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Amebiasis

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Description: Amebiasis is an intestinal illness caused by the parasite Entamoeba histolytica, leading to symptoms ranging from mild diarrhea to severe dysentery.
Type: Amebiasis is an infectious disease caused by the parasite Entamoeba histolytica. It is not a genetically transmitted disease; rather, it is typically acquired through the ingestion of contaminated food or water.
Signs And Symptoms: Most infected people, about 90%, are asymptomatic, but this disease has the potential to become serious. It is estimated that about 40,000 to 100,000 people worldwide die annually due to amoebiasis.Infections can sometimes last for years if there is no treatment. Symptoms take from a few days to a few weeks to develop and manifest themselves, but usually it is about two to four weeks. Symptoms can range from mild diarrhea to dysentery with blood, coupled with intense abdominal pains. Extra-intestinal complications might also arise as a result of invasive infection which includes colitis, liver, lung, or brain abscesses. The blood comes from bleeding lesions created by the amoebae invading the lining of the colon. In about 10% of invasive cases the amoebae enter the bloodstream and may travel to other organs in the body. Most commonly this means the liver, as this is where blood from the intestine reaches first, but they can end up almost anywhere in the body.Onset time is highly variable and the average asymptomatic infection persists for over a year. It is theorized that the absence of symptoms or their intensity may vary with such factors as strain of amoeba, immune response of the host, and perhaps associated bacteria and viruses.In asymptomatic infections, the amoeba lives by eating and digesting bacteria and food particles in the gut, a part of the gastrointestinal tract. It does not usually come in contact with the intestine itself due to the protective layer of mucus that lines the gut. Disease occurs when amoeba comes in contact with the cells lining the intestine. It then secretes the same substances it uses to digest bacteria, which include enzymes that destroy cell membranes and proteins. This process can lead to penetration and digestion of human tissues, resulting first in flask-shaped ulcerations in the intestine. Entamoeba histolytica ingests the destroyed cells by phagocytosis and is often seen with red blood cells (a process known as erythrophagocytosis) inside when viewed in stool samples. Especially in Latin America, a granulomatous mass (known as an amoeboma) may form in the wall of the ascending colon or rectum due to long-lasting immunological cellular response, and is sometimes confused with cancer.The ingestion of one viable cyst may cause an infection.Steroid therapy can occasionally provoke severe amoebic colitis in people with any E. histolytica infection. This bears high mortality: on average more than 50% with severe colitis die.
Prognosis: In the majority of cases, amoebas remain in the gastrointestinal tract of the hosts. Severe ulceration of the gastrointestinal mucosal surfaces occurs in less than 16% of cases. In fewer cases, the parasite invades the soft tissues, most commonly the liver. Only rarely are masses formed (amoebomas) that lead to intestinal obstruction.(Mistaken for Ca caecum and appendicular mass) Other local complications include bloody diarrhea, pericolic and pericaecal abscess.Complications of hepatic amoebiasis includes subdiaphragmatic abscess, perforation of diaphragm to pericardium and pleural cavity, perforation to abdominal cavital (amoebic peritonitis) and perforation of skin (amoebiasis cutis).Pulmonary amoebiasis can occur from liver lesions by spread through the blood or by perforation of pleural cavity and lung. It can cause lung abscess, pulmono pleural fistula, empyema lung and broncho pleural fistula. It can also reach the brain through blood vessels and cause amoebic brain abscess and amoebic meningoencephalitis. Cutaneous amoebiasis can also occur in skin around sites of colostomy wound, perianal region, region overlying visceral lesion and at the site of drainage of liver abscess.Urogenital tract amoebiasis derived from intestinal lesion can cause amoebic vulvovaginitis (May's disease), rectovesicle fistula and rectovaginal fistula.Entamoeba histolytica infection is associated with malnutrition and stunting of growth in children.
Onset: The onset of amebiasis, which is an infection caused by the parasite Entamoeba histolytica, typically occurs within 1 to 4 weeks after exposure. Symptoms may range from mild diarrhea to severe dysentery.
Prevalence: Amebiasis is most prevalent in regions with poor sanitation and hygiene, such as parts of Central and South America, Africa, and the Indian subcontinent. High-risk areas often lack access to clean water and proper sewage systems.
Epidemiology: Amoebiasis caused about 55,000 deaths worldwide in 2010, down from 68,000 in 1990.
In older textbooks it is often stated that 10% of the world's population is infected with Entamoeba histolytica. Nevertheless, this means that there are up to 50 million true E. histolytica infections and approximately seventy thousand die each year, mostly from liver abscesses or other complications. Although usually considered a tropical parasite, the first case reported (in 1875) was actually in St Petersburg in Russia, near the Arctic Circle. Infection is more common in warmer areas, but this is because of both poorer hygiene and the parasitic cysts surviving longer in warm moist conditions.
Intractability: Amebiasis is not typically considered intractable. It can generally be treated effectively with the appropriate antimicrobial medications, such as metronidazole or tinidazole, followed by a luminal agent like paromomycin to eradicate cysts in the intestine. Proper medical intervention and adherence to the prescribed treatment are crucial for successful recovery.
Disease Severity: The severity of amebiasis can vary depending on the extent of the infection and the individual's overall health. It can range from mild, asymptomatic infections to severe, potentially life-threatening conditions. Severe cases may include complications such as liver abscesses or perforation of the intestines. Prompt medical treatment is essential to manage the disease and prevent complications.
Healthcare Professionals: Disease Ontology ID - DOID:9181
Pathophysiology: Amebiasis is caused by the protozoan parasite Entamoeba histolytica. The pathophysiology begins when cysts of E. histolytica are ingested through contaminated food or water.

