The “mango worm” is the common name for the larval stage of the Tumbu fly (Cordylobia anthropophaga). This organism causes cutaneous myiasis, a parasitic skin infestation where the larva develops beneath the skin of a mammal host. The name originates from the fly’s frequent presence in areas where mangos grow, although the fruit itself is not the source of infection.
Understanding the Tumbu Fly Life Cycle
The life cycle begins when the adult female Tumbu fly, a type of blowfly, deposits her eggs. She typically lays between 100 and 300 eggs in batches on dry, sandy soil contaminated with urine or feces, or on damp materials like clothing left outside. The eggs are tiny and hatch quickly, usually within one to three days, releasing the first-stage larvae.
These newly hatched larvae can survive for up to two weeks without a host, waiting on the surface of the contaminated material or soil. When a warm-blooded host, such as a dog or human, comes into contact with the area, the larvae quickly penetrate the unbroken skin. Once beneath the surface, the larva grows rapidly through three distinct stages over approximately 8 to 12 days. The fully developed larva can reach up to 15 millimeters long before it drops out of the host to pupate, completing its parasitic development.
How Infestation Occurs and Where They Are Found
The Tumbu fly is endemic to the warm, humid conditions found throughout large parts of Sub-Saharan Africa, particularly East and Central Africa. Infestation is linked to direct contact with soil or items contaminated by the fly’s eggs. The fly is attracted to odors associated with mammals, including sweat, urine, or feces, making contaminated soil a frequent site for egg deposition.
A primary route of transmission to humans and pets involves laundry that has been dried outdoors. Female flies often lay their eggs on damp clothing, towels, or bedding hanging on a line. When a person or animal subsequently uses or wears the contaminated item, the larvae are activated by the host’s body heat and rapidly burrow into the skin. While humans are susceptible, common hosts include rodents, livestock, and especially domestic dogs, which contract the larvae from lying on infested soil.
Recognizing the Signs of Mango Worm Infestation
The presence of a mango worm beneath the skin results in furuncular myiasis, characterized by the formation of a painful, boil-like lesion. The first sign is often a small red bump, or papule, that may be mistaken for a mosquito bite. This papule gradually enlarges and hardens as the larva grows, forming a distinct, tender nodule that can reach up to an inch in diameter.
A hallmark of the infestation is the presence of a small, dark opening at the center of the boil, known as a punctum. This opening serves as the larva’s breathing hole. Patients frequently report a sensation of movement or a stinging feeling within the lesion, which can cause significant discomfort and interfere with sleep. The lesion may also discharge a serosanguinous fluid, a mixture of blood and serum, which includes the larva’s excretions.
Preventing and Treating Mango Worm Myiasis
Preventing mango worm infestation relies on disrupting the fly’s access to materials that come into contact with skin. In endemic areas, avoiding drying laundry outdoors on lines or the ground is recommended. If outdoor drying is unavoidable, all clothing, towels, and bedding should be thoroughly ironed with a warm iron immediately before use. The heat from the iron is sufficient to destroy any eggs or newly hatched larvae present within the fabric fibers.
When infestation occurs, the larva must be removed intact to prevent complications. A common non-surgical treatment involves suffocating the larva by covering the central breathing hole with an occlusive agent. Applying a thick layer of petroleum jelly, liquid paraffin, or heavy oil blocks the punctum, forcing the oxygen-deprived larva to emerge partially or completely. The larva can then be gently extracted with forceps or by applying light pressure to the sides of the lesion. Squeezing the lesion aggressively is not recommended, as rupturing the larva beneath the skin can lead to severe inflammation and secondary bacterial infection.