61
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      Population Genetics of Schistosoma japonicum within the Philippines Suggest High Levels of Transmission between Humans and Dogs

      research-article

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Background

          Schistosoma japonicum, which remains a major public health problem in the Philippines and mainland China, is the only schistosome species for which zoonotic transmission is considered important. While bovines are suspected as the main zoonotic reservoir in parts of China, the relative contributions of various non-human mammals to S. japonicum transmission in the Philippines remain to be determined. We examined the population genetics of S. japonicum in the Philippines in order to elucidate transmission patterns across host species and geographic areas.

          Methodology/Principal Findings

          S. japonicum miracidia (hatched from eggs within fecal samples) from humans, dogs, pigs and rats, and cercariae shed from snail-intermediate hosts, were collected across two geographic areas of Samar Province. Individual isolates were then genotyped using seven multiplexed microsatellite loci. Wright's F ST values and phylogenetic trees calculated for parasite populations suggest a high frequency of parasite gene-flow across definitive host species, particularly between dogs and humans. Parasite genetic differentiation between areas was not evident at the definitive host level, possibly suggesting frequent import and export of infections between villages, although there was some evidence of geographic structuring at the snail–intermediate host level.

          Conclusions/Significance

          These results suggest very high levels of transmission across host species, and indicate that the role of dogs should be considered when planning control programs. Furthermore, a regional approach to treatment programs is recommended where human migration is extensive.

          Author Summary

          Schistosomiasis is a disease caused by parasitic worms known as schistosomes, which infect about 200 million people worldwide. In the Philippines, as in China, the species of schistosome ( Schistosoma japonicum) which causes the disease infects not only humans, but also many other species of mammals. In China, bovines are thought to be particularly important for harboring and transmitting S. japonicum, whereas in the Philippines infections in bovines are relatively rare. However, dogs, rats and pigs are often infected with S. japonicum in the Philippines, although the extent to which infections in these animals may give rise to human infections is unclear. To help answer this question, we characterized the genetic variation of the parasite in Samar province of the Philippines, and found that S. japonicum samples from humans, dogs, rats and pigs were genetically very similar, with no significant genetic difference between samples from humans and dogs. This suggests that in the Philippines this parasite is frequently transmitted between different mammalian species, particularly between dogs and humans. Reducing levels of infections in dogs may therefore help to reduce infections in humans. The results also suggest high levels of transmission between geographic areas, thus regional co-ordination of treatment programs is recommended.

          Related collections

          Most cited references47

          • Record: found
          • Abstract: found
          • Article: not found

          AutoDimer: a screening tool for primer-dimer and hairpin structures.

          The ability to select short DNA oligonucleotide sequences capable of binding solely to their intended target is of great importance in developing nucleic acid based detection technologies. Applications such as multiplex PCR rely on primers binding to unique regions in a genome. Competing side reactions with other primer pairs or template DNA decrease PCR efficiency: Freely available primer design software such as Primer3 screens for potential hairpin and primer-dimer interactions while selecting a single primer pair. The development of multiplex PCR assays (in the range of 5 to 20 loci) requires the screening of all primer pairs for potential cross-reactivity. However, a logistical problem results due to the number of total number of comparisons required. Comparing the primer set for a 10-plex assay (20 total primer sequences) results in 210 primer-primer combinations that must be screened. The ability to screen sets of candidate oligomers rapidly for potential cross-reactivity reduces overall assay devlelopment time. Here we report the application of a familiar sliding algorithm for comparing two strands of DNA in an overlapping fashion. The algorithm has been employed in a software package wherein the user can compare multiple sequences in a single computational run. After the screening is completed, a score is assigned to potential duplex interactions exceeding a user-defined threshold. Additional criteria of predicted melting temperature (Tm) and free energy of melting (deltaG) are included for further ranking. Sodium counterion and total stand concentrations can be adjusted for the Tm and deltaG calculations. The predicted interactions are saved in a text file for further evaluation.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Molecular ecology of parasites: elucidating ecological and microevolutionary processes.

            We review studies that have used molecular markers to address ecological and microevolutionary processes in parasites. Our goal is to highlight areas of research that may be of particular interest in relation to the parasitic lifestyle, and to draw attention to areas that require additional study. Topics include species identification, phylogeography, host specificity and speciation, population genetic structure, modes of reproduction and transmission patterns, and searching for loci under selection.
              Bookmark
              • Record: found
              • Abstract: not found
              • Article: not found

              Genetic data analysis. II

                Bookmark

                Author and article information

                Contributors
                Role: Editor
                Journal
                PLoS Negl Trop Dis
                plos
                plosntds
                PLoS Neglected Tropical Diseases
                Public Library of Science (San Francisco, USA )
                1935-2727
                1935-2735
                November 2008
                25 November 2008
                : 2
                : 11
                : e340
                Affiliations
                [1 ]Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, United Kingdom
                [2 ]Department of Biostatistics and Epidemiology, College of Public Health, Health Sciences Center, University of Oklahoma, Oklahoma City, Oklahoma, United States of America
                [3 ]Research Institute for Tropical Medicine, Muntinlupa, Philippines
                [4 ]Ateneo de Manila University, Quezon City, Philippines
                [5 ]International Health Institute, Brown University, Providence, Rhode Island, United States of America
                Biomedical Research Institute, United States of America
                Author notes

                Conceived and designed the experiments: HC RO STM JPW. Performed the experiments: JWR EB VT JS DBL. Analyzed the data: JWR. Contributed reagents/materials/analysis tools: DBL. Wrote the paper: JWR HC MGB STM JPW.

                Article
                08-PNTD-RA-0173R3
                10.1371/journal.pntd.0000340
                2582952
                19030225
                8e6dc119-0ec7-4029-9cc3-9cf8ee362e6f
                Rudge et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
                History
                : 30 May 2008
                : 31 October 2008
                Page count
                Pages: 10
                Categories
                Research Article
                Genetics and Genomics/Population Genetics
                Infectious Diseases/Epidemiology and Control of Infectious Diseases
                Infectious Diseases/Helminth Infections
                Infectious Diseases/Neglected Tropical Diseases
                Public Health and Epidemiology/Epidemiology
                Public Health and Epidemiology/Infectious Diseases

                Infectious disease & Microbiology
                Infectious disease & Microbiology

                Comments

                Comment on this article