T. Agatsuma

Paragonimiasis and the genus Paragonimus.

The review concentrates on literature that has appeared since the 1960s. Since then, numerous species of Paragonimus have been described, mainly from Asia but also from Africa and the Americas. Some of these cause disease in humans. Recent information on life cycles and routes of transmission is summarized. All described species and their hosts are listed, with synonyms where known. For well-known species such as Paragonimus westermani, subspecific taxa and strains are reviewed and genetic studies discussed. Paragonimiasis in humans and experimental animals is discussed with emphasis on clinical manifestations and pathology, diagnosis, immune interactions with the host, treatment and public health issues.

Geographical genetic structure within the human lung fluke, Paragonimus westermani , detected from DNA sequences

Nucleotide sequences were obtained for the second internal transcribed spacer of the ribosomal gene repeat and for part of the mitochondrial-cytochrome c oxidase subunit I gene from geographical isolates of Paragonimus westermani from Japan, China, Korea, Taiwan, the Philippines, peninsular Malaysia and Thailand. Sequences were obtained from several other species of Paragonimus for comparative purposes. Two groups were recognized within P. westermani: an NE group (China, Japan, Korea, Taiwan) which was relatively uniform and included both diploid and triploid forms, and a southern group (Malaysia, Thailand, Philippines), members of which were genetically distant from one another. According to both ITS2 and COI data, genetic distances among P. westermani isolates equalled or exceeded those between some distinct species of Paragonimus. The ITS2 sequences were conserved relative to COI sequences. Substitutions among the latter may be approaching saturation within the genus Paragonimus.

Chromosomal differentiation of the Schistosoma japonicum complex

The C-banding pattern, location of telomere sequence and chiasma frequency of four species of the Schistosoma japonicum complex were compared with those of two African species, Schistosoma mansoni and Schistosoma haematobium. In the six species, C-banding patterns of seven autosomes and the two sex chromosomes (Z and W) showed relatively species-specific and geographical (Asian and African) differences. Particularly, a plausible pathway of alteration of chromosome 2 revealed a direction from the A-chromosome to the M- chromosome in terms of rearrangements of pericentric inversion and elimination of constitutive heterochromatin (AM inversion). This chromosome change suggested hypothetically that the S. japonicum complex is the original type, and the African species represents the derived type. Moreover, the mosaic construct of the Asian and African types in Schistosoma sinensium chromosomes prompted us to propose that the species might have been formed by hybrid speciation of the genomes of Asian and African species. Localisation of telomeric repeats enabled Asian and African schistosomes to be distinguished clearly by simple terminal location and by terminal and interstitial locations, respectively. Change of chiasma frequency in the S. japonicum complex might be caused by the reduction of interstitial chiasmate (Xi) in the larger chromosomes, 1 and Z (or W), and the change seems to have progressed to Japan from South East Asia. These data enabled us to predict a tentative evolutionary pathway of schistosomes at the cytogenetic level.

A molecular perspective on the genera Paragonimus Braun, Euparagonimus Chen and Pagumogonimus Chen

The status of the genera Euparagonimus Chen, 1963 and Pagumogonimus Chen, 1963 relative to Paragonimus Braun, 1899 was investigated using DNA sequences from the mitochondrial cytochrome c oxidase subunit I (CO1) gene (partial) and the nuclear ribosomal DNA second internal transcribed spacer (ITS2). In the phylogenetic trees constructed, the genus Pagumogonimus is clearly not monophyletic and therefore not a natural taxon. Indeed, the type species of Pagumogonimus, P. skrjabini from China, is very closely related to Paragonimus miyazakii from Japan. The status of Euparagonimus is less obvious. Euparagonimus cenocopiosus lies distant from other lungflukes included in the analysis. It can be placed as sister to Paragonimus in some analyses and falls within the genus in others. A recently published morphological study placed E. cenocopiosus within the genus Paragonimus and probably this is where it should remain.

Molecular evidence for the synonymy of three species of Paragonimus, P. Ohirai Miyazaki, 1939, P. iloktsuenensis Chen, 1940 and P. sadoensis Miyazaki et al., 1968

The Paragonimus ohirai group, named after P. ohirai Miyazaki, 1939, consists of three nominal species. Paragonimus iloktsuenensis Chen, 1940 and P. sadoensis Miyazaki et al., 1968, the other members of the group, were proposed primarily because of perceived differences in metacercarial morphology and/or host preferences. It has long been recognized that adults of the three were virtually indistinguishable. With the application of genetic techniques, it has become clear that the three forms can exchange genes freely, and that differences in metacercarial morphology constitute a polymorphism probably due to a single gene inherited in Mendelian fashion. Here, additional genetic data (DNA sequences from the second internal transcribed spacer of the nuclear ribosomal gene cluster and from the mitochondrial cytochrome c oxidase subunit I gene) are presented in support of the synonymy.

Relationships between Schistosoma malayensis and other Asian schistosomes deduced from DNA sequences.

