TRYPANOSOMES, TRYPANOSOMIASIS, AND SLEEPING SICKNESS 35 
TRYPANOSOMA EQUTNUM. MAL UE CADERAS' 
A large number of animals have been inoculated with this parasite. 
Rats — White, Black, and Grey 
Rats are easily infected. Subcutaneous inoculation causes the parasites to appear in 
two-and-three-quarters to three-and-a-quarter days. Intraperitoneal, two to two-and- 
a-half days. The average duration is six to eight days. In some few cases parasites 
have been found in the tail-blood in thirty-six hours, the blood is infective at this 
time. 
Mice — White and Grey 
Mice are infected somewhat earlier than rats. The duration of the disease is 
slightly shorter. 
In both rats and mice the incubation period and the duration of the disease is 
lengthened if the inoculated fluid is poor in trypanosomes. Sometimes one notes a 
temporary lessening in the number of the parasites, this usually lasts for one to three 
days, sometimes longer. The parasites then increase and usually continue to do so 
until death. Rats and mice inoculated with blood from animals undergoing treatment 
with arsenic, especially when the treatment has only been in force for a short period, 
develop the disease after a prolonged incubation. The parasites may appear for a few 
days and then disappear to remain absent or once more reappear, such animals are not 
protected. Loss of weight is noted both in rats and mice when showing marked 
infection. In some of the rats inoculated with the attenuated parasite the loss has 
been less marked and of only temporary duration. 
Rabbits 
The average incubation period has been four to five, sometimes six days. The 
duration has been sixteen to fifty-nine days. In a few of these animals the parasites 
have been fairly numerous in the peripheral blood, as many as ten to fifteen to a field 
being recorded. The majority of the infected rabbits duly show the parasites in very 
scanty numbers. The parasites are usually found in the blood when the temperature 
rises. Cases are recorded with a preliminary rise on the fourth to fifth day to 106° to 
io7°F. The fever is irregular, usually not passing 104 0 F. A few days before death 
the rise of temperature may be very marked, death occurring usually with a fall in the 
temperature. Loss of flesh and a somewhat marked anaemia is noted ; this latter 
symptom is not so marked as in rabbits inoculated with T. dimorphon or T. gambiense. 
Oedema at the base of the ears and around the genitals is often marked. Loss of hair 
around the eyes, nose, and base of ears is usually pronounced. 
I. We have been able to study this parasite through the courtesy of Professor Laveran. 
