resurgence of european foulbrood in switzerland ... department of economic affairs, education and...
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Federal Department of Economic Affairs,
Education and Research EAER
Agroscope
www.agroscope.ch I good food, healthy environment
The 2nd of October 2017, Istanbul
Resurgence of European foulbrood in Switzerland: epidemiology and diagnosis
J.D. Charrière; D. Grossar
Swiss Bee Research Center
2OIE Symposium
J.D. Charriere
Brood diseases
European foulbrood
3OIE Symposium
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European Foulbrood (EFB): Pathogenesis
Bacterial brood disease of honey bees
ZBF
Melissococcus
plutonius (Enterococcaceae; White, 1912)
• lanceolate cocci
• non-spore-forming
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J.D. Charriere
European Foulbrood (EFB): Pathogenesis
• infects the intestinal tract of
young honey bee larvae
Forsgren, 2010
Melissococcus
plutonius
• Secondary infections- Paenibacillus alvei
- Enterococcus faecalis
- Achromobacter eurydice
ZBF
• Competition for nutrients
FERA, 2009
5OIE Symposium
J.D. Charriere
Sauerbrut / Wallis 2010
J.D. CharrièreBee Research Agroscope
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European foulbrood (EFB)
• Brood appearance:
• colour change
• position
• flaccid/decomposed
• scales
• Foul/sour odor
• Hygienic behavior
→ Brood area
patchy
The Food and Environment Research Agency, 2009ZBF
ZBF
How to recognize colonies affected by EFB?
FERA, 2009ZBF
ZBF
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Notifiable disease (green)
Dahle et al. Murcia 2014
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Distribution within countries
Dahle et al. Murcia 2014
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EFB cases in
Switzerland
Prevalence in Switzerland
• Until 2002 the number of
EFB-cases registered in
Switzerland was below
80/year
• 992 cases in 2010 -Since
then decreasing tendency
• Most cases are detected
in the canton of Bern and
Thurgau
European foulbrood (EFB)
0
250
500
750
1000 992
401
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Sanitation measures
1km
1 km
Apiary
- Restriction zones of 1 km radius- Destruction of all colonies with clinical symptoms
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European Foulbrood (EFB): Control measures applied in CH
Notifiable disease in Switzerland
Routine checks by bee inspectors
Restriction zone of 1 km radius
Destruction of diseased colonies
Total sanitation of the apiary if more than 50% of the colonies are affected
(killing or artificial swarms)
Visual check of all colonies within the restriction area by bee inspectors
Follow-up checks by the bee inspector after sanitation (also next Spring)
Control measures are costly
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M. plutonius isolates were
thought to be homogenous…
European Foulbrood (EFB):
Diversity of M. plutonius
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…but new studies contradict this opinion.
European Foulbrood (EFB):
Diversity of M. plutonius
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…is a technique for the typing of bacterial isolates using DNA
sequences of multiple housekeeping genes.
Multilocus sequence typing scheme (MLST) for M. plutonius
developed recently (Haynes et al., 2013).
Multilocus Sequence Typing (MLST)
In total 148 Swiss samples analyzed:
97 M. plutonius isolates (2005-2007)
51 M. plutonius isolates (2013)
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Summary
The 148 analyzed Swiss M. plutonius isolates belong to 13
different Sequence Types:
• 40 isolates belong to six novel M. plutonius Sequence
Types identified for the first time in this study
• 108 isolates could be assigned to Sequence Types, identical
to isolates already described (Haynes, 2013; Takamatsu, 2014; Budge, 2014)
• No clear pattern in the distribution of the different sequencing
types
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• Transferring young larvae into plastic
cups with food
• Infection with M. plutonius added to
artificial diet (sugar + royal jelly)
• Rearing in an incubator under
constant conditions in the laboratory
• Daily feeding and monitoring of the
mortality till emergence
ZBF
ZBF
Comparison of the virulence between strains: in vitro larval rearing (Aupinel et al., 2005)
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Isolates differ in their virulence on the
larval level N=116-130 larvae per strain
Virulence of Melissococcus plutonius isolates
Pro
po
rtio
n la
rva
e a
live
Days after infection
control
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European
Foulbrood
outbreak
Social
immunity
Environment
Colony and apiary
density
Beekeeping
practices,
sanitation measures
M. plutonius
Individual
immunity
European foulbrood (EFB)
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1
10
100
1'000
10'000
100'000
1'000'000
0 90 180 270 360 450 540 630 720
CF
U/m
l
Duration of storage at 14° C (days)
Wild-strain, nectar honey
Wild-strain, honeydew
Type-strain, nectar honey
Type-strain; honeydew
Survivorship of M. plutonius in honey
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Thank you for your attention.
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