Diagnosis Intestinal Taeniasis

Taeniasis can be diagnosed on the basis of the following findings: (a) a history of ingesting raw

Fig. 23.13 Proglottids of Taenia solium. Reproduced from Willms (1998) by permission of WB Saunders Company

or undercooked pork (homemade sausages) or beef; (b) discharging of proglottids or worm segments in the stool or the presence of loose proglottids in underclothing or bedding, which has been reported in T. saginata infections; (c) coprological analysis—three consecutive stool examinations using the methods of Faust et al. (1938), Ritchie (1948) or Kato are recommended. The perianal swab method of Graham (1941) may also be used. If proglottids are available, an effort should be made to identify the number of uterine branches under a microscope, by fixing the segments in formalin and dehydrating in glycerol. Less than 12 uterine branches is indicative of T. solium and the patient should be given anthelminthic treatment as soon as possible, as he/she is a potential risk to other humans (Figures 23.13 and 23.14). The patient should be asked to recover the tapeworm and bring it to the laboratory for definitive diagnosis. Care should be taken to identify the scolex to ascertain whether it has an armed or unarmed rostellum (Figure 23.15). If the scolex is not present, the

Fig. 23.14 Proglottids of Taenia saginata. Reproduced from Willms (1998) by permission of WB Saunders Company
Fig. 23.15 Scanning electron micrograph of Taenia saginata scolex. S, sucker. Arrow, neck

proglottids should be prepared for microscopic observation. Patients should be re-examined 4-6 months after treatment, particularly if the scolex was not found or the proglottids were too macerated to be identified. It should be emphasized that the eggs of T. solium and T. saginata are identical under the light microscope. The morphological identification of proglottids and scolices requires laboratory facilities and trained personnel, which are frequently not available in rural areas of developing countries. Recently, several groups have worked out an antigen capture method based on an ELISA technique (Allan et al., 1993) as well as the preparation of specific DNA probes for the detection of Taenia eggs in stool samples, methods which promise rapid and efficacious results and that should be helpful in epidemiological surveys (Chapman et al., 1995).

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