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Main points for 2024

The main points of the 2024 report are:

• the number of reported Campylobacter cases in England rose from 60,055 in 2023 to 70,352 cases in 2024, an increase of 10,297 cases (17.1%) with a resulting rate rise from 104.1 to 121.9 reports per 100,000 population

• reporting rates increased across all regions, with the highest increase in the London region, up 36.1%, and the highest reporting rate was in the North East at 150.1 reports per 100,000 population

• report increases were seen across all age groups but the highest number of laboratory reports remained in the cases aged 50 to 79 years, accounting for 44.0% of the total number of reports

• consistent with the previous 5-year median, in 2024 Campylobacter reporting peaked in the month of June, however high levels of reporting extended to October

• for 22.7% of laboratory reports species were identified by diagnostic laboratories, the majority of which were Campylobacter jejuni (88.4% of all speciated samples)

• 755 Campylobacter isolates underwent whole genome sequencing (WGS) analysis at the National Campylobacter Reference Laboratory; of those typed 84.2% were Campylobacter jejuni and the most prevalent clonal complexes identified were ST-21, ST-464 and ST-48

• of the 9 foodborne outbreaks reported to national surveillance, 5 were likely associated with consumption of liver or products containing poultry liver such as pâté or parfait

Background

Campylobacteriosis is the most common type of bacterial food poisoning caused by the bacterium Campylobacter species. The most common symptoms of campylobacteriosis are diarrhoea (often bloody stools), fever and stomach cramps but can also include nausea and vomiting. Most people recover after about 1 week, however some people may suffer severe or prolonged symptoms and need antibiotic treatment (1). Certain groups of people, including the very young (children less than 5 years of age), the elderly (adults aged 65 years and older) or the immunocompromised (such as people receiving chemotherapy for cancer or transplant patients), are at higher risk of developing more severe illness which can be life-threatening (bacteraemia, sepsis) or cause long-term complications such as reactive arthritis (2), irritable bowel syndrome (3) and Guillain-Barre syndrome (4). Information about treating food poisoning caused by Campylobacter infection is available on the .

Campylobacter lives in the gastrointestinal tract of many animals including livestock such as poultry, sheep and cows, as well as pets such as dogs and cats. These animals can carry Campylobacter without any symptoms and can infect humans. However, the main route of transmission of Campylobacter to humans is foodborne, by the consumption of contaminated food, in addition to drinking untreated water, close contact with an infected person, and also through environmental exposure. Raw or undercooked meat, especially poultry, unpasteurised milk and untreated water (5, 6, 7) are recognised sources of campylobacteriosis. Therefore it is important when handling or preparing these foods, such as raw meat or poultry, to take care avoiding cross-contamination and ensuring food is cooked and stored at appropriate temperatures. More information on food safety in relation to Campylobacter is available on the .

Previous studies have also estimated around 18.1% of Campylobacter infections are associated with foreign travel and not acquired in the UK (8). More information on ‘traveller’s diarrhoea’, and how to avoid and treat it while abroad is available on the .

Campylobacter species are the most frequently reported bacterial pathogens in England with over 50,000 laboratory confirmed reports per year. However, many infections are not laboratory confirmed and go unreported; it has been estimated that the true burden of campylobacteriosis may be 9.3 times higher in the wider community (9). This equates to almost half a million cases a year in England. In humans, the majority of Campylobacter infections are caused by the 2 species, C. jejuni and C. coli, with a higher number reported in summer than in winter (10).

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

COVID-19 pandemic

During 2020, 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), with subsequent non-pharmaceutical interventions (NPIs) implemented to control COVID-19 transmission affected notifications of Campylobacter infections to national surveillance in several ways. These include, but are not limited to, changes which may have impacted ascertainment (for example, changes in healthcare seeking behaviour, access to health care, availability, or capacity of testing) as well as changes which likely impacted incidence (for example, limited foreign travel, closure of hospitality venues and attractions or behavioural changes around food consumption) which will have also varied over time. Therefore, trends presented in this report should be interpreted with caution, and 2020 data (the year a notable impact on Campylobacter reporting to national surveillance was observed (11) are excluded when 5-year medians are calculated.

