Why in News?
American Foulbrood (AFB) is in the news because agricultural authorities recently confirmed a fresh outbreak of the highly destructive disease in Scotland.
About
- Core Definition: A fatal, highly infectious bacterial disease that specifically attacks developing honeybee larvae and pupae.
- Causative Agent: Caused by the Gram-positive, spore-forming bacterium known as Paenibacillus larvae.
- Target Stage: It exclusively impacts the brood (young larvae in the prepupal or older stage) and does not affect adult honeybees directly.
- Global Classification: Classified as a highly dangerous, notifiable animal disease by the World Organisation for Animal Health (WOAH) due to its economic threat to global apiculture.
Transmission & Extreme Spore Resilience
- Infection Pathway: Young larvae contract the bacterium by accidentally consuming food contaminated with bacterial spores.
- Extreme Longevity: The spores are incredibly hardy, resisting extreme temperatures and chemical agents, and can remain dormant yet viable for over 50 years.
- Hive Spreading: Adult bees act as carriers; they spread the spores within and between colonies via natural activities like robbing honey from weak hives and drifting.
- Human Spread: It is easily tracked between different locations by beekeepers through the interchange of infected equipment, combs, and wooden hive tools.
Key Clinical Symptoms
- Spotty Brood Pattern: Infected hives exhibit an irregular, scattered layout often described as a "shotgun pattern".
- Sunken Cappings: The wax coverings over the brood cells become dark, moist, sunken, and frequently show jagged perforations.
- The "Ropiness" Test: If a matchstick or toothpick is inserted into a dying larva, the decaying tissue draws out into a sticky, brown, rope-like thread.
- Foul Odor: The collapsing hive emits a distinct, putrid, non-typical smell of decaying animal matter.
- Hard Scale: Dead larvae dry down into a flat, blackish scale tightly glued to the bottom of the cell wall, which is nearly impossible for worker bees to remove.
Management, Containment, and Prevention
- No Medical Cure: Once a honeybee colony develops an active infection, the disease cannot be cured with traditional antibiotics.
- Mandatory Destruction: The primary and most effective control measure remains the complete incineration (burning) of the infected bees, hives, and associated frames.
- Strict Biosecurity: Beekeepers must execute thorough hive inspections, sanitize tools with alcohol/flame between hives, and avoid buying second-hand woodenware of unknown origin.
- Breakthrough Vaccine: To curb global losses, the US Department of Agriculture (USDA) previously granted a conditional license for the world's first honeybee vaccine. It uses dead Paenibacillus larvae bacteria mixed into "queen candy" to transfer immunity to developing larvae through royal jelly.
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