Research and analysis

Enteric fever (typhoid and paratyphoid) England, Wales and Northern Ireland: 2019

Updated 8 June 2023

Applies to England, Northern Ireland and Wales

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Enteric fever (also known as typhoid and paratyphoid) is an illness caused by the bacteria Salmonella enterica subspecies enterica serovar Typhi (typhoid) or serovars Paratyphi A, B or C (paratyphoid). Typhoid fever is a serious disease and can be life-threatening unless treated promptly with antibiotics. The disease may last several weeks and convalescence takes some time. In the literature, paratyphoid is considered to be typically milder than typhoid and of shorter duration [1] [2].

The bacteria that cause typhoid and paratyphoid only occur in humans. Humans acquire infection through eating food or drinking water that has been contaminated with infected faeces or through direct faecal-oral transmission. Transmission occurs following the ingestion of food or water that has been heavily contaminated (10 or more organisms may be required to cause illness) by the bacterium S. Typhi or S. Paratyphi. In the UK, most cases of typhoid and paratyphoid are acquired abroad in countries and regions of the world where hygiene or sanitation is poor.

This report summarises the epidemiology of laboratory-confirmed cases of S. Typhi and S. Paratyphi reported in England, Wales and Northern Ireland (EWNI) in 2018. It includes both reference laboratory and enhanced enteric fever surveillance data.

Data sources

Confirmed symptomatic cases of S. Typhi and S. Paratyphi in England, Wales and Northern Ireland are diagnosed by the UK Health Security Agency (UKHSA), then Public Health England, Salmonella Reference Service (SRS), within the Gastrointestinal Bacteria Reference Unit (GBRU)¥.

Data for laboratory- confirmed cases from 2007 onwards was extracted from the reference laboratory database using ‘date received by the laboratory’. All S. Typhi and S. Paratyphi isolates referred to the SRS undergo identification using whole genome sequencing (WGS) and single nucleotide polymorphism (SNP) typing [3] [4].

Epidemiological information was obtained from enhanced enteric fever surveillance [5]. Cases occasionally are tested multiple times for confirmation and to check the infection has cleared, therefore data has been deduplicated so that only one laboratory report for each case is counted.

Confirmed asymptomatic, probable and possible cases are analysed separately at the end of this report.

All data was analysed using Excel for Office 365 (Version 2002, Microsoft).

¥ As we only collect data from the UKHSA Salmonella Reference Service, local reports of cases of enteric fever may differ for Wales and Northern Ireland.

General trend

In 2019, 507 laboratory-confirmed symptomatic cases of S. Typhi and S. Paratyphi were reported by the UKHSA SRS in EWNI, which is an increase of 46% when compared to the 348 cases reported in 2018 (Table 1 and Figure 1). This is the largest annual increase observed since 2000. Cases of S. Typhi and S. Paratyphi increased by an average of 12% between 2015 and 2019 (range -3% to +46%), with the largest increases occurring in 2018 and 2019. In 2019, 63% of cases were caused by S. Typhi and 36% by S. Paratyphi A and B (Table 1). There was one case of S. Paratyphi C reported in 2019. This is the first reported case of S. Paratyphi C in EWNI since 2014.

Table 1. Laboratory-confirmed symptomatic cases of enteric fever, England, Wales and Northern Ireland by organism: 2010 to 2019.

Year S.Typhi S. Paratyphi A S. Paratyphi B S. Paratyphi C Mixed infection Total % S. Typhi
2010 285 211 16 - - 512 56%
2011 253 219 7 - 1 480 53%
2012 177 162 12 2 1 354 50%
2013 185 121 6 - - 312 59%
2014 185 114 10 1 1 311 60%
2015 169 107 26 - - 302 56%
2016 172 133 8 - - 313 55%
2017 187 103 15 - - 305 61%
2018 203 126 19 - - 348 58%
2019 321 166 19 1 - 507 63%

Since November 2016, Pakistan has had an ongoing outbreak of extensively drug-resistant (XDR) strain of S. Typhi in Sindh, with resistance seen to most antibiotics used to treat enteric fever, including ampicillin, third generation cepaholsporins (bla CTX- M- 15 extended spectrum beta lactamase producer), fluroquinolones, chloramphenicol and, co-trimoxazole [6]. This outbreak may have contributed to an increasing trend of enteric fever cases seen in the overall UK data (Table 2).

There has been an increase in imported XDR S. Typhi cases from Pakistan, one case reported in 2017, six cases from 2018 and 34 in 2019 [7] [8]. Cases reported travel to several provinces of Pakistan well beyond the area of the reported XDR outbreak.

