Skip to main content
Jerri Bartholomew in front of shrubbery

Jerri L. Bartholomew

Department Head
Emile F. Pernot Distinguished Professorship
Director J.L. Fryer Aquatic Animal Health Laboratory
Department of Microbiology

Jerri L. Bartholomew

Department Head
Emile F. Pernot Distinguished Professorship
Director J.L. Fryer Aquatic Animal Health Laboratory
Department of Microbiology

Background

Education

Ph.D., Oregon State University

Research

Our research focuses on the pathogens that affect the health of wild Pacific salmon populations, particularly myxozoan parasites, which have a complex life cycle, requiring both a fish and annelid host.

Disease Effects on Wild Populations

The myxozoan Ceratomyxa shasta is endemic across the Pacific NW and causes high mortality in juvenile salmon in some river systems. A long-term project in the Klamath River integrates monitoring and research to develop recommendations for fishery management by providing real time data on parasite densities and their predicted effects on juvenile salmon, and by linking areas of high disease risk with physical parameters such as water flows and temperature. We are applyinig similar approaches to the Deschutes River. Research in the Willamette River further investigates C. shasta dynamics in this system as well as conducting surveys for parasites of native and introduced fishes.

Interactions Between Hatchery and Wild Fish

Research being conducted in the Willamette River basin investigates pathogen transmission between hatchery populations and naturally reproducing populations. We are also looking at the effects of multiple infections on salmon survival.

Climate Change Effects on Disease

Climate change is expected to have profound effects on host-pathogen interactions. We are examining how this might affect myxozoan disease by developing predictions for how the phenology of parasite life cycles will change under future climates, how changing flow dynamics will alter disease, and to identify river habitats that should be protected as refugia.

Parasite Evolution and Diversity

Myxozoans not only have complex life histories, but enigmatic relationships as revealed by molecular sequence analysis. Continued investigations into the genetics of C. shasta have revaled that it is actually a parasite complex, with different strains specifically evolving with different salmonid hosts. This finding has caused us to rethink assumptions about host-parasite interactions. We are currently involved in genome sequencing and transcriptomic studies that will aid us in developing better diagnostic tools as well as to answer questions about basic parasite biology and phylogenetic relationships.

Parasite Invasion

The first step in Myxozoan infection is activation of their polar capsules. These specialized cells resemble the nematocysts of their cnidarian relatives and could offer possibilities for development of therapeutants. We are working with Israeli scientists to understand the physical process and the genes that control it, as well as to test candidate treatments that affect the process.

Evolution of the Immune System and Role of Mucosal Immunity

This salmonid-C. shasta relationship has proved an ideal model for investigating mucosal immunity in a primitive host and is the basis for a collaboration with Oriol Sunyer, University of Pennsylvania, funded by the National Science Foundation and National Institutes of Health.

Research Interests

  • Salmon Diseases
  • Myxozoan Parasites
  • Host Resistance Mechanisms
  • Parasite Evolution

Publications

  • Atkinson, S.D., Hallett, S.L., Diaz-Morales, D., Bartholomew, and J.L., deBuron, I. 2019. First myxozoan infection (Cnidaria: Myxosporea) in a marine polychaete from North America and erection of actinospore collective group Saccimyxon. J. Parasitol. 105(2):252-262.
  • Zatti, S.A., Atkinson, S.D., Maia, A.A.M., Corrêa, L.L., Bartholomew, J.L., and Adriano, E.A. 2018. Novel freshwater Ellipsomyxa and Myxobolus species (Cnidaria: Myxozoa) parasiting Brachyplatystoma rousseauxii in the Amazon basin. Parasitol. Intl. 67(5):612-621.
  • Javaheri, A., Babbar-Sebens, M., Alexander, J., Bartholomew, J., and Hallett, S. 2018. Global sensitivity analysis of water age and temperature for informing salmonid disease management. J. of Hydrology, 561:89-97.
  • Atkinson, S.D., Bartholomew, J.L., and Lotan, T. 2018. Myxozoans: Ancient metazoan parasites find a home in phylum Cnidaria. Zool. 129:66-68.
  • Stinson, M.E.T., Atkinson, S.D, and Bartholomew, J.L. 2018. Widespread distribution of Ceratonova shasta (Cnidaria:Myxosporea) genotypes indicates evolutionary adaptation to its salmonid fish hosts. J. Parasitol. 10:1645/18-79.
  • Zatti, S.A., Atkinson, S.D., Maia, A.A.M., Corrêa, L.L., Bartholomew, J.L. and Adriano, E.A. 2018. Novel Myxobolus and Ellipsomyxa species (Cnidaria: Myxozoa) parasiting Brachyplatystoma rousseauxii (Siluriformes: Pimelodidae) in the Amazon basin, Brazil. Parasitol. Int. 67(5):612621.
  • Richey, C.A., Kenelty, K.V., Van Stone Hopkins, K., Stevens, B.N., Martinez-López, B., Barnum, S.M., Hallett, S.L., Atkinson, S.D., Bartholomew, J.L., and Soto, E. 2018. Distribution and prevalence of Myxobolus cerebralis in postfire areas of Plumas National Forest: Utility of environmental DNA sampling. J. Aquat. Animal Hlth. 30(2):130-143.
  • Atkinson, S.D., Hallett, S.L., and Bartholomew, J.L. 2018. Genotyping of individual Ceratonova shasta (Cnidaria: Myxosporea) myxospores reveals intra-spore ITS-1 variation and invalidates the distinction of genotypes II and III. Parasitology March 27:1-6 PMID 29580305.
  • Zatti, S.A., Atkinson, S.D., Maia, A.A.M., Bartholomew, J.L. and Adriano, E.A. 2018. Novel Henneguya spp. (Cnidaria: Myxozoa) from cichilid fish in the Amazon basin cluster by geographic origin. Parasitol. Res. 117(3):849-859.
  • Zatti, S.A., Atkinson, S.D., Maia, A.A.M., Bartholomew, J.L., and Adriano, E.A. 2018. Ceratomyxa gracillima n. sp. (Cnidaria: Myxosporea) provides evidence of panmixia and ceratomyxid radiation in the Amazon basin. Parasitology Jan 17:1-10. PMID: 29338808.