Man-Eating Worms = New Fear Unlocked

Guatemala, like many of its neighbors in Central America, has enjoyed a nearly four decade run without cases of myiasis (maggot infestation) caused by the New World Screwworm (NWS).

In recent months there have been reports of cases involving livestock and wildlife. And in May of this year, the ministry of health here in Guatemala confirmed the first human case.

The CDC describes the spread of NWS myiasis in the following way:

New World screwworm infestations begin when a female fly lays eggs on a wound or orifice of a live, warm-blooded animal. The odor of a wound or an opening such as the nasal or eye openings, umbilicus of a newborn, or genitalia attracts female flies. Wounds as small as a tick bite may attract a female fly to feed. One female can lay 200 – 300 eggs at a time and may lay up to 3,000 eggs during her 10- to 30-day lifespan.

In the last couple of weeks, we have seen two patients at our site with wound myiasis presumably caused by NWS (pictured below left) and its larvae (pictured below right), Cochliomyia hominivorax (of note, hominis = man and vorax = consuming; ...i.e. the larvae are "man-eating"!).

The first patient we saw was a young boy with what appeared to be a run-of-the-mill skin abscess. When my colleague, Dr. Dina, incised the skin, instead of encountering the anticipated collection of pus, she was rudely greeted by a collection of worms.

The second patient, a 67yo female, reported a "bubbling" sensation in a wound on her chest. She has a history of repeatedly declining treatment for breast cancer for the last ten years or so. She has developed a skin ulcer and now- to add insult to injury- that wound is infested with worms.

The mainstay of treatment is mechanical removal of the larvae. This task can sometimes be more challenging than one might imagine as the worms can be fairly elusive and quite numerous. There are some studies, largely in the veterinary medicine literature, looking at the use of ivermectin to treat infestations, but this is not currently an approved indication for this medication (although, admittedly, if I were to note a collection of "man-eating" worms on my person, I would certainly be tempted to consume enough ivermectin to euthanize a horse)

Hopefully, the first patients we have cared for suffering from presumed NWS myiasis will also be the last patients we see with this horrifying condition. Unfortunately, I doubt that is the case. But, at least now that you, dear reader, are aware of the condition, you will be diligent in covering any open wounds and you can join us in our newfound phobia of flies.

Top Photo by Karsten Winegeart on Unsplash

Images and additonal information from: https://www.cdc.gov/myiasis/hcp/clinical-overview/index.html