Inorganic particles in the skin of inhabitants of volcanic areas of Central America: their possible immunomodulatory influence in leishmaniasis and leprosy

Abstract

We have evaluated biopsies from patients with atypical nodular and typical ulcerated lesions of cutaneous leishmaniasis, from leishmanin reactions and skin from normal individuals from Nicaragua, Honduras and Guatemala for the presence of inorganic particles using confocal microscopy with a polarised light source and conventional histopathological techniques. Analysis by semiquantitative confocal microscopy permitted the demonstration of significantly larger numbers of particles in atypical lesions. Silica and aluminium, important components of these particles, were less abundant in particles from normal skin. The histology of these atypical lesions, characterised by 'naked' sarcoidal granulomas with epithelioid differentiation but very few lymphocytes, was very similar to the histological reaction observed after 14 days in persisting inflammation at leishmanin skin test sites. The presence of these unusual lesions in areas of Central American countries characterised by the presence of large amounts of volcanic ash, as well the unexpectedly low prevalence of leprosy in Central America, suggest that environmental factors may contribute significantly to the frequency and clinical manifestations of these infections. Among possible environmental features, the presence of inorganic particles with immunomodulatory properties in the skin may be a significant factor.

American cutaneous leishmaniasis in infancy and childhood

“…In Ecuador the disease is known as angry sore (“sarna brava”), Colombian ulcer, or mountain leprosy (mucocutaneous leishmaniasis) . Interestingly, in some countries of Central America where the disease appears to be modulated by the presence of inorganic particles contained in volcanic emanations, the disease is also known under the term of “mountain leprosy.”…”

“…[6][7][8][9][10] Interestingly, in some countries of Central America where the disease appears to be modulated by the presence of inorganic particles contained in volcanic emanations, the disease is also known under the term of "mountain leprosy." 11,12 Cutaneous leishmaniasis is usually classified under two headings: Old World, which comprises geographically southern Europe, the Middle East, Asia, and Africa, and New World cutaneous leishmaniasis, embracing Latin America. However, while most of the Old World species cause benign cutaneous disease, New World species cause a spectrum of disease ranging from mild cutaneous forms to also include severe mucosal lesions.…”

Effects of Eyjafjallajökull Volcanic Ash on Innate Immune System Responses and Bacterial Growth in Vitro

“…Regarding the Icelandic eruption, Carlsen et al (2012) reported that Icelanders exposed to Eyjafjallajökull volcanic ash had increased prevalence of respiratory symptoms, specifically asthma and chronic bronchitis, compared with a control population in northern Iceland. Although other studies have shown that exposure to volcanic ash increases the risk of developing respiratory infections (Convit et al 2006; Gudmundsson 2011; Naumova et al 2007), there are limited data on the cellular mechanisms involved in this increased lung infection risk. Because airway infections are the result of impaired innate immune mechanisms, we hypothesized that volcanic ash impairs innate immune mechanisms, specifically the function of macrophages and antimicrobial peptides.…”

Environmental Aspects of Zoonotic Diseases

“…In human hosts in Central America, Convit et al (2006) observed an interesting phenomenon linked to a frequent atypical form of cutaneous leishmaniasis (AtypCL) in patients. This atypical benign form is characterized by nonulcerating nodules containing a few parasites (L. chagasi, L. mexicana).…”