- Email: [email protected]
Parasitology in Japan
Parasitology
372
Today, vol. 5, no.
i 2, I989
Parasitology in Japan I, Tada Despite recent criticisms of the raison d’&re of parasitology departments within medical schools in Japan, parasitology is still thriving and about 83% of the 80 medical schools in this country have parasitology or medical zoology departments. During the early I 960s the prevalence of soil- and vector-transmitted parasites was still high in Japan, a situation that could be seen as favourable for parasitologists and their institutions. However, parasitology may not now seem so attractive to those beginning a career in biology or medicine as only 0.5% of the Japanese population were estimated positive for helminth infections (excluding Enterobius). Although Anisakis remains prevalent as a result of the culinary tradition of eating raw fish (sashimi), this infection now seems to have little medical importance. Similarly the occasional case of elephantiasis among elders in rural Okinawan islands reminds us of a past era when bancroftian filariasis was endemic. So can parasitology flourish in a country when its parasites no longer do so, particularly as its young scientists prefer to work in the more quickly advancing fields of biology and medical science? The Japanese Society of Parasitology (Secretary-General, H. Tanaka, University of Tokyo, now Chiba Prefecture Institute of Hygiene) was established in I928 and at present has about 1000 members, including about IO0 from abroad. One of its most important functions is the production of the japanese )xmol of Parasitology (Editor-in-chief, K. Yasuraoka, University of Tsukuba). The society gathers annually at various venues throughout Japan and this year’s meeting was held in Tokyo from 3 to 5 April with H. Oya (Juntendo University) convening as president, and at which over 200 papers were presented. Apart from the annual general meeting, there are four meetings usually held in the autumn by local societies. In his presidential address to the spring meeting, Dr Oya described the role of cytochromes in the evolution of helminths living in anaerobic conditions. One invited speaker, P. Weinstein (University of Notre Dame, France), reviewed the relationship between vitamin BIz and helminths. Other focuses were a symposium entitled ‘Parasite biology and parasitic diseases’and a workshop on ‘Parasitology and development
assistance in developing countries’. This workshop revealed various problems in the expanding programme of international aid projects. In addition to presentations on traditional studies of the morphology, ecology and clinical pathology of parasites, approximately onethird of the papers were on immunological subjects. The recent international trend towards the use of molecular techniques is not yet very popular in Japan. However, circumstances are changing and there are a number of interesting projects in progress on a wide range of parasites. An earlier demonstration of triploidy in Paragonimus westermani in my laboratory’ has led to much debate on the identity and origin of this species. C-banding analysis has revealed that one set of chromosomes differs from two other homologous sets2 and isoenzyme studies have also supported the theory that triploid P. westermani has two different genomes3. Thus the question has arisen as to whether or not the triploid form can be distinguished from the diploid. Kamo’s group (Totton University) working on another helminth of national significance has recently clarified that the cestode that has long been considered as Diphyllobothrium latum in Japan differs morphologically, biochemically and pathogenically from the latter species and has proposed a new species called D. nihonkaiense4. Alternative treatments are being sought for Anisakis to substitute for the drastic endoscopic extirpation from the stomach that is currently used. Chemotherapeutic trials are underway using reagents such as ginger extract? and mebendazole? however, paying more attention to the risks involved in eating raw fish would probably be more effective at eliminating this parasite than treatment. Parasitology in Japan is not confined to locally important species and the emphasis is shifting to tropical diseases. Schistosomiasis has been one of our traditional targets of research. Immunological studies have discovered a mouse monoclonal IgE antibody, SJ I8 E. I , that recognizes a specific epitope on Schistosoma japonicum and will kill schistosomules migrating between the skin and lungs7. Another exciting finding is the detection of mouse type C and A retrovirusrelated sequences in the genomes of 5. japonicum and S. mansoni’. Furthermore,
