Epidemiology of Cryptosporidiosis and Giardiasis: What Pediatricians Need to Know

Cryptosporidium spp. and Giardia duodenalis emissions from humans and animals in the Three Gorges Reservoir in Chongqing, China

Cryptosporidium spp. and Giardia duodenalis are two waterborne protozoan parasites that can cause diarrhea. Human and animal feces in surface water are a major source of these pathogens. This paper presents a GloWPa-TGR-Crypto model that estimates Cryptosporidium and G. duodenalis emissions from human and animal feces in the Three Gorges Reservoir (TGR), and uses scenario analysis to predict the effects of sanitation, urbanization, and population growth on oocyst and cyst emissions for 2050. Our model estimated annual emissions of 1.6 × 10¹⁵ oocysts and 2.1 × 10¹⁵ cysts from human and animal feces, respectively. Humans were the largest contributors of oocysts and cysts, followed by pigs and poultry. Cities were hot-spots for human emissions, while districts with high livestock populations accounted for the highest animal emissions. Our model was the most sensitive to oocyst excretion rates. The results indicated that 74% and 87% of total emissions came from urban areas and humans, respectively, and 86% of total human emissions were produced by the urban population. The scenario analysis showed a potential decrease in oocyst and cyst emissions with improvements in urbanization, sanitation, wastewater treatment, and manure management, regardless of population increase. Our model can further contribute to the understanding of environmental pathways, the risk assessment of Cryptosporidium and Giardia pollution, and effective prevention and control strategies that can reduce the outbreak of waterborne diseases in the TGR and other similar watersheds.

Pit Latrines: A Noninvasive Sampling Strategy to Assess Fecal Pathogen Occurrence in Low Resource Communities

Limited understanding of disease in low resource communities continues to hamper improvements in health. We evaluated household pit latrine sampling as a non-invasive approach to investigate important fecal pathogens such as Giardia lamblia and Cryptosporidium spp. in impoverished communities where health-seeking behavior limits the sensitivity of health facility-based surveillance. Fecal samples were collected from pit latrines in randomly selected households and from patients presenting to the only hospital in the region during the same time periods. Samples were tested with a commercially available ELISA. Giardia household prevalence was 28.7% in 2016 and 48.4% in 2017, while individual samples from hospital submission had a Giardia prevalence of 2.4% in 2016 and 8.0% in 2017. Cryptosporidium was only found in one household. Results suggest that pit latrine surveillance for fecal-borne infections provide course estimates of community infection levels that are unbiased by health seeking behaviors and allow surveillance of vulnerable sectors of a population.