Larvae eating dead human tissue? ugh! What sounds disgusting, however, helps people whose wounds heal only with difficulty. Larvae also have a distinct advantage over antibiotics.
In larvae therapy, so-called biobags are placed on the wound
The larvae or maggot therapy is also known as biosurgery. That doesn't sound all that terrible. But the procedure itself is not quite as bad as many might think, says Professor Uwe Wollina from the Dresden Municipal Clinic.
“There are so-called biobags. They look like tea bags. The larvae are inside. These biobags are placed on the wound. They are usually the larvae of the green fly. They are easy to breed and they belong to the necrophages. They feed only on dead tissue and spare the healthy.” For medical purposes, they are bred under sterile conditions in the laboratory.
Diabetics benefit from larval therapy
The method is used successfully in diabetics in particular. Because they often suffer from wound healing disorders. “The therapy is suitable for chronic wounds, for leg and foot ulcers in diabetics and also for patients with varicose veins. Ulcers can also occur here,” explains Wollina.
If the corresponding areas do not heal at all, there is even a risk that limbs will have to be amputated. Medicine can also get necrosis under control with the help of biosurgery. Because even then tissue dies. The patient can develop sepsis, which can become life-threatening. Larvae therapy helps to prevent this.
The breeding of the larvae must be sterile
Medicine takes advantage of the fly larva's natural ability to break down dead tissue. To do this, the animals release their digestive juices into the wound. There, the dead tissue is first liquefied. This is ensured by special digestive enzymes. The larvae then consume the liquid as food.
“During this time, they grow from around two millimeters in length to up to one centimeter and increase their weight by a hundredfold,” explains Wollina. The biobags remain on the wound for between three and five days. Then they are exchanged. About 80 to 90 percent of dead tissue and bacteria could be removed with this method, the dermatologist continues.
After about three days, the biobags with the maggots are removed and new ones are placed
larvae as an alternative to antibiotics
The larvae not only remove dead tissue, they also disinfect the wounds, produce antibacterial substances and excrete ammonia, which raises the pH value. The effect is similar to that of an antibiotic. Larvae therapy is therefore a possible alternative to counteract the emergence of the dreaded, multi-resistant germs such as MRSA.
“The larvae are also able to improve vascular perfusion and microcirculation,” says Vollina. “This applies above all to the capillaries, the finest branches of the blood and lymph vessels.”
Larvae therapy is tried and tested
Larvae therapy is not new. From the 14th to the end of the 19th century, various surgeons carried out experiments on soldiers using larvae to treat wounds. During the First World War, an American surgeon found that the soldiers' wounds healed much faster and better with the use of larvae. With the discovery of penicillin in 1928, the use of larvae to treat wounds was initially no longer in demand.
After the discovery of penicillin, maggot therapy was hardly in demand
In the meantime, however, this therapy is becoming increasingly important again. “The problems with antibiotic resistance began in the 1980s, and that's when larval therapy was reactivated,” says Wollina.
Larvae therapy is now being practiced again in a number of countries. In addition to Germany, these include the USA, Sweden and Switzerland, but also Thailand. For poorer countries such as Africa, the main problem is that larvae production facilities would have to be created locally. But that is very expensive, according to Wollina.
A skin transplant is the last step
Once the larvae have cleaned the wound and freed it from diseased tissue, there is usually a defect in this area. To speed up its healing, a doctor may apply a skin graft to the affected area. The transplant is about 0.2 to 0.3 millimeters thick and is usually removed from the thigh.
Such an operation is easy and can be performed under local anesthesia. Because only a piece of the top layer of skin is removed, this wound heals quickly like a simple abrasion, and the site where the transplant is applied usually recovers within two weeks.
Without the larval therapy the healing process can take much longer. For people with chronic wounds, this might be a reason to overcome their disgust.