A review of recent information on the Haplosporidia, with special reference to Haplosporidium nelsoni (MSX disease)

Free access article

Issue		Aquat. Living Resour. Volume 17, Number 4, October-December 2004 Bivalve Diseases


Page(s)		499 - 517
DOI		10.1051/alr:2004056

Aquat. Living Resour. 17 (2004) 499-517
DOI: 10.1051/alr:2004056

A review of recent information on the Haplosporidia, with special reference to Haplosporidium nelsoni (MSX disease)

Eugene M. Burreson¹ and Susan E. Ford²

¹ Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, Virginia 23062, USA
² Haskin Shellfish Research Laboratory, Rutgers University, Port Norris, New Jersey 08349, USA

Abstract
The current status of the Haplosporidia is reviewed as well as recent information on Haplosporidium nelsoni, the causative agent of MSX disease in oysters. Recent molecular phylogenetic analyses with greatly increased taxon sampling support monophyly of the Haplosporidia and hypothesize placement of the group as sister taxon to the phylum Cercozoa. Oyster pathogens in the genus Bonamia should be considered haplosporidians based on molecular sequence data. Thus, the group contains 4 genera: Uropsoridium, Haplosporidium, Bonamia and Minchinia. Molecular phylogenetic analyses support monophyly of Urosporidium, Bonamia and Minchinia, but Haplosporidium forms a paraphyletic clade. Reports of haplosporidia worldwide are reviewed. Molecular detection assays have greatly increased our ability to rapidly and specifically diagnose important pathogens in the phylum and have also improved our understanding of the distribution and biology of H. nelsoni and H. costale. Much of the data available for H. nelsoni has been integrated into a mathematical model of host/parasite/environment interactions. Model simulations support hypotheses that recent H. nelsoni outbreaks in the NE United States are related to increased winter temperatures, and that a host other than oysters is involved in the life cycle. Evidence is presented that natural resistance to H. nelsoni has developed in oysters in Delaware Bay, USA. However, in Chesapeake Bay, USA H. nelsoni has intensified in historically low salinity areas where salinities have increased because of recent drought conditions. Efforts to mitigate the impact of H. nelsoni involve selective breeding programs for disease resistance and the evaluation of disease resistant non-native oysters.

Key words: Phylogeny / Diagnostics / Numerical model / Haplosporidia / Haplosporidium nelsoni

Corresponding author: gene@vims.edu

© EDP Sciences, IFREMER, IRD 2004

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.