HELMINTHOLOGIA, 40, 2:65-75, 2003

Taxonomy and biology of proteocephalidean cestodes:current state and perspectives


Institute of Parasitology, Academy of Sciences of the Czech Republic, Branišovská 31, 370 05 České Budějovice, Czech Republic, E-mail: tscholz@paru.cas.cz; *Département des Invertébrés, Muséum d’histoire naturelle,PO Box 6434, CH-1211 Geneva 6, Switzerland


  The order Proteocephalidea includes almost 400 species of tapeworm parasites (Cestoda) of fish, amphibians, and rep-tiles, with one species recently found in a mammal (the black-eared opossum in Mexico). Members of the order ty-pically possess four muscular suckers on the scolex, which may also have an apical organ (glandular or glandulo-mus-cular), a functional or vestigial apical sucker, or a rostellum-like organ armed with hooklets, thus resembling that of cyclophyllidean cestodes. Presumably, a narrow host specificity of species parasitic in siluriform fish in the Neo-tropical region, would make the proteocephalideans a suitable model for studies of parasite-host co-evolution. However, the systematics of the order and the phylogenetic relationships of individual genera and subfamilies are insufficiently known. The validity of the Monticelliidae, one of the only two existing proteocephalidean families, has even been questioned. Molecular data (sequences of 18S and 28S rRNA genes) also support the invalidity of the Mon-ticelliidae. Sequencing has provided valuable information but has still failed to resolve phylogenetic relationships of the Proteocephalidea, especially the numerous genera and species parasitic in Neotropical catfish. It is now obvious from molecular data that the most abundant genera, such as Proteocephalus and Ophiotaenia, are artificial assembla-ges of unrelated taxa, but much more information is neces-sary for a better understanding of interrelationships within individual proteocephalidean subfamilies as well as rela-tionships of proteocephalideans to tetraphyllidean and other cestodes. The information about the life-cycles of proteocephalideans is also scarce, with the most data relat-ed to the development of the species of Proteocephalus and Ophiotaenia from freshwater fish and reptiles in the Holarctic region. In the Neotropics, fish and possibly other lower vertebrates probably serve as the second intermediate or paratenic hosts but no detailed data based on experimental infections or field observations are yet available.


HELMINTHOLOGIA, 40, 2:79-85, 2003

The nitrergic nervous system in flatworms


Department of Biology, Åbo Akademi University, Artillerigatan 6, FIN-20520 Åbo, Finland; 1Institute of Parasitology, Russian Academy of Sciences, Lenin Avenue 33, 117071 Moscow, Russia, E-mail: magustaf@abo.fi


In order to bring the knowledge about the nitrergic nervous system in flatworms one step further, the pattern of cGMP immunostaining (IS), after stimulation with a nitric oxide donor, and in the presence of an inhibitor of phosphodies-terase, was studied in activated plerocercoid larvae of Diphyllobothrium dendriticum and in adult Fasciola hepa-tica. In D. dendriticum, cGMP-IS was detected in multi-polar nerve cells and in nerve fibres close to muscle fibres and in many terminals beneath the tegument. In F. hepa-tica, cGMP-IS was detected in nerve fibres around the oral sucker, in the main nerve cords and around the intestinal ducts. The pattern of cGMP-IS was compared to that of the NADPH-diaphorase staining, the 5-HT-IS, and the GYIR-Famide-IS. The cGMP-IS, the NADPH-d staining and the 5-HT-IS occur in separate sets of nerves. However, in F. hepatica, coexistence was observed between the cGMP-IS and the GYIRFamide-IS.


HELMINTHOLOGIA, 40, 2:87-91, 2003

Phylogeny of anisakid nematodes: a review


Department of Sciences of Public Health, Parasitology Section, University of Rome "La Sapienza", P. le Aldo Moro 5,00185 Rome, Italy,  E-mail: sdamelio@uniroma1.it


  The systematics and classification of anisakid nematodes and the relationships among genera and species have been the subject of many speculations. DNA nucleotide sequen-ces have been used for the inference of the phylogenetic relationships among anisakid taxa. These studies have pro-vided a new insight into the evolution of this parasitic group. Here, three examples of such studies are given: 1) at population level (the Phocascaris phocae/cystophorae pro-blem); 2) at species level (taxonomic rank and evolution of Contracaecum osculatum baicalensis); 3) at genus level (the phylogenetic relationships among species of Contra-caecum and Phocascaris).


HELMINTHOLOGIA, 40, 2:93-95, 2003

Is postcyclic transmission under estimated as an epizootiological factor for acanthocephalans?

B. Nickol

School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA, E-mail: bnickol@unlnotes01.unl.edu


  Postcyclic transmission is taken to mean the transfer of adult worms from one definitive host to another. Such transmission of enteric worms is known to be possible for acanthocephalans of ten species. There have been many claims for the significance of postcyclic transmission, but to be of life history importance, the transferred worms must survive long enough to mature or sexually mature worms must transfer. Unlike paratenic transmission, which results from transfer of cystacanths located extraintestinally in the prey host, the intestinal location of worms to be transferred postcyclically gives no apparent clue to its occurrence in nature. Studies that demonstrate laboratory transfer and survival to maturity and successful transfer of gravid acanthocephalans are beginning to accumulate, however. The apparent ease with which enteric worms are transferred in the laboratory suggests that postcyclic transmission is important in nature. Such transmission of enteric worms through predation or cannibalism could distribute acanthocephalans to groups of animals that otherwise would be inaccessible.


