Distribution of nematophagous fungi and soil-transmitted helminths in outdoor built environments across Latin America

BACKGROUND: Soil-transmitted helminths (STHs) are among the most common global parasitic infections, represent a significant worldwide public health burden, and remain a source of considerable morbidity in Latin America. Nematophagous fungi (NF), such as Arthrobotrys oligospora, naturally inhabit many soil types and are known for their ability to trap and kill nematodes using specialized hyphal structures or secreted enzymes and metabolites. As they prey on different developmental stages of helminths in soil, they may represent an ecological factor influencing helminth persistence and transmission dynamics. METHODS: Using an in vitro test, Toxocara cati eggs were exposed to A. oligospora. By using a flotation, filtration, and bead-beating disruption technique, parasite and fungal DNA were collected and detected by multi-parallel real-time quantitative PCR (qPCR). Similar methods were used to extract DNA from soil samples outside built environments across seven Latin American countries, including Argentina, Bolivia, Brazil, Ecuador, Mexico, Paraguay, and Peru. RESULTS: In vitro testing showed a 40.1% reduction in viable eggs in the presence of A. oligospora, as determined by qPCR (P = 0.0212). Comparing the impact of A. oligospora on T. cati over 14 days revealed a decrease in T. cati DNA concentration compared to control groups (P = 0.0039). Using qPCR to detect A. oligospora, there was a 62.4% decrease in the mean A. oligospora DNA at 14 days. The co-occurrence of NF and STH was evaluated in 805 soil samples from seven Latin American countries representing distinct geoclimatic settings. We observed a significant reduction in helminth abundance (P < 0.05), including Ascaris, Strongyloides, Toxocara, and any helminth. CONCLUSION/SIGNIFICANCE: The ubiquitous presence of A. oligospora in soils and inverse association with STH parasite detection suggest a potential role in environmental helminth transmission patterns.