Geographic Range of Lyme Borreliosis in Mongolia.

INTRODUCTION: In Asia, Borrelia garinii, B. afzelii, and B. bavariensis are transmitted by Ixodes persulcatus ticks and clinically present with a wide range of neurological and arthritic symptoms. This report aims to provide details on the geographic distribution of suspected cases of Lyme borreliosis (LB), reported to local Mongolian hospitals between 2007 and 2017.

METHODS: This report examines 150 reported cases of suspected LB from 13 aimags (provinces) in Mongolia from April 2007 to August 2017, including date and location of infection, method of diagnosis (indirect immunofluorescent assay and/or enzyme-linked immunosorbent assay test), frequency of specific symptoms, and case demographics. Information was gathered through collaboration with the National Center of Communicable Disease and the National Center for Zoonotic Diseases.

RESULTS: Zavkhan and Selenge, located in northern Mongolia, had the highest percentage of reported suspected cases, with 25% and 20%, respectively. Ages ranged from 1 to 78 years, with a mean age of 26 years, however, 37% of individuals were younger than 10. More than twice as many women sought treatment as men, and the distribution of men who sought treatment was skewed toward children and the elderly. Most frequently reported symptoms include fever, rash, headache, and enlarged lymph glands. Furthermore, peak months of tick bite and treatment seeking occurred between April and June.

CONCLUSIONS: Based on these preliminary findings, syndromic surveillance should be expanded across northern Mongolia, with LB considered in differential diagnosis for patients reporting a recent tick bite.