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Cryptosporidium infection stunts kids’ growth

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June 24, 2018

Researchers examined the nonacute effects of diarrhea caused by Cryptosporidium infection in young children and found that it decreased their growth and increased the risk of subsequent infectious disease.

“Our findings show that the previously reported burden of Cryptosporidium was an underestimation of the true burden,” Ibrahim A. Khalil, MD, of the Institute for Health Metrics and Evaluation at the University of Washington in Seattle, and colleagues wrote in The Lancet Global Health.

Khalil and colleagues reviewed the Global Burden of Disease Study (GBD) 2016 for estimates on the burden of Cryptosporidium in children and supplemented the data with findings from a systematic review of published and unpublished cohort studies and a meta-analysis of the effect that Cryptosporidium-associated diarrhea has on physical growth.

According to GBD, in 2016, Cryptosporidium was the fifth-leading cause of diarrhea-related death in children younger than age 5 years. More than 80% of the 57,200 overall deaths linked to the infection occurred in children in this age group, almost half of them in Nigeria.

The researchers estimated that there were 44.8 million episodes of diarrhea from Cryptosporidium infection in children aged 5 years and younger in 2016, with an incidence of 69.7 per 1,000 child-years. The same year, they estimated that acute diarrheal morbidity and mortality caused by the parasites was linked to 4,224,000 disability-adjusted life years (DALYs) worldwide in children in this age group.

According to Khalil and colleagues, children aged 28 to 364 days are particularly affected by Cryptosporidium. In an analysis that accounted for undernutrition-associated DALYs, the researchers found that Cryptosporidium was associated with nearly 250 DALYs per 1,000 child-years in children younger than age 1 year in sub-Saharan Africa, which has the world’s highest burden of the infection. The majority of the burden came from long-term outcomes related to undernutrition, with undernutrition-associated DALYs linked to 61% to 94% of all Cryptosporidium DALYs, they reported.

“Health consequences associated with increased wasting and underweight accounted for most of this additional burden, which exceeded 30% in all super-regions except sub-Saharan Africa,” they wrote.

Based on the meta-analysis, Khalil and colleagues estimated that each episode of diarrhea from Cryptosporidium infection led to significantly decreased height-for-age z scores (HAZ), weight-for-age z scores (WAZ), and weight-for-height z scores (WHZ).

“Our work highlights the acute and long-term effects of infection in children younger than 5 years and illustrates the unequitable distribution of that burden in low-income geographies,” they wrote. “Interventions to improve childhood health and well-being, such as through improved water and sanitation sources and breastfeeding promotion, and a renewed urgency in the development of Cryptosporidium prevention and treatment options could ensure that all children have an opportunity to grow, thrive, and live healthy lives.” – by Jennifer Byrne

Disclosures: The researchers report no relevant disclosures.

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Perspective

Infectious diarrhea is well-recognized as an important cause of death worldwide in children younger than age 5 years. Although Cryptosporidium parasites had long been identified as the cause of self-limited diarrheal illness, many were surprised by the GBD 2015, which identified Cryptosporidium as a major cause of life-threatening pediatric diarrhea. The current study further illuminates the contribution of Cryptosporidium infection to pediatric health. The investigators find that each episode of cryptosporidial diarrhea contributes to poor growth and weight gain in surviving children. Because malnutrition and stunting have both immediate and long-term effects on the health and development of children, this study reveals the dramatic global impact of this protozoan parasite. There is clearly an urgent need to expand public health efforts to control Cryptosporidium infections. Because the only available therapeutic, nitazoxanide, has poor efficacy in the immunocompromised and malnourished patients most at risk, ongoing support for new Cryptosporidium treatments should continue to be a research priority.

Audrey R. Odom John, MD, PhD

Associate professor of pediatrics and molecular microbiology
Washington University School of Medicine, St. Louis

Disclosure: Odom John has no financial disclosures.