. Animal parasites and human disease. Insects as carriers of disease; Medical parasitology. CHAGAS' DISEASE — PARASITE IN BUG 111 transmitting agent of the trypanosome. A few liours after a bug has fed on infected blood the trypanosomes begin to change form in the midgut, becoming round and Leishma7iia-like in form, losing the flagellum and undulating membrane (Fig. 28A, B and C.) Then comes a period of very rapid increase in number, the parasites gradually pushing backward toward the hindgut by sheer multiplication. After about two days Crithidia forms begin to develop and become numerous in
. Animal parasites and human disease. Insects as carriers of disease; Medical parasitology. CHAGAS' DISEASE — PARASITE IN BUG 111 transmitting agent of the trypanosome. A few liours after a bug has fed on infected blood the trypanosomes begin to change form in the midgut, becoming round and Leishma7iia-like in form, losing the flagellum and undulating membrane (Fig. 28A, B and C.) Then comes a period of very rapid increase in number, the parasites gradually pushing backward toward the hindgut by sheer multiplication. After about two days Crithidia forms begin to develop and become numerous in the hindgut, being. Fig. 28. Development of Trypanosoma cruzi in digestive tract of bug (Tria- toma megislu). A, freshly ingested form; B, rounding up and loss of flagellum, 6 to 10 hrs. after ingestion; C, Leishmania-Ukc form in midgut, 10 to 20 hrs. after ingestion; D, redevelopment of flagellum and undulating membrane, 21 hrs. after ingestion; E and F, crithidial forms in hindgut, hrs. after ingestion; G, trypa- nosome form from salivary gland. S days or more after ingestion. (After Chagas.) voided with the excrement from time to time (Fig. 28D, E and F). It has been suggested that these crithidial forms do not plaj^ any part in the transmission of the disease to man but that the}^ rep- resent a return to a primitive condition suited to existence in the bugs, and that they may be transmitted from bug to bug in this form, since the bugs are known to prey to some extent upon each other and a^so upon their excrement. Torres however, considers transmission of the flagellates from bug to bug as very doubtful. Chagas believes that there is a second cycle of development in. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Chandler, Asa Crawford, 1891-1958. New York J. Wiley [etc. ]
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmedical, bookyear1918
