抄録
A trypanosomiasis closely related to Surra prevails among water-buffaloes, zebus and dogs in Formosa. The present paper deals with the systematic study on the prophylactic power of "Bayer 205" against experimental infection of mice, cattle and horses, which were inoculated with the Trypanosome isolated from an infected water-buffalo of Formosa. The results obtained are summarized as follows:
1. The Trypanosome is in all probability identical with Trypanosoma evansi, the causative agent of Surra, according to its geographical distribution, as well as to its morphological characters (Fig. 5) and results of animal experiments (Fig. 1, 6, 7, 2, 3-Cf. IX, 4-Po. XIV)
2. When subcutaneously injected with 0.005g (1/2, dosis tolerata) of "Bayer 205", mice are absolutely protected against the trypanosomal inoculation for 5 months after introduction. In the 6th month, however, the protection is not complete, and still later there is no protection (Table 5).
3. For comparison, we tried similar experiments with a large dose (about 1/2 dosis tolerata) of other trypanocidal preparations, such as trypaflavin, trypanblue, tartar emetic, neotrepol, atoxyl, neosalvarsan and silver salvarsan. Other chemicals revealed no or negligible effect, but neosalvarsan can keep animals non-infective for 3 days after application, and silver salvarsan for about 1 week (Table 1 and 2)
The above mentioned results show that "Bayer 205, " compared with other preparations, has a striking superiority in prophylactic action against the experimental trypanosomiasis of mice.
4. Experiments were again carried out with a smaller dose of "Bayer 205." By the introduction of 0.0001g mice are positively protected from infection for 1 week; but from 2 to several weeks after injection death from infection is generally delayed, while sometimes a complete protection or recovery after infection is observed (Table 3). After the dose of 0.00003g some of the injected mice are completely protected, and others have death delayed for several days. Finally, 0.00001g of the preparation has almost no prophylactic possibility in mice. Then we may accept 0.00003g as the minimum prophylactic dose of the present drug for mice (Table 4).
5. Calves, injected subcutaneously with 1.0g of "Bayer 205" per 100kg of the body weight, remain non-infective for 4 mon- ths after administration (Table 6, Fig. 3).
6. For horses, the same dose of the medicine has no positive protection, even 1 month after introduction. But, their death, compared with controls, is more or less delayed. If 2.0g per 100kg is used, however, the horse is satisfactorily prevented for 31/2 months (Table 7, Fig. 4).
7. Supplementary to the above, the experiment on rinderpest was attempted by the courtesy of Dr. C. Kakizaki. Even so large a dose as 4.0g of "Bayer 205, " however, could not produce any inhibitory action against the development of rinderpest in calves.
From the foregoing results, it is obvious that "Bayer 205" has a decided preeminence to any hitherto known chemotherapeutic drugs as the prophylactica against the trypanosomiasis. The fact that such a chemical artificially synthesized can protect both the small and large animals against the trypanosomal infection for several months, is truly worthy of "paru fantastique a Ehrlich", the phrase expressed by Fourneau (3). The discovery of "Bayer 205" then may be considered as an epoch-making event to open the field of "chemoprophylaxy" as salvarsan to chemotherapy.
