TRYPANOSOMIASIS EXPEDITION TO THE CONGO 
81 
Strain derived from Cerebro-Spinal Fluid of Sleeping Sickness, Case 6, 1 in 
the Congo Free State. 1 
Rats. — Twenty-three experiments. Incubation period : young rats from three 
to nine days ; adult rats from four to ten days. Duration from seventeen to 
one hundred and seventy-six days. Some of the animals have shown parasites fairly 
constantly, and in moderate numbers ; in others the organisms have disappeared for 
some time or have been present in small numbers. We have rats which have lived 
as long as one hundred and seventy-six days, but in the blood of such animals the 
parasites are either found only in rare instances or not at all. 
Mice. — Incubation from four to eleven days. Duration over ninety-two days. 
Parasites usually rare. 
Guinea-pigs inoculated more than fifty days ago have not shown parasites as yet. 
Rabbits. — Incubation after intravenous inoculation from three to four days. 
There was a slight rise of temperature on the day of infection and the following day. 
Cats. — Two experiments. i. Intravenous inoculation from a rat. Incubation 
period, eight days. Parasites were constantly present. On the twelfth day there 
were five to a field. 2. Intraperitoneal inoculation from a rat. Incubation period, 
eight days. No symptoms have as yet been observed. 
Dogs. — Two experiments. 1. An adult dog inoculated intravenously from a 
rat. , Parasites were seen on the fifth day. They were not numerous at first, but are 
increasing and constantly present. 2. A puppy, tour months old, inoculated 
intraperitoneally from a monkey. Incubation period, eight days. No symptoms 
have as yet been observed. 
Goat. — An adult, inoculated intraperitoneally from a monkey. The temperature 
rose on the evening of the fifth day to 106-5° F. ; next day the temperature was 
io4"2° ; a rat inoculated on this day is not yet positive. Parasites have not yet 
been seen in the blood of this goat. 
Monkeys. — 1. Macacus rhesus. Experiment 497. Inoculated intraperitoneally from 
a rat. Incubation period six days. Parasites have been constantly present in the 
blood and have steadily increased in numbers. On the day of the appearance of the 
parasites the temperature rose to ic6 u F. 2. Cercopithecus callitrithus. Inoculated 
February 15 intraperitoneally from a rat. Parasites appeared in the blood on February 
20. The temperature on the 21st was 103"8°F. Trypanosomes were constantly 
present in fair numbers until April 5. Since then they have been rarely found, and 
in only small numbers. No symptoms were observed. The animal was in good 
condition. There was slight diminution of haemoglobin and red cells. 
Dtitton, To.U, and Christy, Human Trypanosomiasis on the Congo, etc., Brit. Med. Jour., Jan. 23, 1904, pp. 186-188. 
This strain was s;nt to us in a rat inoculated with cerebro-spinal fluid from a ca3e of sleeping sickness. 
