American and European Foulbrood: Diagnosis and Quarantine

American and European foulbrood are the most serious bacterial brood diseases, which, if left untreated, lead to the inevitable destruction of the apiary and pose a real threat to the entire region.

Introduction: Why is Foulbrood So Dangerous?

Foulbrood diseases are caused by highly resistant bacteria that attack bee larvae. American foulbrood (Bacillus larvae) is particularly insidious; its spores remain viable for decades – research shows they can germinate even after 20-22 years in a dry environment. These bacteria spread rapidly through drifting bees, robbing, infected equipment, and feeding bees honey of unknown origin.

Field Diagnosis: How to Recognize the Enemy?

The key to saving an apiary is the early detection of the first infected cells. Inspections should be carried out with particular attention to the condition of sealed and unsealed brood.

1. American Foulbrood (Malignant)

Primarily attacks sealed brood (usually 10-15 days old).

• Appearance of Cappings: Wax cappings become darker, sunken (concave), and often perforated.
• Matchstick Test: When piercing the capping with a matchstick or small stick, a sticky, homogeneous mass the color of coffee with milk or dark brown is found inside.
• Ropiness: The mass, when the matchstick is withdrawn, stretches into a thin, cobweb-like thread 10–15 cm long.
• Odor: Characteristic, resembling the smell of old carpenter’s glue or decaying protein.
• Brood Pattern: The brood becomes “spotty” – larvae of different ages and empty cells appear next to each other.
• Scales: Dried larvae form hard, scale-like crusts that adhere very strongly to the cell walls, preventing bees from removing them.

2. European Foulbrood (Benign)

Primarily attacks unsealed brood 3–4 days old.

• Appearance of Larvae: A healthy larva is pearly white and lies curled in a “C” shape. A sick larva loses its luster, becomes dull, yellowish, and flaccid, changing its natural position in the cell.
• Consistency: The decaying mass may be ropy, but unlike American foulbrood, the thread is short (1–4 cm) and breaks easily.
• Odor: Sour, resembling rotting apples, or in more severe cases (with the involvement of Bacillus alvei) – the smell of decaying meat or sweaty feet.
• Removal: Scales from dried larvae are easy for bees to remove or can be removed with tweezers.

Laboratory Tests

If disease is suspected, samples should be sent immediately to a veterinary laboratory.

• Sample: A cut piece of comb measuring 10 x 15 cm with visible disease symptoms (sick and dead brood).
• Packaging: The comb should be wrapped in paper (not plastic!) and delivered within 24 hours of collection.

Quarantine and Eradication: Step-by-Step Instructions

After diagnosis is confirmed, the apiary is placed under quarantine by the district veterinary officer.

Quarantine Parameters:

• Radius: Typically a radius of 5–7 km around the disease outbreak.
• Prohibitions: A complete ban on moving bee colonies, queens, equipment, and bee products outside the infected area.

Eradication Methods:

In cases of severe infestation or disease detected in a new location, radical measures are recommended.

Step 1: Elimination of Severely Diseased Colonies Very weak and heavily infested colonies should be eliminated in the evening when all bees are in the hive.

1. Suffocate the bees with sulfur dioxide (burning sulfur in a smoker) or formaldehyde.
2. Burn the combs along with the dead bees and bury the ashes deeply.

Step 2: Shook Swarm Method (for colonies to be saved) The method is used in the evening, preferably during a honey flow.

1. Move the old hive aside; in its place, put a new, disinfected hive with frames containing foundation.
2. Lay a large sheet of paper (e.g., newspaper) in front of the entrance.
3. Brush or shake all bees from the old frames onto the paper – the bees will move into the new hive on their own.
4. Burn the paper immediately after the operation.
5. It is best to cage the queen for 24 hours to limit immediate brood rearing.
6. Take the old hive and combs to a sealed room for disinfection or melting down.

Equipment Disinfection

The effectiveness of the fight against foulbrood depends on the precision of disinfection. B. larvae spores die at 100°C only after 30-60 minutes, and in wax (120°C) after one hour.

• Hives and Wood: The most effective method is scorching with a blowtorch flame until the wood lightly browns. A 2-3% hot solution of caustic soda (sodium hydroxide) can also be used.
• Small Tools: Boil in water for a minimum of 10–15 minutes.
• Combs (drawn comb): Cut out, melt down, and boil the frames in sodium hydroxide solution or burn them.
• Ground under the Hive: Dig to a depth of 10–15 cm and drench with a 4% formaldehyde solution or sprinkle with chlorinated lime.

Pharmacological Treatment (Supportive)

Administering antibiotics is an auxiliary measure and must be carried out under veterinary supervision.

• Dosage: Typically 400–500 thousand units of antibiotic (e.g., terramycin, tetracycline) per 1 liter of sugar syrup.
• Administration: 100–150 ml of medicated syrup per each bee space between frames occupied by bees, 3 times at 5-day intervals.

Applying the above procedures with the utmost rigor is the only way to eliminate foulbrood from the apiary and protect nearby beekeeping operations. An apiary can only be declared free of the disease one year after the end of treatment and after obtaining negative laboratory test results.