Cross-sectional household transmission study of Cryptosporidium shows that C. hominis infections are a key risk factor for spread

Caoimhe McKerr; Rachel M. Chalmers; Kristin Elwin; Heather Ayres; Roberto Vivancos; Sarah J. O’Brien; Robert M. Christley

doi:10.1186/s12879-022-07086-y

Cross-sectional household transmission study of Cryptosporidium shows that C. hominis infections are a key risk factor for spread

Caoimhe McKerr^*, Rachel M. Chalmers, Kristin Elwin, Heather Ayres, Roberto Vivancos, Sarah J. O’Brien, Robert M. Christley

^*Corresponding author for this work

Field Epidemiology (North West)

Research output: Contribution to journal › Article › peer-review

9 Citations (Scopus)

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Abstract

Background: Infection with the Cryptosporidium parasite causes over 4000 cases of diagnosed illness (cryptosporidiosis) in England and Wales each year. The incidence of sporadic disease has not been sufficiently established, and how frequently this arises from contact with other infected people is not well documented. This project aimed to explore potential transmission in the home and attempt to identify asymptomatic infections, which might play a role in transmission. Risk factors and characteristics associated with spread of infection in the home were described including any differences between Cryptosporidium species.

Methods: The study identified cryptosporidiosis cases from North West England and Wales over a year and invited them and their household to take part. Each household was sent a study pack containing study information and a questionnaire, and stool sample kits to provide samples from consenting household members. Cryptosporidium-positive stool samples, identified by immunofluorescence microscopy, were characterised using molecular methods to help describe any patterns of transmission. Characteristics of households with and without additional cases were described, and compared using odds ratios (OR) and a multivariable logistic regression identified independent risk factors for household transmission. Data collection ran for one year, beginning in September 2018 with an initial pilot phase.

Results: We enrolled 128 index cases and their households. Additional illness occurred in over a quarter of homes, each reporting an average of two additional cases. The majority of these were undiagnosed and unreported to surveillance. This burden was even greater in households where the index case was infected with C. hominis versus C. parvum, or the index case was under five years old, with mums and siblings most at risk of secondary infection. Only having an index case of C. hominis was independently associated with transmission in the multivariable model (OR 4.46; p = 0.01).

Conclusions: Cryptosporidium was a considerable burden in the home. At-risk homes were those where the index was less than five years old and/or infected with C. hominis. Of particular risk were female caregivers and siblings. Hygiene advice should be specifically directed here. This work provides evidence for humans as sources of C. hominis infection and that person-person is a key pathway. We recommend that all stools submitted for the investigation of gastrointestinal pathogens are tested for Cryptosporidium to better capture cases, inclusion of speciation data in routine surveillance, and the consideration of specific clinical advice on prevention for high-risk homes.

Original language	English
Article number	114
Journal	BMC Infectious Diseases
Volume	22
Issue number	1
Early online date	2 Feb 2022
DOIs	https://doi.org/10.1186/s12879-022-07086-y
Publication status	E-pub ahead of print - 2 Feb 2022

Bibliographical note

Funding Information: This research is jointly funded by the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Emerging and Zoonotic Infections (HPRU EZI) and the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Gastrointestinal Infections (HPRU GI) at the University of Liverpool in partnership with Public Health England (PHE), University of East Anglia, University of Oxford and the Institute of Food Research. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, the Department of Health, PHE or Public Health Wales.

Open Access: This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this
licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data

Publisher Copyright: © The Author(s) 2022

Citation: McKerr, C., Chalmers, R.M., Elwin, K. et al. Cross-sectional household transmission study of Cryptosporidium shows that C. hominis infections are a key risk factor for spread. BMC Infect Dis 22, 114 (2022).

DOI: https://doi.org/10.1186/s12879-022-07086-y

Keywords

Cryptosporidium
Epidemiology
Gastrointestinal infection
Household transmission
Person-to-person
Protozoa
Risk factors
Secondary spread
Sporadic disease
Zoonoses

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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McKerr2022Cross-SectionalHouseholdTransmissionStudyOfCryptosporidiumBMCInfectDisFinal published version, 1.22 MBLicence: CC BY

