Research and analysis

Cryptosporidium data 2015 to 2024

Updated 26 June 2025

Main points

The 2024 report shows that:

• the number of reported Cryptosporidium cases in England fell from 6,827 cases in 2023 to 5,708 cases in 2024, a decrease of 1,119 cases (16.4%). However, annual cases in 2024 remained higher than observed between 2015 and 2022
• the highest rate of laboratory confirmed cases was in the South West (15.5 per 100,000 population), where there was a large outbreak of cryptosporidium associated with mains drinking water reported in May 2024
• overall, 57.1% of Cryptosporidium laboratory confirmed cases in England were female
• the highest number of laboratory reports were in children aged 0 to 9 years (28.4% of total reports) followed by adults aged 30 to 39 years (23.7% of total reports)
• there was unusually high activity in spring 2024, with in the highest number of cases reported in April. This contrasted with previous years where a larger peak was observed in the autumn months. This increase was likely associated with outbreak activity as several large outbreaks were reported, predominantly associated with spring lambing events

Background

Cryptosporidiosis is a disease caused by infection with the protozoan parasite Cryptosporidium (1). The most common symptom is diarrhoea, often accompanied by stomach cramps, nausea, vomiting, low-grade fever and loss of appetite. Most people recover within 14 days; however, children under 5 years of age or individuals with weakened immune systems are at higher risk of developing more severe illness due to persistent diarrhoea and the person’s inability to absorb nutrients (2, 3). There is no specific treatment for cryptosporidiosis. Information about managing Cryptosporidium infection is available on the Cryptosporidium: public advice website.

In humans, infections are primarily associated with one of two species of the Cryptosporidium parasite: Cryptosporidium hominis and Cryptosporidium parvum (4). C. hominis almost exclusively infects humans and is usually associated with direct or indirect person-to-person transmission. C. parvum infects both humans and animals (5), most commonly young livestock such as lambs and calves but also sometimes pets including dogs and cats (1, 6). Several other Cryptosporidium species have been isolated from humans, however these detections are less common (1).

In the UK, the two main Cryptosporidium species show seasonal activity and are reported at different times in the year. Cryptosporidium parvum is reported throughout the year but peaks in spring (April and May) while C. hominis peaks in autumn (September to November) with fewer cases during the rest of the year (6). These seasonal trends are influenced by the hosts and transmission route of each species. Cryptosporidium parvum is associated with exposure to farm animals, particularly during visits to petting farms in the lambing season, while C. hominis is often associated with exposure to contaminated water during swimming pool use and international travel. Likely sources of Cryptosporidium are hand-to-mouth after animal contact or touching surfaces or clothing contaminated with animal faeces, swallowed swimming pool water, drinking inadequately treated or contaminated drinking water and less frequently identified, the consumption of food exposed to faeces or contaminated water. Person-to-person transmission is also common (6, 7, 8).

Traditionally, diagnosis is performed by microscopy or immunoassay. However, more sensitive molecular techniques (PCR) are increasingly being used in England, which may have an impact on detections. PCR is used by the national Cryptosporidium Reference Unit (CRU), Public Health Wales for genotyping to differentiate species and subtypes (6). In outbreaks, CRU performs further sub-typing of Cryptosporidium parvum and C. hominis by sequencing part of the gp60 gene (9). Further genetic characterisation using a multi-locus variable number of tandem repeats analysis (MLVA) by fragment sizing has been validated and recently implemented by the CRU for C. parvum for both identifying and investigating outbreaks (10, 11, 12).

This report summarises the trends in reporting of Cryptosporidium cases in England in 2024 with a comparison to reporting in previous years.

COVID-19 Pandemic

During 2020 and 2021 it is likely that the emergence of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease (COVID-19), and subsequent non-pharmaceutical interventions (NPIs) implemented to control COVID-19 transmission affected notifications of Cryptosporidium infections to national surveillance in a number of ways. These include, but are not limited to, changes which may have impacted ascertainment (for example, healthcare seeking behaviour, access to health care, availability or capacity of testing) as well as changes which likely impacted incidence (for example, limited international travel, closure of hospitality and attractions, such as petting farms, or behavioural changes around food consumption) which will have also varied over time. A large reduction of cases due to the COVID-19 pandemic and subsequent NPIs was observed (6). Therefore, trends presented in this report should be interpreted with caution, and 2020 and 2021 data is excluded from the calculation of 5-year medians. This approach is consistent with annual reports of other gastrointestinal pathogens.

