Researchers with the UNC Institute for Global Health and Infectious Diseases have identified persistent Giardia infections as a significant risk factor for impaired linear growth, independent of intestinal inflammation.
CHAPEL HILL, N.C. — A study led by PhD candidate Lester Gutiérrez, MS, with Luther Bartelt, MD, DTM&H, and Sylvia Becker-Dreps, MD, MPH, senior authors with the Institute for Global Health and Infectious Diseases, found Giardia infections during early childhood are strongly associated with impaired linear growth, particularly when infections occur repeatedly or persist over time. The findings reinforce how this common intestinal parasite may contribute to childhood stunting through mechanisms distinct from traditional inflammatory pathways.
Published in PLOS Neglected Tropical Diseases, the study followed 76 children in León, Nicaragua, from birth through age three, collecting more than 2,300 stool samples alongside detailed growth measurements and biomarker analyses. Nearly 58% of children experienced at least one Giardia infection, with most infections occurring without diarrhea or other symptoms.
The Findings
The study found that children with Giardia infections had significantly poorer length-for-age growth outcomes than uninfected children. The strongest effects were observed among children with persistent or recurrent infections and among those infected during the first 18 months of life.
“This work adds to growing evidence that endemic childhood giardiasis can have meaningful consequences for growth and development, even when infections are asymptomatic,” said Bartelt, associate professor of medicine and senior author of the study. “Understanding the biological pathways involved is critical for developing interventions that can reduce the long-term impact of these infections on child health.”
Bartelt recognized typical treatments for giardiasis have not been effective in these settings and that exposures are so high that reinfection almost always occurs. “Since new anti-giardia drugs haven’t been identified, we need to examine disease pathways that could lead to new treatments in parallel with ways to limit exposure and more effectively eliminate the parasite,” he said.
Gutiérrez, first author and post-doc in the Nicaraguan Emerging and Endemic Diseases (NEED) Training Program, with the Fogarty International Center, said the findings point to a need for broader attention to Giardia beyond its role in causing gastrointestinal illness.
“Many of the children we studied showed no obvious symptoms when infected, yet we still observed measurable impacts on growth,” said Gutiérrez. “Our results suggest that repeated exposure to Giardia may affect nutrient absorption and growth signaling pathways in ways that have been underappreciated.”
The research also identified poverty-related household conditions, including earthen floors and inadequate sanitation, as significant risk factors for infection. Geographic analysis revealed concentrated areas of transmission, highlighting opportunities for community-level prevention efforts.
Importantly, the study confirmed findings from other cohorts that growth deficits were not linked to chronic intestinal inflammation typically associated with environmental enteric dysfunction. Instead, infected children exhibited biomarkers consistent with intestinal epithelial damage and reduced growth signaling, including lower levels of insulin-like growth factor-1 (IGF-1), a hormone essential for childhood growth.
“These findings help explain why Giardia-associated growth impairment has been so difficult to understand,” Bartelt said. “The parasite appears to affect growth through pathways involving intestinal function and metabolism rather than classic inflammatory responses.”
Authors include Nadja A. Vielot, Yaoska Reyes, Roberto Herrera, Christian Toval-Ruiz, Javier Mora, Michael B. Arndt, Rebecca Barney, Robert K.M. Choy, Filemón Bucardo and Samuel Vilchez.
Lester Gutiérrez was featured in this earlier story, recognizing his visits to UNC to use laboratory tools not available in León.