Blister Mystery

Abstract

A patient in Sri Lanka presented with a blistering rash in September (Figure 1). What is the diagnosis and how would you treat it? Dermatitis due to blister beetle. Blister beetles (Mylabris pustulata) (Figure 2) are common in South Asia. They are considered pests. Blister beetles are often seen in the vicinity of farmlands during August and September.1Iyer B.H. Guha P.C. Cantharidin from Mylabris pustulata, India.J Indian Inst Sci. 2013; 14: 31Google Scholar They are very sluggish during early morning, becoming more active after sunrise. Blister beetles secrete a yellow-colored oily substance from the leg joints.1Iyer B.H. Guha P.C. Cantharidin from Mylabris pustulata, India.J Indian Inst Sci. 2013; 14: 31Google Scholar, 2Ghoneim K.S. Enhancement of research interests in physiology and biochemistry of blister beetles (Coleoptera: Meloidae): a review.Int Res J Biochem Bioinforma. 2013; 3: 75-92Google Scholar, 3Nyazema N. Cantharidin poisoning: a review.South African Fam Pract. 1989; 10: 70-73Google Scholar This substance contains canthadrine, a skin irritant with high blistering capacity. Blister beetles do not sting or bite, but they release the blistering agent if they are pressed, brushed, or crushed.4James W.D. Berger T.G. Elston D.M. Andrew’s Diseases of the Skin: Clinical Dermatology.11th ed. Saunders Elsevier, Philadelphia2011Google Scholar Skin contact causes a burning, itching, or tingling sensation followed by the appearance of linear or irregular areas of erythema that later form vesicles (Figure 1).4James W.D. Berger T.G. Elston D.M. Andrew’s Diseases of the Skin: Clinical Dermatology.11th ed. Saunders Elsevier, Philadelphia2011Google Scholar, 5Padhi T. Mohanty P. Jena S. Sirka C. Mishra S. Clinicoepidemiological profile of 590 cases of beetle dermatitis in western Orissa.Indian J Dermatol Venereol Leprol. 2007; 73: 333Crossref PubMed Scopus (10) Google Scholar, 6Ajao A.M. Olalubi O.A. Aderolu I.S. et al.Investigation of blister beetle (Lytta vesicatoria) dermatitis outbreak and xontainment at Kwara State University students’ hostels.Sch J Appl Med Sci. 2016; 4: 460-468Google Scholar The vesicles rupture in a few days and form crusts. Secondary infection may occur. Lesions usually heal in a few days when treated with topical antibiotics.4James W.D. Berger T.G. Elston D.M. Andrew’s Diseases of the Skin: Clinical Dermatology.11th ed. Saunders Elsevier, Philadelphia2011Google Scholar, 5Padhi T. Mohanty P. Jena S. Sirka C. Mishra S. Clinicoepidemiological profile of 590 cases of beetle dermatitis in western Orissa.Indian J Dermatol Venereol Leprol. 2007; 73: 333Crossref PubMed Scopus (10) Google Scholar Early cleansing of the contact site with soap or alcohol helps to remove the canthadrine and may prevent the dermatitis.4James W.D. Berger T.G. Elston D.M. Andrew’s Diseases of the Skin: Clinical Dermatology.11th ed. Saunders Elsevier, Philadelphia2011Google Scholar Acknowledgments: I thank the editorial team of the Wilderness & Environmental Medicine journal for their continuous support to improve this manuscript. I acknowledge Dr OA Oluwasogo and Dr AM Ajao for the permission to use Figure 1 for this article.