By Sharon Atieno
With disease-causing organisms proving resistant to modern treatment (antimicrobial resistance or AMR), researchers have turned to conventional methods, including the use of insects.
Researchers at the Kenya Agriculture and Livestock Research Organization (KALRO) are pushing for the use of green bottle fly (Lucilia sericata) for the treatment of chronic and infected wounds. These comprise wounds caused by peripheral vascular diseases and venous lesions related to non-communicable diseases such as cancer, diabetes, and others.
The green bottle fly is a blow fly found in most parts of the world. It is 10-14mm long, slightly larger than a house fly.
According to Paul Muriuki, research scientist, KALRO, they use the first-instar larvae- a newly hatched larvae. They administer as free-range (direct application) or put it in a biosac- a special pouch with a silicon membrane made of a muslin cloth to absorb moisture. The maggots at this stage require aeration to survive.
“Within the biobag, the larvae will just secrete and excrete secretions and excretions onto the wound, whereby they will dissolve. They will work on the dead tissue and liquefy it. Then they will eat from the biobag the sap, the liquefied material. Eating everything that is in that wound, including the flesh-eating bacteria, that is making it difficult to heal,” Muriuki explained.
He adds that they also destroy the enzymes and the biofilm- the protective structure formed by the group of bacteria, preventing the wound from healing. The maggots clean from within the biosac; however, through this method of administration, they remove only 70-80% of the dead tissue.
“You can use the bio bag in deep wounds that have nervous tissue. This helps to reduce the sensation which may cause pain,” he said, adding that major arteries may be found in the deep wounds, thus this method helps to prevent interfering with them.
The free range method is used on wounds that are near the surface or located in the posterior extremities of the body, such as the legs and hands, where the nervous tissue is not very dense.
Though the methods operate similarly, Muriuki notes that in the free range method, the larvae are put directly into the wound, then the wound is dressed with a well-aerated biosac, which is not very tight.
“Here, the maggots are moving in and about the wound. The mechanical movement triggers blood flow to the site, which is healthy for the regenerating tissue. This is because as more blood comes to the site, we will have the molecules on the building blocks required for cells to regenerate,” he said.
After the maggots have removed the dead tissue, they can remove the harmful bacteria that are producing toxins, which cause inflammation around the wound.
Depending on the wound dimension, the treatment is administered in three doses: small, medium, or heavy. Small dose is up to 400 maggots, medium is 1,000 maggots and heavy is about 4,000 maggots. Four to eight maggots per cubic centimeter are ideal to remove the dead tissue.
“When you apply the maggots, you assess after 48 hours. If full debridement (removal of dead tissue) is not done, you consider extending the time to 72 hours,” Muriuki said, adding
“You can’t go for more than 72 hours because the life cycle for this particular fly is very short. You also need to use them when they are actively feeding. After they feed, they reach a point when they stop. They need to rest.”
After applying the larvae, other wound management procedures such as the use of negative pressure, grafting, or application of other regimens (for shallow wounds).
The treatment is relatively cheap, costing Kshs. 4,000 for a single dose of maggots, compared to surgical debridement, which is estimated at Kshs. 50,000.
Besides the price, Muriuki notes that the maggot therapy is advantageous because it can be used in a home-based care arrangement. The caregiver can be trained on the application of the treatment on his or her own.
The technology has been in place since 2010, following a donation of the green bottle fly by the Slovak government. Since the official public rollout in 2015, the organization has worked closely with Kenyatta National Hospital and Nairobi University. Currently, KALRO supplies sterile maggots countrywide.
