Background: Although food-borne infectious diseases occur across all age groups globally, evidence indicates that young children, older adults, and immunocompromised individuals are disproportionately affected due to their increased susceptibility to enteric pathogens. Young children in particular are at higher risk because their immune systems are not yet fully developed and they have lower body mass, which together reduce their ability to resist and recover from food-borne infections. In Mongolia, reported cases of intestinal infectious diseases in 2024 exceeded the ten-year historical average by 504.5 cases, and food- and water-related infections such as hand-foot-and-mouth disease, dysentery, and salmonellosis remain predominant among these conditions. Aim: The objective of this study was to conduct microbiological analyses of school lunches and drinking water provided to general education school students and to evaluate their compliance with relevant national standards. Materials and Methods: A total of 107 school lunch samples and 35 drinking water samples collected from general education schools were included in the study. Microbiological analyses were performed to assess hygiene and safety indicators, including Listeria monocytogenes, Salmonella spp., total coliform count, total viable microbial count (TVC), and intestinal bacteria. Laboratory analyses were conducted at the Microbiology Laboratory of the Food Safety Reference Laboratory under the Standardization and Metrology Authority. Confirmatory identification of microorganisms was performed using the VITEK 2 Compact system. Result: Of the 35 drinking water samples analyzed for 105 parameters, 8.5% (n=3) exceeded the permissible limits for total microbial counts. In the 107 school lunch food samples, a total of 428 microbiological parameters were examined, of which 26.1% (n=28) showed coliform counts above the allowable limits specified in the MNS 6308:2012 standard. Additionally, enterobacteriaceae were detected in 42.9% (n=46) of the food samples. When analyzed by school, 51.5% of the 35 schools (18 schools) had food samples with coliform counts that did not meet the standard requirements, whereas 49.5% (17 schools) showed compliance with the standards. These findings indicate that, on average, one out of every two schools fails to meet the required hygiene practices, proper food production procedures, and microbiological safety standards in meal preparation. Conclusion Microbiological analysis of 107 food samples from 35 general education schools across 428 indicators revealed that 26.1% did not meet the requirements of the MNS 6308:2012 “Microbiological safety and hygiene criteria for food products” standard due to excessive coliform counts. Of the 35 drinking water samples analyzed for 105 indicators, 5.7% (n=2) failed to meet the requirements of the MNS 0900:2018 “Drinking water: Hygiene requirements, quality, and safety assessment” standard with respect to total viable microbial count.

Background: Aetiological mechanisms of demyelinating diseases underlie a very heterogeneous clinical course, ranging from relapsing to progressive, with a longer disease duration leading to physical and cognitive disability. Aim: To identify factors in the development of long-term disability in demyelinating diseases. Materials and Methods: A cross-sectional study was conducted among 64 patients with multiple sclerosis and 33 patients with NMO treated at the Third State Central Hospital. We assessed demographic and clinical data, including the Expanded Disability Status Scale (EDSS). Statistical analysis included descriptive statistics, t-tests, chi-square tests, analysis of variance, correlation, and regression. Result: In MS, relapses (≥1) within 1.0 years of MS onset (OR=5.5, 95% CI 1.11-26.69, p=0.037), optic neuritis (OR=4.3, 95% CI 1.02-21.67, p=0.014), relapse frequency (≥3) (OR=6.6, 95% CI 1.39-31.3, p=0.018), myelitis frequency (≥2) (OR=5.5, 95% CI 1.42-21.67, p=0.014), in NMOSD, time from disease onset to diagnosis (≥3 month) (OR=7.9, 95% CI 1.04-60.7, p=0.046), years of diagnosis (≥3 years) (OR=6.3, 95% CI 1.15-34.12, p=0.034) contributed to disabilty worsening outcomes. Conclusion Disability in demyelinating diseases is affected by many factors.

