Resurgence of European foulbrood in Switzerland ... Department of Economic Affairs, Education and Research EAER Agroscope I good food, healthy environment The 2nd of October 2017,

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

J.D. Charriere

European Foulbrood (EFB): Pathogenesis

Bacterial brood disease of honey bees

ZBF

Melissococcus

plutonius (Enterococcaceae; White, 1912)

• lanceolate cocci

• non-spore-forming

4OIE Symposium

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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J.D. Charriere

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

7OIE Symposium

J.D. Charriere

Notifiable disease (green)

Dahle et al. Murcia 2014

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J.D. Charriere

Distribution within countries

Dahle et al. Murcia 2014

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J.D. Charriere

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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J.D. Charriere

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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J.D. Charriere

M. plutonius isolates were

thought to be homogenous…

European Foulbrood (EFB):

Diversity of M. plutonius

13OIE Symposium

J.D. Charriere

…but new studies contradict this opinion.

European Foulbrood (EFB):

Diversity of M. plutonius

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J.D. Charriere

…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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J.D. Charriere

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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J.D. Charriere

• 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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J.D. Charriere

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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J.D. Charriere

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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J.D. Charriere

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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J.D. Charriere

Thank you for your attention.

[email protected]

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