Estimating Cryptosporidium and Giardia disease burdens for children drinking untreated groundwater in a rural population in India

Abstract

BackgroundIn many low-income settings, despite improvements in sanitation and hygiene, groundwater sources used for drinking may be contaminated with enteric pathogens such as Cryptosporidium and Giardia, which remain important causes of childhood morbidity. In this study, we examined the contribution of diarrhea caused by Cryptosporidium and Giardia found in groundwater sources used for drinking to the total burden of diarrheal disease among children < 5 in rural India.Methodology/Principal findingsWe studied a population of 3,385 children < 5 years of age in 100 communities of Puri District, Odisha, India. We developed a coupled quantitative microbial risk assessment (QMRA) and susceptible-infected-recovered (SIR) population model based on observed levels of Cryptosporidium and Giardia in improved groundwater sources used for drinking and compared the QMRA-SIR estimates with independently measured all-cause (i.e., all fecal-oral enteric pathogens and exposure pathways) child diarrhea prevalence rates observed in the study population during two monsoon seasons (2012 and 2013). We used site specific and regional studies to inform assumptions about the human pathogenicity of the Cryptosporidium and Giardia species present in local groundwater. In all three human pathogenicity scenarios evaluated, the mean daily risk of Cryptosporidium or Giardia infection (0.06–1.53%), far exceeded the tolerable daily risk of infection from drinking water in the US (< 0.0001%). Depending on which protozoa species were present, median estimates of daily child diarrhea prevalence due to either Cryptosporidium or Giardia infection from drinking water was as high as 6.5% or as low as < 1% and accounted for at least 2.9% and as much as 65.8% of the all-cause diarrhea disease burden measured in children < 5 during the study period. Cryptosporidium tended to account for a greater share of estimated waterborne protozoa infections causing diarrhea than did Giardia. Diarrhea prevalence estimates for waterborne Cryptosporidium infection appeared to be most sensitive to assumptions about the probability of infection from ingesting a single parasite (i.e. the rate parameter in dose-response model), while Giardia infection was most sensitive to assumptions about the viability of parasites detected in groundwater samples.Conclusions/SignificanceProtozoa in groundwater drinking sources in rural India, even at low concentrations, especially for Cryptosporidium, may account for a significant portion of child diarrhea morbidity in settings were tubewells are used for drinking water and should be more systematically monitored. Preventing diarrheal disease burdens in Puri District and similar settings will benefit from ensuring water is microbiologically safe for consumption and consistent and effective household water treatment is practiced.

Cryptosporidiosis among Hemodialysis Patients in Jordan: First Preliminary Screening Surveillance

“…Cryptosporidiosis is usually self-resolving in immunocompetent individuals; however, it might lead to life-threatening complications in immunocompromised patients [2]. Cryptosporidiosis causes acute diarrhea with elevated morbidity and mortality in children, immunocompromised patients, such as AIDS patients, cancer patients and hemodialysis patients [3,[9][10][11].…”

Cryptosporidium and Giardia in Wastewater and Surface Water Environments

“…The reported (oo)cyst recovery efficiencies using standard methods also vary considerably, as efficiencies ranging from 22 to 68% have been reported in the literature (Hsu and Huang, 2000; Balderrama‐Carmona et al, 2015; Daniels et al, 2018). Schmidt and Emelko (2011) highlighted that the microorganism counts are dependent on the analytical recovery of the laboratory method.…”

“…In order for QMRA models to accurately assess the potential health risks associated with the utilization of waters contaminated with Cryptosporidium and Giardia spp., it is important that certain crucial factors are considered—for example, protozoa recovery efficiency, the fraction of protozoa species that are human pathogens (not all species cause human disease), and the fraction of viable protozoa in the water source (Daniels et al, 2018). This will not only allow for a more accurate health risk assessment but will also facilitate the accurate comparison between studies, as currently different model assumptions and sources of data are being used.…”

“…However, the authors reported that this assumption can lead to an overestimation of the potential health risk, as not all of the detected (oo)cysts may be viable and able to cause disease. In contrast, Daniels et al (2018) incorporated a percentage viability of detected Cryptosporidium and Giardia into their QMRA model while assessing the health burden associated with using groundwater in rural India. However, the authors had to estimate the proportion of viable (oo)cysts by using published data from environmental water samples collected in North America, as their experimental setup did not allow for the assessment of viability (only detection).…”

Are There Seasonal Variations in Faecal Contamination of Exposure Pathways? An Assessment in a Low–Income Settlement in Uganda

“…Most of these tools have only targeted one season [ 11 ], which is normally the rainy season [ 9 ] or during peak diarrhea season, which is also normally the rainy season [ 12 ]. Seasonal variation in risk pathways is complex and poorly understood, but rainfall has emerged as one of the drivers of faecal risk in different regions [ 13 ], hence faecal contamination is often detected, and in higher concentrations, during the rainy season [ 13 , 14 ].…”