Leishman’s methods and results may be summarized thus: Saline emulsions of the organs of infected ticks were made, after the organs had been most carefully dissected out. The ticks were first kept for several days at certain constant temperatures, such as 24° to 25° C. or blood heat, 37° C. The saline emulsions of the organs were inoculated, separately, into experimental animals, and the results recorded:—
| At 24° C. | At 37° C. | |
| Salivary glands | Negative | Positive |
| Malpighian tubules | Positive | Positive |
| Gut and contents | Positive | Positive |
| Excrement | Positive | Positive |
| Genital organs | Positive | Positive |
Coxal fluid is usually negative; thick, white excrement from Malpighian tubes is positive.
When the ticks were incubated at 21° to 24° C. no spirochætes, as such, were seen in the organs, except perhaps in the gut, where they often disappeared in a few days. When the ticks were previously incubated at 35° to 37° C. for two to three days, spirochætes, as such, reappear in the gut, organs and hæmocœlic fluid. The infection proceeds, not from the salivary gland, but from the infective excrement, that is, from the thick, white material voided by the tick while feeding, usually towards the end of the meal. This Malpighian excrement passes into the wound caused by the bite, being greatly aided by the clear and more limpid coxa fluid, which bathes the under surface of the tick’s body, and mixes with and carries the infective excrement into the wound. Ticks remain infective for a long time.
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 Hindle150 and by Fantham.151 It is essentially similar to that of S. duttoni.
Marchoux and Couvy152 (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 Fantham153 (1914).
Spirochæta recurrentis, Lebert, 1874.
Syn.: Spirochæta obermeieri, Cohn, 1875.
This organism was discovered by Obermeier (1873) in cases of relapsing fever in Berlin. Short forms 7 µ to 9 µ long, and longer (probably adult) forms, 16 µ to 19 µ, are found in the blood. The width is 0·25 µ. Parasites 12 µ or 13 µ long are often observed.
The spirochæte is found in the blood during febrile attacks and relapses, but not during intervening periods. It can be inoculated into monkeys, rats and mice. It can live in the bed-bug, Cimex lectularius, and Nuttall has succeeded in transmitting S. recurrentis from mouse to mouse by the bites of the same bug. The French investigators Sergent and Foley (1908–9) in Algeria, and Nicolle, Blaizot and Conseil (1912) in Tunis, have shown experimentally that S. recurrentis (var. berbera) is transmitted by lice. The latter workers also demonstrated the method of infection that commonly occurs, namely, by the scratching of the skin and crushing of lice containing spirochætes on the excoriated surface of the body.
Lice as transmitting agents for relapsing fever were indicated by Mackie154 in 1907. An epidemic among Indian school children furnished the materials.155 It was noted that out of 170 boys, 137 were infected, and the boys were very verminous. Among the girls, 35 out of 114 suffered, and few lice were found on them. Twenty-four per cent. of the lice taken from the boys contained spirochætes as compared with 3 per cent. of those from the girls. As the epidemic died out among the boys, the lice also became fewer, and an increase in the number of cases among the girls coincided with an increase in the number of lice. Spirochætes were found in the gut, Malpighian tubules and genital organs of the lice. Mackie thought that infection of the patients was brought about by the regurgitation of the spirochætes when the lice fed, but proof of this was lacking.
In 1912, Nicolle, Blaizot and Conseil,156 working in Tunis and using chiefly an Algerian strain of relapsing fever spirochætes (sometimes called S. berbera), showed by direct experiments that infection by means