Additionally there were 2 imported cases of ESBL S. Typhi imported from Iraq in 2019 [9].

Figure 1. Laboratory-confirmed cases of S. Typhi and S. Paratyphi, with % change year to year, England, Wales and Northern Ireland: 2010 to 2019.

Age and sex

In 2019, age and sex were known for all 507 confirmed symptomatic cases; 45% were adults aged between 20 and 39 years (Figure 2); the median age was 26 years (range 1 to 89 years). Those under 15 years accounted for 26% of cases, with 1% (N=3) of the total in children under 2 years (and thus not routinely eligible for vaccination). Overall, there were slightly more male (52%) than female cases.

Figure 2. Laboratory-confirmed cases of enteric fever, England, Wales and Northern Ireland by age and sex: 2019 (N=507)

Geographical distribution

Geographical areas were assigned based on patient postcode; in a small number of cases patient postcode was missing and the sending laboratory postcode was used. The largest proportion of English cases of S. Typhi and S. Paratyphi in 2019 were reported in London (33%), a decrease on the previous year (38% in 2018) (Table 2). The largest relative increase in cases reported in 2019 compared to 2018 was seen in the North East region (275%), followed by the North West region (137%). No regions saw a decrease in cases compared to the previous year.

Table 2. Laboratory-confirmed cases of S. Typhi and S. Paratyphi, England, Wales and Northern Ireland by geographical distribution: 2018 and 2019.

Geographical area (UKHSA centre) 2019 2018 % change
London 164 127 29%
North West 83 35 137%
South East 62 44 41%
West Midlands 56 41 37%
Yorkshire and Humber 38 33 15%
East of England 36 22 64%
East Midlands 23 17 35%
South West 17 14 21%
North East 15 4 275%
England total 494 337 47%
Wales 11 9 22%
Northern Ireland 2 2 0%
EWNI total 507 348 46%

Travel history

In 2019, 99.8% (506/507) of symptomatic laboratory-confirmed cases of S.Typhi and S. Paratyphi had travel history information recorded (that is, whether they had travelled or not) (Figure 3). In 2019, 97% (490/507) of confirmed symptomatic cases with travel history information reported onset of illness within the 28-day timeframe guidelines, and were presumed acquired abroad, similar to 2018 (95%). Of these, 453/490 (92%) had travelled abroad from EWNI and were UK residents, while the remainder were foreign visitors to EWNI (N=20) or new entrants to EWNI (N=17). For 16 cases no foreign travel was reported (compared to 13 in 2018).

Figure 3. Laboratory-confirmed cases of enteric fever, England, Wales and Northern Ireland by travel history: 2010 to 2019.

Figure 4. Reason for travel for laboratory-confirmed cases of enteric fever that travelled abroad from England, Wales and Northern Ireland: 2019 (N=453).

Where reason for travel was documented (N=438), 86% cases travelled abroad from EWNI to visit friends and relatives (VFR) (376/438), (Figure 4). The majority travelled to countries in the Indian subcontinent (Table 3), and acquired the infection while visiting friends or relatives abroad in Pakistan, India and Bangladesh.

Ethnicity was not known for 30 cases that travelled abroad to visit friends and relatives, these individuals travelled to Pakistan (18), India (9), other Asian countries (7) and the Americas (2), with some cases travelling to more than one country.

For those UK resident cases who did not visit friends and relatives where reason for travel was known (N=62), reasons for travel included holidays (50), business/work (paid and voluntary) (6), and other reasons including studying abroad (6). Cases that did not travel to visit friends and relatives travelled to a number of countries, with some cases travelling to more than one country, including:

  • India (26)
  • Pakistan (13)
  • Other countries in Asia (28)
  • The Americas (29)
  • Africa (1)

For 15 cases reason for travel was not stated and all cases reported travel to Asia.

Table 3. Countries of travel and ethnicity for laboratory-confirmed cases of enteric fever that travelled abroad from England, Wales and Northern Ireland to visit friends and relatives: 2019 (N=376*).

