Mansonella streptocerca infection
Mansonella streptocerca infection occurs when a midge takes a blood meal from a human, which allows the transfer of filarial larvae to the bite wound. The filarial larvae develop into adults in the skin, where they produce microfilariae. When a midge takes a blood meal from an infected host, the microfilariae are ingested and develop into larvae in the midge's gastrointestinal tract.
Infection by M streptocerca is usually asymptomatic. Patients may develop pruritus, especially over the thorax and shoulders. Cutaneous signs include hypopigmented macules, excoriations, and lichenification. Patients may also develop axillary or inguinal lymphadenopathy. This disease is slightly more prevalent in males after age 39. Individuals younger than 24 years are seldom affected.
Related topics: Mansonella ozzardi infection, Mansonella perstans infection
B74.4 – Mansonelliasis
238448008 – Streptocerciasis
Differential Diagnosis & Pitfalls
- Onchocerciasis (Onchocerca volvulus) – Causes cutaneous disease and river blindness. Cutaneous symptoms include papular dermatitis, pruritus, lichenification, atrophy, and a "leopard-skin" depigmentation. In skin snips, look for unsheathed larvae and sharply angulated microfilariae that are longer and wider than those in streptocerciasis. The disease is endemic to Africa, Latin America, and the Middle East.
- Loiasis (Loa loa) – Causes subcutaneous and ocular filariasis. Cutaneous symptoms include localized swellings, angioedema, and pruritus. Diagnosis is by surgical extraction of the adult parasite and confirmation of species by morphology. The disease is endemic to Central and West Africa.
- Mansonella perstans (Dipetalonema perstans) infection – Causes painless conjunctival nodules and serous cavity filariasis. In skin snips, look for unsheathed microfilariae. The female reaches 70-80 mm in length. Peripheral blood smear demonstrates microfilariae. The disease is endemic to Africa and South America.
- Atopic dermatitis
- Pruritus secondary to other systemic diseases, including renal or liver failure, thyroid disease, lymphoma, or human immunodeficiency virus infection, among other causes.
- Lichen simplex chronicus
- Contact dermatitis (irritant, allergic)
- Lichen planus
- Cutaneous T-cell lymphoma
- Notalgia paresthetica
- Lichen amyloidosis
- Cercarial dermatitis