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Current clinical concerns on HISTOMONOSISand authorised medicines to treat and prevent the disease
Stephen Lister
Crowshall Veterinary Services, UK
…. of a major catastrophe”
“A minor risk ….
Easy to diagnose
Difficult to manage
The problem
• An animal health catastrophe
• An animal welfare catastrophe
• An economic catastrophe
The problem
• Turkey meat flocks – up to 100% mortality
• Turkey breeder flocks – up to 100% loss of birds & hatching
eggs
• Broiler breeders – variable mortality, ~10% morbidity,
egg drops
• Layers – 1% mortality/week, egg drop
The problem
• Turkey meat flocks– up to 100% mortality
• Turkey breeder flocks– up to 100% loss of birds & hatching
eggs
• Broiler breeders– variable mortality, ~10% morbidity,
egg drops
• Layers – 1% mortality/week, egg drop
The problem
• Turkey meat flocks – up to 100% mortality
• Turkey breeder flocks – up to 100% loss of birds & hatching
eggs
• Broiler breeders – variable mortality, ~10% morbidity,
egg drops
• Layers – 1% mortality/week, egg drop
HISTOMONOSIS – Meat turkey examples
Tried oregano product in drinking water
and Flubenvet in feed - no response!
BLACKHEAD MORTALITY
OCTOBER 2012 - Numbers per day
0
100
200
300
400
500
600
700
800
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
Turkey meat birds – 2 houses, 7,500 birds placed in each house
>50% mortality - rest of flock destroyed on site - very high morbidity
PM
MEAT BIRDS MORTALITYSITE 1 – daily mortality
0
50
100
150
200
250
300
350
5,350 birds/house – 2 houses,cumulative mortality 18%, 22%
Mortality settled but poor condition
Mortality from 7 weeks
MEAT BIRDS MORTALITYSITE 1 – daily mortality
0
50
100
150
200
250
300
350
5,350 birds/house - cumulative mortality 18%, 22%
Mortality settled but poor condition
MEAT BIRDS MORTALITYSITE 2 – daily mortality
0
100
200
300
400
500
600
700
800
900
4,400 birds/house - cumulative mortality 99%, 83%, 83%
Mortality from 7 weeks, 3 houses
Culls
MEAT BIRDS MORTALITYSITE 2 – daily mortality
0
100
200
300
400
500
600
700
800
900
4,400 birds/house - cumulative mortality 99%, 83%, 83%
Mortality from 7 weeks, 3 houses
Culls
Meat flock outbreak
3 sites affected
total cost ~ £300,000
The problem
• Turkey meat flocks – up to 100% mortality
• Turkey breeder flocks – up to 100% loss of birds & hatching
eggs
• Broiler breeders – variable mortality, ~10% morbidity,
egg drops
• Layers – 1% mortality/week, egg drop
Blackhead in 17 week old turkey breeders in rear
• March 2009
• 4 houses on site
• 4 rearing flocks – each 5200 hens + 450 stags
• Uneventful rear to 17 weeks
• House 1 hens went very dull & quiet, stopped feeding. Stags OK
• Very little mortality
SGrain store
Stag shed
A140
S = shower block
MORTALITYNumbers per day
0
1
2
3
4
5
6
7
8
9
10
21 22 23 24 25 26 27
Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags
Flock
went
quiet
MORTALITYNumbers per day
0
1
2
3
4
5
6
7
8
9
10
21 22 23 24 25 26 27
Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags
Flock
went
quiet
50%
Sitting,
Not eating
Post mortem lesions
Advanced lesions within 24 hours
of onset of morbidity
MORTALITYNumbers per day
0
1
2
3
4
5
6
7
8
9
10
21 22 23 24 25 26 27
Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags
Flock
went
quiet
50%
Sitting,
Not eating
MORTALITYNumbers per day
0
1
2
3
4
5
6
7
8
9
10
21 22 23 24 25 26 27
Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags
Flock
went
quiet
Whole flock depressed
Decision
to
slaughter
50%
Sitting,
Not eating
0
1
2
3
4
5
6
7
8
9
10
21 22 23 24 25 26 27
Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags
Flock
went
quiet
Flock
killed
Slaughterhouse warned that there
may be viscera lesions and bad colour
0
1
2
3
4
5
6
7
8
9
10
21 22 23 24 25 26 27
Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags
Flock
went
quiet
Flock
killed
Of 5,200 hens sent for slaughter
54% (2,800) were condemned
Bad colour, bad livers and intestines
Blackhead in 17 week old turkey breeders in rear
• Loss of >5,000 breeders
• Rapid morbidity, poor welfare
• 54% of birds sent for slaughter condemned
• Loss of >500,000 hatching eggs
• Even after prompt diagnosis no treatment options available
BLACKHEAD MORTALITY
SEPTEMBER 2012 - Numbers per day
0
2
4
6
8
10
12
14
16
18
20
7 8 9 10 11 12 13 14 15 16
Turkey breeders in rear at 15 weeks – 5000 hens
PM
Severe dehydration
Severe caecal lesions
No macroscopic liver lesions
Histopathology
confirmed Histomonas
in liver and caecal sections
Turkey Breeders
15 weeks in rear
4 houses on site
Only 1 house affected
BLACKHEAD MORTALITY
SEPTEMBER 2012 - Numbers per day
0
2
4
6
8
10
12
14
16
18
20
7 8 9 10 11 12 13 14 15 16
Turkey breeders in rear at 15 weeks – 5000 hens
Flock
killed
PM
No specific risk
factors identified
Highly biosecure site
Very wet weather
?Movement of soil
onto concrete, walked
into house?
