Diseases & Syndromes of Fish Flashcards
universal clinical signs of disease in fish (4)
- hyperpigmentation
- exophthalmia
- ascites
- abdominal distension
Exopth. = normal globe size being protruded from space-occupying lesion
4 major viruses of salmonids
salmonids = salmon, trout, char, graylings, FW whitefish
- Infectious Pancreatic Necrosis (IPN)
- Infectious Hematopoietic Necrosis (IHN)
- Viral Hemorrhagic Septicemia (VHS & VHS IVb)
- Infectious Salmonid Anemia (ISA)
3 major viruses of Cyprinids
Cyprinids = minnows, carp, goldfish, koi, +++
- Koi Herpes Virus
- Spring Viremia of Carp
- Fish pox/Carp pox
IPN
- geographical location
- transmission
- clinically affected
- Worldwide distribution
- Horizontal = feces & urine; Vertical = egg
- dz in fry & fingerlings; survivors = carriers
IHN
- geographical location
- clincially affected
- Western U.S.
- disease of young salmonids (< 2yrs); survivors = carriers
VHS
- geographical location
- organs affected
- disease status
- ocassional isolation U.S. Pacific Coast
- liver, kidney, splenic & intestinal tissues
- Foreign Animal Disease
Where have recent new epizootic strains of VHS emerged?
- Clinical signs
- Location of lesions
VHS IVb strain = emerging disease in fish of the GREAT LAKES. Is a condidered a FAD
- lethargy, circle-swimming, lying motionless on surface, massive mortalities
- hemorrhagic lesions on the skin, liver, spleen, intestine and swim bladder
ISA
- geographical location
- lesions
- where are significant mortalities seen?
- disease status
Infectious Salmon Anemia
- Scotland, Norway, Chile, Canada; Maine- affects Atlantic Salmon!
- severe hemorrhage of kidney & splenic tissues
- significant mortalities in net pen culture
- Foreign Animal Disease status
Koi Herpes virus
- mortality rate
- common sequela
- acute + high mortality (80-100%)
- survivors = carriers; 2º bacterial & parasitic infections occur
Spring Viremia of Carp
- geographical location
- affected fish
- lesions
- disease status
- Europe, Soviet Union; NC/VA, WI
- acute dx of FARMED carp
- severe hemorrhage of swim bladder & viscera
- Foreign Animal Disease status
swim bladder: contains O2 and aids with buoyancy
Fish pox/Carp pox
- virus type
- geographical occurrence
- pathogenesis
- lesions
- time of year?
- herpes virus (NOT pox!)
- worldwide occurrence
- causes transient, focal but benign hyperplasia of epithelium
- CHRONIC SF dz of cultured cyprinids
- Lesions: raised white nodules on skin & fins
- Winter and early spring
What viral disease’s clinical signs are similar to fish/carp pox?
Lymphocystis
raised white nodules on skin and fins
lymphocystivirus = an iridovirus that causes hypertrophic tumorous growths on the skin and fins of fish
Lymphocystis
- geographical occurrence
- species affected
- pathogenesis
- prognosis
- worldwide occurrence
- chronic disease of FW, brackish and marine fishes
- infects fibroblasts -> grow to > 1000x normal size
- self-limitied/rarely fatal
Brackish water = where river meets ocean // mix of FW & SW)
Fibroblasts = cells that make up ECM-connective tissue
Most bacterial pathogens are gram ___?___, ____?____ pathogens that are ____?____ in the environment and produce ____?____ disease. Most are 2º to ____?____ stress, and typically occur during ____?____ changes.
Most bacterial pathogens are gram ___negative___, ____opportunistic____ pathogens that are ____ubiquitous____ in the environment and produce ____subclinical____ disease. Most are 2º to ____water____ stress, and typically occur during ____seasonal____ changes.
late fall; early spring (outbreaks @ suboptimal temp. ranges)
Which bacteria causes furunculosis in salmon?
boils -> crater lesions
Aeromonas salmonicida
Which bacteria is ubiquitous in FW and causes skin & systemic infections?
Aeromonas hydrophilia
Skin infections fatally impair osmoregulation
Which bacteria has zoonotic potential and is a major pathogen in mariculture facilities?
Vibrio spp.
- skin ulcers +/- septicemia with erythema of skin & oral cavities, hemorhhages of tail/fins/gills
Bacterial pathogen lesions on the skin/gills disrupts what vital function?
Osmoregulation (of salt ions + water)
Most common bacterial pathogen globally
Mycobacterium spp.
affects ALL SPECIES of fish
Mycobacterium spp.
- pathogenesis
- zoonotic potential
- Pathogenesis = chronic, progressive, multi-systemic disease
- significant zoonotic potential, “fish handler’s disease” -> cutaneous papulopustular to nodular disease
Why are parasites more pathogenic in cultured fish vs. wild fish?
Cultured fish:
- increased handling & stress
- closed water system (captivity)
- We also see when they die (potentially leading to higher reports)
Ddx for white spots on fish (4)
Lymphocystis (V) vs.
Carp pox (V) vs.
Ich (P) = FW vs.
Cryptocaryon (P) = SW
Differences and Similarities b/w Ichthyophthirius multifiliis (Ich/White Spot Disease) and Cryptocaryon irritans?
DIFFERENCES:
Ich/White Spot Disease
- Ciliate w/ C-shaped nucleus
- infects all FW fish
Cryptocaryon irritans
- Ciliate w/out C-shaped nucleus
- infects SW fish
SIMILARITIES:
- direct life cycle
- invades skin & gill epithelium of host
What happens if the lamellae are damaged (inflammation, hyperplasia, etc.)
No surface for gas exchange (O2-CO2) -> lethargy, decr. appettie, severely swollen or fragile gill tissue
What stage do you treat the “water molds” - Saprolegnia, Aphanomyces
Fungal disease- branched, on-septate hyphae
- associated with poor water quality or trauma
- Treat the FREE-SWIMMING life stage (Zoosporangium)
All non-infectious diseases of fish are linked to what? What is the pathogenesis?
All linked to poor water quality
- Nitrogenous waste toxicity; must perform water quality testings // have set parameters to measure daily
- Low [nitrogenous waste] -> chronic stress & gill pathology (hyperplasia)
- High [nitrogenous waste] = acutely lethal!
