Abstract
Cryptosporidiosis and giardiasis are recognized as significant enteric diseases due to their long-term health effects in humans and their economic impact in agriculture and medical care. Molecular analysis is essential to identify species and genotypes causing these infectious diseases and provides a potential tool for monitoring. This study uses information on species and genetic variants to gain insights into the geographical distribution and spatial patterns of Cryptosporidium and Giardia parasites. Here, we describe the population heterogeneity of genotypic groups within Cryptosporidium and Giardia present in New Zealand using gp60 and gdh markers to compare the observed variation with other countries around the globe. Four species of Cryptosporidium (C. hominis, C. parvum, C. cuniculus and C. erinacei) and one species of Giardia (G. intestinalis) were identified. These species have been reported worldwide and there are not unique Cryptosporidium gp60 subtype families and Giardia gdh assemblages in New Zealand, most likely due to high gene flow of historical and current human activity (travel and trade) and persistence of large host population sizes. The global analysis revealed that genetic variants of these pathogens are widely distributed. However, genetic variation is underestimated by data biases (e.g. neglected submission of sequences to genetic databases) and low sampling. New genotypes are likely to be discovered as sampling efforts increase according to accumulation prediction analyses, especially for C. parvum. Our study highlights the need for greater sampling and archiving of genotypes globally to allow comparative analyses that help understand the population dynamics of these protozoan parasites. Overall our study represents a comprehensive overview for exploring local and global protozoan genotype diversity and advances our understanding of the importance for surveillance and potential risk associated with these infectious diseases.
Highlights
Infectious diseases are the major leading causes of death and disability worldwide [1]
Using molecular analysis and a review framework we showed that species and genetic variants within genera Cryptosporidium and Giardia found in an island system are not different from other parts of the world
Species and genotypes are widely distributed, new variants will arise when sampling effort increase and their dispersal will be facilitated by human activity. These findings suggest that geographical distribution of species and genotypes within Cryptosporidium and Giardia parasites may yield important clues for designing effective surveillance strategies and identification of factors driving within and cross species transmission
Summary
Infectious diseases are the major leading causes of death and disability worldwide [1]. A substantial number of gastroenteritis cases around the world are caused by the parasitic protozoans Cryptosporidium and Giardia [10,11,12,13,14]. These organisms are recognized as major causes of parasite-induced diarrhoea in humans and other animals that can be spread through various means, but transmitted mainly by interactions between humans and animals and by contaminated water or food [14]. G. intestinalis (synonyms G. lamblia and G. duodenalis) is the most common intestinal protozoan parasite, frequently reported in association with water- and food-borne outbreaks [15, 23, 24], affecting about 280 million people worldwide [25] with some 500,000 new symptomatic cases reported each year in developing countries only [26]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