Cite this

@article{ca3239e666b2427eba6889833daca65a,

title = "Cross-sectional household transmission study of Cryptosporidium shows that C. hominis infections are a key risk factor for spread",

abstract = "Background: Infection with the Cryptosporidium parasite causes over 4000 cases of diagnosed illness (cryptosporidiosis) in England and Wales each year. The incidence of sporadic disease has not been sufficiently established, and how frequently this arises from contact with other infected people is not well documented. This project aimed to explore potential transmission in the home and attempt to identify asymptomatic infections, which might play a role in transmission. Risk factors and characteristics associated with spread of infection in the home were described including any differences between Cryptosporidium species. Methods: The study identified cryptosporidiosis cases from North West England and Wales over a year and invited them and their household to take part. Each household was sent a study pack containing study information and a questionnaire, and stool sample kits to provide samples from consenting household members. Cryptosporidium-positive stool samples, identified by immunofluorescence microscopy, were characterised using molecular methods to help describe any patterns of transmission. Characteristics of households with and without additional cases were described, and compared using odds ratios (OR) and a multivariable logistic regression identified independent risk factors for household transmission. Data collection ran for one year, beginning in September 2018 with an initial pilot phase. Results: We enrolled 128 index cases and their households. Additional illness occurred in over a quarter of homes, each reporting an average of two additional cases. The majority of these were undiagnosed and unreported to surveillance. This burden was even greater in households where the index case was infected with C. hominis versus C. parvum, or the index case was under five years old, with mums and siblings most at risk of secondary infection. Only having an index case of C. hominis was independently associated with transmission in the multivariable model (OR 4.46; p = 0.01). Conclusions: Cryptosporidium was a considerable burden in the home. At-risk homes were those where the index was less than five years old and/or infected with C. hominis. Of particular risk were female caregivers and siblings. Hygiene advice should be specifically directed here. This work provides evidence for humans as sources of C. hominis infection and that person-person is a key pathway. We recommend that all stools submitted for the investigation of gastrointestinal pathogens are tested for Cryptosporidium to better capture cases, inclusion of speciation data in routine surveillance, and the consideration of specific clinical advice on prevention for high-risk homes.",

keywords = "Cryptosporidium, Epidemiology, Gastrointestinal infection, Household transmission, Person-to-person, Protozoa, Risk factors, Secondary spread, Sporadic disease, Zoonoses",

author = "Caoimhe McKerr and Chalmers, \{Rachel M.\} and Kristin Elwin and Heather Ayres and Roberto Vivancos and O{\textquoteright}Brien, \{Sarah J.\} and Christley, \{Robert M.\}",

note = "Funding Information: This research is jointly funded by the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Emerging and Zoonotic Infections (HPRU EZI) and the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Gastrointestinal Infections (HPRU GI) at the University of Liverpool in partnership with Public Health England (PHE), University of East Anglia, University of Oxford and the Institute of Food Research. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, the Department of Health, PHE or Public Health Wales. Open Access: This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article{\textquoteright}s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article{\textquoteright}s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data Publisher Copyright: {\textcopyright} The Author(s) 2022 Citation: McKerr, C., Chalmers, R.M., Elwin, K. et al. Cross-sectional household transmission study of Cryptosporidium shows that C. hominis infections are a key risk factor for spread. BMC Infect Dis 22, 114 (2022). DOI: https://doi.org/10.1186/s12879-022-07086-y",

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TY - JOUR

T1 - Cross-sectional household transmission study of Cryptosporidium shows that C. hominis infections are a key risk factor for spread

AU - McKerr, Caoimhe

AU - Chalmers, Rachel M.

AU - Elwin, Kristin

AU - Ayres, Heather

AU - Vivancos, Roberto

AU - O’Brien, Sarah J.

AU - Christley, Robert M.

N1 - Funding Information: This research is jointly funded by the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Emerging and Zoonotic Infections (HPRU EZI) and the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Gastrointestinal Infections (HPRU GI) at the University of Liverpool in partnership with Public Health England (PHE), University of East Anglia, University of Oxford and the Institute of Food Research. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, the Department of Health, PHE or Public Health Wales. Open Access: This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data Publisher Copyright: © The Author(s) 2022 Citation: McKerr, C., Chalmers, R.M., Elwin, K. et al. Cross-sectional household transmission study of Cryptosporidium shows that C. hominis infections are a key risk factor for spread. BMC Infect Dis 22, 114 (2022). DOI: https://doi.org/10.1186/s12879-022-07086-y

