emerging diseases in tilapia: future prevention methods will alleviate the economic threat c....
TRANSCRIPT
Emerging diseases in Tilapia: Future prevention methods will
alleviate the economic threat
C. Komar*, L. Labrie, J. Ng, B. Sheehan, W. Enright and Z. Tan
Intervet Norbio [email protected]
Outline
• One observation: diseases are now a reality in tilapia farming
• One piece of advice: identify and understand diseases present in your fish farm
• One important question: what should be farmer’s expectation to a fish vaccine
• A few practical aspects of vaccination in tilapia
Streptococcosis
Columnaris
Francisella spp.
Iridovirus
Parasitic diseases
monogenean
Oodinium sp.
Tilapia used to be considered as
a hardy or disease-resistant fish
But this is changing…
Hatchery
Sex-reversal
1 g 10 g 100 g 1 kg0 g
Pat
hoge
nP
has e Nursery Pre-grow-out Grow-out
Flavobacterium columnare
Francisella spp.
Edwardsiella tarda
Iridovirus
Streptococcus spp. (Sa; Si)
Saprolegnia & Branchiomyces
Nocardia seriolae
Trichodina & Dactylogyrus
Nodavirus?
Note: importance of the disease is roughly in proportion to the size of the arrow bars
Major Diseases Affecting Tilapiaduring the Farming Cycle
Outline
• One observation: diseases are now a reality in tilapia farming
• One piece of advice: identify and understand diseases present in your fish farm
• One important question: what should be farmer’s expectation to a fish vaccine
• A few practical aspects of vaccination in tilapia
Know your enemy : how to evaluate the health status of
your farming operation
Random sampling is not the ideal method to study disease
• If a disease causes 30% mortality over 12 months
• The probability to find 1 sick fish in a random sample of 10 fish is <1%
How to get an accurate picture of the diseases present in your farm?
• Even during a disease outbreak, most fish in the population are healthy
• Sample moribund fish with clear external signs
• Samples should be processed by a professional laboratory
Bacterial isolation
Bacterial identification and antibiogram
Tree Diagram for 131 Cases
Unweighted pair-group average
Percent disagreement
Lin
kag
e D
ista
nce
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
G
P4
57
S.M
UTA
NS
IN
S1
36
IN
S1
32
IN
S1
31
IN
S1
29
IN
S1
33
IN
S1
35
IN
S1
27
IN
S4
21
IN
S4
06
IN
S4
20
IN
S1
23
IN
S4
19
IN
S4
18
R
FF
75
7
INS
12
1
INS
40
9
INS
41
2
INS
411
IN
S4
05
IN
S4
04
IN
S4
03
IN
S4
10
IN
S3
26
IN
S3
25
IN
S3
24
IN
S4
14
IN
S4
16
IN
S4
15
IN
S4
13
IN
S4
08
IN
S4
07
R
T4
89
R
T4
88
R
T4
87
R
T4
86
R
T4
85
R
T4
84
IN
S4
17
IJ
F2
11
IJF
21
0
IJF
20
0
IJF
19
9
IJF
19
8
IJF
19
7
IJF
19
6
IJF
19
5
IJF
19
4
IJF
18
2
INS
06
8
INS
13
0
INS
12
5
INS
13
4
INS
12
2L
.LA
CT
IS
INS
42
2
SB
26
9
PP
78
3
RF
F7
87
T
I75
9
TI7
73
T
I76
5
TI7
61
T
I76
0
TI7
55
T
I77
6
TI7
49
T
I78
0 R
FB
S7
79
T
I77
7
TI7
75
T
I77
4
TI7
63
T
I76
2
TI7
48
T
I74
7
TI7
56
T
I18
8
TI1
87
H
BG
83
1S
.ZO
OE
PI
S
B2
49
RF
BS
77
8
SB
31
0
INS
42
5
INS
42
4
INS
42
3
SB
53
0
GS
N8
23
G
SN
82
2 R
FB
S7
45
S
B2
70
S
B2
68
IN
S4
26
S
B4
30
G
P4
58
S
B2
50
S
B2
33
S
B2
32
S
B2
29
S
B2
23
S
B2
22
S
B2
21
S
B2
34
S
B2
20
T
F7
86
T
F7
85
S
B2
35
CS
SB
10
6
SB
19
1
SB
19
0
SB
12
8
SB
12
6
SB
13
9
SB
13
8
SB
12
7
SB
10
6
INS
25
1
INS
25
0
INS
24
9
PP
78
4
INS
116
IN
S11
5
SN
70
3
SN
70
2
SN
70
4
SN
70
1
SN
71
2
TI0
18
T
I01
7
Antibiotic Mar 05
Chloramphenicol R
Nitrofurantoin S
Tetracycline S
Flumequine S
Neomycine S
Trimethoprim - sulfamethoxazole R
Ampicilline S
AMoxicilline S
Gentamicine R
Rifampicine S
Kanamycine R
Perfloxacine R
Norfloxacine S
Iridovirus positive at 568bp
PCR Analysis for Viral Disease
Nodaviruspositive at
426 bp
Electromicroscopy
Iridovirus
500 nm
Histopathology
H&E x200: brain H&E x400: eye
H&E x20: lateral muscle
Factors in disease expression
• Nutrition
• Fish density
• Micro-organisms
Factors in disease expression
Factors in disease expression
• Fish density
• Micro-organisms
Factors in disease expression
• Biosecurity
• Water quality parameters
• Stress level
Factors in disease expression
Water quality
Micro-organisms
Fish: density/quality/size/handling
Feeding
Critical level of stress not reached: system ok
Stress level
Feeding
Factors in disease expression
Water quality
Micro-organisms
Fish
Critical level of stress reached: system suboptimal
Stress level
Feeding
Factors in disease expression
Water quality
Fish
Critical level of stress breached: situation of “disease”
Micro-organisms
Stress level
Fish health management• Therapeutic treatment
– Antimicrobials• Antibiotics• Antiparasitics• Antifungals
• Prevention – good health management– Biosecurity/quarantine/exclusion (Responsible movement of live AA)– Selection– Sanitation– Nutrition and feed management– Vaccination
Outline
• One observation: diseases are now a reality in tilapia farming
• One piece of advice: identify and understand diseases present in your fish farm
• One important question: what should be farmer’s expectation to a fish vaccine
• A few practical aspects of vaccination in tilapia
The concept of vaccination
Water quality
Micro-organisms
Feeding
Fish
“Vaccines are preparations of antigens derived from pathogenic organisms, rendered non-pathogenic by various means, which will stimulate the immune system in such a way as to increase the resistance to disease from subsequent infection by a pathogen.”
