Life History of Echinostoma barbosai sp. n. (Trematoda: Echinostomatidae)

Abstract

The life cycle of Echinostoma barbosai, a new Brazilian species with 37 collar spines, has been completed experimentally. The planorbid snails Biomphalaria glabrata, B. tenagophila, and B. straminea serve as experimental first intermediate hosts. Sporocysts develop in the heart. First-generation rediae, when they remain in the heart cavity, produce rediae only; those passing to the viscera also produce cercariae. There are three or more redial generations. The same species of snails serve as second intermediate hosts, metacercariae being found in the pericardial sac and posterior part of the kidney. Adult worms are experimentally obtainable from chicks, ducklings, and pigeons. The natural host is unknown. Antagonistic interaction occurs when certain echinostome rediae develop together with sporocysts of various unrelated trematodes in the same snail (Lie, Basch, and Umathevy, 1965; Lie, 1966a). The various echinostomes in Biomphalaria glabrata (Say) are now being studied to observe interaction between these parasites and Schistosoma mansoni Sambon, 1907. During the course of these studies a new Echinostoma species having 37 collar Received for publication 25 May 1966. * Supported by the University of California International Center for Medical Research and Training (Hooper Foundation, San Francisco School of Medicine) with Research Grant TW 00144 from the Office of International Research, NIH, U. S. Public Health Service, and by Grant No. MSC-Hooper Foundation-02-Trevey Fund from the University of California School of Medicine Committee on Research, San Francisco Medical Center. spines was obtained from the Brazilian B. glabrata. Its life cycle is reported herein. MATERIALS AND METHODS Two of several hundred B. glabrata, collected near Recife, Brazil and flown to San Francisco, shed echinostome cercariae that formed the starting point for this study. These cercariae encyst in various snails. Adult pigeons and 2-week-old chicks and ducklings served as experimental hosts and were killed after egg-producing worms had developed. The worms were collected and eggs were obtained by teasing the uterus. Albino B. glabrata obtained from the National Institutes of Health, Bethesda, Maryland, served as first intermediate hosts. In living albino snails sporocysts and rediae are visible in the tissues. Infected snails were kept at a room temperature ranging from 26 to 29 C. The techniques employed in previous studies of Malayan echinostomes (Lie, 1963, 1965, 1966b, c) were used. All measurements are in microns unless otherwise stated. FIGURES 1-13a. Echinostoma barbosai sp. n. (Camera lucida drawings, unless otherwise stated. Projected scales are 50 ,u.) 1. Miracidium showing apical papilla, gut, eyespots, flame cells, and lateral processes. 2. Miracidium showing epidermal cells and excretory duct outlets. 3. Sporocyst containing rediae, birth pore in lower left corner. 4. Old empty sporocyst. 5. Mature first-generation redia containing rediae. 6. Second-generation redia containing cercariae. 7. Freehand drawing of cercaria showing arrangement of flame cells. 8-10. Patterns of papillae, shown only on tail and anterior part of cercaria. Papillae with seta indicated by small circles, those without seta by double circles; primitive excretory pore on tail by oval black body. 8. Ventral anterior part. 9. Dorsal anterior part. 10. Tail, left lateral view; fin folds not indicated. lla and lb. Freehand drawings of gland cell outlets in a cercaria. Para-esophageal gland-cell outlets indicated with black dots, penetration gland-cell outlets on dorsal lip of oral sucker with black triangles. lla. Ventral surface; note eight outlets on dorsal lip of oral sucker, four penetration gland cell outlets and four para-esophageal gland cell outlets. Ilb. Dorsal surface of same cercaria. Patterns on ventral and dorsal surface not entirely symmetrical since a number of outlets are not visible. 12. Tail, lateral view, showing dorsal and ventral fin folds. 13a. Tail, ventral view, with latero-ventral fin folds only. FIGURE 13b. Echinostoma audyi. Tail, ventral view, with small latero-ventral fin folds; same scale as Figure 13a.