What is the Difference Between Amoebiasis and Giardiasis

The key difference between amoebiasis and giardiasis is that amoebiasis is a lower gastrointestinal tract infection caused by parasitic protozoan Entamoeba histolytica while giardiasis is an upper gastrointestinal tract infection caused by parasitic protozoan Giardia lamblia.

Parasitic protozoa infect humans and cause serious diseases. Entamoeba histolytica and Giardia lamblia are two intestinal pathogenic protozoa. E. histolytica causes amoebiasis by colonizing the colon wall, while G. lamblia causes giardiasis by colonizing the duodenum, jejunum, and ileum.  Both these infections transmit through the oral-faecal route via the ingestion of cysts or oocysts in faeces. Therefore, poor hygienic conditions are a major cause of these diseases. Diarrhea is common in both diseases. Personal hygiene is one of the best precautions to prevent these diseases.

CONTENTS

1. Overview and Key Difference
2. What is Amoebiasis 
3. What is Giardiasis
4. Similarities – Amoebiasis and Giardiasis
5. Amoebiasis vs Giardiasis in Tabular Form
6. Summary – Amoebiasis vs Giardiasis

What is Amoebiasis?

Amoebiasis is a protozoan infection happening in the lower gastrointestinal tract of humans. The causative agent of amoebiasis is Entamoeaba histolytica, which is an intestinal pathogenic protozoan. E. histolytica has two stages as trophozoites and cysts. The trophozoites of E. histolytica have a cytolethal effect on the cells of the bowel wall through a toxin. E. histolytica colonizes the colon wall and disseminates to other organs such as the liver. When invading other organs, life-threatening amoebiasis may occur, causing an amoebic liver abscess. The symptoms of amoebiasis are diarrhea, abdominal pain, fever, sepsis, liver abscesses and skin lesions.

Figure 01: Amoebiasis

The transmission of E. histolytica occurs through the oral-faecal route. Ingesting this organism through contaminated food or water should be prevented in order to control amoebiasis. Hence, personal hygiene is very important in this aspect. Due to poor sanitation, amoebiasis is a major reason for morbidity and mortality in developing countries.

What is Giardiasis?

Giardiasis is an upper gastrointestinal tract infection caused by G. lamblia. G. lamblia is a parasitic protozoan that is anaerobic. There are two morphological forms of G. lamblia as trophozoite stage and cysts. The trophozoite stage is multi flagellated and pear-shaped. The infective stages of G. lamblia transmit to humans through the oral-faecal route. Giardiasis happens due to the ingestion of fecal contaminated drinking water, food or direct contact with feces. Once ingested cysts of G. lamblia, it colonizes the duodenum, jejunum, and ileum, causing infection in the upper gastrointestinal tract. The major symptoms of giardiasis are persistent diarrhea, malabsorption, loose stools, gassiness, cramping, fatigue, liver or pancreatic inflammations.

Figure 02: G. lamblia

Poor hygienic conditions are the major reason for giardiasis. Therefore, personal hygiene, water treatment, and appropriate cleaning and storage of vegetables are several steps that can be taken to prevent giardiasis.

What are the Similarities Between Amoebiasis and Giardiasis?

• Both amoebiasis and giardiasis are gastrointestinal tract diseases caused by parasitic protozoa.
• These diseases occur through oral-faecal route transmission.
• These infections occur through the ingestion of infective stages of pathogens such as cysts or oocysts in feces.
• Poor hygienic condition is one of the major reasons for the occurrence of these diseases.
• Diarrhea, abdominal pain, and weight loss are common symptoms of both diseases.
• Personal hygiene, water treatment, and proper cleaning and storage of vegetables are several preventive measures for these diseases.
• The trophozoite stage of both causative agents is motile.
• Both causative agents exist in two stages: trophozoites and cysts.

What is the Difference Between Amoebiasis and Giardiasis?

Amoebiasis is an intestinal disease caused by E. histolytica, while giardiasis is an intestinal disease caused by G. lamblia. So, this is the key difference between amoebiasis and giardiasis. Amoebiasis is a lower gastrointestinal tract infection, but giardiasis is an upper gastrointestinal tract infection. Moreover, E. histolytica colonizes the colon wall and may disseminate to other organs, while G. lamblia colonizes the duodenum, jejunum, and ileum.

The following infographic lists the differences between amoebiasis and giardiasis in tabular form for side by side comparison.

Summary – Amoebiasis vs Giardiasis

Pathogenic parasitic protozoa can infect the human intestinal tract and cause serious diseases such as amoebiasis and giardiasis, etc. E. histolytica causes amoebiasis, which is a lower gastrointestinal tract infection. G. lamblia causes giardiasis, which is an upper gastrointestinal tract infection. Unlike G. lamblia, E. histolytica colonizes the colon wall and may disseminate to other organs such as the liver, causing life-threatening amoebiasis. Both diseases transmit via the oral-faecal route. Hence, personal hygiene practices are very important to prevent these diseases. Diarrhea and abdominal pain are two common symptoms of both diseases. Thus, this is the summary of what is the difference between amoebiasis and giardiasis.

Reference:

1. Hemphill, Andrew, et al. “Comparative Pathobiology of the Intestinal Protozoan PARASITES Giardia Lamblia, Entamoeba Histolytica, And Cryptosporidium Parvum.” Pathogens (Basel, Switzerland), MDPI, 29 July 2019.
2. Delgado, Amanda. “Giardiasis: Causes, Symptoms, and Treatment.” Healthline, Healthline Media, 17 Sept. 2018.

Image Courtesy:

1. “Amebiasis LifeCycle” By CDC – (Public Domain) via Commons Wikimedia
2. “Giardia lamblia SEM 8698 lores” By CDC / Janice Haney Carr – (Public Domain) via Commons Wikimedia

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