The magnitude and duration of the impacts on reporting differed by gastrointestinal pathogen due to differences in severity, transmission routes and risk factors (13, 14). Therefore, the number of years impacted and consequentially excluded from the calculation of 5-year medians also differs by pathogen, for example 2020 and 2021 for Cryptosporidium but only 2020 for Campylobacter.

Methods

This report covers all Cryptosporidium notifications in England. National surveillance of cryptosporidiosis in England is coordinated by the Gastrointestinal Infections, Food Safety and One Health Division (GIFSOH) at the UK Health Security Agency (UKHSA) in collaboration with the national reference laboratory, the Cryptosporidium Reference Unit at Public Health Wales. As a live laboratory reporting system was used for extraction, the data is subject to change and historical totals may differ from those previously published (see Data sources section for more information). The laboratory report date was used for all data analyses in this report. All data presented in this report is correct as of 17 April 2025.

Population data was obtained from the Office for National Statistics (ONS) for England. Mid-year population estimates for the relevant year were used to provide denominators for the calculation of rates. All rates are calculated as per 100,000 population.

Regional classification was based on place of residence of reported cases and classified using the Nomenclature of territorial units for statistics, level 1 (NUTS1) codes (15).

The deprivation level of an area (Index of Multiple Deprivation decile) was mapped to each case using patient home postcode (16).

When calculating the median of the previous 5 years, 2020 and 2021 were excluded due to the impacts of the COVID-19 pandemic, therefore the 5-year median was calculated from the same period in 2017 to 2019 and 2022 to 2023.

Cryptosporidium laboratory data 2015 to 2024

Annual data 2015 to 2024

Figure 1 and Table 1 show the trend of Cryptosporidium laboratory reports in England from 2015 to 2024. The rate of Cryptosporidium laboratory reports per 100,000 population decreased by 16.1% from 11.8 in 2023 to 9.9 in 2024, but remained higher than pre-pandemic years.

Figure 1. Annual laboratory reports of Cryptosporidium in England from 2015 to 2024

Table 1. Annual laboratory reports of Cryptosporidium in England from 2015 to 2024

Year	Number of laboratory reports	Laboratory reports per 100,000 population
2015	4981	9.1
2016	5261	9.5
2017	4000	7.2
2018	4759	8.5
2019	4333	7.7
2020	2145	3.8
2021	2510	4.4
2022	3736	6.5
2023	6827	11.8
2024	5708	9.9

Regional data in 2024

Table 2 displays the number of Cryptosporidium laboratory reports and the rate per 100,000 population per region in 2024.

In 2024, the South West of England had the highest rate of laboratory reports at 15.5 per 100,000 population, with the lowest rate in London (6.4 laboratory reports per 100,000 population). Rates decreased from 2023 to 2024 in all regions except for the South West where the rate increased by 12.3% from 13.8 to 15.5 reports per 100,000 population.

Table 2. Regional distribution of laboratory reports of Cryptosporidium in England in 2024

Region	Laboratory reports	Laboratory reports per 100,000 population
East Midlands	362	7.3
East of England	526	8.1
London	574	6.4
North East	307	11.3
North West	1031	13.6
South East	738	7.8
South West	899	15.5
West Midlands	778	12.8
Yorkshire and the Humber	493	8.8

Age and sex distribution in 2024

Figure 2 shows the age and sex distribution of Cryptosporidium laboratory reports in England during 2024. Overall, 57.1% were female (n=3245), with a high number of cases reported in females aged 20 to 29 and 30 to 39 years. Overall, children aged 0 to 9 were most affected accounting for 28.4% of total laboratory reports (n=1614), followed by adults aged 30 to 39 years (23.7%, n=1348); 25 laboratory reports were excluded where the age or sex was unknown.

Figure 2. Age and sex distribution of laboratory reports of Cryptosporidium in England in 2024 (n = 5,683)

Index of Multiple Deprivation (IMD) in 2024

Table 3 displays the number of Cryptosporidium cases resident in postcodes of each Index of Multiple Deprivation (IMD) decile. IMD decile could not be established for 51 cases without a valid postcode. The median IMD decile of Cryptosporidium cases was 6 (inter quartile range: 3 to 8).

