Amoebiasis

Published: 22nd Jun, 2020

A team of researchers from the Jawaharlal Nehru University (JNU) has developed new drug molecules against the protozoa that cause amoebiasis.

Context

Amoebiasis or amoebic dysentery is a common parasitic enteral infection. It is caused by the protozoan parasite Entamoeba histolytica.
Amoebiasis is present all over the world. Each year, about 40000 to 110000 people die from amoebiasis infection.
Amoebiasis may present with no symptoms or mild to severe symptoms including abdominal pain, diarrhea, or bloody diarrhea.
Severe complications may include inflammation and perforation resulting in peritonitis. People affected may develop anemia.
Types The clinical spectrum ranges from asymptomatic infection, diarrhoea and dysentery to fulminant colitis and peritonitis as well as extraintestinal amoebiasis.
- Acute amoebiasis can present as diarrhoea or dysentery with frequent, small and often bloody stools.
- Chronic amoebiasis can present with gastrointestinal symptoms plus fatigue, weight loss and occasional fever.
- Extraintestinal amoebiasis can occur if the parasite spreads to other organs, most commonly the liver where it causes amoebic liver abscess.
- Amoebic liver abscess presents with fever and right upper quadrant abdominal pain

What is Entamoeba histolytica?

According to the World Health Organization (WHO), Entamoeba histolytica is the third-leading cause of morbidity and mortality due to parasitic disease in humans.
histolytica is classified as a category B biodefense organism because of its environmental stability, ease of dissemination, resistance to chlorine, and it is easily spread through contaminated food products.
Besides the GI tract, E. histolytica can affect many organ systems.

Treatment

Prevention of amoebiasis is by improved sanitation. Two treatment options are possible, depending on the location.
Amoebiasis in tissue is treated with metronidazole, tinidazole, nitazoxanide, dehydroemetine or chloroquine.
A luminal infection is treated with diloxanide furoate or iodoquinoline. Effective treatment may require a combination of medications.
Infections without symptoms require treatment, but infected individuals can spread the parasite to others.

The findings

This protozoan is anaerobic or micro-aerophilic in nature such that it cannot survive high concentrations of oxygen.
However, during infection, it faces a high surge of oxygen inside the human body. The organism synthesises large amounts of cysteine to counter oxidative stress.
This pathogen deploys cysteine as one of the essential molecules in its defence mechanism against high oxygen levels.
Entamoeba expresses two crucial enzymes for synthesising cysteine. Researchers from JNU have characterised and determined the molecular structures of both these crucial enzymes.

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