HELMINTHOLOGIA, 40, 2:97-102, 2003

The future of anthelmintics in sustainable parasite control programs for livestock

P. J. Waller

c/- SWEPAR, National Veterinary Institute, Uppsala SE-751 89, Sweden, E-mail: Peter.Waller@sva.se


  The development of resistance to all the currently available anthelmintic classes by the important nematode parasites of grazing livestock presents a major challenge to the continuation of efficient livestock productivity. The situation is most serious in the small ruminant (sheep and goat) industries, particularly in the hot and humid regions of the world, but is escalating at such a rate that all countries with significant sheep and goat numbers must consider that tackling this problem is an urgent priority. Although anthelmintic resistance in cattle parasites appears to be of minor concern, there is clear evidence that this is now increasing. This review presents an overview of the principles developed by experts, on ways to manage the conflicting objectives of efficient worm control and at the sa-me time delay the selection for anthelmintic resistance.


HELMINTHOLOGIA, 40, 2:103-108, 2003

Trichinella prevalence in the domestic and sylvatic cycle and its importance as foodborne pathogen

K. Nöckler

Federal Institute for Risk Assessment, Diedersdorfer Weg 1, 12277 Berlin, Germany, E-mail: k.noeckler@bfr.bund.de


  Human trichinellosis poses a threat for human health world wide. The paper refers to the current situation in Europe where four autochthonous Trichinella species namely T. spiralis, T. britovi, T. nativa and T. pseudospiralis were discovered up to now. Every year human trichinellosis cases occur in many European countries due to the consumption of raw or improperly treated pork, wild boar or horse meat which could pass the food chain because of a failure in meat inspection. In this context epidemiological aspects of Trichinella in the domestic and sylvatic cycle are explained and natural and artificial factors for the maintenance as well as risk factors to acquire trichinellosis are presented. Conclusions refer to the current needs for improv-ing consumer protection according to the “White Paper on Food Safety” of the European Commission which gives emphasis on a modern risk analysis consisting of risk assessment, risk communication and risk management measures.


HELMINTHOLOGIA, 40, 2:109-115, 2003

Aspects of human helminthiasis in sub-Saharan Africa


WHO Collaborating Centre for Soil-Transmitted Helminthiases, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, Scotland, E-mail: dwtc@tyndrum.demon.co.uk


  The people of sub-Saharan Africa are the world’s most heavily afflicted population in terms of the burden of disease involving helminth infections. Despite numerous control programmes, helminth infections persist and, in some case, may be increasing. The current situation is reviewed and new initiatives based on deworming measures are discussed. Attention is drawn both to progress and to the challenges that must be overcome if morbidity due to helminthiasis is to be controlled and reduced in sub-Saharan Africa.


HELMINTHOLOGIA, 40, 2:117-121, 2003

Development of molecular tools to explore genetic diversity in Echinococcus multilocularis

J. M. Bart, I. Breyer1, B. Gottstein1, T. Romig2, R. Piarroux

Santé Environnement Rural, Université de Franche-Comté, Besancon, France; 1Institute of Parasitology, University of Berne, Berne, Switzerland, E-mail. bruno.gottstein@ipa.unibe.ch; 2Section Infectiology, University of Ulm, Ulm, Germany, E-mail: romig@uni-hohenheim.de


  In order to identify risk factors for the occurrence of alveolar echinococcosis on both regional and local levels in Europe, studies have to be performed to describe factors influencing the infection pressure to the human population, with special emphasis on the changing epidemiological situation in transmitting animals. However, risk of infection may not only be determined by the abundance of, and contact with, parasitic eggs, but also by genetically fixed differences in pathogenicity between parasite strains. Therefore, typing of isolates collected from different areas in foxes, as well as in humans presenting with various lesions, should lead to a better understanding of the putative role of the genetic diversity of Echinococcus multilocularis. In addition, if such differences would correlate with the region of origin, a valuable tool would be available to trace sources of infection. Unfortunately, to date, with the genetic markers currently used, very limited variation have been detected within the world-wide population of E. mul-tilocularis. Consequently, the differences, in terms of pre-valence, pathogenicity or susceptibility to chemotherapy, observed in humans in the three main foci (Europe, Asia and North America) could not be correlated with the putative genetic typing of the parasite. Development of highly sensitive molecular tools which can detect genetic variations in small populations, would be useful for tracking the spatial and temporal dynamics of the infection of humans. With regard to results obtained with other pathogens, such as Leishmania, Candida, Schistosoma, microsatellite analysis and single nucleotide polymorphisms (SNPs) asses-sed by single-stranded conformational polymorphism or Constant Denaturant Capillary Electrophoresis (CDCE) may prove their relevance and their power of discrimi-nation and finally allow for a distinction between closely-related genotypes.