Background: Numerous studies have shown that air pollution is a serious public health threat and risk worldwide. Mongolia is the world leader in outdoor and indoor air pollution, and the morbidity and mortality caused by it are increasing every year. People spend most of their lives indoors, and it is necessary to regularly assess and study indoor air pollution. Aim: To study the concentration of PM2.5 particles in the indoor air of households in Ulaanbaatar and Darkhan cities in relation to some symptoms of respiratory diseases. Materials and Methods: The study was conducted using an analytical cohort design from October 2023 to July 2025, and the 4 districts of the central Ulaanbaatar city and Darkhan cities were included in the study. A total of 240 households were included in the study, including 48 households living in ger and house, 24 households living in apartments, and 48 households living in ger and house, and 24 households living in apartments from Ulaanbaatar city. A direct measurement device (PurpleAir) was installed in the households for 3-4 weeks to measure PM2.5 particles in the indoor air for 24 hours. After measuring PM2.5 particles in the indoor air of the household, data were collected through questionnaires from the participants aged 18-60 who participated in the study and underwent health examinations. The results were processed using STATA-19.0 and R programs. Result: 213-239 households were selected for the study, including households living in 17-26 apartments, 42-58 houses, and 38-50 houses. The 24-hour average concentration of PM2.5 particles in the ambient air of households in Ulaanbaatar city was measured relatively higher in winter and summer than in households in Darkhan city. Among the districts of Ulaanbaatar city, the highest concentration of PM2.5 particles was measured in Songinokhairkhan district, and the lowest concentration was measured in Bayanzurkh district. Considering the cities by heating type, households with stoves are more polluted than households with centralized heating. In Darkhan city, the lowest concentration was measured in apartments (22.78-31.53 μg/m³), houses (44.53-68.17 μg/m³), and the highest concentration was measured in traditional felt houses (houses) (63.20-68.25 μg/m³). In Ulaanbaatar, PM2.5 concentrations were relatively high in all types of housing, including apartments (41.61-58.37 μg/m³), houses (79.22-92.50 μg/m³), and traditional felt dwellings (76.69-86.31 μg/m³). In the summer, PM2.5 concentrations in Darkhan were 3.10-10.03 μg/m³ in apartments, 7.67-14.37 μg/m³ in houses, and 7.98-17.90 μg/m³ in traditional felt dwellings (houses). The concentration of PM2.5 particles in the ambient air of the settlement is statistically significantly associated with shortness of breath, fatigue, weakness, muscle pain, nausea, palpitations, sneezing, runny nose, conjunctivitis, pain in the eye socket, tearing of the eyes, headache, fever, nasal congestion, cough, loss of appetite, sore throat, phlegm, wheezing, and chest pain. Conclusion The 24-hour average concentration of PM2.5 particles in indoor air in households in Ulaanbaatar and Darkhan cities is higher than the Mongolian standard during winter and is statistically significantly associated with some symptoms of respiratory diseases.

Background: CagA (cytotoxin-associated gene A protein) is an oncoprotein produced by Helicobacter pylori, a bacterium implicated in gastric carcinogenesis. CagA has been identified in all H. pylori strains isolated from patients with gastric cancer. To date, comparative studies investigating the genetic diversity of the cagA gene at the international level remain limited, and its pathogenic mechanisms have not yet been fully elucidated. Aim: To characterize the global and regional diversity of the cagA gene in H. pylori, and to evaluate the relationship of its prevalence and genotypic variants with gastric cancer. Materials and Methods: This molecular epidemiological study analyzed 9,276 H. pylori genomes from human hosts across 93 countries that were publicly available in international databases as of November 2024, together with 300 newly generated whole-genome sequences of H. pylori isolates from the Mongolian population that had not previously been deposited in public databases. To determine the genetic diversity of this oncogene, comprehensive genome bioinformatics analyses were performed, including genomic, phylogenetic, genotypic, and in silico protein analyses. Result: After quality control, 7,150 H. pylori genomes were included in the final analysis. Overall, 80.9% (n=5,783) of H. pylori strains were found to harbor the cagA gene, with the highest prevalence observed in Asia and the lowest in Europe. Maximum-likelihood phylogenetic analysis revealed substantial genotypic diversity of cagA and marked geographic variation in its distribution. Specifically, five distinct CagA protein types were identified, two of which represented previously undescribed novel types. The distribution of CagA types was found to correlate more strongly with the incidence of gastric cancer than the mere presence of cagA-positive H. pylori. Conclusion The majority of H. pylori strains in human populations worldwide harbor the CagA oncoprotein, with an overall prevalence of approximately 81%. Differences among CagA types may contribute to regional variation in gastric cancer risk. The diversification and evolutionary changes of the cagA gene may reflect recent processes of genetic admixture, which in turn shape its geographic and ethnic distribution as well as its pathogenic potential.