Breeder flock outbreak
Loss of 5000 hens
Loss of >550,000 hatching eggs
Total direct cost ~ £350,000
or ~ 420,000 Euros
These turkeys need our help !
Therapeutic Options
• No authorised medicines for treatment
• No authorised medicines for prevention
• Medicines previously licenced lost licences due to issues relating to mutagenicity and carcinogenicity
Therapeutic Options
• Previous options were:
–Dimetridazole (DMZ, Emtryl)
–Nifursol (Salfuride)
• Both were effective as preventive
in feed additives and DMZ as
water treatment
Dimetridazole - DMZ
• DMZ placed in Annex IV of Regulation 2377/90 (ban of use as VMP in food animals) in September 1995 as no agreed MRL could be set due to concerns on mutagenicity in rodents
• DMZ was still available for in feed use under Feed Additive Regulation 70/524 for prevention of Histomoniasis in turkeys and guinea fowl
Dimetridazole - DMZ
• Scientific Committee on Animal Nutrition (SCAN) concluded no consumer health risk from DMZ in September 2000, …… BUT
• EU Commission made a formal decision to withdraw DMZ from all use in turkeys – banned as medicinal feed additive in May 2002
Nifursol (Salfuride)
• In 2003 SCAN concluded that the safety for consumers could not be ensured on the basis of the data made available for the evaluation
• “As both the acceptable daily intake (ADI) and the human exposure to nifursol residues (including metabolites) cannot be established, the safety of nifursol for the human consumer cannot be ensured”
What other options are available ????
Therapeutic Options ??
• Use of DMZ to treat an
affected breeder flock, if
prevented from entering the
food chain at end of lay (as for
horse passport system)?
Use of DMZ in breeders ??
• Most breeder flocks are members of
Government controlled health
schemes – specific veterinary control
• Veterinary Health Plan could cover
requirements for strict control and
identification of treated flocks to
ensure no human consumption
Use of DMZ in breeders ??
• Not possible under current
legislation unless new data
presented to enable DMZ to
be removed from “Annex IV”
–Currently lack of sufficient data on
human safety
Personal communication with Dr Isaura de Conceicao Duarte,
Head of Animal and Public Health,
European Medicines Agency (EMA), January 2013
Therapeutic Options ??
• Variety of antimicrobials, herbal remedies tried with variable but limited success–Doxycycline, chlortetracycline,
oxytetracycline, tiamulin, amoxycillin, oregano etc etc etc
• Other options ???????????
Enhanced biosecurity ?
BUT outbreaks in high health
status breeding farms
Can we do better ?
Yes, but not the whole answer
Other Options – “wish list”!
• Histomonostat– preventive, in feed, safe
• Therapeutic options– effective and cost effective – under
MUMS legislation – minor use, minor species (reduced dossier requirements)
• Vaccination– effective and commercially available
…. of a major catastrophe”
“A minor risk ….
…. of a major catastrophe”
“A minor risk ….
An animal health,
animal welfare and
economic catastrophe
Solutions are needed-a cooperative approach
to veterinary control and food safety
Stephen ListerCrowshall Veterinary Services
www.crowshall.co.uk