The magnitude and duration of the impacts on reporting differed by gastrointestinal pathogen due to differences in severity, transmission routes and risk factors (12, 13). Therefore, the number of years impacted and consequentially excluded from the calculation of 5-year medians also differs by pathogen, for example only 2020 for Campylobacter but 2020 and 2021 for Salmonella.

Methods

All data presented in this report are correct as of 17 April 2025. This report covers all Campylobacter species in England. As a live laboratory reporting system was used for extraction, the data are subject to change and historical totals may differ slightly. The laboratory report date was used for all data analyses in this report.

Population data were sourced 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 (NUTS1) codes.

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

When calculating the median of the previous 5 years, 2020 was excluded due to the impacts of the COVID-19 pandemic, therefore the 5-year median was calculated from the same period in 2018 to 2019 and 2021 to 2023.

Isolates of Campylobacter spp. received by the National Campylobacter Reference Laboratory on Amies charcoal swabs were cultured at 37 to 42°C for 24 to 48 hours under microaerophilic conditions. Genomic DNA was recovered using a QIAGEN QIAsymphony SP and DSP Viral/Pathogen Midi Kit, fragmented and tagged for multiplexing with Nextera XT DNA Sample Preparation Kits, followed by rapid run, paired-end sequencing on an Illumina NextSeq 1000 platform. The 7-loci multi-locus sequencing type (MLST) was determined using (14) within the UKHSA WGS pipeline. The MLST typing scheme for Campylobacter jejuni and Campylobacter coli assigns an allelic profile to each isolate based on 7 chromosomal housekeeping loci (15), known as the sequence type (ST). Closely genetically related STs are then grouped into a clonal complex (CC). Some STs will not fall within a CC and novel Campylobacter strains may not yet have a defined ST in the typing database.

Campylobacter Laboratory data for 2015 to 2024

Annual data 2015 to 2024

Figure 1 and Table 1 show the trend in the number of Campylobacter laboratory reports and the rate of reporting in England from 2015 to 2024. Since 2022, the rate of Campylobacter reporting has been increasing each year and is now above pre COVID-19 pandemic levels. In 2024, by comparison to 2023, the number of Campylobacter laboratory reports increased from 60,055 to 70,352 (up 17.1%) with a corresponding rise in the reporting rate from 104.1 to 121.9 per 100,000 population (up 17.1%).

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

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

Year	Number of laboratory reports	Laboratory reports per 100,000 population
2015	51,817	94.5
2016	49,077	88.8
2017	52,818	95.0
2018	56,287	100.6
2019	56,440	100.4
2020	44,728	79.4
2021	56,233	99.4
2022	54,882	96.1
2023	60,055	104.1
2024	70,352	121.9

Regional data in 2024

Table 2 displays the number of Campylobacter laboratory reports per region in 2024 as well as the rate per 100,000 population and Figure 2 shows the regional rates on a map. Compared to 2023, the rate of Campylobacter laboratory reports per 100,000 population increased during 2024 in all regions, and were broadly comparable in the East Midlands, North East and Yorkshire and Humber regions.

In 2024, the North East region had the highest rate of reporting at 150.1 laboratory reports per 100,000 population (an increase of 9.5 % compared to 2023) and the lowest rate was in East Midlands, with 96.9 laboratory reports per 100,000 population (an increase of 4.6 % compared to the previous year). The largest rate increases compared to 2023 were in London, East of England and the South East, the rates rose from 75.0 to 102.1 per 100,000 population (up 36.1%), 89.5 to 112.9 per 100,000 population (up 26.1%) and 117.7 to 142.9 per 100,000 population (up 21.4%) respectively.

