Fig. 55.—Spirochæta duttoni and its coccoid bodies in the tick (O. moubata).—Mononuclear cells of the tick (O. moubata) containing (a) Spirochæte breaking up into coccoid bodies; (b) Similar tick-cell containing coccoid bodies or granules. Such mononuclear cells occur in various organs of ticks and in developing Malpighian tubules. (Original. From preparations by Fantham.)
The spirochætes in the gut of infected ticks divide by a process of multiple transverse fission into granules, which are composed of chromatin (fig. [54]). These granules—sometimes known as coccoid bodies—are capable of multiplication. Leishman first found them in clumps inside the cells of the Malpighian tubules (cf. fig. 55).
To summarize, when spirochætes are ingested by a tick, some of them pass through the gut-wall into the hæmocœlic (body) fluid. They then bore their way into the cells of various organs (fig. 55a) and break up into coccoid bodies. In this manner the granules find their way into the ovaries and ova, thus explaining how the young ticks are born infected. Inoculation of these chromatinic granules usually produces infection. Infective granules are also seen in the rudiments of the Malpighian tubules of embryo ticks. Bosanquet and Fantham (1911), independently, have shown that molluscan spirochætes also break up into similar granules or coccoid bodies. Gross has also demonstrated multiple transverse fission in molluscan forms. Marchoux and Couvy (1913) and Wolbach (1914) consider the granules or coccoid bodies to be degeneration products. This is unlikely (see below).
Schuberg and Manteufel have found that certain O. moubata, perhaps 30 per cent. of the specimens of a given neighbourhood, may acquire a natural active immunity against infection with S. duttoni.
S. duttoni, or a closely allied form (by some termed S. novyi), occurs in Colombia, and is spread by the tick Ornithodorus turicata. In Panama a similar spirochæte is probably spread by O. talaje.
Spirochæta gallinarum, Stephens and Christophers, 1905
(= Spirochæta marchouxi, Nuttall, 1905).
This Spirochæte, which occurs in fowls and is pathogenic, is transmitted by the tick Argas persicus. It is about 10 µ to 20 µ long. There is a pathogenic spirochæte known to occur in geese, named by Sakharoff (1891) S. anserina, and found in Caucasia. This may be the same as S. gallinarum, in which case the name S. anserina will have priority. These organisms cause fever, diarrhœa, anæmia and death. The life history of the avian pathogenic spirochætes has been studied by Balfour, by Hindle[150] and by Fantham.[151] It is essentially similar to that of S. duttoni.
Marchoux and Couvy[152] (1913) consider that the “fragmentation of the chromatin” in spirochætes is a process of degeneration. Working with A. persicus and S. gallinarum, they state that a large number of the spirochætes ingested by the Argas almost immediately pass through the wall of the alimentary canal and appear in the hæmocœlic fluid. Marchoux and Couvy consider that Leishman’s granules may be found in the Malpighian tubules of various Arachnids. They found spirochætes in the cephalic glands of infected Argas. They consider that spirochætes remain as wavy spirochætes within the tick, if they are to be infective, though the spirochætes may become so thin as to be invisible! The latter argument is obviously weak, and it was never asserted that all granules in the Malpighian tubules of infected ticks were derived from spirochætes. With dark-ground illumination small, refractile spirochætal granules may be seen to grow into spirochætes. The granule phase of spirochætes has recently been discussed by Fantham[153] (1914).
Spirochæta recurrentis, Lebert, 1874.