1. **Ingestion and Excystation**: Once ingested, the cysts travel to the small intestine, where they undergo excystation to release trophozoites.

2. **Colonization**: The trophozoites migrate to the colon, where they can adhere to the epithelial cells of the colonic mucosa.

3. **Invasion and Tissue Destruction**: The trophozoites then invade the mucosal lining, leading to tissue destruction. This invasion can cause ulcerations and lead to symptoms such as diarrhea, abdominal pain, and dysentery.

4. **Systemic Spread**: In severe cases, the trophozoites can breach the intestinal wall and spread to extraintestinal sites such as the liver, causing abscesses, most commonly a liver abscess.

5. **Encystation and Transmission**: Some trophozoites revert to the cyst form and are excreted in the feces, thereby continuing the transmission cycle when conditions are favorable.

Complications arise due to the organism's ability to lyse host cells, induce apoptosis, and degrade tissues through proteolytic enzymes, leading to ulceration, bleeding, and secondary bacterial infections.
Carrier Status: Carrier Status: Individuals can be asymptomatic carriers of the Entamoeba histolytica parasite, which causes amebiasis. These carriers can transmit the infection to others through fecal-oral routes, often via contaminated food or water.
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Mechanism: Amebiasis is primarily caused by the protozoan parasite Entamoeba histolytica.

**Mechanism:**
1. **Ingestion**: The infection begins when a person ingests the cyst form of Entamoeba histolytica through contaminated food or water.
2. **Excystation**: In the small intestine, the cysts transform into trophozoites, the active form of the parasite.
3. **Colonization**: Trophozoites migrate to the large intestine, where they adhere to the intestinal mucosa and can invade the epithelial lining.
4. **Tissue Damage**: The parasite causes localized tissue destruction, leading to ulcer formation, inflammation, and potential dissemination to other organs, particularly the liver, resulting in abscesses.

**Molecular Mechanisms:**
1. **Adhesion**: Entamoeba histolytica uses surface lectins like the Gal/GalNAc lectin to adhere to host cells.
2. **Cytolysis**: The parasite releases cysteine proteases and phospholipases that degrade host tissue and immune elements.
3. **Phagocytosis**: Trophozoites consume host cells and bacteria, contributing to tissue damage and ulcer formation.
4. **Immune Evasion**: Entamoeba histolytica can evade the immune response by varying surface antigens, inducing apoptosis in host immune cells, and resisting complement-mediated lysis.
Treatment: E. histolytica infections occur in both the intestine and (in people with symptoms) in tissue of the intestine and/or liver. Those with symptoms require treatment with two medications, an amoebicidal tissue-active agent and a luminal cysticidal agent. Individuals that are asymptomatic only need a luminal cysticidal agent.
Compassionate Use Treatment: Amebiasis is typically caused by the parasite *Entamoeba histolytica*. The primary treatment for amebiasis involves the use of antiparasitic medications, such as metronidazole or tinidazole followed by a luminal agent like paromomycin to eliminate cysts in the intestine.

As for compassionate use treatments, this category is typically reserved for experimental drugs that are not widely available outside clinical trials but show promise in treating serious conditions without existing effective treatments. No specific experimental or compassionate use treatments are currently established for amebiasis, as standard therapies are generally effective.

