Presentation on theme: "FISH 424: Fish Health Management"— Presentation transcript:
1 FISH 424: Fish Health Management Virology Lecture: ISAVSVCVWSIVVHSV
2 Infectious Salmon Anemia Virus (ISAV) Hosts and Geographic RangeHighly infectious for Atlantic salmonpotential asymptomatic carriers of the virusSearun brown troutrainbow troutAtlantic herring
3 Infectious Salmon Anemia (ISAV) Viral infection is found in Seawater (Net pens):Norway (1984)United Kingdom (1998)East coast Canada (1998)East coast United States (2000)Chile (1999)Viral infection is almost exclusively found in fish in seawater although one incident in Norway occurred in par in freshwater.
6 Infectious Salmon Anemia (ISAV) Etiological agent1st described as Hemorrhagic Kidney Syndromemember of the orthomyxoviridae family.8 negative strands of RNA enclosed in a lipid envelopVirions between nm in diameter
7 Infectious Salmon Anemia (ISAV) Transmission Electron Micrographs
8 Infectious Salmon Anemia (ISAV) Virulence and Pathologylethargic, swim near the water surfacepetechial hemorrhage on skin and finsanemia, exophthalmia, ascitesPale gillshepatomegally, splenomegallypetechia in the visceral fatFish infected with ISA become lethargic, have erratic swimming and tend to swim near the water surface.Disease of infected fish tend to produce pectechial hemorrhage on the skin and fins
10 Infectious Salmon Anemia (ISAV) Transmission:Almost exclusively occurrs during saltwater stagesHorizontal (fish to fish contact)Coprophagy (feeding on feces)Sea lice can transmit ISAv from infected to susceptible fishTransfer by contaminated equipment / People / boat traffic / location near fish processing plants
11 Infectious Salmon Anemia (ISAV) Figure 3. Infection status of areas versus number of well-boat visits. Infection status is 0 for no infection, 1 for suspected infection, and 2 for confirmed infectionAlexander G. Murray,*† Ronald J. Smith,* and Ronald M. Stagg* *Fisheries Research Services Marine Laboratory, Aberdeen, United Kingdom; and †University of Aberdeen, Aberdeen, United Kingdom
12 Infectious Salmon Anemia (ISAV) DiagnosisIsolation through tissue cultureSHK-1 and CHSE-214 cellsIFAT (indirect fluorescent antibody test) on tissue imprintsRT-PCR (reverse transcriptase poylmerase chain reaction)Remember doing a tissue imprint
13 Infectious Salmon Anemia (ISAV) ManagementSince the virus is readily transmitted in seawaterShown net pen operations within 5-6 km of an infected site can become contaminatedculture sites be spaced no less than 5-6 km apartwaste water from slaughter and processing facilities should be thoroughly disinfectedcontrol of ship and personnel movements among sitescompulsory slaughter of infect stocks (eradication)Attempts to require vaccinationThere is no theraputic measure to reduce outbeaks and infection and since the virus is readily transmitted in seawater and studies have shown
14 Spring Viremia of Carp Virus (SVCV) Spring Viremia of Carp Virus (SVCV)Hosts and Geographic RangeNatural infections have been recognized in common carp and koi carp (Cyprinus carpio)Historically only in Europe and RussiaRecently, SVC has been reported in koi in the United States for the first time
15 Recent News HeadlinesSpring Viremia of Carp virus (SVCv) was recently identified in a backyard koi and goldfish pond located in Snohomish County, Washington State2. Spring viremia of carp (SVC) was confirmed in ornamental koi carp in Pike County, Missouri on July 13, 20043. SVC has previously been reported in Europe, the Middle East and Asia. More recently, it has been reported in North and South America. In the US, SVC outbreaks occurred in North Carolina in 2002 and Washington in June The virus has also been reported in feral common carp populations in Wisconsin and Illinois. SCV is an OIE notifiable disease.
17 Spring Viremia of Carp Virus Etiological agentFamily RhabdoviridaeBullet shaped morphologysingle-stranded RNA containing 5 genes
18 Spring Viremia of Carp Virus Virulence and PathologyDarkening of the skinDistended abdomenExopthalmiaPetechial hemorrhage of the skin, gills, and eyesPale gillsHemorrhage in the swim bladderCatarrhal enteritisinflammation of the intestinesinflammation of a mucous membrane
19 Example of exopthalmia and abdominal distention Clinical signs of disease:Darkening colorationAbdominal distensionExopthalmia
20 Spring Viremia of Carp Virus Virulence and Pathologyvirus affects carp at all ages but victims are mostly young fish.Outbreaks depend on the temperatureHigh mortality occurs at water temperatures of 10 to 17°C, typically in spring.At >20 °C, elevated immune response protects carp from infection and re-infectionThe optimum temperature for viral replication in vitro is 20-22°C (68-72°F), however, this is also an optimum temperature range for immune function of susceptible species (Fijan 1999). Clinical and experimental data indicate that maximum mortality can be expected at water temperatures below 18°C (64°F) (Fijan 1999; McAllister 1993).These findings have led experts (Wolf 1988; Ahne 1980; Fijan 1999) to suggest that outbreaks of SVC can be prevented or stopped in mature fish by raising water temperatures above 20°C (68°F); however, the results of such attempts have not been well documented. Because of the potential severity of the disease, depopulation is recommended.