a surface protein of BALB virus 2 has been found in the tegument and vitellaria of schistosomes. These discoveries suggest the possibility of a new profile of parasite evasion mechanisms that relate to antigenic mimicry. In malariology, a vaccine model using Plasmodium berghei, strain NK65XAT9, attenuated by X-irradiation, is noted for its stability and the good protective immunity it engenders. Another promising study has shown that the pl90 antigen from P. falciparum is encoded by dimorphic alleles and missing silent copies”. Investigations along these lines seem likely to produce results of importance for vaccination trials. In Japan the recent tendency has been for retiring parasitologists to be replaced as department chiefs by parasitologists turned immunologists. This is certainly encouraging to the development of parasite immunology In a rather conservative environment, and in the near future it is hoped that more molecular biologists will be recruited. On the other hand, staff properly trained in field techniques are still in demand because of the extension of field studies in developing countries resulting from the recent increase in development assistance projects sponsored by the Japanese government. Parasitology in Japan is assured In the immediate future and it will be interesting to see some of the Japanese contributions to this subject in future issues of Parasitology Today. References I Sakaguchi, Y. and Tada, I. (I 976) Chromosome I$ Serv. 20,23-24 2 Hlral, H. et al. (1985) Z. Porcwtenkd. 71, 6 17-629 3 Agatsuma, T. and Habe, S. (I 985) Parasrtolog): 9 I, 489-497 4 Yamane, Y. et al. (I 986)ShimaneJ. Med. Ser. IO, 29-48 5 Kasuya. S. eta/. (I 989)Jpn.J. Parositol. 38, Suppl. 92 6 Oshlma. T. et al. (1989) jpn. 1. Parosrtol. 38, Supple. 93 7 Kojma. S. et al. (I 987) J, Immunol. 139, 20442049 8 Tanaka, M. et al. Parositofogy(in press) 9 Suzuki, M. et al. (I 987) Zbl. Bakt. Hyg. A 264, 3 19-325 IO Tanabe, K. et al. (1987) J. Mol. 6101. 195. 273-287
lsoo Tada Diseases,
is at the Kumamoto
University,
860, jopan,
Kumamoto become
Department
a member
Parasitology
Today.
ond
of Parasitic 2-2-I has
of the editorlal
Horyo, recently board
of
372
Today, vol. 5, no.
i 2, I989
Parasitology in Japan I, Tada Despite recent criticisms of the raison d’&re of parasitology departments within medical schools in Japan, parasitology is still thriving and about 83% of the 80 medical schools in this country have parasitology or medical zoology departments. During the early I 960s the prevalence of soil- and vector-transmitted parasites was still high in Japan, a situation that could be seen as favourable for parasitologists and their institutions. However, parasitology may not now seem so attractive to those beginning a career in biology or medicine as only 0.5% of the Japanese population were estimated positive for helminth infections (excluding Enterobius). Although Anisakis remains prevalent as a result of the culinary tradition of eating raw fish (sashimi), this infection now seems to have little medical importance. Similarly the occasional case of elephantiasis among elders in rural Okinawan islands reminds us of a past era when bancroftian filariasis was endemic. So can parasitology flourish in a country when its parasites no longer do so, particularly as its young scientists prefer to work in the more quickly advancing fields of biology and medical science? The Japanese Society of Parasitology (Secretary-General, H. Tanaka, University of Tokyo, now Chiba Prefecture Institute of Hygiene) was established in I928 and at present has about 1000 members, including about IO0 from abroad. One of its most important functions is the production of the japanese )xmol of Parasitology (Editor-in-chief, K. Yasuraoka, University of Tsukuba). The society gathers annually at various venues throughout Japan and this year’s meeting was held in Tokyo from 3 to 5 April with H. Oya (Juntendo University) convening as president, and at which over 200 papers were presented. Apart from the annual general meeting, there are four meetings usually held in the autumn by local societies. In his presidential address to the spring meeting, Dr Oya described the role of cytochromes in the evolution of helminths living in anaerobic conditions. One invited speaker, P. Weinstein (University of Notre Dame, France), reviewed the relationship between vitamin BIz and helminths. Other focuses were a symposium entitled ‘Parasite biology and parasitic diseases’and a workshop on ‘Parasitology and development
