Objective: To investigate the prevalence of gastrointestinal helminth infections among farmers of different age groups and the risk factors influencing disease transmission in different geographic settings with intermittent treatment in Delta North Agricultural Zone in Nigeria. Methods: This cross-sectional study was carried out among all age groups in some farming communities in freshwater swamp forest and lowland rainforest of Delta North Agricultural Zone. Kato Katz method was used to detect gastrointestinal helminth infections in stool samples. Study participants totalled 20 698 including 11215 (54.2%) males and 9483 (45.8%) females. Additionally, diagnostic tests performance for Schistosoma mansoni using Kato Katz and PCR were compared. Results: This study identified six parasites namely, Schistosoma mansoni, Ascaris lumbricoides, hookworm, Trichuris trichiura, Enterobius vermicularis and Strongyloides stercoralis, with a total prevalence of 21.6%. The freshwater swamp forest had a slightly higher prevalence (21.8%) with six parasite species than that of the lowland rainforest (21.0%) with five species, but the difference was not statistically significant (P > 0.05). Factors that influenced disease transmission include sex, age, behaviour, type of infection, culture and environment, with vulnerabilities higher among children and females (P < 0.05). Additional investigation comparing Kato Katz method and PCR using Schistosoma mansoni 121 bp primer on 120 samples showed prevalence of 0.0% for Kato Katz and 4.2% for PCR. Conclusions: This study revealed persistent gastrointestinal helminth infections in areas where there is intermittent mass antihelminthic administration. This underscores the need for integrated control of gastrointestinal helminthiasis in farming communities.