High Prevalence of Giardia duodenalis Assemblage B Infection and Association with Underweight in Rwandan Children

Abstract

Background Giardia duodenalis is highly endemic in East Africa but its effects on child health, particularly of submicroscopic infections, i.e., those below the threshold of microscopy, and of genetic subgroups (assemblages), are not well understood. We aimed at addressing these questions and at examining epidemiological characteristics of G. duodenalis in southern highland Rwanda. Methodology/Principal Findings In 583 children <5 years of age from communities and health facilities, intestinal parasites were assessed by triplicate light microscopy and by PCR assays, and G. duodenalis assemblages were genotyped. Cluster effects of villages were taken into account in statistical analysis. The prevalence of G. duodenalis as detected by microscopy was 19.8% but 60.1% including PCR results. Prevalence differed with residence, increased with age, and was reduced by breastfeeding. In 492 community children without, with submicroscopic and with microscopic infection, underweight (weight-for-age z-score <−2 standard deviations) was observed in 19.7%, 22.1%, and 33.1%, respectively, and clinically assessed severe malnutrition in 4.5%, 9.5%, and 16.7%. Multivariate analysis identified microscopically detectable G. duodenalis infection as an independent predictor of underweight and clinically assessed severe malnutrition. Submicroscopic infection showed respective trends. Overall, G. duodenalis was not associated with gastrointestinal symptoms but assemblages A parasites (proportion, 13%) were increased among children with vomiting and abdominal pain. Conclusions/Significance The prevalence of G. duodenalis in high-endemicity areas may be greatly underestimated by light microscopy, particularly when only single stool samples are analysed. Children with submicroscopic infections show limited overt manifestation, but constitute unrecognized reservoirs of transmission. The predominance of assemblage B in Rwanda may be involved in the seemingly unimposing manifestation of G. duodenalis infection. However, the association with impaired child growth points to its actual relevance. Longitudinal studies considering abundant submicroscopic infections are needed to clarify the actual contribution of G. duodenalis to morbidity in areas of high endemicity.

Giardia intestinalis infection associated with malnutrition in children living in northeastern Brazil

“…G. intestinalis infection was also observed to influence nutritional status in northeastern Brazil [31][32][33]. In Rwanda, G. intestinalis infection was identified as a predictor of being underweight and severe malnutrition [30]. Similarly, giardiasis was also a strong predictor of low HAZ in Colombia and Iran, and has also been shown to be significantly associated with lower body weight, serum zinc levels, and serum iron levels in Egypt [11,13,34].…”

“…In many regions, it is possible that the STH control strategies, which are performed without parasitological diagnoses, are contributing to the neglect of basic laboratory infrastructure and the diversion of personnel training away from parasitological diagnoses. When used in cross-sectional studies, molecular diagnostic techniques generally yield higher prevalence rates due to their improved sensibility, suggesting that some infections are not detected by light microscopy [30]. However, the higher cost of diagnostic PCR prohibits its use at the community level in many developing countries.…”

Molecular Testing for Clinical Diagnosis and Epidemiological Investigations of Intestinal Parasitic Infections

“…In contrast, a study in Australia found assemblage A to be associated with diarrhea, while assemblage B was found mainly in asymptomatic children (100). In a study among Rwandan children, assemblage A was associated with vomiting and abdominal pain (101). There are also examples of studies where clinical differences associated with the two assemblages were not identified (102,103).…”

Loop-Mediated Isothermal Amplification: An Advanced Method for the Detection of Giardia

“…This includes neglected tropical diseases (NTDs). The geohelminths (soil-transmited helminths [STHs]) and the intestinal G. duodenalis parasite alone infect hundreds of millions of people in SSA [32,33].…”