The term “sand flea” is often confusing, referring to multiple organisms. The parasitic insects people “catch” cause tungiasis, an inflammatory skin disease. This condition results from the burrowing of the female chigoe flea, Tunga penetrans, which is native to Central and South America and has spread to sub-Saharan Africa.
Clarifying the Organism
The name “sand flea” is commonly used for two groups of creatures found near the ocean. One group includes harmless beach hoppers, which are small crustaceans related to shrimp and crabs. These amphipods do not bite humans; they feed on decaying matter. The other organism is the true parasitic species, Tunga penetrans, which is a tiny insect and the smallest known flea. This chigoe flea causes tungiasis.
The Mechanics of Infestation
People “catch” these parasitic fleas through direct contact with contaminated soil or sand. The adult chigoe flea thrives in warm, dry environments, such as beaches, stables, farms, and the dirt floors of homes in endemic communities. After mating, the female flea seeks a warm-blooded host to embed herself and reproduce.
The flea’s limited jumping ability means it infests areas of the body that contact the ground, primarily the feet, toes, and heels. The mated female anchors herself to the skin and burrows into the epidermis using her mouthparts. Once embedded, she feeds on the host’s blood and swells rapidly, sometimes expanding her size up to 2,000 times while producing eggs. The flea leaves only its posterior end exposed, allowing it to breathe, excrete feces, and expel eggs onto the ground to continue the life cycle.
Immediate Symptoms and Complications
The initial burrowing is often painless, but symptoms appear quickly as the flea engorges itself. A small, inflamed nodule forms at the site of penetration, characterized by a white halo or ring with a black dot in the center (the exposed rear of the parasite). This lesion quickly becomes intensely itchy and painful, and the area swells.
Multiple lesions, particularly on the soles of the feet, can lead to severe discomfort and difficulty walking. The intense itching often leads to scratching, which breaks the skin and introduces bacteria, resulting in secondary infections. Complications include abscesses, cellulitis, and systemic infections like tetanus or gangrene. Chronic infestation may result in permanent tissue damage, disfigurement, and loss of toenails.
Prevention and Management
The most effective way to avoid infestation is to prevent contact between the skin and contaminated soil in endemic areas. Wearing closed-toe shoes or thick sandals is recommended, as the flea cannot jump high enough to bypass covered feet. Applying insect repellent containing DEET or Picaridin, or a specialized repellent like Zanzarin, to the feet and lower legs provides protection.
Avoid sitting or lying directly on the sand or soil where the fleas live. If an infestation is suspected, do not attempt removal at home with unsterilized tools like pins or needles. Medical management involves the sterile, surgical removal of the embedded flea by a healthcare professional using specialized instruments. After removal, the wound should be cleaned and treated with an antibiotic cream to prevent secondary infection, and the host’s tetanus vaccination status is checked.