21 Spring Viremia of Carp Virus Transmission:Occurs by horizontal transmissionExcretion of SVCV via feces and urine from infected fishParasitic transfer of SVCV from diseased to healthy fishvirus could stay infective in the water for more than 4 wks and 6 wks in the mudsource of infection may be contaminated equipmentvertical transmission of SVCV is not an important source of infection
22 Spring Viremia of Carp Virus Diagnosis (Standard Screening Method )Isolation of SVCV in cell cultureFHM or EPC tissue culture cellsIndirect fluorescent antibody test on infected culture cellsorEnzyme-linked immunosorbent assay (ELISA)or Neutralization Antibody testPCR Spring viremia of carp can be diagnosed by clinical signs,
23 Spring Viremia of Carp Virus ManagementIn rearing facilities with a controlled environment, elevation of temperature above 20° C can prevent or stop SVC outbreaksavoidance of SVCV by using spring or well waterEradication of diseased fishControl movement of fishAnglers should not transfer fish or fish parts from one body of water to anotherVaccination provides good protection
24 White sturgeon iridovirus (WSIV) Host and Geographic RangeWhite SturgeonNorth America
25 WSIV HistoryRecognized as the most prevalent viral pathogen in White Sturgeon.Significant mortality in commercial and conservation aquaculture.Northern California commercial sturgeon farmsLower Columbia River in Oregon and WashingtonSnake River in Southern IdahoKootenai River in northern IdahoBritish ColumbiaFor the past 16 years, WSIV has been recognized as the most prevalent viral pathogen in White sturgeon.This virus has caused significant mortality in both commercial and conservation aquaculture.It was first detected in 1988 in commercial farms in northern California where annual losses were common. since the 1990’s the virus has been detected in cultured sturgeon in the lower columbia river in Oregon and Washington, the Snake river in southern Idaho, the Kootenai river in northern Idaho. The virus has also been isolated in a commercial rearing facility in British Columbia.LaPatra et. al. 1994
26 WSIV: Manifestation of Disease Clinical disease can be inducedOvercrowding, transport, handling, etc.Slow chronic wasting syndromeFry and fingerlings (1st year)Mortality assumed to be due:AnorexiaRespiratory functionOsmoregulatory functionSecondary infectionClinical disease can be triggered by subjecting sturgeon harboring the virus to stressful condtions such as…over crowding, transport, handling, etc.Is characterized as a slow chronic wasting syndrome that primarily affects fry and fingerlings of the first year of growth and mortality is assumed to be due to anorexia. Respiratory disfunction, and failure to control osmoregulation. And secondary infections
27 WSIV: Clinical Signs of Disease Some of the clinical signs are a darkeniing coloration along with this emaiated body appearanceDarkening Pigmentation Emaciated body
28 Manifestation of disease Virus has an affinity for epithelial tissue:SkinGillOropharynxOlfactory (barbels)This virus is characterized as being epitheliotrophic, meaning that it has an affinity for epithelial tissue.Primarily the skin, gills, oropharynx, and olfactory organs, such as the barbells.Because this virus is difficult to grow in tissue culture, The most common diagnostic method used for detecting a WSIV infection is by histology where you can see these large hypertrophied cells within the epithelial tissue of these preferred organs.skin and gill.Histology shows:Hypertrophied cells with swollen cytoplasm
29 TEM of WSIV infected cells 5000XA closer look at these infected cells by electron microscopy shows numerous virus particles within the cytoplasm which supports previous findings that approx 70% of the virus remains cell associated.
30 TEM of WSIV From Kootenai River white sturgeon skin (2004) WSIV MorphologyIcosahedral morphologySize ( nm)Double capsidDense nucleiod centerThe virus particles have an icosahedral morphology typical of other iridoviruses that are approximately nm in size, have a characteristic double capsid formation and a dense nucleoid center where, presumably, the genetic information is storedTEM of WSIV From Kootenai River white sturgeon skin (2004)
31 White sturgeon iridovirus (WSIV) TransmissionShown to be transmitted from infected fish to healthy individualsmay be endemic in most wild Northwest white sturgeon populations.Virus may be vertically transmitted from adult to offspring during spawning.
32 White sturgeon iridovirus (WSIV) Diagnosis of infectionDifficult to propagate reliably in tissue cultureHistology for the detection of large hypertrophied cells within the epithelial tissue of the skin, gills, and barbels.Because this virus is difficult to grow in tissue culture, The most common diagnostic method used for detecting a WSIV infection is by histology where you can see these large hypertrophied cells within the epithelial tissue of these preferred organs.
