Principles of Aquaculture Diagnostics

1
Principles of Aquaculture Diagnostics

• Dr. Craig Kasper
• FAS 2253
• Fall 2006

2
Introduction

• Readings from Chapters 1-5 of Noga (1996)
• What are diagnostic tests?
• A series of tests designed to determine the
  health status of a healthy population of animals
  vs. that of a population of animals deemed
  unhealthy. (Healthy vs. sick)

3
Introduction

• 2. Why should they be performed?
• Often involves establishing a background or
  baseline information concerning the health of a
  population of animals, i.e. parasite load,
  nutritional status, bacterial exposure.
• Anything that is considered abnormal is also
  known as a lesion.

4
Introduction

• 3. How should these tests be performed?
• Hopefully, under strict guidelines using quality
  control and S.O.Ps with a list of written
  procedures! But doesnt always happen.
• Look for American Association of Veterinary
  Laboratory Diagnosticians accreditation (ADVLD).

5
Introduction

• 4. Who is qualified to perform these tests?
• a. Two issues should be addressed here, esp. if
  you are the one performing the tests.
• i. Moral Can I do it? (I might actually have
  the skills.)
• ii. Legal Am I licensed to do it? (Can I
  testify in court? Am I liable if I am wrong?
  Rem drugs, pharmacy, licenses, etc.
• What would I need? DVM, Ph. D., affiliation with
  university or organization (lab), ACVP,
  Diplomate, AFS pay dues for being a fish health
  inspector!

6
Introduction

• 5. What should be included in the diagnostic
  evaluation?
• a. Animals
• b. Facilities
• c. Environment, i.e. water quality, feed
• d. Questions for the producer/owner!
• May be the most important piece of information.

7
Introduction

• What is the final outcome of the diagnostic?
  What should the lab tell you?
• Your fish have a clear case of acute multifocal
  necrotizing supperative hepatisis!
• WHAT??? Translation PLEASE!!

8
Introduction

• Acute multifocal necrotizing supperative
  hepatitis
• Time location dead neutraphils
  inflammation
• cells of the liver
• A rapid onset of dead white blood cells
  throughout an inflammed liver, put simply your
  fish have bacterial hepatitis!

Why didnt you just say so?
9
Introduction

• 6. What is the final outcome of the diagnostics?
• a. Morphological Diagnosis (only?)
• b. Recommendations re husbandry?
• c. Treatment recommendations?
• d. Changes in facilities, environment?
• e. LABS WONT PERFORM TESTS TO DETERMINE IF FISH
  ARE SAFE FOR HUMAN CONSUMPTION.

10
Introduction

• The clinical evaluation
• a. History
• b. Physical Examination
• c. Clinical Signs
• d. Gross lesions
• e. Cytologic evaluation
• f. Biopsy
• g. Necropsy
• h. Ancillary testing
• bacteriology
• virology
• Toxicology (water and animal samples)
• Clinical pathology (serum chemistries,
  hematology)j

11
Introduction

• Sample sizes and inferences about a population
  based on samples.
• Must have sufficient number or diagnosis is
  meaningless.
• Over-interpretation
• Under-interpretation

12
Statistics Sampling Size
Lot size Number of fish to sample
50 100 35 45
250 500 50 55
gt2000 60
Based on assumed 5 prevalence level in the
population.
13
Symptoms vs. Signs

• Symptoms Description of how an individual feels
  to a proessional health care specialist. Why
  doesnt this work for aquatic critters?
• Clinical signs Observation of behavior of
  non-healthy animals.

14
Common Clinical Signs

• Anorexia
• Flashing
• Piping
• Lethargy
• Erratic Swimming Patterns
• Isolation
• Loss of Fright Response

15
Lesions vs. Pus, Crud or Goop?

• A lesion simply stated isany abnormal
  (unhealthy) tissue.
• Lesions may contain purulent exudate, hemorrhage,
  necrotic muscle, etc.

16
Examples of Lesions

• Ascites
• Exophthalmia
• Hemorrhage and/or congestion
• Cutaneous erosions and ulcerations
• Gill necrosis
• Abscesses
• Granulomas

17
DO CLINICAL SIGNS LESIONS ALLOW YOU TO MAKE A
DIAGNOSIS?
18
NO!Clinical signs and lesions suggest to you
the possible disease processes. The diagnosis
can only be made by isolating or demonstrating
the presence of the pathogenic organism with a
concurrent disease process.
19
(No Transcript)