AMOEBIASIS

Amoebiasis



Introduction

Amoebiasis is the infection of the large intestine that is caused by the parasite Entamoeba histolytica. It may lead to mild or chronic diarrhea to even dysentery. It majorly affects the people living in tropical areas. They are vulnerable to this infection due to their poor sanitary lifestyle. Entamoeba histolyticas is the most common pathogens found in tropical parts of the world. After Giardia Lamblia, it is regarded as the significant causative agent of diarrhea. Moreover, it is also the fourth major cause of death worldwide due to protozoan infection. About 10% of the populations are afflicted by E. Histolytica. It is a common infectious disease in tropical areas like India, South America and Mexico (Haque R, 2003).

Entamoeba Histolytica is a one-celled parasite that can be found in two forms i.e. the infectious cyst form or the fragile trophozoite form. The microbe infects the intestine by attacking the intestinal mucosa, eventually causing amoebic colitis. This infection may lead to asymptomatic conditions or may produce extra intestinal infections i.e. hepatic sore can occur (Markell E, 1999).

Fig 1. Entamoeba Histolytica

Discussion

Causative agent of Amoebiasis

Amoebiasis is one of the most dangerous infectious diseases of the tropical regions. The causative agent of this disease is a protozoan i.e. Entamoeba Histolytica, which is the only pathogenic micro-organism in the enteric amoeba class (Steven and Hume, 1998). Protozoans have been known to cause many diseases in human and are known as the endosymbiotic of some ruminants. Their site of action is mainly blood and the gastrointestinal tract. These sites also play a principal role in the proliferation and division of these micro-organisms (Cox, 2002).

Usually the cyst forms enter into humans by the vectors (those agents that transfer the infection such as mosquito, insects and flies). Their transmission is either via food or water supply. The protozoan capable of infecting the GIT is called as enteric protozoa (Garcia, 2001). The route of transmission of enteric protozoan is either by the fecal oral route. The life cycle of such protozoan can be classified into two stages i.e. cyst stage and the trophozoite stage. Water supplies contaminated with cysts can lead to amoebiasis (Garcia, 2001).

After ingestion of the infected water or food, the cysts transforms into the trophozoite form which shows active metabolism and possess motility. During the trophic phase, the parasite takes up nutrients that it requires and uses the asexual mode of reproduction in order to multiply. Whereas, some of these trophozoite forms, are reversed back into their cyst forms during unfavorable conditions. These cysts are then excreted via human excreta (Graczyk, 2005).

Life cycle of Entamoeba histolytica

The enteric infections' life cycle consists of two stages as mentioned earlier i.e. the cysts and trophozoites stages.

1. Infection is caused by the ingestion of cysts that are present in contaminated food and water.

2. When the cyst enters the body, excystation occurs once it enters into the small intestine.

3. Trophozoites then multiply by binary fission in the large ...