The Animal Parasites of Man

by Harold Benjamin Fantham; Max Braun; J. W. W. Stephens; Fred. V. Theobald

Another ally of the Trypanosomidæ, Trypanophis, lives in the cœlenteric cavity of Siphonophores. It has also an extra terminal flagellum (Poche, Keysselitz). [Trypanoplasma and Trypanophis belong to the Bodonidæ, see p. [63]].

Finally it was shown that Trypanosomes occurred in human beings. Although Nepveu’s early report of trypanosomes in the blood of malarial patients may be doubtful, subsequent researches by Forde and Dutton demonstrated trypanosomes (fig. [28]) in the blood of a European, apparently suffering from malaria, living in the Gambia. Dutton (1902) called the human trypanosome, T. gambiense. The expedition despatched by the Liverpool School of Tropical Medicine (1902) to Senegambia found trypanosome infections in six cases among a thousand inhabitants examined.

About the same time attention was devoted to the disease of West African negroes known for a century as “sleeping sickness.” Castellani (1903) was the first to succeed in demonstrating the presence of trypanosomes (at first called T. ugandense) in centrifugalized cerebro-spinal fluid obtained by puncture from cases of sleeping sickness in Uganda. Similar discoveries were made by Bruce, who also found trypanosomes in the blood of those attacked with sleeping sickness. Sambon regarded a species of Glossina as the transmitter. From consideration of the geographical distribution of the disease Christy regarded Glossina palpalis as the transmitter. Brumpt first thought it was G. morsitans, but, later, supported the view of G. palpalis. Bruce, Nabarro and Greig also named the same insect as the transmitter, not only for geographical reasons but also because healthy apes became infected by the bite of certain G. palpalis. The inoculation of cerebro-spinal fluid from subjects of sleeping sickness into the spinal canal of apes (Macacus) had the same result.

Just as the discovery of the malarial parasites called forth a whole flood of research memoirs which were followed by a second series on the relation of the mosquitoes to malaria, so a similar outpouring occurred after the discovery of the pathogenic trypanosomes of mammals and men. In both cases the inquiry was not limited to the stages in man and other vertebrate hosts, but the fate of the parasites in the intermediate (invertebrate) hosts was investigated, and allied species were obtained from many different hosts.

Novy and MacNeal (1903) were the first to cultivate trypanosomes in artificial media (blood-agar).

In 1910 Stephens and Fantham recorded the presence of another human trypanosome, T. rhodesiense, from a case of sleeping sickness in Rhodesia, where G. palpalis was absent. Kinghorn has since demonstrated that T. rhodesiense is transmitted by G. morsitans. Kinghorn and Yorke believe that big game (e.g., antelope) is the reservoir of T. rhodesiense.

The output of literature on trypanosomiasis in men and animals is enormous. To cope with it the Sleeping Sickness Bureau Bulletin was founded in 1908, and it is now (since November 1912) continued as a section of the Tropical Diseases Bulletin, wherein current literature is reviewed.

General.

Trypanosomes occur in the blood of representatives of all the vertebrate classes. Often the trypanosomes occur so scantily in the blood that they are overlooked on examination. A useful aid in detecting the flagellates in such cases consists in the use of cultures of the blood of the host on artificial media. Stimulated by the medium multiplication occurs, and hence the parasites are more easily detected. [For the composition of such culture media see Appendix.]

There is a periodicity in the appearance of the trypanosomes in the peripheral blood of the host, due to alternating phases of multiplication and of rest on the part of the parasites. Such periodicity has been established both by biological and enumerative methods. Again, a seasonal variation has been observed in the occurrence of certain trypanosomes in the peripheral circulation of the hosts; for example, some trypanosomes (e.g., T. noctuæ in birds) are found only in the summer in the blood, while in the winter they occur in the internal organs.