Lab Diagnosis of European Foulbrood

European Foulbrood (abbreviated EFB) is a honey bee brood disease caused by the bacterium Melissococcus plutonius (Figure 1).

Figure 1: Melissococcus plutonius is a short, lancet-shaped bacterial cell which does not form spores. The cell occurs singly, in pairs, or in chains.

Beekeepers and apiary inspectors can make a diagnosis of EFB by looking for the symptoms described in the following web-page

• European Foulbrood: A Bacterial Disease Affecting Honey Bee Brood

Also, a field test kit can be employed, which is described in the following web-page

• Diagnostic Kits for American and European Foulbrood

For a definitive diagnosis, a brood sample should be mailed to the USDA-ARS Bee Research Laboratory at Beltsville Agricultural Research Center for a microscopic examination.

Figure 2. Paenibacillus alvei and Melissococcus plutonius

The Beltsville lab will examine a sample of the material using light microscopy and look for bacteria that is affecting the brood. The causative organism of EFB is the bacterium Melissococcus plutonius. The lab will typically find M. plutonius in about 10-20% of the EFB samples examined. However, there are several other organisms that do not cause disease but are only associated with M. plutonius. These other organisms, most commonly Paenibacillus alvei (Figure 2) overgrow M. plutonius so it can’t be found. Due to these other organisms only being associated with M. plutonius, the lab will still identify the sample as being EFB if these other organisms are found, and M. plutonius is not seen.

Between the years 2008 – 2004, the Beltsville Bee Research Laboratory examined between 799 – 1062 brood samples each year. From these samples, the following percentages were found to have EFB:

• 2008 – 4.7%
• 2007 – 6.4%
• 2006 – 4.5%
• 2005 – 4.2%
• 2004 – 1.4%

Bee disease diagnostics from the Beltsville Bee Research Laboratory is free of charge, but samples are only accepted from the United States and Canada. A sample of comb at least 2 x 2 inches with as much of the effected brood as possible should be sent. This sample should not contain honey. The sample should be wrapped in paper and mailed in a heavy cardboard box. Plastic, wax, or foil wrappings should not be used as this leads to decomposition and the growth of mold.

For the mailing address, more detailed instructions, and information about other bee diagnostic services, see the USDA Bee Disease Diagnosis Service website.

Reference:

Diagnosis of Honey Bee Diseases; Shimanuki, H. and Knox, D. A.; USDA-ARS Agriculture Handbook Number 690;

Download a .pdf of Diagnosis of Honey Bee Diseases here

Author: Bart Smith, USDA-ARS Bee Research Laboratory, Beltsville Agricultural Research Center
Photos by: Bart Smith
Editor: Michael Wilson, University of Tennessee