At least three Schistosoma species can infect humans in South-East Asia. The most widespread of these is S. japonicum Katsurada, 1904 which may represent a species complex and occurs in many countries including China, Japan and the Philippines. The second species is S. mekongi Voge, Bruckner and Bruce, 1978 which is endemic to a small area near the junction of Laos, Cambodia and Thailand. Most recently described is S. malayensis Greer, Ow-Yang and Yong, 1988 from a restricted area of peninsular Malaysia. This is primarily a parasite of rats but has also been found in people Davis, on the basis of snail intermediate host phylogeny and biogeography, proposed that S. malayensis and S. mekongi are sister taxa relative to S. japonicum. The three studies on allozymes among these taxa also support this hypothesis.

Genetic structure of Trypanosoma cruzi in central America and its comparison with South American strains

Genetic characterization by isozyme analysis was performed on 68 isolates of Trypanosoma cruzi; 57 from Guatemala in Central America and 11 from South American countries. Ten zymodemes (isozyme patterns) were identified by examining zymograms of 12 enzymes (13 loci). These zymodemes were classified to 3 major distinctive groups: (1) major Guatemalan, (2) minor Guatemalan and (3) unique South American, by the genetic distances and the phylogenetic dendrogram drawn by UPGMA. Based on the results obtained, genetic structures and phylogenetic relations of T. cruzi in Guatemala and South America are discussed. Clonal reproduction seemed to be consistent with the observation of deviation from Hardy-Weinberg equilibrium in several loci.

Molecular and catalytic properties of an arginine kinase from the nematode Ascaris suum

We amplified the cDNA coding for arginine kinase (AK) from the parasitic nematode Ascaris suum, cloned it in pMAL plasmid and expressed the enzyme as a fusion protein with the maltose-binding protein. The whole cDNA was 1260 bp, encoding 400 amino acids, and the recombinant protein had a molecular mass of 45,341 Da. Ascaris suum recombinant AK showed significant activity and strong affinity ( K(m)(Arg) = 0.126 mM) for the substrate L-arginine. It also exhibited high catalytic efficiency ( k(ca)/K(m)(Arg) = 352) comparable with AKs from other organisms. Sequence analysis revealed high amino acid sequence identity between A. suum AK and other nematode AKs, all of which cluster in a phylogenetic tree. However, comparison of gene structures showed that A. suum AK gene intron/exon organization is quite distinct from that of other nematode AKs. Phosphagen kinases (PKs) from certain parasites have been shown to be potential novel drug targets or tools for detection of infection. The characterization of A. suum AK will be useful in the development of strategies for control not only of A. suum but also of related species infecting humans.

In vivo and in vitro cellular response to Schistosoma japonicum eggs in hosts with differing susceptibilities

A comparative study of the cellular response to Schistosoma japonicum eggs was conducted in order to explore its significance, using hosts with differing susceptibilities to the parasite. In experimentally induced, synchronized hepatic granuloma formation, animal species formed each characteristic feature of the granulomas, and the magnitude of tissue reaction was significantly larger in highly susceptible hosts, such as mice and hamsters, while less susceptible hosts, such as rats and quails, formed smaller granulomas. Confluent neutrophils were seen within the tissue lesions for mice and hamsters, while rats and quails showed obviously scanty neutrophils. Guinea pigs failed to develop any granulomas. When splenic cells and bone marrow cells were used for in vitro granuloma formation, bone marrow cells showed markedly higher reactions than splenic cells from naive or sensitized animals and the reactivities of bone marrow cells from susceptible hosts, mice and hamsters, were clearly higher than those from rats, indicating similar results to those of in vivo granuloma formation. This study indicates that the in vivo and in vitro cellular response to S. japonicum eggs varies greatly according to the hosts susceptibility, independent of whether the host is a naive or sensitized animal. Our results seem to support the concept that the parasites exploit the host immune system in order to complete their life‐span.

Updated phylogenetic scheme based on the complete mitochondrial protein-coding sequence for common parasitic flatworms

Introduction: The climate of reform and change is evident in the current Australian health care system where significant challenges are faced due to a growing burden of chronic disease, an aging population, workforce issues, and unacceptable inequities in access to services and health outcomes. Improved management of chronic conditions and a focus on health promotion and prevention are key priority action areas. It is vital that the health workforce has the appropriate knowledge and skills to work in a holistic approach that allows them to contribute to the downstream, midstream, upstream actions that will be required to address the future challenges. This presentation describes workforce health promotion capacity building initiatives developed in Northern Australia. Methods and Materials: A range of courses have been developed to build workforce capacity including a 5-day Core Health Promotion Short Course and tertiary level courses including a postgraduate certificate, postgraduate diploma and Master of Public Health (Health Promotion). Results: Between 2007 and 2011, fourteen 5 day short courses in health promotion were conducted for 254 participants. Follow up impact evaluation shows that the courses succeed in providing knowledge, skills, confidence and enthusiasm to undertake health promotion work but that a lack of understanding of health promotion from co-workers and managers, lack of organisational support and commitment, lack of resources, competing clinical priorities, and lack of time were barriers for undertaking health postgraduate courses commenced in 2010. Conclusions: There is strong support for workforce development in health promotion in north Queensland. Short courses and tertiary level training are one way to achieve this. However shifting health service delivery to a more upstream approach to address chronic disease requires broader capacity building within health services and systems including leadership, partnerships, resource allocation and organisational development.