Correspondence
Taenia saginata
N Engl J Med 2000; 342:1139-1140April 13, 2000
- Article
To the Editor:
The Image in Clinical Medicine by Matuchansky and Lenormand (Dec. 2 issue)1 is excellent, but why was it labeled Taenia saginata? The two species of intestinal taenia that are commonly found in humans are T. saginata and T. solium, which may be easily distinguished by the shape and structure of their segments (proglottids) but not by their image on an x-ray film.
T. saginata also differs from T. solium with regard to the motility of its individual segments, which are shed by the adult worm as echinococcus species are in dogs. The absence of motility in T. solium is probably an adaptation to the feeding behavior of pigs, which eat feces and thus can easily ingest whole segments.
In 1965 I became infected with T. saginata in West Africa; I then observed the activities of the parasite for about three months.2,3 Although most of the segments passed with stools, active passage that was not linked with defecation occurred on about two thirds of the days. Segments crawl over the perineum, contract vigorously, and squeeze out most of their eggs within a few minutes. I did not feel any discomfort or symptoms other than an unpleasant sensation at the moment that the parasite was passed.
Matuchansky and Lenormand make no reference to an active passage of the parasite. This makes me think that either the investigation was incomplete (no specific questioning of the patient and no cellophane-tape examination of the perianal area) or the parasite in question was T. solium. If the patient was a regular consumer of raw beef, did he also ingest raw pork in the form of adulterated meat products?
To treat infection with T. solium, it would be prudent not to use drugs such as niclosamide that provoke digestion of the parasite, which may lead to the dissemination of eggs and thus to cysticercosis. It is important to identify the species before choosing the treatment.
3 ReferencesAndrei E. Beljaev, M.D.
World Health Organization, Alexandria 21563, Egypt1
Matuchansky C ,Lenormand Y . Taenia saginata. N Engl J Med 1999;341:1737-1737
Full Text | Web of Science | Medline2
Beljaev AE ,Monisov AA . On the production of proglottids at the initial stage of taeniarhynchosis. Med Parazitol Parazit Bolezni 1967;36:487-4883
Beljaev AE, Alekseeva MI. Taeniarhynchosis. Moscow: Central Postgraduate Medical Institute, 1980.
To the Editor:
Until Matuchansky and Lenormand are able to establish the diagnosis of T. saginata infection by recovering the proglottids of the parasite from their patient, the translucent filling defect noted in the x-ray film of the small bowel should be considered either an artifact or the most common helminthic infection of humans worldwide, Ascaris lumbricoides. In infection with adult ascaris, the small bowel is the normal habitat. In infection with pure male adult ascaris, no eggs are passed in the stool. Thus, the disappearance of the filling defect on a repeated barium contrast study of the small bowel can be explained in several ways. It might have been an artifact. The male adult ascaris might have migrated (not uncommonly to the biliary tract). Better yet, the worm might have been passed without the patient's noticing.
Melchor E. Madarang, M.D.
St. Michael's Medical Center, Newark, NJ 07102Author/Editor Response
The authors reply:
To the Editor: In response to Beljaev: the results of a search for taenia in stools are by no means always conclusive during the parasite's period of maturation, which may go on for several months. Indeed, T. saginata is mature only after it has reached a minimal length of 3 to 4 m; there is very little release of proglottids outside or with the stools before this length has been attained. This explains our negative parasitologic findings during the first few months, despite the patient's symptoms. Questioning was rigorous, but the patient had never observed either his stools or his underwear. The cellophane-tape examination of the perianal area was negative. The taenia species found in France are almost all T. saginata (beef tapeworm); T. solium (pork tapeworm) has become very rare because of rigorous monitoring of pig breeding.1 Our patient had eaten raw beef regularly for about six months, but he never consumed pork.
In response to Madarang: the image on the x-ray film does not appear to be specific to A. lumbricoides, the length of which is 15 to 17 cm (male) or 20 to 25 cm (female) and which has a digestive tract. A highly characteristic image of A. lumbricoides, absent in taenia, is that of a digestive tract filled with barium at the end of the day the contrast study1 was performed or on the day after; this image was not seen on the x-ray film of our patient. In our image, the translucent filling defect, which occupies the preterminal ileal loop, remains the same untapered width at its extremities; indeed, on the images of the whole intestine (not shown), it extended well beyond the preterminal loop by more than 100 cm. In addition, the patient's clinical response to niclosamide makes A. lumbricoides infection unlikely. It is also highly unlikely that the finding was an artifact, because it remained the same on all the films and because it had none of the patterns reported in the differential diagnosis of small-bowel disease that could be misinterpreted as worms (patterns caused by sacroiliac joints, threads of mucus, or mucosal folds).2
2 ReferencesClaude Matuchansky, M.D.
Yves Lenormand, M.D.
Lariboisière Hospital, 75010 Paris, France