Presumed country of origin Ethnicity: Pakistani Ethnicity: Indian Ethnicity: Bangladeshi Ethnicity: Other Asian Ethnicity: Black African Ethnicity: Black Caribbean Ethnicity: White British Ethnicity: Other White Ethnicity: Other/Mixed Ethnicity: Not stated Total
Pakistan 206 3 2 1 - - - 1 - 18 231
India 7 83 - 1 - - - - 1 9 101
Bangladesh - - 24 - - - - - - - 24
Other Asia 11 - 1 5 1 - - - 3 6 27
Africa 1 - - - 5 - 1 - - - 7
Americas - - - - - 1 - - - 1 2
Oceania - 1 - 1 - - - - - 1 1
Total 225 87 27 8 6 1 1 1 4 35 395 *

*Note that some cases travelled to more than one country; all countries are included here so the totals will be higher than the actual number of cases.

Non travel-associated cases

In 2019, there were 16 confirmed cases of symptomatic enteric fever where the case reported that they did not travel in the 28 days prior to becoming symptomatic – 12 were caused by S. Typhi, 2 by S. Paratyphi A, 1 by S. Paratyphi B and 1 by S. Paratyphi C.

Of the 16 non-travel-associated cases, 7 cases had contact with a family member or friend who travelled to an endemic country – 2 of these additionally being identified as part of 2 separate 5- SNP clusters. An additional 3 cases were identified as part of 3 separate 5-SNP clusters, but they did not have contact with a family member or friend who travelled to an endemic country.

No potential source was identified for the remaining 6 cases, though one these cases had travelled to an endemic region in the previous 12 months. For 2 cases, infection was discovered during treatment for other conditions, and may represent chronic carriage.

Confirmed asymptomatic cases

In 2019, there were 2 confirmed cases of asymptomatic enteric fever caused by S. Paratyphi A (n=1), and S. Typhi (n=1). One of these cases travelled to Pakistan and was identified as part of a 5-SNP cluster, which included family members of the case. The other case travelled to India, and was not associated with an epidemiological cluster.

Probable and possible cases

In 2019, there were 5 probable and 14 possible cases of enteric fever as defined in the Public Health Operational Guidelines for Enteric Fever [10]. Of these, all 19 travelled abroad from the UK. Travel history information for the probable and possible cases is detailed in Table 4.

Caution should be used when interpreting this data as it has not been confirmed by the UKHSA reference laboratory.

Table 4. Country of travel and reason for travel for probable and possible cases of enteric fever that travelled abroad from England, Wales and Northern Ireland: 2019 (n=19*).

World region of travel Visit friends and relatives Holiday Study abroad Total
India 6 1 - 7
Pakistan 2 - - 2
Hong Kong - - 1 1
Ghana 1 - 1 2
Indonesia 2 1 - 3
Cambodia 3 1 - 4
Nigeria 1 - - 1
Turkey 1 - - 1
Thailand 3 1 - 4
Bangladesh - 1 - 1
Total 19 5 2 26

*Note that some cases travelled to more than one country; all countries are included here so the totals will be higher than the actual number of cases.

Information resources

References

1. Cook GC and Zumla A. ‘Manson’s tropical diseases’ Elsevier Health Sciences 2009.

2. Heymann DL. ‘Control of communicable diseases manual’ American Public Health Association 2008.

3. Chattaway MA and others. ‘The Transformation of Reference Microbiology Methods and Surveillance for Salmonella With the Use of Whole Genome Sequencing in England and Wales’. Frontiers in Public Health 2019, volume 7, page 317.

4. Dallman, TJ and other. SnapperDB: A database solution for routine sequencing analysis of bacterial isolates bioRxiv 189118.

5. Typhoid and paratyphoid: guidance, data and analysis (online) (viewed 20 January 2022).

6. World Health Organization Disease Outbreak News Item. Typhoid fever - Islamic Republic of Pakistan (viewed 20 January 2022).

7. Nair S, and others. ‘ESBL-producing strains isolated from imported cases of enteric fever in England and Wales reveal multiple chromosomal integrations of blaCTX-M-15 in XDR Salmonella Typhi’. Journal of Antimicrobial Chemotherapy 2021, volume 76, issue 6, pages 1459-1466.

8. Chattaway MA, and others. ‘Phylogenomics and antimicrobial resistance of Salmonella Typhi and Paratyphi A, B and C in England, 2016-2019’ Microbial Genomics 2021, volume 7, issue 8, 000633.

9. Godbole G, and others. ‘Ceftriaxone-resistant Salmonella Typhi in a traveller returning from a mass gathering in Iraq’. Lancet Infectious Diseases 2019, volume 19, issue 5, 467. PMID: 31034389.

10. Health Protection Agency and the Chartered Institute of Environmental Health. Public Health Operational Guidelines for Typhoid and Paratyphoid (Enteric Fever) London, Health Protection Agency 2012 (viewed 20 January 2022).

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