].

1. 1Li 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. 2Usuda 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/
3. 3Nagaraja 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/
4. 4Stanley 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/
5. 5Guillén 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/