Chronic exposure to intestinal parasites and bacterial enteropathogens among children in rural Madagascar: Implications for asymptomatic carriage and co-infections.

BACKGROUND

Intestinal infections remain highly prevalent among children living in rural, resource-limited settings, where repeated exposure to environmental pathogens begins early in life. In such contexts, enteric infections often represent chronic colonization rather than acute disease, frequently involving simultaneous carriage of parasitic and bacterial pathogens. Despite growing interest in intestinal co-infections, data on parasitic-bacterial co-occurrence, particularly among asymptomatic children in endemic settings, remain limited. Madagascar, characterized by high endemicity of intestinal parasites and major gaps in water and sanitation infrastructure, provides a relevant setting to investigate these patterns.

METHODOLOGY/PRINCIPAL FINDINGS: A community-based cross-sectional study was conducted among 242 children under 15 years of age from three rural communities in northwestern Madagascar. Stool samples were examined using light microscopy for intestinal parasites and real-time PCR for selected protozoan and bacterial enteropathogens. At least one intestinal pathogen was detected in 64.9% of children. Parasitic infections predominated (46.7%), with Giardia intestinalis identified as the most common pathogen (43.4%), while bacterial enteropathogens were detected in 23.1% of participants, mainly Campylobacter spp. and diarrheagenic Escherichia coli. Mixed infections were frequent: 23.6% of children harbored two or more pathogens, and parasitic-bacterial co-infections accounted for a substantial proportion of detected cases. Notably, most infections-including mixed infections-were asymptomatic. Infection patterns varied across study sites and were associated with environmental exposures such as water source, sanitation access, contact with livestock, and exposure to surface water.

CONCLUSIONS/SIGNIFICANCE: Intestinal parasitic-bacterial co-infections are common among children in rural Madagascar and often occur without overt clinical symptoms. These findings highlight the limitations of symptom-based and single-pathogen diagnostic approaches in endemic settings. Integrated diagnostic strategies combining microscopy and molecular methods, together with improvements in water and sanitation infrastructure, are essential to address the hidden burden of chronic intestinal infections in vulnerable pediatric populations.