A.E. Ellis, 1988
The concept of vaccination
Water quality
Micro-organisms
Feeding
Fish
Vaccination
Pathogens (bacteria, viruses…)
Resistance to infection
Mortality
Treatment
Healthy
Infection
Diseased
95% survival
Development of Fish VaccinesDevelopment of Fish Vaccines
Disease InformationDisease Information
Aetiology of DiseaseAetiology of Disease
Characterization of IsolatesCharacterization of Isolates
Definition of DiseaseDefinition of Disease
Challenge Model Devel.Challenge Model Devel.
Vaccine DevelopmentVaccine Development
Vaccine Production Vaccine Production
Lab Vaccination TestsLab Vaccination Tests
Pre-Licensing StudiesPre-Licensing Studies
LicensingLicensing
Marketing PreparationMarketing Preparation
Product IntroductionProduct Introduction
Normally 5 – 8 years in R&D
Normally 5 – 8 years in R&D
Epidemiology and disease investigation
Laboratory phase
Field and licencing
phase
Outline
• One observation: diseases are now a reality in tilapia farming
• One piece of advice: identify and understand diseases present in your fish farm
• One important question: what should be farmer’s expectation to a fish vaccine
• A few practical aspects of vaccination in tilapia
Intervet Norbio Singapore Pte. Ltd.(operated January 2000)
Intervet Norbio Singapore Pte. Ltd.(operated January 2000)
Dedicated to disease research and product development for aquatic animal health in the warmwater environment
Dedicated to disease research and product development for aquatic animal health in the warmwater environment
Seriola spp.
Marine fish
Tilapia
Norvax®Strep SiOnset and duration immersion
0
20
40
60
80
100
1 3 5 7
45 75 59.7 53.4
Time in weeks PV / % mortality in controls
RPS
val
ues
Norvax® Strep SiOnset and duration injection
0
20
40
60
80
100
73.3% 66.7% 86.7% 100% 73.3% 80.0%
Wk 1 Wk 2 Wk 3 Wk 6 Wk 9 Wk 12
% mortality in controls / time PV
RPS
Data from the field have shown full protection for 14 months
Sea bass: S. iniae infections
0.01 0.1 1 10 100 1000 10000
Weight of fish (g) log scale
S. iniae isolated Other cause
Immersion (0.5 – 10 g)
Injection (15 – 100 g)
Choice of applicationComparison of application methods
Oral Immersion Injection
Application +++ ++ -
Stress +++ + +
Effectiveness -/+ ++ +++
Duration -/+ ++ +++
Immunity ? Hum Hum + Cell
Combination of antigens
? + +++
Hatchery
Sex-reversal
1 g 10 g 100 g 1 kg0 g
Pat
hoge
nP
has e Nursery Pre-grow-out Grow-out
Flavobacterium columnare
Francisella spp.
Edwardsiella tarda
Iridovirus
Streptococcus spp. (Sa; Si)
Saprolegnia & Branchiomyces
Nocardia seriolae
Trichodina & Dactylogyrus
Nodavirus?
Note: importance of the disease is roughly in proportion to the size of the arrow bars
Vaccination window
Vaccination window
Important aspects of vaccination
• Vaccination window: fish must be vaccinated before to be in contact with the disease
• Vaccine stimulates the specific immune system: no cross-protection between S. iniae and S. agalactiae in laboratory challenges
• 1 skilled person can inject 1,000 fish in one hour
• A team of 4 injectors working 8 hours a day can vaccinate 30,000 fish per day
Take home message• Prevention is better than cure• Vaccination is a tool for better health management and not a
substitute for other important health management measures (biosecurity, good husbandry practices, etc…)
• It has been a successful disease management method in the salmon industry for the last 15 years.
• Vaccination in tilapia will help the sustainable development of this industry
• Vaccination works like an insurance:– You pay an insurance policy in case that you will get sick.– Fish must be vaccinated before they are in contact with the
disease– As for an insurance policy, vaccination is specific to certain
pathogens– Vaccination against Streptococcus iniae will protect against
this specific disease only
Thank you!
Acknowledgements
Support from the Intervet team and manycollaborators throughout the world is
highly appreciated.