Off-label treatments are those that utilize approved drugs for indications not specifically approved by regulatory authorities. In the context of amebiasis, there are no widely recognized off-label treatments since the existing medications like metronidazole and tinidazole are usually highly effective. However, research into new treatments or combinations of existing drugs could potentially provide off-label options in the future, especially in cases where standard therapy is not effective or contraindicated.

Experimental treatments for amebiasis might include investigational drugs being tested in clinical trials. Current experimental approaches could focus on novel antiparasitic agents, immunotherapies, or improvements in delivering existing drugs more effectively.

To find the latest information on experimental or off-label treatments for amebiasis, medical professionals typically refer to clinical trial registries, recent medical research, and treatment guidelines from infectious disease authorities.
Lifestyle Recommendations: For amebiasis, here are some lifestyle recommendations:

1. **Maintain Good Hygiene**: Wash your hands thoroughly with soap and water before eating and after using the restroom.
2. **Safe Water**: Drink only purified or boiled water. Avoid ice cubes that may be made from untreated water.
3. **Food Precautions**: Avoid eating raw vegetables and fruits unless they are peeled and washed properly. Be cautious with street food.
4. **Safe Sanitation**: Ensure proper disposal of human waste and avoid exposure to fecal matter.
5. **Avoid Sharing Personal Items**: Do not share utensils, towels, or other personal items with individuals who have been diagnosed with amebiasis.

These strategies can help reduce the risk of contracting and spreading amebiasis.
Medication: Amebiasis is primarily treated with a class of medications known as amebicides. The two main types of drugs used are luminal amebicides, which target the parasite in the intestine, and tissue amebicides, which target the parasite in tissues.

1. **Luminal Amebicides**:
- **Paromomycin**
- **Iodoquinol**
- **Diloxanide furoate**

2. **Tissue Amebicides**:
- **Metronidazole**
- **Tinidazole**

The specific choice of medication depends on whether the infection is asymptomatic, intestinal, or extraintestinal (such as liver abscesses). Often, treatment involves a combination of both luminal and tissue amebicides to ensure complete eradication of the parasite.
Repurposable Drugs: Repurposable drugs for amebiasis include:

1. **Nitazoxanide** - Originally for protozoal infections, it has shown efficacy against Entamoeba histolytica, the causative agent of amebiasis.
2. **Rifaximin** - An antibiotic used for gastrointestinal infections, it has potential anti-amebic properties.

These drugs are considered based on their antimicrobial activity and potential efficacy in treating amebiasis. However, standard treatments include metronidazole or tinidazole followed by a luminal agent such as paromomycin to eradicate cysts.
Metabolites: Amebiasis is an infection caused by the protozoan parasite Entamoeba histolytica. The primary metabolites associated with this disease include acetic acid, carbon dioxide, ethanol, and fatty acids. The parasite undergoes anaerobic metabolism, leading to the production of these metabolites.
Nutraceuticals: For amebiasis, nutraceuticals are food-derived products that may offer health benefits and potentially aid in the treatment or prevention of the disease. Some nutraceuticals considered for amebiasis include:

1. **Probiotics**: These beneficial bacteria can help modulate gut flora and enhance immunity, potentially reducing the severity of infection caused by Entamoeba histolytica.

2. **Garlic Extract**: Allicin, a component of garlic, has shown anti-parasitic properties against Entamoeba histolytica in some studies.

3. **Berberine**: An alkaloid found in several plants, berberine has demonstrated antimicrobial activity and may help in combating amebiasis.

However, it is important to note that while these nutraceuticals might offer supportive benefits, they should not replace conventional medical treatments such as antiparasitic medications for amebiasis. Always consult healthcare providers for appropriate diagnosis and treatment.
Peptides: Amebiasis is an infection caused by the parasite Entamoeba histolytica. It primarily affects the intestines but can spread to other organs, most commonly the liver. Treatment typically includes antiparasitic medications such as metronidazole or tinidazole.

Research into peptides for targeting this parasite is ongoing, focusing on antimicrobial peptides (AMPs) that could potentially disrupt the parasite's cell membrane or interfere with its biological processes. These peptides are still mostly in experimental stages.

Nanotechnology approaches, like the development of nanocarriers, are being investigated to improve drug delivery, enhance therapeutic efficacy, and minimize side effects. Nanoparticles can be engineered to target the parasite more effectively and deliver drugs directly to infected tissues.