A majority of Zambian children live in impoverished communities that lack safe water and proper sanitation, exposing them to urogenital and intestinal helminths. Efforts to mitigate this plight have been implemented through mass drug administration aimed at deworming school-age and under-five children against schistosomiasis and soil-transmitted helminths. However, the disease status of adults living in the same communities as the treated children remains unknown. The aim of this study was to describe the potential contribution of infected adult populations to the transmission of these infections in southern Zambia. A cross-sectional study was conducted in April and May 2013 as part of baseline survey for a larger study in Mazabuka and Siavonga Districts. Stool and urine samples of 2829 adults from five catchment areas were collected and processed using Kato-Katz and urine filtration methods, respectively. Adults from Siavonga had a 13.9% combined prevalence of Schistosoma haematobium and S. mansoni, and 12.1% combined prevalence of Ascaris lumbricoides and hookworm. There was no S. mansoni in Mazabuka, and only a 5.3% prevalence of S. haematobium and 7.4% combined prevalence of A. lumbricoides and hookworm. Additionally, no Trichuris trichiura infections were observed in the two districts. Despite most of these infections being categorized as light intensity, heavy infection intensities were also found for all four parasite species. If this infected adult population is left untreated, the possibility of it acting as a reservoir of infections and ultimately transmitting the infections to treated children remains. Therefore, there is need to consider alternative treatment strategies that incorporate adults, thereby reducing the risk of contaminating the environment and perpetuating transmission to children.