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Richey CA, Kenelty KV, Van Stone Hopkins K, Stevens BN, Martínez-López B, Barnum SM, Hallett SL, Atkinson SD, Bartholomew JL, Soto E. Distribution and Prevalence of Myxobolus cerebralis in Postfire Areas of Plumas National Forest: Utility of Environmental DNA Sampling. JOURNAL OF AQUATIC ANIMAL HEALTH 2018; 30:130-143. [PMID: 29710407 DOI: 10.1002/aah.10014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 01/11/2018] [Indexed: 06/08/2023]
Abstract
Myxobolus cerebralis is a myxozoan parasite and the etiological agent of whirling disease in salmonids. The parasite's life cycle involves waterborne spores and requires both a salmonid fish and the benthic freshwater oligochaete worm Tubifex tubifex (Oligochaeta: Tubificidae). Wildfires can lead to the erosion of fine sediments into stream channels and have been implicated as promoting environmental conditions that are suitable for the survival and success of T. tubifex, whose presence in turn can affect the prevalence of M. cerebralis. Analysis of environmental DNA (eDNA) has the potential to be a powerful tool for evaluating the presence of microorganisms, for which direct observation is impossible. We investigated the presence of M. cerebraliseDNA in river water and river sediment samples collected from areas affected by recent fire activity in Plumas National Forest, California. We compared eDNA loads in the environment to M. cerebralis infection in T. tubifex and sentinel-exposed Rainbow Trout Oncorhynchus mykiss and the presence of T. tubifex lineages in the same environment. For the latter, we developed a multiplex quantitative PCR assay for detection of T. tubifex lineages I, III, and V. Lineage IIIT. tubifex and M. cerebralis (eDNA as well as DNA extracted from fish and worm tissues) were detected only in samples obtained from areas affected by the Moonlight wildfire. The association between M. cerebralis infection in sentinel-exposed fish and eDNA detection in environmental samples only approached significance at a P-value of 0.056. However, given the difference in relative effort between the two sampling methods (host versus nonhost environment), our data suggest that eDNA sampling of water and substrate is a promising approach for surveillance of myxozoan fish parasites.
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Affiliation(s)
- Christine A Richey
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, 95616, USA
| | - Kirsten V Kenelty
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, 95616, USA
| | | | - Brittany N Stevens
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, 95616, USA
| | - Beatriz Martínez-López
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, 95616, USA
| | - Samantha M Barnum
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, 95616, USA
| | - Sascha L Hallett
- Department of Microbiology, Oregon State University, Corvallis, Oregon, 97331, USA
| | - Stephen D Atkinson
- Department of Microbiology, Oregon State University, Corvallis, Oregon, 97331, USA
| | - Jerri L Bartholomew
- Department of Microbiology, Oregon State University, Corvallis, Oregon, 97331, USA
| | - Esteban Soto
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, 95616, USA
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Li D, Zhai Y, Gu Z, Liu Y. Development of a multiplex PCR method for the simultaneous detection of four myxosporeans infecting gibel carp Carassius auratus gibelio. DISEASES OF AQUATIC ORGANISMS 2017; 124:31-39. [PMID: 28357984 DOI: 10.3354/dao03100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Gibel carp Carassius auratus gibelio (Bloch), a commercially important freshwater-cultured fish in China, is threatened by myxosporeans, particularly Thelohanellus wuhanensis, Myxobolus honghuensis, M. wulii and M. turpisrotundus. Here, we developed a multiplex PCR assay for simultaneous detection of these 4 myxosporeans. The specific primers for each species were designed based on the 28S rDNA gene of T. wuhanensis, the ITS-5.8S rDNA of M. honghuensis and M. wulii, and the 18S rDNA gene of M. turpisrotundus. Specificity testing confirmed that the 4 primer sets have no cross-reactivity with other related myxosporean species tested. Detection limits of the multiplex PCR assay were 0.2, 0.3, 3.1 and 3.8 spores for T. wuhanensis, M. honghuensis, M. wulii and M. turpisrotundus, respectively. Following screening of 104 field samples, the analytical sensitivity of the present multiplex PCR assay was found to be similar to the sensitivity obtained by the singleplex PCR assays and was higher than that of microscopic examination. Moreover, Kappa analysis showed a strong agreement between the results of the singleplex and multiplex PCR assays, indicating that the developed multiplex PCR assay was an efficient approach for the diagnosis of the 4 myxosporeans infecting gibel carp.
