Seroprevalence and risk factors of Borrelia burgdorferi sensu lato and Rickettsia species infection in humans in Mongolia, 2016-2020.

Borrelia burgdorferi sensu lato and Rickettsia spp. are worldwide causes of tick-borne infections. We aimed to estimate the seroprevalence of immunoglobulin G (IgG) antibodies against different tick-borne diseases (TBDs) and determine risk factors among Mongolians from 2016 to 2020. Blood samples were obtained from voluntary participants with a history of suspected tick bite who visited our hospital, and IgG antibodies against Rickettsia and Borrelia were detected using enzyme-linked immunosorbent assay (ELISA). The IgG antibody seropositivity rate against Rickettsia was 21.8% (1032/4724), while 3.4% (162/4724) of participants tested positive for serum IgG antibodies against Borrelia by ELISA.Binary logistic regression analysis was performed to evaluate risk factors for tick-borne rickettsiosis (TBR) and tick-borne borreliosis (TBB) using IgG serum sample. Age, occupation, and residence were significantly associated with these diseases; however, sex did not show any significant association. Seroprevalence was significantly higher among herders (40.6%, 95% confidence interval [CI]: 35.5-45.8; odds ratio [OR] 0.61; P < 0.001) and students (32.8%, 95% CI: 30.2-35.4; OR 0.75; P < 0.001) than among individuals with other occupations. The 25-29 age group had a slightly higher seroprevalence (35.1%, 95% CI: 28.1-42.6; OR 0.61; P < 0.006) than those in other age groups. Province was a stronger predictor of TBR than occupation and age group. In univariate subgroup analysis by age group, occupation, and residence were significantly associated with TBR seroprevalence, whereas age and province were associated with TBB seroprevalence. Thus, risk factors for TBD include residence, occupation, and age group. This study was conducted using samples from all Mongolian provinces and the capital city, and the risk factors and prevalence of Rickettsia and Borreliaare highlighted.

Seroprevalence and risk factors of tick-borne encephalitis in Mongolia between 2016 and 2022.

The tick-borne encephalitis virus (TBEV) is a zoonotic agent that causes severe encephalitis in humans and is transmitted through the bites of infected ticks. Ixodes ticks are the primary vector for TBEV in Mongolia, and approximately 3.4% carry the TBEV. The ticks are capable of not only transmitting these viruses but also serve as excellent reservoir hosts. The Dermacenter tick species may have similar properties. TBEV is a significant cause of virus-related diseases of the central nervous system in many European countries as well as in China, Russia, and Mongolia. Our objectives were to investigate TBEV seroprevalence and infection risk factors in different biogeographical zones and provinces, especially in the highly endemic areas of Mongolia. Serum samples were collected from individuals who experienced tick bites (n = 993) in Mongolia between 2016 and 2022. Enzyme-linked immunosorbent assay of the samples was performed to evaluate for TBEV-specific immunoglobulin (Ig)M and IgG. We analyzed the risk factors and seroprevalence of TBEV infection among these individuals using a cross-sectional, questionnaire-based study. Statistical analyses were performed using a multistage cluster sampling survey design, and all data were analyzed using the R software. TBEV IgM and IgG antibodies were detected in 8.1% (80/993) and 20.2% (201/993) of all serum samples, respectively. The seroprevalence was significantly higher in men (68%, 95% confidence interval [CI]: 1.63-3.13, odds ratio [OR]: 2.25) than in women (p < 0.001). Additionally, the seroprevalence was significantly higher among unemployed (35.0%, 95% CI: 0.31-0.84, OR: 0.51) than employed individuals (p < 0.001). The seroprevalence was the highest among the 25-29 and 35-39-year age groups (11%, 95% CI: 1.29-5.51, OR: 2.65 and 11%, 95% CI: 0.94-3.87, OR: 1.9, respectively), and the lowest in the 65-69-year age group (4%, 95% CI: 0.46-6.15, OR: 1.83) (p < 0.001). Furthermore, the seroprevalence was the highest in Selenge province and the capital city Ulaanbaatar (40%, 95% CI: 1.73-21.7, OR: 5.07 and 28%, 95% CI: 0.51-6.89, OR: 1.57, respectively) and the lowest in Bayan-Ulgii and Dornod provinces (0.5%, 95% CI: 0.06-12.4, OR: 1.33 and 0.5%, 95% CI: 0.03-6.24, OR: 0.72, respectively). TBEV infection incidence remained low in most regions of Mongolia but increased in endemic areas. Furthermore, in the univariate subgroup analysis, age, occupation status, and residential area were significantly associated with TBEV seroprevalence.

