The genus was founded for a flagellate parasite, Prowazekia cruzi, discovered in a culture of human fæces in Brazil. Various other species have been referred thereto. The genus is separated from Bodo by the possession of a second nucleus, the so-called kinetonucleus or blepharoplast. It differs from Trypanoplasma in the absence of an undulating membrane. It is heteromastigote, that is, it possesses two dissimilar flagella, one anteriorly directed and the other lateral and trailing.
The principal species are:
Prowazekia urinaria, Hassall, 1859.
Syn.: Bodo urinarius, Hassall, 1859; Trichomonas irregularis, Salisbury, 1868; Cystomonas urinaria, Blanchard, 1885; Plagiomonas urinaria, Braun, 1895.
Hassall[47] in 1859 first found Bodo-like flagellates in human urine. He examined fifty samples of urine from patients suffering from albuminuria and from cholera. The reaction of the urine was alkaline or sometimes only feebly acid. The flagellates were only seen after the urine had been standing for several days. Hassall named the organism Bodo urinarius, and gave a very good description of it with illustrations. The flagellate, which was round or oval, measured 14 µ by 8 µ. The organism had “one, usually two, and sometimes three lashes or cilia.” In 1868 Salisbury described a similar flagellate in the urine under the name Trichomonas irregularis. Künstler in 1883 described the latter parasite under the name B. urinarius. In 1885 Blanchard, considering Künstler’s organism a different parasite from Hassall’s, called it Cystomonas urinaria. Braun, in 1895, gave the name Plagiomonas urinaria. Barrois (1894) considered Künstler’s and Hassall’s organisms to be identical and not to be true parasites of man. Sinton,[48] in 1912, found the flagellate in the deposit, after centrifuging, of a 24-hour old specimen of alkaline urine from a Mexican sailor in the Royal Southern Hospital, Liverpool. Sinton found a kinetic nucleus or blepharoplast in the organism, and therefore placed it in the genus Prowazekia.
Fig. 24.—Types of Prowazekia urinaria. (a) sausage-shaped; (b) round; (c) carrot-shaped form. (After Sinton.)
The flagellate stage (fig. 24) of the organism is polymorphic, and may be either (a) sausage-shaped, 10 µ to 25 µ in length by 2·5 µ to 6 µ in breadth; (b) round or oval, varying from 4 µ in diameter to oval forms 15 µ by 10 µ; (c) a carrot-shaped form, of varying size up to 25 µ by 4 µ. The kinetic nucleus is large and pear-shaped. Near it are basal granules, closely applied to one another, from which the flagella arise. There is a small cytostome near the roots of the flagella. There is a well-marked karyosome in the nucleus. The movement is jerky. The shorter, anterior flagellum may be used in food-capture. In life, bacteria have been seen to be ingested. Food-vacuoles tend to accumulate at the posterior (aflagellar) end. A contractile vacuole may be present, near the base of the cytostome, and may really be the dilated fundus of the latter. Division occurs by binary fission. The organism can encyst (fig. 25, a), when the flagella are lost, and round or oval cysts are found, 5 µ to 7 µ in diameter. After a time flagella are formed inside the cyst, and the organism emerges therefrom in its typical flagellate form (fig. 25, b-f).
Sinton’s case is interesting. He obtained the flagellate only twice from the same patient, a Mexican then in hospital in Liverpool. The flagellate was not found in the patient’s fæces, nor was it found in the urine on later occasions when taken aseptically.