Table 3. Number of Cryptosporidium cases per Index of Multiple Deprivation (IMD) decile in England 2024

IMD deciles	Total number of cases (%)
1 (Most deprived)	439 (7.8)
2	428 (7.6)
3	511 (9.0)
4	555 (9.8)
5	595 (10.5)
6	677 (12.0)
7	631 (11.2)
8	628 (11.1)
9	626 (11.1)
10 (Least deprived)	567 (10.0)
Total	5,657

Seasonal variation in 2024

Figure 3 shows the seasonal trend of laboratory reporting for Cryptosporidium in England during 2024 by month. In 2024, the number of laboratory reports per month was consistently higher than the 5 year median (2017 to 2019 and 2022 to 2023, excluding 2020 and 2021) apart from in August to September when reports were comparable to the 5 year median. The number of cases reported in April and May 2024 (n=1530) was considerably higher than the 5-year median over the same period (n=666). Unusually, the spring peak in 2024 was larger than the peak observed in the Autumn months.

Figure 3: Seasonality of laboratory reports of Cryptosporidium in England by month in 2024 with median number of reports by month in 2017 to 2023 (excluding 2020 and 2021) (n = 5,708)

Outbreak data in 2024

In 2024, there were 32 Cryptosporidium outbreaks reported to national surveillance; 3 C. hominis, 25 C. parvum and 4 outbreaks where the species of Cryptosporidium was not reported (Table 4). Overall, the total number of people affected was 1544 with 547 laboratory confirmed cases, of which at least 69 were hospitalised (the data is not collected routinely/systematically) but there were no reported deaths. The larger outbreaks were reported at commercial farm settings with lamb handling events. Cryptosporidium parvum outbreaks were more commonly related to open or commercial farm settings while C. hominis outbreaks were more common in nurseries or swimming pools.

Table 4. Outbreaks of Cryptosporidium reported in England in 2024 [note 1]

Agent	Total affected	Laboratory confirmed	Hospital admissions [note 2]	Deaths [note 2]	Setting	Month
Cryptosporidium hominis	7	4	Unknown	Unknown	Nursery	January
Cryptosporidium parvum	4	4	1	Unknown	Commercial farm with accommodation	March
Cryptosporidium parvum	4	4	2	Unknown	Public open farm	March
Cryptosporidium parvum	482 [note 3]	83	17 [note 3]	Unknown	Commercial farm holding public lambing event	April
Cryptosporidium parvum	781 [note 3]	154	41	Unknown	Commercial farm holding public lambing event	April
Cryptosporidium parvum	12	12	Unknown	Unknown	Public open farm	April
Cryptosporidium hominis	9	9	Unknown	Unknown	Swimming pool, holiday park	April
Cryptosporidium parvum [note 4]	2	2	Unknown	Unknown	Public open farm	April
Cryptosporidium parvum [note 4]	20	20	Unknown	Unknown	Public open farm	April
Cryptosporidium species	8	8	Unknown	Unknown	Public open farm	April
Cryptosporidium parvum	17	17	Unknown	Unknown	Public open farm	April
Cryptosporidium parvum	4	4	Unknown	Unknown	Commercial farm with accommodation holding public lambing event	April
Cryptosporidium parvum	13	13	Unknown	Unknown	Public open farm	April
Cryptosporidium parvum	13	8	Unknown	Unknown	Public open farm	April
Cryptosporidium parvum	6	6	Unknown	Unknown	Public open farm	April
Cryptosporidium species	11	2	Unknown	Unknown	Commercial farm holding public lambing event	April
Cryptosporidium parvum	103 [note 3]	10	Unknown	Unknown	Commercial farm holding public lambing event	April
Cryptosporidium parvum	4	4	2	Unknown	Public open farm	April
Cryptosporidium species	5	5	Unknown	Unknown	Public open farm	May
Cryptosporidium parvum	3	2	Unknown	Unknown	Lambing event at land-based college	May
Cryptosporidium parvum	5	2	Unknown	Unknown	School	May
Cryptosporidium parvum	4	4	Unknown	Unknown	Public open farm and farm shop	May
Cryptosporidium parvum	Unknown	143 [note 5]	4	Unknown	Mains drinking water	May
Cryptosporidium parvum	Unknown	2	Unknown	Unknown	Community farm	May
Cryptosporidium species	2	2	Unknown	Unknown	Public open farm	May
Cryptosporidium parvum	2	2	Unknown	Unknown	Public open farm	June
Cryptosporidium parvum	3	2	Unknown	Unknown	Farm shop (milkshake)	June
Cryptosporidium parvum	2	2	Unknown	Unknown	Public open farm	July
Cryptosporidium hominis	6	6	Unknown	Unknown	Nursery	August
Cryptosporidium parvum	5	5	Unknown	Unknown	Water park	September
Cryptosporidium parvum	3	3	Unknown	Unknown	Public open farm	September
Cryptosporidium parvum	4	3	2	Unknown	Swimming pool	November

Note 1: Number of cases affected, and number laboratory confirmed for cases resident in England.

