The human botfly, known scientifically as Dermatobia hominis, is a species of fly whose larvae can infest human skin, a condition called myiasis. This infestation typically begins when an adult female botfly captures another insect, such as a mosquito, and attaches its eggs to it. When this carrier insect lands on human skin, the warmth of the body causes the botfly eggs to hatch, and the tiny larvae then burrow into the skin. While generally not life-threatening, a botfly infestation can cause discomfort and requires medical attention.
Identifying the Signs
A botfly infestation often presents as a slowly enlarging, boil-like lesion on the skin. The affected area may show redness and slight swelling, becoming a firm, raised skin lesion.
A hallmark sign of a botfly lesion is the presence of a central pore or breathing hole. There may also be a serous, bloody, or sometimes purulent discharge from this central opening.
Individuals may experience various sensations around the infested site. These can include itching, a mild to sharp pain, and a distinct sensation of movement beneath the skin. The larva grows within the skin for approximately 6 to 10 weeks, and as it develops, the nodule may increase in size, reaching up to 2.5 centimeters in diameter.
Confirming the Infestation
Medical professionals typically confirm a botfly infestation through a physical examination, assessing the characteristic skin lesion and considering the patient’s travel history to endemic regions.
Dermoscopy can be employed to visualize the larva’s internal structures or its movement within the lesion. This technique allows for a clearer view of the larva’s posterior end, which may be visible through the central pore.
In cases where diagnosis remains uncertain, ultrasound imaging is a sensitive tool. High-resolution Doppler ultrasound can effectively visualize the larva within the subcutaneous tissue, showing its shape and movement. While blood tests might show elevated levels of white blood cells, the definitive diagnosis relies on identifying the larva itself.
Seeking Medical Help
If a botfly infestation is suspected or confirmed, it is important to seek professional medical attention promptly. Healthcare providers are equipped to accurately diagnose and manage these cases. Attempting self-removal is generally not recommended due to several risks.
Self-extraction can lead to incomplete removal of the larva, which may result in inflammation, foreign body reactions, or secondary bacterial infections. The larva has backward-facing spines that help it anchor within the tissue, making direct pulling difficult and potentially causing the larva to rupture or leave fragments behind.
Medical professionals employ various methods for safe and complete removal. Surgical excision, where the larva is carefully removed under local anesthesia, is often the preferred approach. Other techniques may include occluding the breathing hole with substances to deprive the larva of oxygen, encouraging it to emerge, or injecting lidocaine into the lesion to create pressure that forces the larva out. Following removal, the wound is typically cleaned, and an antibiotic ointment may be prescribed to prevent infection.
Reducing Your Risk
For individuals traveling to or residing in areas where botflies are common, several preventive measures can reduce the risk of infestation. Wearing protective clothing, such as long-sleeved shirts, long pants tucked into socks or boots, and hats, creates a physical barrier against carrier insects.
Using insect repellents containing active ingredients like DEET or picaridin on exposed skin can deter mosquitoes and other biting insects. Additionally, treating clothing and bed nets with permethrin provides an extra layer of protection.
Inside homes, using window screens helps prevent insects from entering. When drying clothes outdoors in endemic regions, it is advisable to iron them thoroughly before wearing, as botfly eggs can be deposited on fabrics and hatch when exposed to body heat.