Clinical and histopathological study of Simulium (blackfly) dermatitis from North-Eastern India--a report.

BACKGROUND Simulium dermatitis is a common problem in humans and animals in areas where Simulium species occur. It is characterized by chronic eruptions of pruritic papules, vesicles, and erythematous wheals resulting from a hypersensitivity reaction to biting of simuliids or blackflies. It can result in severe skin complications where the man-biting species of Simulium are available. MATERIALS AND METHODS We report two clinical cases of Simulium dermatitis from the North-Eastern region of India. Histopathological study was carried out in one of the cases and the other one was successfully treated with medication. RESULTS Clinical features like intense itching, which accompanies the eruption, resulting in excoriations, scarring, and permanent hyperpigmentation were reported. Histopathological study revealed the characteristic features of Simulium bite reaction, such as vesicles filled with serous fluid, dermal edema, and perivascular infiltrates rich in eosinophils and lymphocytes. CONCLUSION The clinical manifestations and severity of Simulium dermatitis are serious matters of concern in hypersensitive persons.