Hypothesis: Cryptosporidium genetic diversity mirrors national disease notification rate.

Katsuhisa Takumi,Simone M Cacciò,Joke Van Der Giessen,Lihua Xiao,Hein Sprong

doi:10.1186/s13071-015-0921-3

Abstract

BackgroundCryptosporidiosis is a gastrointestinal disease affecting many people worldwide. Disease incidence is often unknown and surveillance of human cryptosporidiosis is installed in only a handful of developed countries. A genetic marker that mirrors disease incidence is potentially a powerful tool for monitoring the two primary human infected species of Cryptosporidium.MethodsWe used the molecular epidemiological database with Cryptosporidium isolates from ZoopNet, which currently contains more than 1400 records with their sampling nations, and the names of the host species from which the isolates were obtained. Based on 296 C. hominis and 195 C. parvum GP60 sequences from human origin, the genetic diversities of Cryptosporidium was estimated for several nations. Notified cases of human cryptosporidiosis were collected from statistics databases for only four nations.ResultsGenetic diversities of C. hominis were estimated in 10 nations in 5 continents, and that of C. parvum of human origin were estimated in 15 nations. Correlation with reported incidence of human cryptosporidiosis in four nations (the Netherlands, United States, United Kingdom and Australia) was positive and significant. A linear model for testing the relationship between the genetic diversity and incidence produced a significantly positive estimate for the slope (P-value < 0.05).ConclusionsThe hypothesis that genetic diversity at GP60 locus mirrors notification rates of human cryptosporidiosis was not rejected based on the data presented. Genetic diversity of C. hominis and C. parvum may therefore be an independent and complementary measure for quantifying disease incidence, for which only a moderate number of stool samples from each nation are sufficient data input.

Highlights

IntroductionDisease incidence is often unknown and surveillance of human cryptosporidiosis is installed in only a handful of developed countries
Cryptosporidiosis is a gastrointestinal disease affecting many people worldwide
The highest genetic diversity was estimated from 94 GP60 sequences from Australia, whereas the lowest genetic diversity was estimated from seven GP60 sequences from Italy

Summary

Introduction

Disease incidence is often unknown and surveillance of human cryptosporidiosis is installed in only a handful of developed countries. A genetic marker that mirrors disease incidence is potentially a powerful tool for monitoring the two primary human infected species of Cryptosporidium. Cryptosporidium parasites that are important for humans are classified into the two main species, C. hominis and C. parvum, and further into subtype. Cryptosporidium isolates from humans and from animals in various countries have been sequenced and compiled into a database [10, 11]. This database, made possible by a European consortium (ZoopNet), is a source of molecular and epidemiological information about the protozoan infection in humans and in animals (Giardia and Cryptosporidium). The broad geographic range is a strong asset of the database, if we can infer the population risk of human cryptosporidiosis from the regional sequence data

Methods

Results

Discussion

Conclusion