Scabies infection boosts one’s risk of developing myasthenia gravis (MG), new research from Taiwan shows.
Scabies is an infectious, highly contagious skin disease caused by the mite Sarcoptes scabiei. It is characterized by severe itching of the skin and affects around 300,000 people a year worldwide, especially in developing countries.
Groups at risk include preschool children, adolescents, the elderly, residents of nursing homes, institutionalized patients and people with compromised immune systems.
Patients with scabies show increased levels of the cytokines interleukin (IL)-4, IL-10, IL-13, IL-17 and IL-23. The infection is already linked to chronic kidney disease (CKD) and chronic obstructive pulmonary disease (COPD), but the precise mechanisms are unknown.
Specifically, high concentrations of pro-inflammatory cytokines, including IL-17, have been found in the serum of MG patients, and these elevated IL-17 levels are resistant to therapy. Despite the current lack of information, the common inflammatory mechanisms observed in scabies and MG suggest an association between these two diseases.
The research was led by Jui-Ming Liu, a scientist at both Taiwan’s National Defense Medical Center and Taoyuan General Hospital. Liu’s team evaluated the link between scabies and MG by conducting a nationwide population-based study, armed with data from Taiwan’s National Health Insurance Research Database.
The study tracked 5,429 patients with scabies and 20,176 people without the mites over a seven-year period to identify new onset MG disease. It revealed that 40 (or 0.7 percent of all) the scabies patients and 84 (or 0.4 percent) of the controls developed MG. That translates into those with scabies having a 27 percent higher risk of developing MG.
The results also showed that patients with hypertension, CKD, chronic liver disease, cerebral vascular accidents and COPD are also at higher risk of MG. And in the case of COPD, immune-mediated inflammatory processes may be involved in both diseases.
“IL-17 also plays an important role in the pathophysiology of COPD,” says the study, adding that “prompt diagnosis and treatment of scabies may decrease the risk of subsequent MG” — and that “as medicine advances and people live longer, the disease burden of MG will become larger and larger and is thus worthy of our attention.”