Friday, October 4, 2013

Asian Giant Hornets: Firefighters in Ankang, China Fight Back as Death Toll Hits 42, and Injuries Hit 1,600

ITN VIDEO: Victims in hospital with sting wounds and firefighters shown fighting hornets and removing hornet nests.

Firefighters in northwest China are removing nests while wearing protective suits and using fire and aerosol spray to fend off the two-inch Asian Giant Hornets (Vespa Mandarina).  Ankang’s firefighters have removed over 300 hornet nests from crowded residential areas since July in an attempt to prevent injuries and deaths.

Hospitals in the city of Ankang, China have been forced to set up specialist units and medical committees to cope with the large number patients suffering from multiple stings. Many people are in critical condition, and some are not expected to survive. In early stats released in October 2013,  42 people have been killed, and 1600 have been injured by stings from Asian Giant Hornets.

Highly toxic venom injected in multiple puncture wounds have been found on victims. Many of the wounds look ulcerated and show signs of tissue destruction. Some naysayers have claimed that venom of Asian Giant Hornets isn't any more lethal than other wasps and bees, but experts say that the toxin is a special mix that can destroy tissue with a cytolytic peptide (specifically, a mastoparan) that can damage tissue by stimulating phospholipase action from the victim's tissue. The venom also contains its own intrinsic phospholipase. Mastoparan is a peptide toxin from wasp venom that is basically a biochemical hazmat situation at the cellular level -- causing cells to spill out their interior contents (exocytosis). Histamine, serotonin and catecholamines are released. Proteins are disassociated by Mastoparan. Phospholipase is an enzyme that hydrolyzes (destroys) phospholipids, which are components of all cell membranes.

Asian Giant Hornet venom also contains a neurotoxin called mandaratoxin (MDTX), which is a single-chain polypeptide with a molecular weight of approximately 20,000.  MDTX can be lethal even to people who are not allergic if the dose is sufficient. In research of MDTX, scientists discovered with an intracellular recording from the presynaptic nerve fiber, MDTX blocked the action potential mainly by reducing the sodium current (nerve impulses work from flow of sodium ions across nerve cell membranes). In very small amounts (nanomole range), MDTX irreversibly blocked the excitatory postsynaptic potential of tissue in a walking lobster leg.

The sensation of pain is described as a "hot nail driven into tissue."

Most of the victims have been rural farmers working outdoors in rice fields. A 68-year-old was killed after wind blew a hornets nest over, or when he accidentally knocked over the nest. The hornets swarmed him, stung him multiple times, and killed him. Victims in Hanzhong and Shangluo have also been killed and injured.

Ankang, China is in a Subtropical monsoon climate region of China. The frost-free period, according to is as long as 210-270 days, which lasts on average more than 8 months. It is unknown if the hornets migrate from more tropical regions.

See also Purification and properties of a presynaptically acting neurotoxin, mandaratoxin, from hornet (Vespa mandarinia).


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