Avian Aquatic Reservoirs and Zoonotic Potential of Helicobacter spp. in Wetlands from the Southern Caribbean Sea.

Helicobacter species are increasingly recognized in environmental reservoirs, yet their prevalence and diversity in tropical wetland ecosystems remain poorly understood. This study aimed to assess the prevalence, distribution, and diversity of Helicobacter spp. in a tropical wetland ecosystem, specifically within the Cuare Wildlife Refuge, Venezuela, focusing on waterbirds and associated aquatic matrices. We collected samples from avian faeces, water, plankton, oysters, soils, and microbial mats during two periods (October/2011 and March/2012). Analysis involved culture in HP selective medium, genus-specific PCR, 16S rRNA gene sequencing, phylogeny and water quality assessment. Helicobacter DNA was detected in 57% of samples (n = 148), with varying prevalence: water (94%), plankton (100%), oysters and soils (80%), microbial mats (50%), and avian faeces (42%). Prevalence in bird faeces was higher in resident (69%) than migratory (41%) species and showed a positive correlation with water salinity in October 2011 (r = 0.94, p < 0.05). Despite urease activity, all culture attempts on selective medium failed. Phylogenetic analysis revealed sequences clustering within H. pylori, H. pametensis, H. kayseriensis, H. brantae, and H. pullorum-related clades, alongside potentially novel lineages, highlighting significant diversity and zoonotic potential. Elevated enterococci levels (> 35 MPN/100 mL), exceeding guideline values, suggest sewage inputs and threats to this wildlife habitat. These findings identify waterbirds as carriers and wetlands as reservoirs for diverse commensal, pathogenic and zoonotic Helicobacter species in a relevant marine protected area of the Caribbean Sea.