Pemphigus is an autoimmune condition of the skin. Its unique geographic distribution provides clues to its origin and treatment options. Certain regions of Brazil, Colombia and Tunisia have a relatively high incidence of pemphigus in young adults and children. A 14-year study in Brazil showed that environmental triggers may play a key role.
A variety of pemphigus called Fogo selvagem (FS) is endemic to a subtropical area of Brazil from 5 to 25 degrees south latitude, at an altitude of 1,600 to 2,600 feet. FS patients are usually outdoor agricultural workers, living in close proximity with rodents, bedbugs, Reduvid bugs, black flies and sand flies. New cases of FS are most common at the end of the rainy season, when insect multiplication is highest. Leishmaniasis, Onchocerciasis and Chagas disease share the same regional distribution. These diseases are all believed to be transmitted by insects.
Pemphigus is not an infectious disease, but researchers speculate that the saliva of blood-sucking insects may trigger the condition in genetically susceptible individuals. Patients who move to an industrialized city often see an improvement in their condition. Thus, removing the environmental trigger may be an effective treatment.
Once triggered, the immune system produces antibodies to specific proteins that are important for cell adhesion in the skin. Since the skin is readily accessible to researchers, the molecular mechanisms of pemphigus are well characterized.
Without treatment, pemphigus has a poor prognosis. According to Brazilian researchers, it was once said that if the patient survived for more than a year, then the diagnosis of pemphigus was wrong. The introduction of steroids in the 1950's offered a much better future to patients. Additional drug treatments include azathioprine, cyclophosphamide, methotrexate, mycophenolate mofetil, and cyclosporine. As with other autoimmune conditions, plasmapheresis and immunoadsorption offer some hope for cleaning out the antibodies that are attacking the skin. Intravenous immunoglobulin (IVIg) is also helpful for some patients.