The distribution and association of parasitic infections among human blood group in selected health facilities in Amhara National Regional State, Ethiopia: cross-sectional study, 2025

There is conflicting evidence in the literature regarding the association between parasitic infections and human ABO blood groups. Understanding which blood groups may be more susceptible to specific intestinal parasites requires additional data from diverse populations and research settings. Therefore, this study aimed to evaluate the association between intestinal parasitic infections and ABO blood group types in the Amhara region of Ethiopia. A health facility-based cross-sectional study was conducted from February to April 2025 in four cities of the Amhara National Regional State, Ethiopia. A total of 550 study participants were enrolled. Stool specimens were examined for intestinal parasites using direct wet mount microscopy. Blood typing for ABO blood groups was performed using standard agglutination methods. Data were analyzed to assess associations between parasite infection and blood group types. Among 550 participants, the overall prevalence of intestinal parasitic infections was 38.9% (214/550). The distribution of ABO blood groups was as follows: blood type O was the most common (45.3%), followed by type A (30.5%), type B (19.8%), and type AB (4.4%). The highest prevalence of intestinal parasites was observed among individuals with blood type AB (11/24; 45.8%), while the lowest was recorded among those with blood type O (93/249; 37.3%). Species-specific analysis revealed that Entamoeba histolytica was most prevalent in blood type O (93/249; 51.6%), whereas Ascaris lumbricoides showed uniformly low prevalence across all blood groups, ranging from 2.1% to 4.2%. A statistically significant association was found between ABO blood groups and protozoan infections (p < 0.05); however, no significant association was observed with helminth infections (p > 0.05). Overall, individuals with blood type AB demonstrated the greatest susceptibility to intestinal parasitic infections. However, a higher prevalence of Entamoeba histolytica was observed in those with blood type O, suggesting a potential species-specific association that warrants additional investigation. There is a significant link between ABO blood groups and protozoan infections, but this connection does not extend to helminth infections. Future community-based and molecular studies are essential to clarify the mechanisms behind these blood group-related differences in susceptibility.