Hindle's account is clear cut and circumstantial, and is quite in line with the work of Balfour, and of Leishman. Radically different is the interpretation of Marchoux and Couvy (1913). These investigators maintain that the granules localized in the Malpighian tubules in the larvæ and, in the adult, also in the ovules and the genital ducts of the male and female, are not derived from spirochætes but that they exist normally in many acariens. They interpret the supposed disassociation of the spirochæte into granules as simply the first phase, not of a process of multiplication, but of a degeneration ending in the death of the parasite. The fragmented chromatin has lost its affinity for stains, remaining always paler than that of the normal spirochætes. On the other hand, the granules of Leishman stain energetically with all the basic stains.
Further, according to Marchoux and Couvy, infection takes place without the emission of the coxal fluid and indeed, soiling of the host by the coxal fluid diluting the excrement is exceptional. All of the organs of the Argasid are invaded by the parasites, but they pass from the cœlom into the acini of the salivary glands and collect in its efferent canal. The saliva serves as the vehicle of infection.
Thus, the question of the life cycle of Spirochæta gallinarum, and of spirochætes in general, is an open one.
It should be noted that Argas persicus, the carrier of Spirochæta gallinarum, is a common pest of poultry in the southwestern United States. Though the disease has not been reported from this country, conditions are such that if accidentally introduced, it might do great damage.
Other Spirochæte Diseases of Animals—About a score of other blood inhabiting spirochætes have been reported as occurring in mammals, but little is known concerning their life-histories. One of the most important is Spirochæta theileri which produces a spirochætosis of cattle in the Transvaal. Theiler has determined that it is transmitted by an Ixodid tick, Margaropus decoloratus.
Typhus Fever and Pediculidæ
Typhus is an acute, and continued fever, formerly epidemically prevalent in camps, hospitals, jails, and similar places where persons were crowded together under insanitary conditions. It is accompanied by a characteristic rash, which gives the disease the common name of "spotted" or "lenticular" fever. The causative organism is unknown.
Typhus fever has not generally been supposed to occur in the United States, but there have been a few outbreaks and sporadic cases recognized. According to Anderson and Goldberger (1912a), it has been a subject of speculation among health authorities why, in spite of the arrival of occasional cases in this country and of many persons from endemic foci of the disease, typhus fever apparently does not gain a foothold in the United States. These same workers showed that the so-called Brill's disease, studied especially in New York City, is identical with the typhus fever of Mexico and of Europe.
The conditions under which the disease occurs and under which it spreads most rapidly are such as to suggest that it is carried by some parasitic insect. On epidemiological grounds the insects most open to suspicion are the lice, bed-bugs and fleas.