• Zoonotic Transmission of Cryptosporidium: A systematic review and Future Directions
  • Nima komeili,1,*
    1. undergraduated student,faculty of veterinary medicine , ferdowsi university of mashhad, mashhad,iran.


  • Introduction: A wide range of hosts can be infected by Cryptosporidium species, enteric parasites that are found all over the world and have a wide distribution. Viral-oral transmission occurs through contaminated water, food, or direct contact with humans and animals. Although first described in 1907 by Tyzzer , Cryptosporidium did not come to prominence until the early 1980s. This is when it was identified as a cause of severe and protracted diarrhea and death in HIV+/AIDS patients. It is now recognised as a major pathogen in children and immunocompromised adults and after rotavirus is the most serious diarrheal pathogen in young children . There was a large waterborne outbreak of Cryptosporidium in Milwaukee in 1993 that affected over 400,000 residents. Though it is under-reported, Cryptosporidium is a well-known and major cause of gastroenteritis outbreaks both in the water and in food. Among the reasons for this are the resistance of the environmental stage, the oocyst, to disinfectants, such as chlorine treatments in drinking and recreational water. Several Cryptosporidium species from mammals and birds, such as C. parvum, C. meleagridis, C. canis, C. felis, and C. ubiquitum, are significant zoonotic pathogens, causing animal contact-associated or waterborne and foodborne cryptosporidiosis in humans.Although six common species are identified in humans, including C. hominis and C. parvum.This review aims to summarise the currently available data on zoonotic transmission of Cryptosporidium species and genotypes. It also outlines future studies required to better understand this ubiquitous parasite's transmission dynamics.
  • Methods: Four global databases (PubMed, Web of Science, Scopus and Google scholar) were searched. The searching process was accomplished using MeSH terms alone or in combination: ( “Coccidian” OR “Opportunistic protozoa” OR “Cryptosporidium” OR “Cryptosporidiosis”) AND (“Prevalence” OR “Epidemiology”) AND (“humen” OR “zoonotic”) ,6200 studies funded. After removing duplicates and excluding ineligible reports, 127 articles, containing 160 datasets, were eligible to be included in this systematic review .42 relevent articles with complete abstracts were included in the study.
  • Results: Cryptosporidium species are widespread enteric parasites with diverse hosts, primarily transmitted through the fecal-oral route via contaminated water, food, or contact with humans and animals. Initially described in 1907, Cryptosporidium gained prominence in the 1980s as a cause of severe diarrhea and mortality in HIV/AIDS patients. It is now recognized as a significant pathogen in children and immunocompromised individuals, ranking as the second most common cause of diarrhea in young children after rotavirus. Cryptosporidium is notorious for causing both waterborne and foodborne gastroenteritis outbreaks, as its oocysts are resistant to disinfectants. Various Cryptosporidium species, including C. parvum and C. meleagridis, are zoonotic, posing risks to humans through animal contact, waterborne transmission, or contaminated food. The parasite has a complex life cycle involving ingestion and excystation of oocysts, leading to infectious thick-walled oocyst shedding in feces. In humans, cryptosporidiosis can lead to watery diarrhea, abdominal pain, vomiting, malnutrition, cognitive deficits, and even colon cancer. While typically self-limiting in healthy individuals, it can become chronic, particularly in immunocompromised hosts, and neonatal livestock may experience severe diarrhea and death. At the moment, the only FDA-approved drug, nitazoxanide, is also widely ineffective and while Halocur® (halofuginone lactate) is available in some countries as a prophylactic, its effectiveness is variable, and it cannot be given to animals already suffering from diarrhea. In addition, there is no approved vaccine. Due to Cryptosporidium species' morphological similarity, 18S ribosomal RNA typing is crucial for identification. C hominis and C parvum are the most important human genotypes among 44 species and >120 genotypes. Cryptosporidiosis epidemiology is heavily influenced by zoonotic transmission. Waterborne outbreaks are a global concern, with reports from various countries.
  • Conclusion: Cryptosporidium, a globally distributed enteric parasite, poses a significant public health concern due to its wide host range and transmission through contaminated water, food, and direct contact. Cryptosporidium's resilience, notably the resistance of its environmental stage, the oocyst, to disinfectants, contributes to its persistence and its role as a major cause of gastroenteritis outbreaks. Several Cryptosporidium species from mammals and birds are significant zoonotic pathogens, with zoonotic transmission not fully understood in some cases. Future research is needed to enhance our understanding of the transmission dynamics of this ubiquitous parasite
  • Keywords: Cryptosporidium, parasite , zoonosis