Common Parasites Pictures

What sample is needed to find common parasites?

1. Preferably, take a fresh stool sample.
2. Thick and thin peripheral blood smears.
3. The serum for serological studies.

What are the disadvantages of stool examination?

1. It will not differentiate between present and past infection.
2. Can not find drug resistance.
3. May not find causative agent.

What precautions are needed for stool examination?

1. Foreign materials in the stool may create problems like barium, bismuth, mineral oil, and non-absorbable antidiarrheal drugs.
2. The use of drugs like tetracycline may change the flora if given one week before the stool examination.

A short review of common Parasites is described.

Enterobius Vermicularis

1. The ova is oval and asymmetric, with one side flattened.
2. Size is 55 × 26 micrometers.
3. In underdeveloped countries, 10% of the pediatric population may be infected.

 Ascaris Lumbricoides

1. It is a large intestinal roundworm. It has a common resemblance to common earthworms.
2. The fertile ovum is 60 x 45 micrometers. It has a thick shell and is surrounded by an albuminous covering.
3. The infertile ovum is 90 x 40 micrometers. This is surrounded by an irregular albuminous covering.
4. Female worm ranges from 20 to 35 cm in length.
   1. It may be as thick as a lead pencil.
5. Males are rarely more than 30 cm in length.
   1. Males are more slender and have prominent incurved tails.

Fertilized Ovum

Ancylostoma Duodenal

1. It is called Old World hookworm.
2. Ankylostoma adults are greyish-white or pinkish. The head is slightly bent in relation to the rest of the body.
3. Male worm measures nearly 1 cm by 0.5 mm.
4. Females are longer and stouter.
5. The mouth is well developed, with a pair of teeth on either side of the median line and a smaller pair in the depth of the buccal capsule.
6. Hookworm eggs, when passed in the stool, are unsegmented or in the early stage of cleavage.
   1. Ovum measures 60 to 65 x 40 micrometers. It is oval and has a thin shell.
7. Usually, the embryo is at the four-cell stage.

 Trichuris Trichiura

1. This is also called a whipworm. It is more common in areas with poor sanitation.
   1. The name whipworm is very descriptive. The thick posterior part of the body forms the stock, and the long, thin anterior portion is like a lash.

2. The ovum size is 52 x  23 micrometers.
3. It is barrel-shaped with distinctive ends.

Common parasites: Trichuris Trichiura

Giardia Lamblia

1. Trophozoites are found in the upper part of the small intestine, where they live attached to the mucosa.
   1. These may be found in the gallbladder and biliary tract.
   2. Trophozoite form measures 12 to 15 micrometers. It is pyriform and has two nuclei.
   3. Trophozoite unstained shows progressive motility like a falling tree leaf.
   4. Trophozoite stained shows nuclei in the area of the sucking disc.
   5. There are two median bodies posterior to the disc.
2. Cysts unstained are ovoid in shape,
   1. Stained cysts show 4 nuclei and four median bodies.

Entamoeba Histolytica

1. Entamoeba Histolytica is found in roughly 10% of the world’s population—actually, it may be 1%. The rest may be due to Entamoeba dispar.
2. Entamoeba Histolytica was described in 1875 in a Russian Peasant.
3. Entamoeba Histolytica mainly inhabits the large intestine, where they eat RBCs and may cause ulcers.
4. Entamoeba Histolytica causes chronic dysentery.

 Iodamoeba butschlii

1. Iodamoeba butschlii is an amoeba, and its name was given due to the presence of characteristic glycogen vacuoles in the cyst.
2. Iodamoeba butschlii has variable shapes.
3. It is easily recognized in the iodine preparation.
4. Trophozoites in unstained smear is difficult to recognize.
   1. These measure 4 to 20 µm in diameter.
   2. These have sluggish progressive movements and have hyaline pseudopods.
5. Cyst ranges from 6 to 16 µm in diameter.
   1. A refractile cyst wall surrounds an unstained cyst.
   2. These cysts are irregular in outline.
   3. The glycogen vacuole is prominent even in unstained cysts.
   4. When stained with iodine, the glycogen vacuole is a dark brown mass.

Trichomonas vaginalis

1. Trichomonas vaginalis is closely related to Trichomonas Hominis.
2. Trichomonas vaginalis size is 5 to 15 µm but may reach 30 µm.
3. In vaginal secretions, you may see jerky movements, nondirectional motility.
   1. It is motile due to the presence of anterior flagella.
   2. The movement is rapid and jerky.