Background: Ambient and household air pollution remain leading risk factors for global morbidity and mortality. Exposure to fine particulate matter (PM₂.₅) is associated with increased risks of cardiovascular and respiratory diseases, as well as lung cancer, metabolic and neurological disorders, and immune dysfunction. In urban areas of Mongolia, air pollution reaches critical levels during the winter season. Although improved solid fuels have been introduced in recent years, their impact on both outdoor and indoor air quality remains insufficiently characterized. Aim: To compare outdoor and household air pollution levels in Ulaanbaatar and Darkhan cities. Materials and Methods: Outdoor air pollution data for Ulaanbaatar were obtained from fixed monitoring stations of the National Agency for Meteorology and Environmental Monitoring for the period 2014–2026, with seasonal comparisons performed. For indoor air quality assessment, a longitudinal study was conducted among 240 households (apartments, houses, and traditional gers) in Ulaanbaatar and Darkhan from 2023 to 2026. PM₂.₅ concentrations were measured using real-time sensors (PurpleAir sensor), deployed for 14–21 days per season (winter and summer) in each household, recording data at 10-minute intervals over 24-hour periods. Result: Between 2014 and 2026, the 24-hour mean concentrations in Ulaanbaatar were 60.5 µg/m for PM₂.₅, 117.3 µg/m for PM₁₀, 37.3 µg/m for NO₂, 41.8 µg/m for SO₂, and 27.5 µg/m for O₃. While particulate matter levels showed a decreasing trend following the introduction of improved fuels, SO₂ concentrations increased, and overall pollution levels remained higher than those observed in Darkhan. Indoor PM₂.₅ concentrations were higher in Ulaanbaatar compared to Darkhan (60.7±86.1 vs 48.4±96.7 µg/m). Significant differences were observed by housing type (p<0.0001), with higher concentrations in households using solid fuels (houses and gers) and lower levels in apartments. These findings indicate substantial variability in indoor air pollution by city, housing type, and season, with persistently elevated exposure levels. Conclusion Outdoor air pollutant concentrations in Ulaanbaatar, including particulate matter, NO₂, and SO₂, exceed national standards and WHO guideline values by 1–4 times. Indoor PM₂.₅ pollution is higher in Ulaanbaatar than in Darkhan and varies significantly by housing type and season, indicating a high and heterogeneous exposure burden among urban populations.

Background: According to the 2024 national health statistics of Mongolia, colorectal cancer accounts for 5.1% of all newly diagnosed cancers, with 74.1% detected at an advanced stage. Although population-based screening programs have recently been implemented, no studies have established a risk factor–based scoring system with an optimal cut-off value or evaluated its clinical utility in resource-limited settings in Mongolia. Aim: To develop a modified APCS (mAPCS) scoring system and evaluate its clinical applicability for colorectal cancer screening. Materials and Methods: A hospital-based prospective cross-sectional study was conducted between December 2024 and February 2026 at the outpatient clinics of the Mongolian National University of Medical Sciences and the Mongolia–Japan Hospital. A total of 447 eligible participants were enrolled. Anthropometric measurements (height and weight) were obtained, and six categories of questionnaires (demographic data, APCS risk score, behavioral factors, medical history, and medication use) were administered. Eleven participants declined colonoscopy; therefore, 436 participants underwent colonoscopic examination, with histopathological evaluation performed when indicated. Results: A total of 436 participants were included, of whom 282 (64.7%) were female, with a mean age of 54.8±11.5 years. Colorectal adenomas (advanced and non-advanced) and colorectal cancer were detected in 199 (45.6%) participants. Among them, 43 (21.6%) had advanced colorectal neoplasia. Multivariable regression analysis identified age ≥55 years (OR 4.8), BMI ≥28 kg/m² (OR 3.6), and a family history of colorectal cancer (OR 3.1) as independent risk factors for advanced neoplasia. The optimal cut-off value for the mAPCS score was 4, with an overall diagnostic accuracy of 41.7% (sensitivity 97.7%, specificity 35.6%). Conclusions 1. Age ≥55 years, BMI ≥28 kg/m², and a family history of colorectal cancer were identified as independent risk factors for advanced colorectal neoplasia. At a cut-off value of ≥4, the mAPCS scoring system demonstrated high sensitivity (97.7%), low specificity (35.6%), high negative predictive value (99.2%), and low positive predictive value (14.2%). 2. Therefore, the mAPCS scoring system may serve as a useful tool for risk stratification and efficient allocation of limited resources in colorectal cancer screening.