Molecular Characteristics of Rickettsia in Ticks Collected along the Southern Border of Mongolia.

Tick-borne infections are a significant threat to public health, particularly in regions where individuals frequently enter tick habitats. Roughly 26% of the population in Mongolia practice nomadic pastoralism and are considered at high risk of exposure to ticks and the diseases they carry. This study tested ticks from Mongolia's southern border for Rickettsia spp. to better understand the epidemiology of tick-borne diseases in the region. Dermacentor nuttalli and Hyalomma asiaticum ticks (n = 4022) were pooled and tested for Rickettsia spp. by real-time PCR. Melt-curve analyses and Sanger sequencing were used to identify Rickettsia species. Approximately 64% of the 786 tick pools tested positive for Rickettsia bacteria. Melt curve analyses identified four different Rickettsia species circulating in these tick pools. Amplicon sequencing of the ompA gene identified Rickettsia spp. that closely resembled R. raoultii and R. sibirica. Dermacentor nuttalli ticks from Govi-Altai had the highest maximum likelihood estimation infection rate 48.4% (95% CI: 41.7-56.5%), while Hyalommaasiaticum collected in Omnogovi had a rate of 7.6% (95% CI: 6.2-9.2%). The high detection of Rickettsia suggests a substantial risk of infection in southern Mongolia. Further studies are necessary to investigate the clinical burden of tick-borne diseases in Mongolia.

A systematic review of zoonotic enteric parasitic diseases among nomadic and pastoral people.

INTRODUCTION: Zoonotic enteric parasites are ubiquitous and remain a public health threat to humans due to our close relationship with domestic animals and wildlife, inadequate water, sanitation, and hygiene practices and diet. While most communities are now sedentary, nomadic and pastoral populations still exist and experience unique exposure risks for acquiring zoonotic enteric parasites. Through this systematic review we sought to summarize published research regarding pathogens present in nomadic populations and to identify the risk factors for their infection. METHODS: Using systematic review guidelines set forth by PRISMA, research articles were identified, screened and summarized based on exclusion criteria for the documented presence of zoonotic enteric parasites within nomadic or pastoral human populations. A total of 54 articles published between 1956 and 2016 were reviewed to determine the pathogens and exposure risks associated with the global transhumance lifestyle. RESULTS: The included articles reported more than twenty different zoonotic enteric parasite species and illustrated several risk factors for nomadic and pastoralist populations to acquire infection including; a) animal contact, b) food preparation and diet, and c) household characteristics. The most common parasite studied was Echinococcosis spp. and contact with dogs was recognized as a leading risk factor for zoonotic enteric parasites followed by contact with livestock and/or wildlife, water, sanitation, and hygiene barriers, home slaughter of animals, environmental water exposures, household member age and sex, and consumption of unwashed produce or raw, unprocessed, or undercooked milk or meat. CONCLUSION: Nomadic and pastoral communities are at risk of infection with a variety of zoonotic enteric parasites due to their living environment, cultural and dietary traditions, and close relationship to animals. Global health efforts aimed at reducing the transmission of these animal-to-human pathogens must incorporate a One Health approach to support water, sanitation, and hygiene development, provide education on safe food handling and preparation, and improve the health of domestic animals associated with these groups, particularly dogs.