Table 2. Regional distribution of laboratory reports of Campylobacter in England, 2024 (n=70,352)

Region	Laboratory reports	Laboratory reports per 100,000 population
East Midlands	4,838	96.9
East of England	7,302	112.9
London	9,131	102.1
North East	4,069	150.1
North West	9,179	120.8
South East	13,546	142.9
South West	8,216	141.4
West Midlands	7,390	121.4
Yorkshire and the Humber	6,681	119.4

Figure 2. Map of regional rates of Campylobacter laboratory reports per 100,000 population in England, 2024

Age and sex distribution in 2024

Figure 3 shows the age and sex distribution of Campylobacter laboratory reports in England during 2024, 91 laboratory reports were excluded where case age or sex was unknown. Overall, the 2024 distribution is consistent with 2023 distribution; 55.0% of reported cases were male and the most affected cases were aged 50 to 79 years, accounting for 44.0% of the total number of laboratory reports.

Figure 3. Age and sex distribution of laboratory reports of Campylobacter in England, 2024 (n=70,261)

Index of Multiple Deprivation (IMD) in 2024

Table 3 displays the number of Campylobacter cases resident in postcodes of each IMD decile. Valid postcodes were unavailable for 388 cases so could not be matched to IMD decile. There were no notable changes in IMD of Campylobacter cases compared to 2023, the median IMD decile of Campylobacter cases remained 6 (inter quartile range: 3 to 8).

Table 3. Number of Campylobacter cases per IMD decile in England during 2024

Index of Multiple Deprivation (IMD) deciles	Total number of cases (%)
1 (Most deprived)	5,708 (8.2)
2	5,916 (8.5)
3	6,383 (9.1)
4	7,036 (10.1)
5	7,201 (10.3)
6	7,257 (10.4)
7	7,568 (10.8)
8	7,691 (11.0)
9	7,636 (10.9)
10 (Least deprived)	7,568 (10.8)
Total	69,964

Seasonal variation in 2024

In 2024 in England, the number of Campylobacter laboratory reports per month broadly followed the same seasonal trend as the median of the previous 5 years, 2018 to 2019 and 2021 to 2023 (excluding 2020), with peak reporting in June (Figure 4). However, high levels of reporting extended later in the year and the drop usually observed in August did not occur until October 2024.

Figure 4. Seasonality of laboratory reports of all Campylobacter species in England, 2024

Campylobacter typing in 2024

Diagnostic laboratories

In 2024 in England, 22.7% of Campylobacter samples (n=15,937) were speciated by diagnostic laboratories. Of the speciated isolates, the majority were Campylobacter jejuni, 88.4% (n=14,081) followed by Campylobacter coli, 11.2% (n=1,781) (Table 4).

Table 4. Identification of Campylobacter isolates in England, 2024 (n=15,937)

Campylobacter species	Total number of laboratory reports (%)
Campylobacter jejuni	14,081 (88.4)
Campylobacter coli	1,781 (11.2)
Campylobacter fetus	22 (0.1)
Campylobacter lari	18 (0.1)
Campylobacter upsaliensis	35 (0.2)

National Campylobacter Reference Laboratory

In 2024, 755 Campylobacter isolates were sequenced and passed quality assurance checks for analysis. Table 5 summarises the isolates by species; 84.2% were Campylobacter jejuni (n=636), 12.2% were Campylobacter coli (n=92) and less than 1.0% of isolates were identified as Campylobacter upsaliensis, Campylobacter lari or Campylobacter fetus. 2.3% (n=17) of isolates contained multiple Campylobacter species.

Table 5. Summary of species identified by whole genome sequencing analysis

Result	Number of isolates	Percentage of isolates
Campylobacter jejuni	636	84.2%
Campylobacter coli	92	12.2%
Campylobacter upsaliensis	4	0.5%
Campylobacter lari	4	0.5%
Campylobacter fetus	2	0.3%
Mixed Campylobacter species	17	2.3%
Total	755	-

Across the 728 isolates typed 27 CCs and 140 STs were identified. In total there were 86 isolates in 29 STs which did not have an assigned CC, of which 20 isolates fell into 16 groups which were also unassigned to a ST (Table 6).

The most prevalent clonal complexes were ST-21 (20.3%), ST-464 (10.6%) and ST-48 (7.6%). Figure 5 shows the frequency Campylobacter jejuni isolates by ST for those with 15 or more isolates and Figure 6 shows the same but for Campylobacter coli ST-828 with 5 or more isolates.

