YOKOYAMA Naoaki Professor

ThemeTo establish the control strategy for piroplasmosis from molecular biological and epidemiological approachs

Field Protozoology, Parasitology, Veterinary medicine, Livestock hygiene studies
Keyword Protozoa, Veterinary protozoan disease, Veterinary parasitic diseases, livestock hygiene, diagnosis, treatment, prevention, Babesia, Theileria, Neospora, Toxoplasma, Coccidia


Bovine piroplasmosis (bovine theileriosis and babesiosis) caused by species of genera Babesia and Theileria, is characterized by fever and anemia. The disease usually results in severe economic losses in cattle industry worldwide. However, preventive and control measures against bovine piroplasmosis have often been ineffective. With an ultimate aim of minimizing the incidence of bovine piroplasmosis, we conduct research to 1) determine the current status of bovine piroplasmosis in Japan and other endemic countries; 2) identify tick vectors transmitting bovine Theileria, and thereby establish systematic tick-control measures; 3) determine immunological responses against Theileria infection in cattle and develop vaccine; 4) clarify the mechanisms by which Babesia invades erythrocytes with the objective of vaccine development; 5) establish effective techniques and tools to analyze the genetic polymorphism in vaccine candidate antigens; and 6) develop made-to-order type subunit vaccines effective in different endemic regions. To expedite our aim of eliminating bovine piroplasmosis, we maintain a strong international collaborative network and accept postgraduate students and young postdoctoral researchers for the development of human resources in countries where bovine piroplasmosis is endemic.

Tick in Mongolia
Epidemiological survey in Mongolia
Epidemiological survey in Vietnam

List of current research topics

  • The influence of deer piroplasma on the onset of bovine small piroplasmosis
  • Development study of diagnostic method for bovine babesiosis in Sri Lanka
  • Development of vaccine against bovine piroplasmosis for increasing the efficiency of cattle grazing management and productivity
  • Development study of custom-made subunit cocktail vaccine against bovine babesiosis
  • Epidemiological studies on animal protozoan diseases in Mongolia and development of effective diagnostics measures
Academic degree D. Vet.
License Veterinarian
Self introduction

I graduated from Aichi Prefectural Handa Senior High School. I went to the department of veterinary medicine after being inspired by a book on ethology. As an undergraduate, I was interested in animal infectious diseases and I went on to graduate school. I'm proud to have studied a wide variety of microorganisms, such as bacteria as an undergraduate, viruses as a grad student, tumor viruses at the Aichi Cancer Center Research Institute, and protozoa at the National Research Center for Protozoan Diseases. At the National Research Center for Protozoan Diseases, I researched the pathophysiology of piroplasmosis parasites, which cause fever and anemia in cattle and horses. I also study how these protozoa proliferate and how they move through their life cycle, in order to diagnose and treat piroplasmosis and to develop a vaccine. I'm in charge of medicine involving protozoans, parasitology and infectious diseases. I like fishing and reading. I enjoy fishing in the mountain streams and sea of Tokachi.

Room addressNational Research Center for Protozoan Diseases
Room number105
Mail address yokoyama atmark obihiro.ac.jp


National Research Center for Protozoan Diseases/Department of Disease Control/Research Unit for Molecular DiagnosticsNational Research Center for Protozoan Diseases/Department of Global Cooperation/Research Unit for International SurveillanceResearch Center for Global Agromedicine/Department of Veterinary Medicine
Related industries Veterinary medicine, Livestock sanitation
Affiliated academic society The Japanese Society of Veterinary Science, Japanese Society of Veterinary Parasitologists, Japanese Society of Parasitology, Japanese Society of Tropical Medicine, Japan Society of Medical Entomology and Zoology
Academic background 1994 Department of Veterinary Science, Gifu University (Graduate)
1997 Department of Veterinary Science, The University of Tokyo (Doctoral course completion)
1997-2000 Researcher,Division of Virology, Aichi Cancer Center Research Institute
2000-2003 Lecturer,National Research Center for Protozoan Diseases,Obihiro University of Agriculture and Veterinary Medicine
2003-2012 Associate professor,National Research Center for Protozoan Diseases,Obihiro University of Agriculture and Veterinary Medicine
2012- Professor, National Research Center for Protozoan Diseases,Obihiro University of Agriculture and Veterinary Medicine