Study on epidemiological characteristics of tick-borne borreliosis in humans in regestered Mongolia from 2005-2023

Abstract

Background: Lyme borreliosis (Lyme disease) is caused by spirochaetes of the Borrelia burgdorferi sensu lato species complex, which are transmitted by Ixodes ticks. It is a zoonotic disease that affects the joints, the heart and the nervous system, often presenting with a characteristic skin rash. In Mongolia, 270 human cases of lyme borreliosis were recorded between 2005-2023. This study explored the epidemiological characteristics of these Lyme disease cases. Aim: To study the prevalence of tick-borne borreliosis and human disease status registered in Mongolia. Materials and Methods: Using data from the platform of Zoonotic Information System at the NCZD, we summarized epidemic and spatial characteristics of Lyme disease which regestered in Mongolia for the 18 year time period from 2005 through 2023. Results: In this study, 173 (64.1%) of the subjects were women and 97 (35.9%) were men. In terms of age, children of young age and school age were the most infected. Zavkhan province recorded the highest number of human cases of tickborne borreliosis. When grouping tick-borne borreliosis patients by employment, 86 (32%) were unemployed, 52 (19%) were high school students, 42 (16%) were self-employed, 32 (12%) were unknown, and 26 (10%) were kindergarten children, 23 (8%) were self-employed, and 9 (3%) were herders. In terms of season, 97 cases (37%) were recorded in April and 79 (30%) in May, respectively, which were the two highest months, and the season of infection was statistically significant (p<0.001). In Mongolia, human cases of tick-borne borreliosis have been registered in 81 districts of 16 provinces and seven districts of Ulaanbaatar city. However, no cases of human disease were recorded in Uvs, Gobi-Altai, Umnugobi, Dornogobi, and Sukhbaatar and the highest number of cases was recorded in Zavkhan province, which was statistically significant (p<0.001). There was a total of 73 cases (27%) recorded in Zavkhan province, and 57 (78%) of these cases were from Tosontsengel soum, which was statistically significant (p<0.001). Conclusion: In Mongolia, 270 cases of tick-borne borreliosis in humans were reported between 2005 and 2023, mostly were recorded in Tosontsengel Sum, Zavkhan Province, which indicates that the region has become the epicenter of the disease. It is noteworthy that relatively young people are affected by tick-borne borreliosis, and the majority of age groups are women and young children. Although the incidence of tick-borne borreliosis reached its peak in 2016 and has been decreasing in recent years, there is a need to provide preventive training and health education to risk groups in during April and May, which is the peak season of the disease.