A review of outbreaks of cryptosporidiosis due to unpasteurized milk



This review analysed outbreaks of human cryptosporidiosis due to raw milk. The objective of our study was to highlight and identify underestimated and underreported aspects of transmission of the parasite as well as the added value of genotyping Cryptosporidium isolates.


We conducted a descriptive literature review using the digital archives Pubmed and Embase. All original papers and case reports referring to outbreaks of Cryptosporidium due to unpasteurized milk were reviewed. The cross-references from these publications were also included.


Outbreaks have been described in the USA, Australia, and the UK. Laboratory evidence of Cryptosporidium from milk specimens was lacking in the majority of the investigations. However, in most recent reports molecular tests on stool specimens along with epidemiological data supported that the infection was acquired through the consumption of unpasteurized milk. As the incubation period for Cryptosporidium is relatively long (days to weeks) compared with many other foodborne pathogens (hours to days), these reports often lack microbiological confirmation because, by the time the outbreak was identified, the possibly contaminated milk was not available anymore.


Cryptosporidiosis is generally considered a waterborne intestinal infection, but several reports on foodborne transmission (including through raw milk) have been reported in the literature. Calves are frequently infected with Cryptosporidium spp., which does not multiply in milk. However, Cryptosporidium oocysts can survive if pasteurization fails. Thus, pasteurization is essential to inactivate oocysts. Although cryptosporidiosis cases acquired from raw milk are seldom reported, the risk should not be underestimated and Cryptosporidium should be considered as a potential agent of contamination. Genotyping Cryptosporidium isolates might be a supportive tool to strengthen epidemiologic evidence as well as to estimate the burden of the disease.

This is a preview of subscription content, log in to check access.

Fig. 1


  1. 1.

    Cacciò SM, Chalmers RM. Human cryptosporidiosis in Europe. Clin Microbiol Infect. 2016;22:471–80.

    Article  Google Scholar 

  2. 2.

    Chalmers RM, Giles M. Zoonotic cryptosporidiosis in the UK—challenges for control. J Appl Microbiol. 2010;109:1487–97.

    CAS  Article  Google Scholar 

  3. 3.

    Casemore DP. Epidemiological aspects of human cryptosporidiosis. Epidemiol Infect. 1990;104:1–28.

    CAS  Article  Google Scholar 

  4. 4.

    Lima AA, Samie A, Guerrant RL. Cryptosporidiosis. In: Guerrant RL, Walker DH, Weller PF, editors. Tropical infectious diseases. Philadelphia: Elsevier-Churchill Livingstone; 2011. p. 640–663.

    Google Scholar 

  5. 5.

    Chen XM, et al. Cryptosporidiosis. N Engl J Med. 2002;346:1723–31.

    Article  Google Scholar 

  6. 6.

    Bouzid M, et al. Risk factors for Cryptosporidium infection in low and middle income countries: a systematic review and meta-analysis. PLoS Negl Trop Dis. 2018;12:e0006553.

    Article  Google Scholar 

  7. 7.

    Rehn M, et al. Post-infection symptoms following two large waterborne outbreaks of Cryptosporidium hominis in Northern Sweden, 2010–2011. BMC Public Health. 2015;15:529.

    Article  Google Scholar 

  8. 8.

    Widerström M, et al. Large outbreak of Cryptosporidium hominis infection transmitted through the public water supply. Sweden Emerg Infect Dis. 2014;20:581–9.

    Article  Google Scholar 

  9. 9.

    Robertson LJ, Chalmers RM. Foodborne cryptosporidiosis: is there really more in Nordic countries? Trends Parasitol. 2013;29:3–9.

    Article  Google Scholar 

  10. 10.

    Mota A, et al. Risk assessment of cryptosporidium and giardia in water irrigating fresh produce in Mexico. J Food Prot. 2009;72:2184–8.

    Article  Google Scholar 

  11. 11.

    Yoshida H, et al. An outbreak of cryptosporidiosis suspected to be related to contaminated food, October 2006, Sakai City, Japan. Jpn J Infect Dis. 2007;60:405–7.

    CAS  PubMed  Google Scholar 

  12. 12.

    Quiroz ES, et al. An outbreak of cryptosporidiosis linked to a foodhandler. J Infect Dis. 2000;181:695–700.

    CAS  Article  Google Scholar 

  13. 13.

    Hamnes IS, et al. Prevalence of giardia and cryptosporidium in dairy calves in three areas of Norway. Vet Parasitol. 2006;140:204–16.

    Article  Google Scholar 

  14. 14.