Note 2: Clinical outcome is not known for all cases and the data reported represents cases who have hospitalisations or deaths reported to national surveillance.

Note 3: Number from self-reported survey undertaken with event attendees.

Note 4: Some confirmed cases had co-infection of Cryptosporidium parvum and Shiga toxin-producing Escherichia coli.

Note 5: 126 confirmed outbreak cases based on typing. 143 includes lab confirmed but where typing was not possible.

Conclusions

In 2024 the rate of Cryptosporidium laboratory reports per 100,000 population in England decreased when compared with 2023, from 11.8 in 2023 to 9.9 in 2024, but remained higher than the rate reported in pre-pandemic years. Children under 9 years of age continue to be the most affected age group and more female cases were reported than male cases, consistent with previous years. The highest rate of laboratory confirmed cases was in the South West, where there was a large outbreak of Cryptosporidium associated with mains drinking water reported in May 2024 (17).

Unusually, in 2024 cryptosporidium activity was highest in the spring months (March-May) with the rate of cases substantially above the five-year median (2017 to 2019, 2022 to 2023). This increase was likely associated with outbreak activity as several large outbreaks were reported, predominantly associated with spring lambing events.

Overall, 32 outbreaks of Cryptosporidium were reported to national surveillance in 2024, comprising 1544 cases of which 547 cases were laboratory confirmed. Although self-limiting, cryptosporidium is associated with prolonged diarrhoea and significant morbidity, with up to 5% of cases requiring hospital care during the larger outbreaks in the spring. 24 (75%) outbreaks (20 C. parvum, 4 unspeciated) were linked to lambing events or to open (petting) farms, of which 21 (88%) occurred between March and May. In 2024, there were fewer C. hominis outbreaks and fewer outbreaks associated with swimming pools reported. Cryptosporidium hominis was identified in 3 outbreaks (9.4% of total outbreaks), 2 occurring in nursery settings and one in a swimming pool setting. Cryptosporidium isolates were not speciated in 12.5 % of outbreaks.

The autumn peak, which is when C. hominis activity is highest, was of a similar magnitude to the five-year median. However, an unseasonal increase of C. parvum was noted by the reference laboratory during this period. Reasons for the increase require further investigation but are likely to be multifactorial. Changes to diagnostic testing which include the introduction of more sensitive PCR methods may be contributing to the increasing trend seen post-pandemic.

Data sources

This report was produced using data derived from four data sources:

1. the UK Health Security Agency (UKHSA), formerly Public Health England (PHE), Second Generation Surveillance System (SGSS). This is a live laboratory reporting system therefore numbers are subject to change. In 2015, PHE upgraded the laboratory reporting system so direct comparisons between data reported from the previous system (LabBase2) and the new system (SGSS) requires cautious interpretation;
2. the Gastrointestinal Infections, Food Safety and One Health (GIFSOH) Division’s eFOSS (electronic foodborne and non-foodborne outbreak surveillance system), which is also a live laboratory reporting system and therefore numbers are subject to change;
3. the national Cryptosporidium Reference Unit at Public Health Wales undertakes genotyping and supports outbreak investigations, therefore species and subtypes are derived from this data;
4. the population data used for England were sourced from the Office for National Statistics, mid-year 2023 estimates are available at Population estimates - Office for National Statistics.

Data caveats

This report was produced using laboratory data for England only, therefore the number of Cryptosporidium laboratory reports published in previous reports which include data from other UK countries may differ to those included in this report.

Acknowledgements

We are grateful to:

• the NHS and private sector diagnostic laboratories, microbiologists and local authorities, health protection and environmental health specialists who have contributed data and reports to national surveillance systems
• the epidemiologists and information officers who have worked on the national surveillance of intestinal infectious diseases
• colleagues in the national Cryptosporidium Reference Unit (Public Health Wales) for providing the Reference Laboratory Services and laboratory surveillance functions and expertise
• UKHSA (formerly PHE) Information Management Department for maintenance and quality assurance of UKHSA national surveillance databases used for Gastrointestinal Infections (GI) pathogen surveillance at the national level
• UKHSA (formerly PHE) Local Public Health Laboratories and Food Water and Environmental Microbiology Services for providing a surveillance function for GI pathogens and testing of food and environmental samples routinely and during outbreak investigations

Prepared by: Gastrointestinal Infections, Food Safety and One Health Division, UKHSA
For queries relating to this document, please contact: EEDD@ukhsa.gov.uk

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