Table 6. Summary of Campylobacter jejuni and Campylobacter coli isolates by clonal complex and sequence type, for sequence types with 5 or more isolates

Species	Clonal complex	Sequence Type	Number of isolates	Percentage of isolates
C. jejuni	ST-206	122	7	1.0%
C. jejuni	ST-206	2149	5	0.7%
C. jejuni	ST-21	6175	74	10.2%
C. jejuni	ST-21	21	34	4.7%
C. jejuni	ST-21	50	17	2.3%
C. jejuni	ST-21	53	14	1.9%
C. jejuni	ST-21	19	9	1.2%
C. jejuni	ST-22	22	6	0.8%
C. jejuni	ST-257	257	14	1.9%
C. jejuni	ST-353	10,846	35	4.8%
C. jejuni	ST-353	400	9	1.2%
C. jejuni	ST-353	6461	7	1.0%
C. jejuni	ST-353	12327	5	0.7%
C. jejuni	ST-354	354	6	0.8%
C. jejuni	ST-42	42	9	1.2%
C. jejuni	ST-441	441	18	2.5%
C. jejuni	ST-443	51	12	1.6%
C. jejuni	ST-45	45	20	2.7%
C. jejuni	ST-45	137	6	0.8%
C. jejuni	ST-464	5136	58	8.0%
C. jejuni	ST-464	464	19	2.6%
C. jejuni	ST-48	48	55	7.6%
C. jejuni	ST-52	2066	14	1.9%
C. jejuni	ST-658	1044	7	1.0%
C. jejuni	Unassigned	9897	30	4.1%
C. coli	ST-828	829	20	2.7%
C. coli	ST-828	827	13	1.8%
C. coli	ST-828	9012	9	1.2%
C. coli	ST-828	1055	6	0.8%
C. coli	ST-828	825	5	0.7%
ST with less than 5 isolates [note 1]	Ìý	Ìý	185	25.4%
Total	Ìý	Ìý	728	100.0%

Note 1: 82 isolates assigned CC and ST, 29 isolates with but unassigned CC and 16 isolates with CC and ST unassigned.

Figure 5. Campylobacter jejuni isolates summarised by clonal complex and sequence type, for sequence types with 15 or more isolates

Figure 6. Campylobacter coli clonal complex ST-828 isolates summarised by sequence type, for sequence types with 5 or more isolates

Foodborne outbreak data in 2024

In 2024, there were 9 Campylobacter (unspeciated) outbreaks reported to UKHSA (Table 7). Overall, the total number of people affected was 122 with 28 laboratory confirmed cases, of which 5 were admitted to hospital but there were no reported deaths. Compared to 2023 the number of outbreaks increased 80% from 5 to 9, and while the number of laboratory confirmed cases only increased by 16.7%, the number affected more than doubled. The larger outbreaks were associated with consumption of liver or products containing chicken or lamb liver such as a pâté or parfait. Three outbreaks were reported in care home settings and the remaining 6 outbreaks were linked to eating outside of the home, pubs restaurants or events.

Table 7. Foodborne outbreaks of Campylobacter reported in England in 2024 [Note 2]

Agent	Total affected	Laboratory confirmed	Hospital admissions [Note 3]	Deaths [Note 3]	Setting	Food description
Campylobacter species	4	3	0	Unknown	Restaurant	Unknown
Campylobacter species	21	6	1	0	Care home	Lamb’s liver
Campylobacter species	8	2	0	Unknown	Care home	Unknown
Campylobacter species	2	2	0	Unknown	Care home	Unknown
Campylobacter species	6	2	0	Unknown	Restaurant	Chicken liver pâté
Campylobacter species	2	2	2	Unknown	Pub	Liver
Campylobacter species	3	3	0	Unknown	Hotel	Chicken
Campylobacter species	15	1	0	Unknown	Restaurant	Duck and chicken liver parfait / beef / rarebit
Campylobacter species	61	7	2	Unknown	Stadium	Chicken liver parfait

Note 2: number of cases affected, and number laboratory confirmed is for cases resident in England.

