Question

Identify the parasite below. O Giardia cyst O Trypanosoma O Balantidium coli trophozoite Balantidium coli cyst

Answer 1

Answer: Blantidium coli cyst.
Explanation: Blantidium coli is a species of protozoa that cause the disease Blantidiasis in the intestine of pigs. The same kind of infection is seen in humans as well, but not frequent. The presence of this infection can be manifested by the presence of this organism in the excreta.
The given microscopic image can be identified as Blantidium coli cyst due to its typical appearance. They have a spherical or near spherical shape with a well defined cyst wall. A kidney shaped nucleus is there in the image. The nucleus is large and is called macro nucleus. Cilia is not seen in the microscopic image. All other organelles inside the cyst appears to be granular in nature. All these features are seen in the image provided, hence, Blantidium coli cyst is the correct answer.
The reason for other options being wrong are:
Giardia cyst is not the correct answer. This is because, firstly, Giardia cysts are ovoid in shape. The presence of intra cytoplasmic fibres are clearly marked. The number of nucleus may be up to 4 per cyst. These features are absent in the image provided. Hence, Giardia cyst is not the correct answer.
Trypanosoma is not the correct answer. This is because, they have an irregularly shaped membrane. They are flagellated. Their nucleus is found at the centre. They have a structure called kinetoplast (mitochondrial DNA found in the vicinity of nucleus) near the posterior part of the cell. These features are absent in the image provided. Hence Trypanosoma is not the correct answer.
Blantidium coli Trophozoites is not the correct answer. This stage of Blantidium coli is the reproductive stage while the cyst is the stage causing infection. The Trophozoites are oblong to late in shape with a tapering or narrow end. Cilia is a sure feature of Trophozoites of Blantidium coli. The nucleus is kidney shaped. There is a large macro nuclei and a small micronuclei inside them. These features are absent in the given image. Hence, Blantidium coli Trophozoites is not the correct answer.

Hence, the correct answer is Blantidium coli cyst.