33 White sturgeon iridovirus (WSIV) ManagementIdeally, avoidance of WSIV by using spring or well water to rear juvenile sturgeonMinimize stress of sturgeon during early life stageControl movement of fish
34 Viral Hemorrhagic Septicemia is 1 of the 7 most important diseases of finfish worldwide and is listed by the OIE as notifiableO.I.E. World Organization for Animal HealthAquatic Animal Health Code 2006USDA Animal and Plant Health ServiceDesignated at the US Regulatory Authority on Animal Health
35 USDA APHIS Criteria for Diseases/Pathogens of Regulatory Significance Causes significant impact on production, wild resources, or human healthInfectious disease and can be spread by commerceInvolves host species in interstate or international commerce and be of concern to US trading partners that are free of the diseaseReliable diagnostic methods available
36 USDA APHIS Criteria for Diseases/Pathogens of Regulatory Significance Causes significant impact on production, wild resources, or human healthInfectious disease and can be spread by commerceInvolves host species in interstate or international commerce and be of concern to US trading partners that are free of the diseaseReliable diagnostic methods availableNo human health risk with VHSVNo treatment for VHSVVHSV has been found ONLY in wild fish in the Great Lakes Basin
37 Time Line of VHSV 1938- described in RBT in Europe (FW) 1963- virus isolated and described (FW)1988- saltwater (SW) VHSV hosts in USA1990 to present- VHSV is found endemic in SW hosts on US East and West Coasts2003-present- Great Lakes VHSV causes mass mortality in a variety of FW hosts, including sport fish important to Idaho
38 How bad can it get? 2006 Freshwater drum mortality in Lake Erie New virus in naïve hosts becomes epizooticMillions of pounds of FW drum“Windrows of fish” along the beach piled up 10’ wide and 4’ high
41 Disease Signs of VHSVHemorrhagic: Causes leaking of blood from vesselsespecially under the skin and internal organsSepticemia: Virus in blood and spreadsthroughout the body in circulationPop eye: Caused by pressure of hemorrhagepushing beneath the eye
42 Host Range of VHSV 37 host species FW and SW worldwide 28 FW species 19 FW species are important to Idaho including rainbow trout, salmon, bass, bluegill, crappie, and perchHost range is unheard of for other fish viruses!
43 Current VHS Outbreaks:2007 Lake HuronLake St. ClairLake OntarioSt. Lawrence R.Conesus Lake*Lake ErieBudd Lake*Lake Winnebago** Not connected by water – baitfish suspectedLake Michigan
44 Current VHS Outbreaks:2007 Lake HuronLake St. ClairLake OntarioSt. Lawrence R.Conesus Lake*Lake ErieBudd Lake*Lake Winnebago*Summer, 2007 NYDEC SurveillanceLake Michigan
45 Genetic Differences of VHSV Shows an East Coast Origin 3.7%-5%2.1%
46 How did VHSV get into the Great Lakes? Commercial ballast waterNatural movement of infected fishHuman recreational activitiesSport fishing activities (bait minnows, contaminated fishing equipment, illegal fish stocking)BoatingAnimal activities (mammals, birds)Basically, vectors are unknown!
47 Overview Two genetic types of VHSV correlate West coast and East Coast VHSV in the Great Lakes likely came from an East Coast hostConventional cell culture methods detects Great Lakes VHSV strainsVHSV is more stable in freshwater than in sea water.VHSV lasts up to one month when held at 50ºF
48 APHIS Federal Order VHSV Federal Order was issued 10/24/2006 Emergency Action taken to prevent the spread of VHSVMust be followed-up by formal rulemaking
49 Current Provisions Under the Federal Order VHS susceptible species are prohibited from moving out of the 8 States and 2 Canadian Provinces bordering the Great Lakes except under certain conditionsMovement to slaughter with adequate disinfectionMovement to a research or diagnostic lab with adequate disinfectionMovement of live fish testing negative for VHSV by laboratory assaysMovement of salmonids from Canada that meet USFWS inspection requirementsCatch-and-Release fishing activities
50 Implications of VHSV for Idaho 20 years surveillance has been negativein cultured and wild fishSport fishing valued at $ 360 million$ 110 million trout culture industry at riskESA-listed anadromous salmon and steelhead cultured in IdahoMust prevent VHSV introduction into Idaho
51 What has IDFG done to reduce risk? Live fish for bait prohibitedBanned importation of all fish from Great Lakes Basin (GLB)Supported APHIS Federal OrderBanned frozen baitfish from GLBPartnering with Idaho Department of Agriculture and trout industry on emergency rule to prevent introduction
52 Future needs:Risk assessment of potential vectors leading to Biosecurity Plan for IdahoImportations of live fish & eggsPrivate pondsAquatic nuisance speciesAquatic baits other than fishEducation of anglers to reduce risksSupport research on VHSV susceptibility of Idaho fish stocksIdaho Fish Health and Sterility Management Policy