Trypanosoma Equiperdum, Trypanosoma Brucei and Trypanosoma Hippicum Infections in Laboratory Animals

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  • Bacteriology Laboratory, Florida State University, Tallahassee, Florida
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Summary and Conclusions

Infections with T. equiperdum, T. brucei and T. hippicum have been produced in white rats, white mice, rabbits, hamsters, cotton rats, guinea pigs and deer mice. When the inoculum was standardized as to volume, number and age of parasites and route of injection, the incubation periods were as follows:

T. equiperdum (days)T. brucel (days)T. kippicum (days)
White rat (mature)233
White rat (young)133
White mouse133
Guinea pig359
Rabbit31028
Hamster344
Cotton rat224
Peromyscus mouse2610

The three strains of trypanosomes induced the same general symptoms in each species of the experimental hosts. The disease in the white rat, white mouse, hamster and cotton rat was an acute, progressive, fatal infection accompanied by a uniform increase in the parasite count of the blood.

Rabbits showed an unusual involvement of the respiratory tract, inflammation of the external genitalia and edematous lesions at various places on the skin, particularly about the eyes, ears and nose. Trypanosomes could be found in these areas in the early stages of their development, later the lesions became encrusted and broke down and the trypanosomes disappeared. The animals survived for periods of one to four months during which time the organisms were rarely found in the blood.

In the guinea pig there were no outward manifestations of the disease until shortly before death. The parasite count of the blood fluctuated within wide limits and the so-called relapse phenomenon was frequently observed.

The trypanosomes produced a chronic infection in the deer mouse. The animals survived, in some instances, more than three months. As in the guinea pig, the parasites varied from day to day, on occasions blood specimens examined daily for more than a week would be negative, to be followed by specimens rich in organisms. In all the infected hosts, with the exception of the rabbit, the parasites were small, slender, active forms at the time of their appearance in the blood. As the disease progressed they increased in size with many dividing stages present. In acute infections they became vacuolated, agglutinated, and at the time of the death of the animal no actively motile forms were found.

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