Africanized Honey Bees

Africanized Honey Bees:  Apis mellifera scutellata
In 1956, scientists in Brazil were looking for a way to increase honey production made by the local bees. As part of their experiment they imported honeybees from Africa and to their surprise some of the imported bees managed to escape and began mating with the local honeybees. The result was a hybrid cross between two species of bees, which were named the “Africanized honeybee”. These hybrid bees proved to be aggressive and dangerous. They were soon referred to as “Killer bees” because their stings had the ability to kill humans. Since 1990 scientists estimate that there have been at least 17 deaths in the United as a result of a Killer bee envenomation (KOLECKI, 1998). In another study involving a small group of patients the cause of death following honeybee stings was respiratory failure.

Clinical studies of Apis Mellifera have shown that many who encounter their potential fatal sting do not survive. The prevalence of this insect is rather high in Brazil as well as many other countries including the U.S. and due to their aggressive nature they are a concern for public safety. There are clinical cases of patients who have survived numerous Africanized bee stings, however they did suffer physically. Clinical manifestation of the bee toxin was characterized by diffuse and wide spread edema, a burning sensation in the skin, weakness, dizziness, and hypotension. Acute renal failure also developed and was attributed to hypotension, intravascular hemolysis and myoglobinuria due to the direct toxic effect of the massive quantity of injected venom (KOLECKI, 1998).

 It has also been observed that multiple Africanized bee stings can cause death in adults. Case reports of people who had been stung by the Africanized bee indicated that even healthy adolescents were likely to experience muscular weakness, diffuse edema, general paresthesia, nausea, vomiting and loss of consciousness (DAHER et al., 2003).
Clinical research has suggested that systematic toxic effects of bee venom are generally seen on patients who have at least 50 stings. The potentially lethal number of stings is estimated to be about 500, with death occurring due to a direct systemic effect of the venom due to a large amount of toxin flowing through the body (KOLECKI, 1998).

The bee's venom contains toxins such as mellitin, which if the main component and has hemolytic and vasoactive properties, it is analogs to the C9 component of the complement cascade and it is able to metabolize the arachidonic acid; phospholipase A2, it is the most active component within the animals venoms, it has myotoxic action; biogenics amines, it is involved with signalization of systems such as immune and nervous; hyaluronidase, degrades the extracellular matrix.  

It also contains apamin, a neurotoxin which could contribute to the lysis of red blood cells and leukocytes (ERLER et al., 2011). The Africanized bee stings are particularly interesting because even after the stinger is detached from the insect body it continues to inject venom because the long sting shaft remains inside the skin. This poses concern for the complete and effective removal of the stinger because it is possible for a portion of the stinger to remain inside the body and continue to release venom. Relative mortality rates from insect bites and stings have been estimated from several case studies and it is assumed to be between 15-25% (DAHER et al., 2003).

Daher, E., Silvia-Junior, G., Bezerra, G., et al. 2003. Case Report: Acute Renal Failure After Massive Honeybee Stings. Rev. Inst. Med. Trop. Säo Paul. Vol:45 (1) 45-50.

Erler, S., Lommatzsch, S., and Lattorff, H.M.G. 2012. Comparative analysis of detection limits and specificity of molecular diagnostic markers for three pathogens in the key pollinators Apis mellifera and Bombus terrestris. Parasitology Research. Vol:110 (1) 1403-1410.
Kolecki, Paul. 1999. Delayed Toxic Reaction Following Massive Bee Envenomination. Annals of Emergency Medicine. Vol:33 (1) 114-118.