By Prof. Mahmoud Rushdi Faculty of Veterinary Mdii Medicine Assiut University Egypt Precautions to be taken during collection and preservation of fecal sample 2 1
Precautions during collection of fecal sample 1. Fecal sample must be collected directly from the rectum. 2. Fecal sample must be preserved in clean container that keeps the moisture as sealed plastic bag, plastic cup with cover or screw capped glass container. 3. Sufficient quantity of the sample must be obtained to permit through examination. 4. It is essential to label the container with number, name and date of collection. 5 Precautions during collection of fecal sample 6 6. Fecal sample must be preserved directly after collection in cold container. 7. Fecal sample must be transported directly after collection to the laboratory. 8. Samples that will be examined in the same day of collection must be kept in the refrigerator. 9. For prolonged storage, formalin 3% must be added to the fecal sample. 10.In case of negative results, fecal sample must be collected and examined for three days. 3
Parasitological analysis of Feces I. Gross (Macroscopical or physical examinations) II. Microscopical Examination of Feces 7 Gross (Macroscopical or physical examination) 1. Volume (per 24 hours) 2. Color of faeces 3. Odour of faeces 4. Consistency of faeces 5. Presence of blood 8 4
Physical examination 6. Presence of mucous 7. Presence of fibrin 8. Presence of undigested food material 9. Presence of adult worm or segments. 9 1. Volume (per 24 hours) Normal amount of feces varies according to animal species, amount of feed intake and amount of water intake. Abnormal values: Increase.. Diarrhea. Decrease Constipation Absence.. Intestinal obstruction 10 5
2. Color of feces Color of feces is influenced by: Nature of feed. Concentration of bile in the feces. Rate of passage of ingesta through the digestive tract. Dark brown or black feces may be due to: a. Hemorrhage in the stomach or small intestine. b. Feeding diet rich in meat. c. Oral administration of iron, sulphur or bismuth compound. d. Elimination of excessive amount of bilirubin. Red color Blood 11 3. Odour of feces Freshly voided feces are normally odorless. Offensive or fetid odour occurs in cases of: Obstruction of bile flow. Excessive protein intake. Coccidia infestations or salmonella infection. 12 6
4. Consistency of feces Depends upon: Water content. Type of feed. Rate of passage of ingesta through the digestive tract. Watery feces observed in cases of diarrhea. Milk fed animal excrete feces with medium consistency. Dehydration causes the formation of firm balls of feces. 13 5. Presence of blood Bleeding in the rectum causes appearance of ffresh red dblood on the outer surface of fecal balls. Feces mixed with dark red colour indicate hemorrhage in the small intestine. Bleeding into the stomach, gives feces black tarry colour (melena). 14 7
6. Presence of mucous Large amount of mucous passed with small amount of liquid feces tinged with blood is indicative of acute inflammation. Severe constipation may be accompanied by presence of mucous. 7. Presence of fibrin Long strand of fibrin indicates fibrinous enteritis. 15 8. Presence of undigested food material It indicates improper p mastication and digestion. 9. Presence of adult worm or segments 16 8
II. Microscopical Examination of Feces 1. Qualitative evaluation methods a. Direct smear. b. Concentration techniques: 1. Sedimentation. 2. Floatation. 3. Sedimentation floatation technique. 17 Microscopical Examination of Feces c. Baermann wetzel funnel technique. d. Vaida technique. e. Culture of nematode larvae. f. Identification of oocyst. 2. Quantitative evaluation methods McMaster technique. 18 9
1. QUALITATIVE EVALUATION METHODS a. Direct smear Importance: Very quick and simple to prepare. Is efficient only when parasitic ova or oocysts are present in increased numbers. Interpretation 1. Test is screen. 2. Negative cases necessitate that concentration techniques are required. 3. Positive cases need further examination with high power magnification that may assist their identification. 19 b. Concentration techniques: 1. Sedimentation Principle 1. QUALITATIVE EVALUATION METHODS The sedimentation technique is a qualitative method for detecting trematode eggs in the faeces. Most trematode eggs are relatively l large and heavy compared to nematode eggs. This technique concentrates them in sediment. 20 10
b. Concentration techniques 2. Floatation Principle Flotation method is a qualitative test for the detection of nematode, cestodes eggs and coccidia oocysts in the faeces. It is based on the separating of eggs from faecal material and concentrating them by means of a flotation fluid with an appropriate specific gravity. 21 3. Sedimentation - floatation technique Principle The sedimentation and flotation method technique is a qualitative method for detecting trematode eggs in the sediment and also for the detection of nematode, cestodes coccidia oocysts in the flotation fluid. eggs and 22 11
c. Baermann Wetzel funnel technique Principle The Baermann technique is used to isolate lungworm larvae from faecal samples of cattle and equines and infective larvae from faecal cultures. It is based on the active migration of larvae from faeces suspended in water and their subsequent collection and identification. 23 d. Vaida technique Principle The Vaida technique is used to isolate lungworm larvae from faecal samples of sheep and goat. It is based on the active migration of larvae from faeces suspended in water and their subsequent collection and identification. 24 12
e. Culture of nematode larvae Principle Many nematode eggs are similar and species such as Haemonchus, Mecistocirrus, Ostertagia, Trichostrongylus, Cooperia, Bunostomum, and Oesophagostomum cannot be clearly differentiated from the eggs in faecal samples. For these parasites, differentiation can be achieved by the use of faecal cultures. They provide a suitable environment for the hatching and development of helminth eggs into the infective stage. 25 5. Sporulation of coccidian Oocyst This technique is needed to identify coccidia. Mix a fresh sample of faeces with several volumes of 2.5 % potassium dichromate solution and transfer thin layer of the mixture to Petri dish or other glass container. Oxygen is necessary for oocyst development. Sporulation will occur in few days to weeks. 26 13
2. QUANTITATIVE EVALUATION METHODS (McMaster Counting Technique) The simplest and most effective method for determining the number of eggs or oocysts per gram of faeces is the McMaster Counting Technique. 27 The McMaster counting technique is a quantitative technique to determine the number of eggs present per gram of faeces (e.p.g.). A flotation fluid is used to separate eggs from faecal material in a counting chamber (McMaster) with two compartments. 14