Trichomonas vaginalis is a flagellated protozoan parasite that causes vaginitis and cervicitis in women and asymptomatic urethritis and prostatitis in men. Mast cells have been reported to be predominant in vaginal smears and vaginal walls of patients infected with T. vaginalis. Mitogen-activated protein kinase (MAPK), activated by various stimuli, have been shown to regulate the transcriptional activity of various cytokine genes in mast cells. In this study, we investigated whether MAPK is involved in ROS generation and exocytotic degranulation in HMC-1 cells induced by T. vaginalis-derived secretory products (TvSP). We found that TvSP induces the activation of MAPK and NADPH oxidase in HMC-1 cells. Stimulation with TvSP induced phosphorylation of MAPK and p47^phox in HMC-1 cells. Stimulation with TvSP also induced up-regulation of CD63, a marker for exocytosis, along the surfaces of human mast cells. Pretreatment with MAPK inhibitors strongly inhibited TvSP-induced ROS generation and exocytotic degranulation. Finally, our results suggest that TvSP induces intracellular ROS generation and exocytotic degranulation in HMC-1 via MAPK signaling.

Entamoeba histolytica is an important cause of diarrheal disease worldwide; however, its contribution to diarrheal illness in Mongolia remains poorly understood. We investigated the seroprevalence of E. histolytica among hospitalized patients with diarrhea, characterized bacterial and viral enteric pathogens in stool specimens from E. histolytica-seropositive patients, and evaluated associated environmental and behavioral risk factors. A hospital-based cross-sectional study was conducted among 83 patients hospitalized with diarrhea at the National Center for Communicable Diseases, Ulaanbaatar, between July 16 and August 20, 2025. Serum samples were tested for E. histolytica-specific IgG antibodies by ELISA. Stool specimens from seropositive patients were further analyzed for bacterial and viral enteric pathogens using multiplex PCR assays. Demographic, environmental, and behavioral risk factors were assessed using structured questionnaires. Preschool-aged children constituted the largest proportion of all hospitalized patients with diarrhea (43.4%, P=0.001). E. histolytica-specific IgG antibodies were detected in 7 of 83 participants (8.4%). Among E. histolytica-seropositive patients, bacterial enteric pathogens were detected in 71.4% (5/7) of stool specimens, including enterotoxigenic, enteroaggregative, and enteropathogenic Escherichia coli. No viral pathogens were detected. Multivariable logistic regression analysis showed that consumption of unwashed fruits and vegetables was significantly associated with E. histolytica seropositivity (adjusted odds ratio, 6.2; 95% confidence interval, 1.6–15.2; P=0.026). These findings highlight the need for improved laboratory diagnostic capacity and enhanced food hygiene interventions to facilitate the diagnosis and prevention of amoebic diarrhea.