The organism commonly called the mango worm is actually the larva of the tumbu fly, Cordylobia anthropophaga. This parasitic fly is native to the tropical and subtropical regions of sub-Saharan Africa, where it causes skin infestation in mammals, including humans and dogs. The mango worm is not established as an endemic species in the United States. Cases occur almost exclusively in individuals who have recently traveled to regions where the fly is common. The larva causes cutaneous myiasis, developing just beneath the skin’s surface, meaning isolated infections are possible due to international travel.
Geographical Status and Entry Points
The presence of the mango worm in the United States is overwhelmingly tied to international travel, classifying the few US cases as “imported myiasis.” The fly requires a specific warm and humid environment to complete its life cycle, conditions that are not consistently present across the continental US to support a widespread, self-sustaining population. The natural environment in most of the US does not allow the adult fly to thrive and reproduce effectively enough to become an established public health concern.
Infection occurs when a traveler contacts eggs or newly hatched larvae while visiting endemic African regions. The female fly often deposits eggs in sandy or damp soil, especially when contaminated with animal waste, or on items left to dry outdoors, such as clothing or bedding. When these infested items are brought back to the US, the larvae can hatch and seek a host, leading to an infection that manifests after the traveler has returned home. Transmission involves contact with contaminated materials, not person-to-person spread.
Travelers visiting high-risk areas can reduce the potential for infestation by taking simple precautions with their laundry. Clothing should not be dried on the ground or left outdoors overnight. If outdoor drying is unavoidable, ironing all items immediately after they are brought inside, paying special attention to seams, can kill any eggs or newly hatched larvae.
The Life Cycle and Identification
The lifecycle begins when the female fly lays approximately 100 to 300 eggs on soil or damp fabric. These eggs hatch quickly, typically within two to four days, giving rise to the first-stage larvae. The microscopic larvae can survive in the environment for up to two weeks while they wait for a suitable host, such as a dog, rodent, or human.
Upon contact with a host’s skin, the larva quickly burrows beneath the surface, beginning its parasitic feeding stage. Over the next eight to twelve days, the larva develops through two more stages, growing into a pale, grub-like “worm” that feeds on the host’s subcutaneous tissue. The developing larva creates a distinct, boil-like lesion in the skin, called a furuncle.
This lesion features a small opening, known as a punctum, which the larva uses as a breathing hole. Once the larva is fully mature, reaching up to about 15 millimeters in length, it naturally exits the host’s skin. The maggot then drops to the ground and burrows into the soil to begin the pupal stage, transforming into an adult fly to restart the cycle.
Recognizing and Treating Infestation
The initial sign of infestation is typically a small, red, itchy bump, which may be mistaken for a mosquito or spider bite. Over a few days, this bump progresses into a painful, firm nodule that resembles a boil, characteristic of furuncular myiasis. Patients often report a sensation of movement or “creeping” within the lesion, along with intermittent sharp pain.
A defining feature is the small, dark central opening in the boil, which is the larva’s breathing hole. A watery or pus-like discharge may drain from this punctum. To treat the infestation, the larva must be removed intact to prevent an inflammatory reaction from any remaining body parts.
One common technique involves covering the breathing hole with a thick substance like petroleum jelly or mineral oil. This occlusion deprives the larva of oxygen, forcing it to partially emerge, at which point it can be carefully extracted with forceps. It is important to seek medical attention for removal, as a healthcare professional ensures the larva is fully extracted and the wound is properly cleaned. Antibiotics may be prescribed if there is evidence of a secondary bacterial infection.