1. Wellcome Parasitology Unit No. 2, Institute of Pathobiology, Haile Sellasie I University, Addis Ababa, Ethiopia
2. U.S. Naval Research Unit No. 5, APO New York 09319, USA
3. Department of Vertebrate Zoology, Smithsonian Institution, U.S. Naval Medical Research Unit No. 5, APO New York 09319
4. Wellcome Parasitology Unit No. 2