Note 3: clinical outcome is not known for all cases and the data reported represents cases who have hospital admissions or deaths reported to national surveillance.

Conclusions

Campylobacteriosis remains the most common cause of bacterial gastroenteritis in England. Compared to 2023, in 2024 the number of Campylobacter laboratory reports increased by 17.1%, from 60,055 to 70,352, which is the highest number of reports recorded in the last 10 years. The rate of reporting in 2024 exceeded the rates of previous years at 121.9 reports per 100,000 population. Reporting rose across all regions and age groups in 2024 and after accounting for under-reporting it is likely there were over 650,000 cases in the wider community, representing a substantial burden on the population. When considering the trends in Campylobacter cases over time, data from 2020 should be interpreted with caution given the multi-factorial impacts of the COVID-19 pandemic on reporting (11) and for this reason 2020 is not included in the calculation of the 5-year median.

Multiple factors have likely contributed to this increase including, but not limited to:

• increased ascertainment due to introduction of more sensitive molecular enteric diagnostic testing at some laboratories
• climate factors
• changes in international travel or food supply chains
• behavioural changes in food handling and preparation

One notable difference in 2024 was that after reporting peaked in June the elevated reporting rate continued until October, 2 months longer than usual. Further analysis and research are underway to understand the relative contributions of each factor to the observed rise.

Similar to 2023, the highest number of laboratory-confirmed cases were in the South East, and there were more male cases (55.0%) reported than female cases. Overall, those aged 50 to 79 years (50 to 59, 60 to 69 and 70 to 79 year age groups) accounted for almost half of cases (44%).

Overall, a subset of samples tested were speciated (22.7%) at diagnostic laboratories and only 1.1% underwent WGS analysis at the National Campylobacter Reference Laboratory, with the majority classified as Campylobacter jejuni. The most prevalent clonal complexes identified were ST-21 CC, ST-464 CC and ST-48 CC, collectively accounting for 30.1% of cases. Despite representing only a small proportion of the overall burden, the WGS data provides a unique insight into the molecular epidemiology of Campylobacter in England.

The increase in the number of Campylobacter cases was also evident in the number of outbreaks reported to national surveillance, which rose from 5 in 2023 to 9 in 2024. These outbreaks were larger too, comprising 122 known cases of which 28 cases were laboratory confirmed. Five outbreaks were associated with the consumption of various types of liver and products containing liver, 1 by consumption of chicken; highlighting these foods as higher risk and the need to follow food safety advice when handling, cooking or storing them.

Data sources

This report was produced using data derived from 2 data sources. The first is the Second Generation Surveillance System (SGSS) operated by the UK Health Security Agency (UKHSA) (formerly Public Health England (PHE)). This is a live laboratory reporting system, therefore numbers are subject to change.

The second data source is the Gastrointestinal Infections, Food Safety and One Health (GIFSOH) Division’sÌýElectronic Foodborne and non-foodborne Outbreak Surveillance System (eFOSS), which is also a live laboratory reporting system and therefore numbers are subject to change.

The population data used for England were sourced from the .

Data caveats

This report was produced using laboratory data for England only, therefore the number of Campylobacter 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, including those who have investigated and reported outbreaks to the electronic foodborne and non-foodborne gastrointestinal outbreak surveillance system (eFOSS)
• the epidemiologists and information officers who have worked on the national surveillance of intestinal infectious diseases
• colleagues in the Gastrointestinal Bacteria Reference Unit (GBRU) for providing the Reference Laboratory ÌìÃÀÓ°Ôº and laboratory surveillance functions and expertise
• UKHSAÌý(formerlyÌýPHE) Information Management Department for maintenance and quality assurance ofÌýUKHSAÌýnational surveillance databases used for gastrointestinal infections (GI) pathogen surveillance at the national level
• UKHSAÌý(formerlyÌýPHE) Local Public Health Laboratories and Food Water and Environmental Microbiology ÌìÃÀÓ°Ôº for providing a surveillance function forÌýGIÌýpathogens 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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