Amoebiasis (Amoebic Dysentery): Cause and Symptoms
Biology · Human Health and Diseases · NEET
Amoebiasis, also called amoebic dysentery, is caused by Entamoeba histolytica, a protozoan parasite that lives in the large intestine of humans. It spreads when houseflies carry the parasite from the faeces of an infected person to food. Memory hook: "Ento-AMOEBA histolytica = large intestine + housefly carrier" — the only common protozoan gut disease in your NCERT list.
Transmission of amoebiasis: Entamoeba histolytica passes from an infected person's faeces, is carried by houseflies (mechanical carrier) onto food and water, and reaches a healthy person's large intestine, causing amoebic dysentery.
Your doubts, answered
Is amoebiasis caused by a bacterium or a protozoan?
Amoebiasis is caused by a PROTOZOAN, not a bacterium. The parasite is Entamoeba histolytica. NEET often lists it with malaria (Plasmodium) as the two important protozoan diseases of humans. If you pick bacteria, you lose the mark.
Which organ does Entamoeba histolytica infect?
It infects the LARGE INTESTINE of humans. That is why the main symptoms are gut problems like constipation, abdominal pain, and stools with mucus and blood. It does NOT infect the liver or lungs in the basic NCERT line, so remember: large intestine.
How does amoebiasis spread — housefly or mosquito?
By HOUSEFLIES, not mosquitoes. Houseflies act as MECHANICAL carriers. They pick up the parasite from the faeces of an infected person and drop it on food. Mosquito is the vector for malaria and filariasis, not amoebiasis. This swap is a classic NEET trap.
What is the difference between amoebiasis and malaria?
Both are protozoan diseases, but the parasite, organ, and carrier differ. Amoebiasis = Entamoeba histolytica, large intestine, housefly (mechanical carrier). Malaria = Plasmodium, red blood cells and liver, female Anopheles mosquito (biological vector). Do not mix the carriers.
Is amoebiasis the same as amoebic dysentery?
Yes. NCERT uses both names for the same disease. 'Amoebic dysentery' just points to the dysentery-type symptoms (loose stools with mucus and blood) caused by the amoeba Entamoeba histolytica.
⚠️ The NEET trap ✗ Amoebiasis is caused by a mosquito-borne pathogen, like malaria and filariasis. ✓ Amoebiasis is caused by Entamoeba histolytica and is spread by HOUSEFLIES acting as mechanical carriers, not by mosquitoes. Mosquitoes spread malaria (Plasmodium) and filariasis (Wuchereria). 🧠 Mosquito = blood diseases (malaria, filariasis). Housefly = gut disease (amoebiasis). Match the carrier to the site.
Real NEET questions
2021
Match List I with List II.
List I: (a) Filariasis (b) Amoebiasis (c) Pneumonia (d) Ringworm
List II: (i) Haemophilus influenzae (ii) Trichophyton (iii) Wuchereria bancrofti (iv) Entamoeba histolytica
A · (a)-(i); (b)-(ii); (c)-(iv); (d)-(iii)
B · (a)-(ii); (b)-(iii); (c)-(i); (d)-(iv)
C · (a)-(iv); (b)-(i); (c)-(iii); (d)-(ii)
D · (a)-(iii); (b)-(iv); (c)-(i); (d)-(ii) ✓
Solution: Amoebiasis (b) is caused by Entamoeba histolytica (iv). Also Filariasis (a) = Wuchereria bancrofti (iii), Pneumonia (c) = Haemophilus influenzae (i), Ringworm (d) = Trichophyton (ii). This gives a-iii, b-iv, c-i, d-ii, which is option D.
2018
In which disease does a mosquito-transmitted pathogen cause chronic inflammation of lymphatic vessels?
A · Ringworm disease
B · Ascariasis
C · Elephantiasis ✓
D · Amoebiasis
Solution: Elephantiasis (filariasis) is caused by Wuchereria, spread by female mosquitoes, and inflames the lymphatic vessels of the lower limbs. Amoebiasis is wrong because it is a protozoan gut disease of the large intestine spread by houseflies, not a mosquito-borne lymphatic disease.
Solved Human Health and Diseases NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Entamoeba histolytica, a protozoan parasite that lives in the large intestine of humans.
What are the main symptoms of amoebiasis?
Constipation, abdominal pain and cramps, and stools with excess mucus and blood clots. That is why it is called amoebic dysentery.
How is amoebiasis transmitted?
Houseflies act as mechanical carriers. They carry the parasite from the faeces of an infected person to food, and a healthy person is infected by eating that contaminated food or water.
Is amoebiasis a bacterial disease?
No. It is a protozoan disease. The two protozoan diseases you must know for NEET are amoebiasis (Entamoeba) and malaria (Plasmodium).
Which part of the body is affected in amoebiasis?
The large intestine, which leads to the dysentery-type gut symptoms.