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Affiliation(s)
- Dan Li
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan 430070, PR China
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Sarker S, Kallert DM, Hedrick RP, El-Matbouli M. Whirling disease revisited: pathogenesis, parasite biology and disease intervention. DISEASES OF AQUATIC ORGANISMS 2015; 114:155-175. [PMID: 25993890 DOI: 10.3354/dao02856] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Whirling disease (WD) is an ecologically and economically debilitating disease of rainbow trout Oncorhynchus mykiss caused by the actinosporean spores of the parasite Myxobolus cerebralis. M. cerebralis has a complex, 2-host life cycle alternating between salmonid fish and the oligochaete host Tubifex tubifex. The parasite alternates between 2 spore forms as transmission stages: an actinosporean triactinomyxon spore that is produced in the oligochaete host and a myxosporean spore that develops in the salmonid host. Waterborne triactinomyxon spores released from infected T. tubifex oligochaetes attach to the salmonid host by polar filament extrusion elicited by chemical (nucleoside) and mechanical (thigmotropy) stimuli-a process which is rapidly followed by active penetration of the sporoplasms into the fish epidermis. Upon penetration, sporoplasms multiply and migrate via peripheral nerves and the central nervous system to reach the cartilage where they form trophozoites which undergo further multiplication and subsequent sporogenesis. M. cerebralis myxospores are released into the aquatic environment when infected fish die and autolyse, or when they are consumed and excreted by predators. Myxospores released into the water are ingested by susceptible T. tubifex where they develop intercellularly in the intestine over a period of 3 mo through 4 developmental stages to give rise to mature actinospores. In this article, we review our current understanding of WD-the parasite and its alternate hosts, life cycle and development of the parasite in either host, disease distribution, susceptibility and resistance mechanisms in salmonid host and strategies involved in diagnosis, prevention and control of WD.
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Affiliation(s)
- Subhodeep Sarker
- Clinical Division of Fish Medicine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria
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Ayre KK, Caldwell CA, Stinson J, Landis WG. Analysis of regional scale risk of whirling disease in populations of Colorado and Rio Grande cutthroat trout using a Bayesian belief network model. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2014; 34:1589-605. [PMID: 24660663 DOI: 10.1111/risa.12189] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Introduction and spread of the parasite Myxobolus cerebralis, the causative agent of whirling disease, has contributed to the collapse of wild trout populations throughout the intermountain west. Of concern is the risk the disease may have on conservation and recovery of native cutthroat trout. We employed a Bayesian belief network to assess probability of whirling disease in Colorado River and Rio Grande cutthroat trout (Oncorhynchus clarkii pleuriticus and Oncorhynchus clarkii virginalis, respectively) within their current ranges in the southwest United States. Available habitat (as defined by gradient and elevation) for intermediate oligochaete worm host, Tubifex tubifex, exerted the greatest influence on the likelihood of infection, yet prevalence of stream barriers also affected the risk outcome. Management areas that had the highest likelihood of infected Colorado River cutthroat trout were in the eastern portion of their range, although the probability of infection was highest for populations in the southern, San Juan subbasin. Rio Grande cutthroat trout had a relatively low likelihood of infection, with populations in the southernmost Pecos management area predicted to be at greatest risk. The Bayesian risk assessment model predicted the likelihood of whirling disease infection from its principal transmission vector, fish movement, and suggested that barriers may be effective in reducing risk of exposure to native trout populations. Data gaps, especially with regard to location of spawning, highlighted the importance in developing monitoring plans that support future risk assessments and adaptive management for subspecies of cutthroat trout.
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Affiliation(s)
- Kimberley Kolb Ayre
- Institute of Environmental Toxicology, Huxley College of the Environment, Western Washington University, Bellingham, WA, USA
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