Laboratory Diagnosis of Parasitic Diseases PDF

Labeling: Ensure all specimens are labeled with the patient's name, date, and time of collection. Specimen Collection :Use a clean, leak-proof container, avoiding contamination. Timing: Collect before antiparasitic treatment and as close to symptom onset as possible. Frequency: Three specimens on a...

Labeling: Ensure all specimens are labeled with the patient's name, date, and time of collection. Specimen Collection :Use a clean, leak-proof container, avoiding contamination. Timing: Collect before antiparasitic treatment and as close to symptom onset as possible. Frequency: Three specimens on alternate days, with the third after using purgatives. Examination Time: Liquid stool: within 15–30 min. Semisolid stool: within 1 hour. Formed stool: within 24 hours. Delay may cause trophozoite disintegration. Mucoid bloody stool: Found in acute amoebic dysentery, intestinal schistosomiasis, and invasive balantidiasis Dark red stool indicates upper gastrointestinal (GIT) bleeding and a bright red stool is suggestive of bleeding from lower GIT Frothy pale offensive stool (containing fat) found in giardiasis Adult worms : worms or segments of tapeworm may be seen Direct Wet Mount (Saline and Iodine): Saline and iodine drops are placed on a slide. A small amount of stool is mixed in each drop to form a smooth suspension. Cover slips are added, and the slide is examined under the objectives. Permanent stained smear are required for accurate diagnosis of intestinal parasites. Commonly used methods are: Iron-hematoxylin stain Trichrome stain Modified acid-fast stain All these permanent stained smears help in the accurate diagnosis by staining their internal structures. Employed when parasite output is low in stool (eggs, cysts, larvae). (Trophozoites are destroyed). - Sedimentation Techniques : Parasites settle after centrifugation. - Formalin-ether, formalin-ethyl acetate, and formalin-acetone methods. - Floatation Techniques : Parasites float due to specific gravity. - Sodium chloride, zinc sulfate, and Sheather's sugar.  Cellophane Tape)Scotch tape method( Used to detect Enterobius vermicularis (pinworm) eggs. A piece of transparent tape is pressed against the perianal area in the morning, then placed on a slide for microscopic examination. Scotch tape method  Duodenal contents It is very useful for the detection of small intestine parasites like, Giardia intestinalis and larva of Strongyloides stercoralis. Duodenal fluid can be collected by entero test Blood is commonly used to diagnose malaria, filariasis, and trypanosomiasis. Parasites like Trypanosoma and microfilariae may be seen in fresh blood by observing motility, but stained smears provide more accurate identification. Blood can be collected from the fingertip, earlobe, or venipuncture with or without anticoagulants, and several methods are used to detect parasites. Thin Blood Smear: Purpose: This technique is used to examine the morphology of blood cells and detect blood-borne parasites Procedure: -Place a small drop of blood on the slide. -Use another slide to spread the blood into a thin layer. -Air dry and fix with methanol. -Stain with Giemsa or Leishman stain and examine under a microscope. Thin Blood Smear 2. Thick Blood Smear: Purpose: To detect low parasite densities. Procedure: -Place a larger drop of blood on the slide. -Spread into a thick area (about 1 cm in diameter). -Air dry without fixing to keep red cells intact. -Stain with Giemsa or Leishman stain and examine for parasites. -Washing with water or a special solution to remove hemoglobin.  Immunological Diagnosis (Serology) Molecular Methods Biopsy (e.g., skin, muscle, liver) to identify parasites that invade tissues, such as Leishmania) Skin Tests Culture Methods (vitro culture of Leishmania) Animal Inoculation Homework Xenodiagnosis