Role of TNF-α genetic variants in coinfection with Helicobacter pylori and the Entamoeba complex: a cross-sectional study

Helicobacter pylori and Entamoeba histolytica are among the most common gastrointestinal pathogens worldwide, particularly in developing countries where sanitation conditions favor transmission. Co-infection by these organisms may influence disease manifestation and host immune response. This study aimed to determine the prevalence and molecular characterization of Entamoeba species and Helicobacter pylori among patients with gastrointestinal symptoms attending Kasr El-Aini hospital. It also investigated the association of tumor necrosis factor-alpha (TNF-α) gene polymorphisms at positions − 1031 T/C and − 308G/A with susceptibility or protection against these infections. A total of 372 stool samples were collected and classified into four groups: Helicobacter pylori-only, Entamoeba-only, co-infected, and control. Controls were recruited from the same clinical setting and confirmed negative for both Helicobacter pylori and Entamoeba histolytica by molecular assays. Microscopic examination was first performed for parasitic detection, followed by DNA extraction and polymerase chain reaction (PCR) for species identification of Entamoeba dispar, Entamoeba moshkovskii, Entamoeba histolytica, and Helicobacter pylori. Among 93 samples positive for the Entamoeba complex, Entamoeba moshkovskii was the predominant species (53.8%), followed by Entamoeba. dispar (29.0%) and Entamoeba histolytica (17.2%). Mixed infections were observed in 19 cases. Sociodemographic factors, including age, sex, residence, water source, and animal contact, were significantly associated with the presence of Entamoeba species. Among 93 Helicobacter pylori-positive participants, 44.1% carried the cytotoxin-associated gene A (CagA) virulence factor. Sex and tap water consumption showed significant associations with Helicobacter pylori infection and co-infection. Genotyping analysis revealed that the TNF-α − 1031 T/C TT genotype and T allele were more frequent in healthy controls, suggesting a protective role, while no significant difference was observed for the − 308G/A polymorphism. This study highlights a notable prevalence of Entamoeba moshkovskii among the Entamoeba complex and a considerable rate of co-infection with Helicobacter pylori. Environmental and host factors, particularly water source and sex, play important roles in infection dynamics. The TNF-α − 1031C allele appears to confer protection against gastrointestinal infection. These findings emphasize the need for improved diagnostic screening and public health measures to limit transmission and co-infection in endemic areas.