PY - 2022/2/2

Y1 - 2022/2/2

N2 - Background: Infection with the Cryptosporidium parasite causes over 4000 cases of diagnosed illness (cryptosporidiosis) in England and Wales each year. The incidence of sporadic disease has not been sufficiently established, and how frequently this arises from contact with other infected people is not well documented. This project aimed to explore potential transmission in the home and attempt to identify asymptomatic infections, which might play a role in transmission. Risk factors and characteristics associated with spread of infection in the home were described including any differences between Cryptosporidium species. Methods: The study identified cryptosporidiosis cases from North West England and Wales over a year and invited them and their household to take part. Each household was sent a study pack containing study information and a questionnaire, and stool sample kits to provide samples from consenting household members. Cryptosporidium-positive stool samples, identified by immunofluorescence microscopy, were characterised using molecular methods to help describe any patterns of transmission. Characteristics of households with and without additional cases were described, and compared using odds ratios (OR) and a multivariable logistic regression identified independent risk factors for household transmission. Data collection ran for one year, beginning in September 2018 with an initial pilot phase. Results: We enrolled 128 index cases and their households. Additional illness occurred in over a quarter of homes, each reporting an average of two additional cases. The majority of these were undiagnosed and unreported to surveillance. This burden was even greater in households where the index case was infected with C. hominis versus C. parvum, or the index case was under five years old, with mums and siblings most at risk of secondary infection. Only having an index case of C. hominis was independently associated with transmission in the multivariable model (OR 4.46; p = 0.01). Conclusions: Cryptosporidium was a considerable burden in the home. At-risk homes were those where the index was less than five years old and/or infected with C. hominis. Of particular risk were female caregivers and siblings. Hygiene advice should be specifically directed here. This work provides evidence for humans as sources of C. hominis infection and that person-person is a key pathway. We recommend that all stools submitted for the investigation of gastrointestinal pathogens are tested for Cryptosporidium to better capture cases, inclusion of speciation data in routine surveillance, and the consideration of specific clinical advice on prevention for high-risk homes.

AB - Background: Infection with the Cryptosporidium parasite causes over 4000 cases of diagnosed illness (cryptosporidiosis) in England and Wales each year. The incidence of sporadic disease has not been sufficiently established, and how frequently this arises from contact with other infected people is not well documented. This project aimed to explore potential transmission in the home and attempt to identify asymptomatic infections, which might play a role in transmission. Risk factors and characteristics associated with spread of infection in the home were described including any differences between Cryptosporidium species. Methods: The study identified cryptosporidiosis cases from North West England and Wales over a year and invited them and their household to take part. Each household was sent a study pack containing study information and a questionnaire, and stool sample kits to provide samples from consenting household members. Cryptosporidium-positive stool samples, identified by immunofluorescence microscopy, were characterised using molecular methods to help describe any patterns of transmission. Characteristics of households with and without additional cases were described, and compared using odds ratios (OR) and a multivariable logistic regression identified independent risk factors for household transmission. Data collection ran for one year, beginning in September 2018 with an initial pilot phase. Results: We enrolled 128 index cases and their households. Additional illness occurred in over a quarter of homes, each reporting an average of two additional cases. The majority of these were undiagnosed and unreported to surveillance. This burden was even greater in households where the index case was infected with C. hominis versus C. parvum, or the index case was under five years old, with mums and siblings most at risk of secondary infection. Only having an index case of C. hominis was independently associated with transmission in the multivariable model (OR 4.46; p = 0.01). Conclusions: Cryptosporidium was a considerable burden in the home. At-risk homes were those where the index was less than five years old and/or infected with C. hominis. Of particular risk were female caregivers and siblings. Hygiene advice should be specifically directed here. This work provides evidence for humans as sources of C. hominis infection and that person-person is a key pathway. We recommend that all stools submitted for the investigation of gastrointestinal pathogens are tested for Cryptosporidium to better capture cases, inclusion of speciation data in routine surveillance, and the consideration of specific clinical advice on prevention for high-risk homes.

KW - Cryptosporidium

KW - Epidemiology

KW - Gastrointestinal infection

KW - Household transmission

KW - Person-to-person

KW - Protozoa

KW - Risk factors

KW - Secondary spread

KW - Sporadic disease

KW - Zoonoses

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Cross-sectional household transmission study of Cryptosporidium shows that C. hominis infections are a key risk factor for spread

Abstract

Bibliographical note

Keywords

UN SDGs

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