Pity poor Rochelle Harris who recently returned from Peru with a mild headache that turned out to be caused by 10 maggots residing in her ear canal, grown from eggs deposited there by a rather intrepid New World screwworm fly. The maggots burrowed a hole of 12mm into her inner ear, but managed to be removed by doctors who smothered the bugs with olive oil, forcing them to come to the surface. Her story has now been reported with rather macabre glee by all branches of the online media and Harris has featured on a Discovery Channel documentary series called ‘Bugs, Bites and Parasites’.
The New World screwworm fly, or Cochliomyia, are a genus of blowflies, the most common two species being species Cochliomyia hominivorax andCochliomyia macellaria. Cochliomyia hominivorax is rather an unpleasant customer. With a preference for living flesh and the ability to dig itself in deep into humans and livestock alike, the United States Department of Agriculture led a very focused campaign to eliminate the fly from the USA. Beginning in the 1950s, huge numbers of sterlie male flies were released in Florida. This exploited the nature of female hominivorax , which are only capable of mating and reproducing once in their lifetimes. Thus reproduction rates plummeted and now Cochliomyia hominivorax could be considered to be eliminated from the USA and Mexico, though regular checks of livestock must be carried out, to prevent the species from reestablishing itself.
In general, C. macellaria are of little threat to healthy humans and livestock as they are only capable of consuming already necrotic tissue.The species had a brief career in surgical maggot therapy, however the stigma of being part of the screwworm family proved too much (that and their annoying tendency to reinfect healing wounds) and they were replaced by the more easily controlled blowfly Lucilia sericata.
stigma of being part of the screwworm family proved too much
The activity of maggots has been used to treat wounds for thousands of years, as they eat away infected and necrotic tissue, leaving the healthy flesh to heal. Although it lost popularity during the second world war due to the rise of penicillin, some hospitals still used the technique, specifically using specially sterilized Lucilia sericata maggots, to heal deep burns and abscesses right up to the 1990s before it was phased out completely.
In recent years however, maggot therapy has come back into play. As of 2005, any doctor in the USA or most of western Europe can prescribe maggot therapy to treat a patient. This is due to the massive rise in antibiotic resistant bacterial infections occurring in hospitals throughout the western world.
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| Lucilia sericata |
This is where Lucilia sericata maggots shine. Not only do they consume all rotting tissue, thus reducing further bacterial spread, research from Swansea University has identified two antibacterial compounds excreted by L. sericatawhich are effective in the disruption of growth of several species of bacteria, including 12 MRSA strains. Maggot slime extracted and tested in the lab was shown to powerful enough to exhibit strong antimicrobial properties whilst in clinical use they are capable of ridding up to 92% of Staphylococcus soft tissue infections.
Researchers are currently looking into refining larvae slime (hoping to achieve the same antimicrobial effect without the whole maggots-in-an-open-wound deal) to extract and purify the antimicrobial compounds to a clinical standard. Til then we must be grateful to our blowfly friend, not only have they treated battlefield wounds since the days of the Roman Empire, but their powerful drive not to share their lunch has meant that they have evolved to be what may become the next important species in medicine.
And please, do not self medicate with maggots at home.
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