Growth and Development of Strongyloides ratti Sandground, 1925, in the Albino Rat

Abstract

Growth and development of S. ratti were studied following percutaneous infection of albino rats with filariform larvae. The minimum time for each phase of migration or development was de- termined. Migration of larvae from the skin to the intestine was not simultaneous. Filariform larvae first arrived in the lungs 15 to 16 hr after exposure and were first encountered in the small intestine by the 34th hr. Two molts were observed, both in the intestine, the first 47 and the second 74 hr after exposure. The minimum time for development to maturity was 74 hr. Full size, however, was attained only after about 120 hr. Measurements taken at different stages of development of the parasite showed that length increments were maximal during the interim between the two parasitic molts and after the second molt. Development of S. ratti in the host is compared with that of other species of Strongyloides. Since first described by Sandground in 1925, Strongyloides ratti has been a subject for nu- merous investigations on various aspects of its biology and physiology. Till recently, however, little was known about the course of its de- velopment and growth in the host. The present investigation was undertaken with the aim of elucidating these points. A step in this direc- tion was recently taken by Abadie (1963) who followed the life cycle of S. ratti in the albino rat. In the present paper information on the parasitic molts as well as on rates of growth in various stages of development is presented. MATERIALS AND METHODS