    Hasan MH, et al. Detection of Cryptosporidium oocysts in ovine and caprine raw milk in relation to rearing management. Assiut Vet Med J. 2018;64:47–50.

    Google Scholar 

  15. 15.

    Harp JA, et al. Effect of pasteurization on infectivity of Cryptosporidium parvum oocysts in water and milk. Appl Environ Microbiol. 1996;62:2866–8.

    CAS  Article  Google Scholar 

  16. 16.

    Boor KJ, et al. A 100-year review: microbiology and safety of milk handling. J Dairy Sci. 2017;100:9933–51.

    CAS  Article  Google Scholar 

  17. 17.

    Doman B et al. Cryptosporidium outbreak associated with the consumption of unpasteurized cow milk, New Mexico. 2017. https://cste.confex.com/cste/2017/webprogram/Paper8610.html. Accessed 27 Nov 2019.

  18. 18.

    Rosenthal M, et al. Centers for Disease Control and Prevention (CDC). Notes from the field: cryptosporidiosis associated with consumption of unpasteurized goat milk, Idaho, 2014. MMWR Morb Mortal Weekly Rep. 2015;64:194–5.

    Google Scholar 

  19. 19.

    Harper CM, et al. Outbreak of Cryptosporidium linked to drinking unpasteurised milk. Commun Dis Intell Q Rep. 2002;26:449–50.

    PubMed  Google Scholar 

  20. 20.

    Gelletlie R, et al. Cryptosporidiosis associated with school milk. Lancet. 1997;350:1005–6.

    CAS  Article  Google Scholar 

  21. 21.

    Djuretic T, et al. General outbreaks of infectious intestinal disease associated with milk and dairy products in England and Wales: 1992–1996. Commun Dis Rep CDR Rev. 1997;7:R41–45.

    CAS  PubMed  Google Scholar 

  22. 22.

    Soave R, et al. Cryptosporidiosis in a rural community in central Mexico. J Infect Dis. 1989;159:1160–2.

    CAS  Article  Google Scholar 

  23. 23.

    Freidank H, Kist M. Cryptosporidia in immunocompetent patients with gastroenteritis. Eur J Clin Microbiol. 1987;6:56–9.

    CAS  Article  Google Scholar 

  24. 24.

    Badoui L, et al. Intestinal cryptosporidiosis in HIV-infected patients in the department of infectious diseases. BMC Infect Dis. 2014;14:P52.

    Article  Google Scholar 

  25. 25.

    Dumant AC, et al. Clinical and epidemiological characteristics of Cryptosporidium spp. infections in paediatric patients in France, 2015–2017. J Pediatr Gastroenterol Nutr. 2018;66:486.

    Google Scholar 

  26. 26.

    European Centre for Disease Prevention and Control. Annual epidemiological report for 2016—Cryptosporidiosis. Stockholm: ECDC; 2018.

    Google Scholar 

  27. 27.

    Chalmers RM, Cacciò S. Towards a consensus on genotyping schemes for surveillance and outbreak investigations of Cryptosporidium, Berlin, June 2016. EuroSurveill. 2016;21:30338.

    Article  Google Scholar 

  28. 28.

    Laberge I, et al. Detection of Cryptosporidium parvum in raw milk by PCR and oligonucleotide probe hybridization. Appl Environ Microbiol. 1996;62:3259–64.

    CAS  Article  Google Scholar 

  29. 29.

    Food and Agriculture Organization of the United Nations, FAO (1990) The technology of traditional milk products in developing countries. https://canadianpreppersnetwork.com/cd3wd/disk5/_ag_milk_products_tradit_unfao_en_lp_112630_.pdf. Accessed 28 Nov 2019.

  30. 30.

    Jittapalapong S, et al. Prevalence of Cryptosporidium among dairy cows in Thailand. Ann N Y Acad Sci. 2006;1081:328–35.

    Article  Google Scholar 

Download references


This work was funded by the Italian Ministry of Health “Fondi Ricerca Corrente–Linea 3, progetto 8", to IRCCS Sacro Cuore Don Calabria Hospital.

Author information



Corresponding author

Correspondence to Tamara Ursini.

Ethics declarations

Conflict of interest

The authors declare that they have no competing interests.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Ursini, T., Moro, L., Requena-Méndez, A. et al. A review of outbreaks of cryptosporidiosis due to unpasteurized milk. Infection (2020). https://doi.org/10.1007/s15010-020-01426-3

Download citation


  • Cryptosporidium
  • Cryptosporidiosis
  • Protozoan parasite
  • Unpasteurized milk
  • Outbreaks