If you are eating or plan on eating something soon, stop reading now. This is generally the only thing I have encountered as a podiatrist that has caused me to lose my appetite. I have seen more cases of gas gangrene than I can remember, debrided some pretty awful necrotic wounds and changed some pretty terrible negative pressure wound therapy (NPWT) dressings. I can do all of those things and then head straight down for lunch. However, there is one thing that never fails to induce nausea in my clinical activities: maggots.
We had a patient in the hospital this week. He is pleasant gentleman in his 90s with dementia. We were consulted after admission for wounds on his right leg that had progressed to cellulitis. We saw the patient, dressed his wounds and painted some povidone-iodine in between the toes to keep them clean. The next day we received a page stating that his foot was covered in maggots. We immediately headed to the patient’s room and confirmed this unexpected finding. The maggots had emerged in all of the interdigital spaces of the right foot. Yesterday, there was nothing visible on examination. Today, the nurses are all avoiding his room.
This is not the first time I have encountered these little guys and I know it will not be the last. However, when maggots do appear, you would usually see them upon presentation in the emergency room or upon initial consultation with the patient. It is unusual that they show up the day after the patient is admitted. This turn of events prompted me to do some research.
Maggots As A Wound Finding: What You Should Know
According to the University of Florida’s Entomology and Nematology website (which was the most reputable source I found), the common house fly is able to lay 75 to 150 eggs at a time. These eggs are about a millimeter long and are small and white in color. The fly will lay her eggs in a moist environment close to a food source, such as garbage, or, in our case, a wound.1
Then about a day later, the eggs hatch into maggots. They begin to feed on whatever food source they were left near. The maggots are about eight mm long and are what we typically encounter at a wound site. As disgusting as they are, they are not all bad. They feed on the dead material and leave the healthy tissue behind. There is even literature out there about maggot therapy for diabetic foot wounds. However, regardless of the generally harmless consequences, maggots are still not something you care to find on your patient.
In my experience, hydrogen peroxide works very well to remove the maggots.They do not particularly like the peroxide so those that are not washed away leave the area as fast as they can squirm. A good set of forceps can be helpful for stragglers or runaways. Irrigate the area with copious amounts of the peroxide as there may be some eggs that have yet to hatch. I always employ some mechanical cleansing with the peroxide and a 4x4 gauze pad as well. After the area is cleared and cleaned, keep it dry, dressed and bug-free.
Now let us get back to our patient. It turns out that this gentleman has some rather rigid toes that are very close together. These stiff toes are often the site of macerated tissue, hence our initial povidone-iodine treatment. Povidone-iodine doesn’t actually kill the fly eggs. So as good as this treatment was against bacteria, it did not do much to destroy our little friends. Our best guess is that the eggs were laid just prior to admission and they showed up in the early morning less than a day later. With the critters evicted and the area well cleansed, we redressed the patient’s foot with some povidone-iodine soaked 4x4 gauze in between the toes and changed the dressing again later that day for another quick cleaning. The next day, we performed another dressing change and no maggots were evident.
In this patient’s situation, the maggots likely appeared due to moist web spaces. I have more often encountered them in patients with hard, scaly, ichthyotic skin occurring with long-standing lower extremity edema. This scaly skin develops cracks and crevices from which these little creatures can emerge.
This is never a call you want to get but it does happen. It may ruin your appetite and your weekend, but at least the wound bed is cleaner after one removes the maggots. If anyone has any other treatment pearls for addressing the presence of maggots, please share them in the comments. As always, I appreciate any input or opinions.
- University of Florida Entomology And Nematology. House fly. Available at: http://entnemdept.ufl.edu/creatures/urban/flies/house_fly.HTM. Published August 1998. Updated April 2017. Accessed August 5, 2019.