Background: Inflammatory bowel disease (IBD) is a chronic immune-related condition caused by interactions between genetics, immune dysfunction, gut microbiota changes, and environmental factors, often presenting as persistent or recurring diarrhea. Clinically, it commonly presents with chronic diarrhea and other gastrointestinal symptoms. The global prevalence of IBD is increasing, currently affecting approximately 0.5% of the population, with projections suggesting a rise to nearly 1% by 2030. Fecal calprotectin is a neutrophil-derived S100 calcium-binding protein that is elevated in intestinal mucosal inflammation and serves as a reliable noninvasive biomarker of inflammatory activity. Due to its high stability and close association with intestinal inflammatory activity, fecal calprotectin has been established as a dependable, non-invasive marker for identifying intestinal inflammation. In clinical practice, it is extensively used to distinguish IBD from functional gastrointestinal disorders, especially irritable bowel syndrome, among patients presenting with chronic diarrhea. However, its diagnostic utility in Mongolia remains underexplored, and this study aims to determine its sensitivity and specificity in inflammatory bowel disease and compare its diagnostic performance with other inflammatory markers. Aim: To determine the sensitivity and specificity of fecal calprotectin in inflammatory bowel disease and to compare it with other inflammatory markers. Materials and Methods: A total of 109 participants aged 18-87 years with chronic diarrhea, who attended the gastroenterology outpatient clinics of the Mongolia–Japan Hospital and Intermed Hospital between December 2024 and December 2025 and provided informed consent, were enrolled in this study. Data were collected using structured questionnaires, and laboratory investigations included complete blood count, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and measurement of fecal calprotectin levels from stool samples. Based on fecal calprotectin results, selected participants underwent colonoscopic examination as clinically indicated. Results: Among the 109 participants included in the study, 17.4% were diagnosed with inflammatory bowel disease (IBD), with a mean age of 47.41±15.52 years. Fecal calprotectin levels were significantly higher in the IBD group compared to the control group (p<0.001). Fecal calprotectin demonstrated a weak positive correlation with C-reactive protein (CRP) and leukocyte count (p=0.042, p=0.06), while no significant correlation was observed with erythrocyte sedimentation rate (ESR). At a cutoff value of 250 µg/g, fecal calprotectin showed a sensitivity of 94.4%, specificity of 69.2%, positive predictive value (PPV) of 37.8%, and negative predictive value (NPV) of 98.4%. Receiver operating characteristic (ROC) curve analysis identified an optimal cutoff value of approximately 400 µg/g (AUC=0.919, Youden index=0.724), at which the sensitivity remained 94.4% and specificity increased to 78.0%. In contrast, CRP and ESR demonstrated comparatively lower diagnostic performance, with AUC values of 0.640 and 0.644, respectively. Conclusion This study demonstrates that fecal calprotectin has superior diagnostic performance compared to conventional inflammatory markers in differentiating inflammatory bowel disease (IBD). An optimal cutoff value of approximately 400 µg/g yielded the highest sensitivity and specificity. Therefore, fecal calprotectin may serve as a valuable tool in clinical practice for both screening and diagnostic confirmation.

Background: Transitioning HIV care toward a client-centered model is a key strategy for improving treatment outcomes and controlling the spread of HIV infection. Evaluating service accessibility, quality, and client satisfaction is essential for improving strategic planning and strengthening health service delivery. Aim: To assess the accessibility and quality of client-centered health services among people living with HIV. Materials and methods: A facility-based cross-sectional study was conducted. Data were collected using structured questionnaires from 50 clients and 30 health managers who participated voluntarily. The reliability of the questionnaire, measured using Cronbach’s alpha, ranged from 0.673 to 0.783. Data were analyzed using SPSS version 23.0 with both descriptive and analytical statistical methods. Quantitative variables were summarized using means and standard deviations, and statistical significance was determined at p < 0.05. Results: HIV-related services were found to be highly centralized at the NCCD, particularly for blood testing (96.8%) and inpatient care (71.4%). Overall, 84% of clients reported the need to access services outside NCCD, with the highest demand for internal medicine (32%), dental services (14%), and surgical services (14%). Among the barriers to accessing care, 75% were related to stigma and discrimination associated with HIV status, while 18% were linked to healthcare workers’ attitudes. In addition, 56.7% of healthcare facilities had not conducted HIV-related training, and only 40% had dedicated rooms ensuring confidentiality. Client satisfaction was strongly correlated with healthcare providers’ attitudes and communication (R = 0.614) and confidentiality (R = 0.578), both showing significant associations (p = 0.000). Conclusion HIV services remain highly centralized at NCCD, while the readiness of primary and referral healthcare facilities remains insufficient. Strengthening a client-centered care approach requires improving healthcare workers’ attitudes and communication, ensuring confidentiality, and implementing continuous HIV-related training for healthcare providers.

