title: Hypothesis: Cryptosporidium genetic diversity mirrors national disease notification rate.
abstract: BACKGROUND
  Cryptosporidiosis 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.
  
  
  METHODS
  We 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.
  
  
  RESULTS
  Genetic 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).
  
  
  CONCLUSIONS
  The 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.
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), P.O. Box 1, Bilthoven, 3720, The Netherlands. katsuhisa.takumi@rivm.nl.
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Takumi
authors.affiliation: Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Rome, Italy. simone.caccio@iss.it.
authors.forename: Simone M
authors.initials: SM
authors.lastname: Cacciò
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), P.O. Box 1, Bilthoven, 3720, The Netherlands. joke.van.der.giessen@rivm.nl.
authors.forename: Joke
authors.initials: J
authors.lastname: van der Giessen
authors.affiliation: Division of Foodborne, Waterborne and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, USA. lax0@cdc.gov.
authors.forename: Lihua
authors.initials: L
authors.lastname: Xiao
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), P.O. Box 1, Bilthoven, 3720, The Netherlands. hein.sprong@rivm.nl.
authors.forename: Hein
authors.initials: H
authors.lastname: Sprong
mesh_terms: D001315:Australia / Q000453:epidemiology; D003457:Cryptosporidiosis / Q000453:epidemiology* / Q000469:parasitology; D003458:Cryptosporidium / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D018563:Disease Notification; D014644:Genetic Variation; D006801:Humans; D009426:Netherlands / Q000453:epidemiology; D010802:Phylogeny; D006113:United Kingdom / Q000453:epidemiology