Family. Piroplasmidæ, França.
The parasites included in this provisional family or group belong to the Hæmosporidia. They are minute organisms, sometimes amœboid, but usually possessing a definite form. They are endoglobular, being contained within mammalian red blood corpuscles, but they produce no pigment. The true Piroplasmata, belonging to the genus Babesia, destroy the host corpuscles, setting free the hæmoglobin, which is excreted by the kidneys of the cow, sheep, horse, dog, etc., acting as host. The disease produced, variously called piroplasmosis or babesiasis, is consequently characterized by a red coloration of the urine known as hæmoglobinuria, or popularly as “red-water.” One of the best known piroplasms is Piroplasma bigeminum or Babesia bovis (probably the latter name is correct), which is the causal agent of “Texas fever” or “red-water” in cattle and is spread by ticks.
Fig. 90.—Nuttallia equi, life-cycle as seen in red blood corpuscles in stained preparations of peripheral blood. (After Nuttall and Strickland.)
Of recent years, researches on the morphology of these blood parasites has led to their separation into various genera and species. However, our knowledge is still very far from complete. The various genera recognized by França[210] (1909), and placed in a provisional family, Piroplasmidæ, may be listed, though further research may lead to emendations:—
(1) Babesia (Starcovici) or Piroplasma (Patton). Pyriform parasites, dividing by a special form of budding or gemmation with chromatin forking, as well as by direct binary fission. Parasitic in oxen, dogs, sheep, horses, etc.
(2) Theileria (Bettencourt, França and Borges). Rod-shaped and oval parasites occurring in cattle and deer. T. parva is the pathogenic agent of African East Coast fever in cattle.
(3) Nuttallia (França). Oval or pear-shaped parasites, with multiplication in the form of a cross. N. equi[211] (fig. 90) of equine “piroplasmosis” (nuttalliosis). N. herpestidis in a mongoose.
(4) Nicollia (Nuttall). Oval or pear-shaped parasites with characteristic nuclear dimorphism, and with quadruple division at first fan-like, then like a four-leaved clover. N. quadrigemina from the gondi.