Experimental Trichiniasis Infections in Monkeys.

Abstract

Apparently no experimental infections with Trichinella spiralis have been attempted in monkeys. In a summer's program of work at the Gorgas Memorial Laboratory, Panama, the following 7 species of Central American monkeys were found susceptible to infection with this parasite: the white-throated monkey, Cebuscapucinus, the black spider, Ateles dariensis, the red spider, Ateles geoffroyi, the brown and black howler, Alouatta palliata palliata and A. palliata inconsonans, the marmoset, Leontocehus geoffroyi, the yellow titi, Saimiri örstedii, and the night monkey, Aotus zonalis. All infections were given according to the body weight of the animals with counted numbers of trichina larvae obtained free from infected muscle by artificial digestion, and administered through a stomach tube. Doses of 5 larvae or more per gm. of body weight were invariably fatal, death occurring in from 3 to 41 days, depending on the size of the dose (Table I). Symptoms of fever, edema, and a marked eosinophilia, which characterize trichiniasis in human beings, did not develop in the monkeys. It will be noted (Table I) that considerable numbers of adult worms were still present in the intestines of monkeys that died 4 to 6 weeks after infection. The number of larvae that developed in the muscles in 6 monkeys was determined by grinding up and digesting the whole carcass. The relation of the number of larvae in the muscle to the number of larvae fed to the these monkeys ranged from 396 times to 1,108 times the infecting dose and averaged 698 times. These figures indicate that each female trichina produced about 1,500 larvae during the course of the infection. Other experiments have shown that rats develop a very definite immunity to reinfection with Trichinella spiralis.