Species of Cryptosporidia Causing Subclinical Infection Associated With Growth Faltering in Rural and Urban Bangladesh: A Birth Cohort Study

Abstract

Background: Cryptosporidiosis is a major cause of childhood diarrhea in low- and middle-income countries and has been linked to impairment of child growth. This study investigated the burden of cryptosporidiosis and its impact on child growth in both a rural and an urban site in Bangladesh.

Methods: Pregnant women in the second trimester were identified at 2 sites in Bangladesh, 1 urban and 1 rural. Their offspring were enrolled at birth into the study (urban, n = 250; rural, n = 258). For 2 years, the children were actively monitored for diarrhea and anthropometric measurements were obtained every 3 months. Stool samples were collected monthly and during diarrheal episodes with Cryptosporidium infection and causative species determined by quantitative polymerase chain reaction assays.

Results: Cryptosporidium infections were common at both sites and mostly subclinical. In the urban site, 161 (64%) children were infected and 65 (26%) had ≥2 infections. In the rural site, 114 (44%) were infected and 24 (9%) had multiple infections. Adjusted for potential confounders, cryptosporidiosis was associated with a significantly greater drop in the length-for-age z score (LAZ) at 24 months from LAZ at enrollment (Δ-LAZ), an effect greatest in the children with multiple episodes of cryptosporidiosis. The most common species in Mirpur was Cryptosporidium hominis, whereas Cryptosporidium meleagridis predominated in Mirzapur.

Conclusions: Cryptosporidiosis is common in early childhood and associated with early growth faltering in Bangladeshi children. Predominant Cryptosporidium species differed between the 2 sites, suggesting different exposures or modes of transmission but similar consequences for child growth.

Clinical trials registration: NCT02764918.

Figure 1.

Study flow diagram. Abbreviation: qPCR, quantitative polymerase chain reaction.

Figure 2.

Cryptosporidiosis cumulative incidence curves by study site using Kaplan-Meier method for any (A), diarrheal (B), and subclinical (C) Cryptosporidium infections. Blue line = Mirpur; red line = Mirzapur.

Figure 3.

Association of cryptosporidiosis and unadjusted mean change in length-for-age z score at 24 months compared with enrollment (Δ-LAZ). A, Stratified into children with no cryptosporidiosis (n = 205) or any cryptosporidiosis (n = 259) detected during follow-up. P value by t test. B, Stratified into zero (n = 205), 1 (n = 174), or ≥2 (n = 85) episodes of cryptosporidiosis during follow-up. P values by post hoc Tukey multiple comparisons test following analysis of variance.

Figure 4.

Cryptosporidium species detected and infection phenotype at urban Mirpur (A) and rural Mirzapur (B) sites. Solid bar indicates the number of diarrheal infections and open bar indicates subclinical infections.