assistance in developing countries’. This workshop revealed various problems in the expanding programme of international aid projects. In addition to presentations on traditional studies of the morphology, ecology and clinical pathology of parasites, approximately onethird of the papers were on immunological subjects. The recent international trend towards the use of molecular techniques is not yet very popular in Japan. However, circumstances are changing and there are a number of interesting projects in progress on a wide range of parasites. An earlier demonstration of triploidy in Paragonimus westermani in my laboratory’ has led to much debate on the identity and origin of this species. C-banding analysis has revealed that one set of chromosomes differs from two other homologous sets2 and isoenzyme studies have also supported the theory that triploid P. westermani has two different genomes3. Thus the question has arisen as to whether or not the triploid form can be distinguished from the diploid. Kamo’s group (Totton University) working on another helminth of national significance has recently clarified that the cestode that has long been considered as Diphyllobothrium latum in Japan differs morphologically, biochemically and pathogenically from the latter species and has proposed a new species called D. nihonkaiense4. Alternative treatments are being sought for Anisakis to substitute for the drastic endoscopic extirpation from the stomach that is currently used. Chemotherapeutic trials are underway using reagents such as ginger extract? and mebendazole? however, paying more attention to the risks involved in eating raw fish would probably be more effective at eliminating this parasite than treatment. Parasitology in Japan is not confined to locally important species and the emphasis is shifting to tropical diseases. Schistosomiasis has been one of our traditional targets of research. Immunological studies have discovered a mouse monoclonal IgE antibody, SJ I8 E. I , that recognizes a specific epitope on Schistosoma japonicum and will kill schistosomules migrating between the skin and lungs7. Another exciting finding is the detection of mouse type C and A retrovirusrelated sequences in the genomes of 5. japonicum and S. mansoni’. Furthermore,
a surface protein of BALB virus 2 has been found in the tegument and vitellaria of schistosomes. These discoveries suggest the possibility of a new profile of parasite evasion mechanisms that relate to antigenic mimicry. In malariology, a vaccine model using Plasmodium berghei, strain NK65XAT9, attenuated by X-irradiation, is noted for its stability and the good protective immunity it engenders. Another promising study has shown that the pl90 antigen from P. falciparum is encoded by dimorphic alleles and missing silent copies”. Investigations along these lines seem likely to produce results of importance for vaccination trials. In Japan the recent tendency has been for retiring parasitologists to be replaced as department chiefs by parasitologists turned immunologists. This is certainly encouraging to the development of parasite immunology In a rather conservative environment, and in the near future it is hoped that more molecular biologists will be recruited. On the other hand, staff properly trained in field techniques are still in demand because of the extension of field studies in developing countries resulting from the recent increase in development assistance projects sponsored by the Japanese government. Parasitology in Japan is assured In the immediate future and it will be interesting to see some of the Japanese contributions to this subject in future issues of Parasitology Today. References I Sakaguchi, Y. and Tada, I. (I 976) Chromosome I$ Serv. 20,23-24 2 Hlral, H. et al. (1985) Z. Porcwtenkd. 71, 6 17-629 3 Agatsuma, T. and Habe, S. (I 985) Parasrtolog): 9 I, 489-497 4 Yamane, Y. et al. (I 986)ShimaneJ. Med. Ser. IO, 29-48 5 Kasuya. S. eta/. (I 989)Jpn.J. Parositol. 38, Suppl. 92 6 Oshlma. T. et al. (1989) jpn. 1. Parosrtol. 38, Supple. 93 7 Kojma. S. et al. (I 987) J, Immunol. 139, 20442049 8 Tanaka, M. et al. Parositofogy(in press) 9 Suzuki, M. et al. (I 987) Zbl. Bakt. Hyg. A 264, 3 19-325 IO Tanabe, K. et al. (1987) J. Mol. 6101. 195. 273-287
lsoo Tada Diseases,
is at the Kumamoto
University,
860, jopan,
Kumamoto become
Department
a member
Parasitology
Today.
ond
of Parasitic 2-2-I has
of the editorlal
Horyo, recently board
of