A historical review of the study on biology of the dwarf tapeworm Hymenolepis nana

Abstract

The purpose of the research: to submit a review of national and foreign literature on biological research of Hymenolepis nana. Materials and methods. Papers on morphology and biology of H. nana (starting from the first discovery of H. nana in 1851 by German parasitologist T. Bilharz until the present moment) written by 26 native and 11 foreign authors served as research material. When analyzing the literature, special attention was paid to the results of the morphological study and development cycle of H. nana taking into account the developmental stages of cestodes. Results and discussion. Specific data on morphology of H. nana and pictures of scolex and proglottids of the dwarf tapeworm using scanning electronic microscopy were provided. Structure of H. nana eggs was described in detail. Most papers are dedicated to the study of biological features of development. Sometimes, H. nana is reproduced by budding (passing through the following development cycle: megalospheres, metamers, invagination, scolexogenesis, larval cysts). Eggs were found in animals’ feces 17-18 days after infestation. H. nana lives in human body for several years, and sometimes 20-38 years. Issues related to the species identity of H. nana and H. fraternal, and mechanisms of transmission and prevalence of infection are discussed. Prevalence of hymenolepiasis in different countries depends not on climate conditions but on the degree of population density. Contamination of hands is an important factor influencing the frequency of hymenolepiasis autoinvasion in patients. The role of rodents as a source of H. nana infection is not essential.