Backgroun: Air pollution is a major global public health concern that poses serious risks to human health regardless of a country’s level of economic or technological development. According to the World Health Organization (WHO, 2021), nine out of ten people worldwide breathe polluted air, and air pollution is responsible for the deaths of approximately 800 people every hour and 13 people every minute. Prolonged exposure to polluted air has been linked to a wide range of chronic illnesses, including chronic obstructive pulmonary disease (COPD), lung and bronchial cancers, asthma, and stroke. In Mongolia, air pollution reaches its highest levels during the winter months, particularly in Ulaanbaatar, where the majority of the country’s population resides. A study conducted by Enkhjargal G. (2012) reported that the concentrations of PM10 and PM2.5 in Ulaanbaatar were 7–8 times higher than the WHO recommended guidelines. In response to such challenges, many countries have increasingly adopted low-cost, direct measurement devices such as PurpleAir to monitor air quality. These devices are valued for their accessibility, network connectivity, and potential role in smart city pollution management systems. Despite their global application, there remains a lack of research in Mongolia on the use of PurpleAir sensors to measure PM2.5 concentrations and compare the results with official monitoring station data. Addressing this gap is essential for improving local air quality monitoring capacity and informing effective public health and environmental policies. Aim: Determination of PM2.5 particulate matter pollution in the outdoor environment of Ulaanbaatar city using a direct measurement device (Purple Air). Materials and Methods: A cross-sectional study design was employed. Direct measurement devices (Purple Air) were installed in selected districts of central Ulaanbaatar between December 2024 and February 2025, measuring PM2.5 concentrations at two-minute intervals over 24-hour periods. All data were statistically processed and analyzed using the SPSS-26 software package. Results: The average concentration of PM2.5 particles in the air of Ulaanbaatar city in winter is 66.68 μg/m3. Compared to the districts, the highest concentration was determined in SKHD (118.58±90.22 μg/m3), while the lowest concentration was determined in KHUD (42.37±43.51 μg/m3). Compared to the days of the week, the highest concentrations were measured on Monday (76.68±71.98 μg/m³), Saturday (77.50±71.63 μg/m³), and Sunday (80.34±74.45 μg/m³). The highest concentration of PM2.5 particles occurred from 6 pm to 1 am, and the lowest concentration was measured during the day (between 2 pm and 4 pm). The highest concentration of PM2.5 was measured in December (74.22±73.45 μg/m3), while the lowest concentration was measured in February (50.25±57.44 μg/m3). Conclusion The concentration of PM2.5 in the air of Ulaanbaatar city is 1.7 times higher than the general standard and technical requirements of Mongolia in winter, and the highest concentration is in the SKHD. The highest concentration of PM2.5 occurs more often in December and at night than in the winter months.

Background: Particulate matter with an aerodynamic diameter of 2.5 micrometers or smaller (PM2.5) penetrates deep into the alveoli through the respiratory tract and is characterized by its ability to induce oxidative stress, systemic inflammation, and vascular inflammation. Mongolia ranks among the countries with the highest levels of air pollution. In Ulaanbaatar, where more than half of the country’s population resides, wintertime PM2.5 concentrations often exceed 200 μg/m³, which is about eight times higher than the World Health Organization (WHO) guideline value. A study involving 1,200 adults in Ulaanbaatar showed that quality of life deteriorated sharply during periods of high air pollution, with effects more pronounced among individuals who already had impaired respiratory function. Aim: To examine the relationship between indoor household PM2.5 concentrations and lung function indicators among adults in Ulaanbaatar and Darkhan. Materials and Methods: This analytical cross-sectional study recruited adult participants from Ulaanbaatar and Darkhan through targeted sampling. Household air quality was measured using PurpleAir sensors, which were installed in participants’ homes for one month. After exposure measurement, lung function was assessed via spirometry. Statistical analyses were conducted using SPSS version 25.0. Results: A total of 236 participants were included: 114 (48.3%) from Ulaanbaatar and 122 (51.7%) from Darkhan. The sample consisted of 111 men (47.0%) and 125 women (53.0%). The mean indoor PM2.5 concentration was 66.24 μg/m³ (SD 44.87 μg/m³), ranging from a minimum of 7.79 μg/m³ to a maximum of 264.55 μg/m³. Stratification by housing type showed the highest PM2.5 levels in gers (82.34 μg/m³), followed by detached houses (67.34 μg/m³), while apartments had the lowest concentrations (32.24 μg/m³). Correlation analysis revealed statistically significant negative associations between PM2.5 levels and measures of expiratory function, including the FEV1/FVC ratio, peak expiratory flow (PEF), and mid-expiratory flow (FEF25–75). Reduced forced vital capacity (FVC) was observed in 9.4% of participants, reduced forced expiratory volume in one second (FEV1) in 15.3%, and a decreased FEV1/FVC ratio in 3.8%. Conclusion Indoor household PM2.5 concentrations were highest in gers, and expiratory flow-related lung function parameters showed significant negative associations with particulate exposure. This suggests that indoor PM2.5 primarily affects airflow limitation rather than overall lung volumes in this population.