Research and analysis

Common animal-associated infections (England): first quarter 2023

Updated 29 February 2024

Applies to England

Background

This quarterly report is produced by the Emerging Infections and Zoonoses team in the Clinical and Emerging Infections Directorate, UK Health Security Agency (UKHSA). As of 2023, these reports will display data for England only. Data for Wales will be reported separately by Public Health Wales. Previous reports, presenting data for both England and Wales, can be found on the GOV.UK website.

The report summarises laboratory-confirmed (and probable for leptospirosis) cases of selected zoonoses reported in England between January and March 2023 (first quarter) and includes additional information on the quarterly trends for hepatitis E, leptospirosis, Lyme disease and toxoplasmosis.

It is important to note that not all cases will present to healthcare services, and cases may be treated empirically based on clinical suspicion without a confirmatory test. Therefore, the numbers in this report are expected to be an underestimate of the true burden of zoonotic disease in England, likely biasing towards severe infections as individuals with severe or symptomatic disease may be more likely to be tested. Furthermore, not all zoonoses presented in this report are notifiable in England. As such, it is likely not all confirmed laboratory test results are reported to UKHSA. For a list of notifiable diseases and causative organisms in England please see the Notifiable diseases and causative organisms: how to report webpage.

The impacts of the public health measures implemented in England due to the coronavirus (COVID-19) pandemic during 2020 and 2021 should be considered when making comparisons with this time period.

Data reported as provisional is subject to change due to late notifications and de-duplication.

The data presented in this report supersedes data in previous reports due to late notifications and de-duplication.

Overview

Table 1. Animal-associated infections in England: quarterly confirmed laboratory reports by specimen date Q1 2021 to Q1 2023

Disease (organism)	Q1 2021	Q2 2021	Q3 2021	Q4 2021	Total (2021)	Q1 2022	Q2 2022	Q3 2022	Q4 2022	Total (2022)	Q1 2023*	Total (2023*)
Anthrax (Bacillus anthracis)	0	0	0	0	0	0	0	0	0	0	0	0
Brucellosis (Brucella spp.)	1	2	3	1	7	1	3	4	2	10	0	0
Hepatitis E	348	349	74	300	1,271	322	393	343	455	1,513	341	341
Leptospirosis (Leptospira spp.)	7	5	16	26	54	4	10	26	12	52	3	3
Lyme disease (Borrelia burgdorferi)
All cases	118	220	565	230	1,133	139	233	549	247	1,168	152	152
Acute infections	58	142	471	173	844	89	187	419	169	864	83	83
Pasteurellosis (Pasteurella spp.)	161	214	196	145	716	173	214	230	184	801	151	151
Psittacosis (C. psittaci / C. abortus)	2	1	1	1	5	0	0	0	0	0	3	3
Q-fever (Coxiella burnetii)
All cases	2	2	5	2	11	6	2	8	7	23	3	3
Acute infections	1	2	5	2	10	4	1	5	5	15	3	3
Toxoplasmosis (Toxoplasma gondii)†	46	50	39	52	187	54	37	57	45	193	63	63

*Provisional data.

† Based on date specimen received.

Hepatitis E

The national hepatitis E virus (HEV) surveillance reports reference laboratory data (Public Health Laboratory Birmingham and Blood Borne Virus Unit Colindale) together with additional cases reported by local laboratories through the Second Generation Surveillance System (SGSS). The combined data sets provide a more accurate reflection of the number of acute HEV infected cases reported in England.

There were 341 laboratory-reported cases of HEV infection in the first quarter of 2023. This is an increase compared to 322 cases reported in the first quarter of 2022. Figure 1 shows the number of HEV infections by quarter between 2018 and 2023. The data shows a decline in cases in 2020 (n=1,066) followed by a continued increase since 2021.

Figure 1. Laboratory confirmed cases of hepatitis E in England by quarter, Q1 2019 to Q1 2023

Of the cases reported in the first quarter of 2023, 190 (55.7%) were male (aged 17 to 100 years, median 60.5 years) and 151 (44.3%) were female (aged 9 to 97 years, median 59 years; Table 2). The persisting observation of the predominance of older men (aged 45 years and over) remains unexplained.

Table 2. Laboratory confirmed cases of hepatitis E in England by age group and sex, Q1 2023

Age group (years)	Male	Female	Total
0 to 14	0	1	1
15 to 24	7	12	19
25 to 44	39	36	75
45 to 64	66	45	111
Over 64	78	57	135
Total	190	151	341

Leptospirosis

Data for leptospirosis was obtained from the Rare and Imported Pathogens Laboratory (RIPL, UKHSA Porton). As of 1 August 2020, a laboratory confirmed case of leptospirosis is defined by a positive 16S rRNA PCR result only. An Immunoglobulin M (IgM) enzyme-linked immunoabsorbent assay (EIA) continues to be performed on all samples of suspected leptospirosis cases. A case with a positive leptospirosis IgM result will usually be treated clinically on the basis of this result, even in the absence of a positive PCR result. A case with a positive IgM but without a confirmatory PCR result is therefore reported as a probable case for surveillance purposes. National surveillance of probable cases of leptospirosis was introduced in 2021.

There were 3 confirmed cases and 14 probable cases of leptospirosis reported cases in the first quarter of 2023, compared to 4 confirmed and 22 probable cases reported in the same quarter of 2022. Figure 2 shows the number of confirmed cases reported by quarter over the past 5 years (2019 to 2023).

Figure 2. Laboratory confirmed and probable cases of leptospirosis in England by quarter, Q1 2019 to Q1 2023

In the first quarter of 2023, all confirmed cases (n=3; 100%) were male (aged 44 to 61 years). Cases were reported in the East of England (1), London (1) and the North West (1).

Of the confirmed cases, 1 reported recent travel abroad to the Caribbean. Of the 3 confirmed cases, 2 reported a potential exposure of contact with rats.

Lyme disease

Data for Lyme disease was obtained from the Rare and Imported Pathogens Laboratory (RIPL, UKHSA Porton). The total number of confirmed Lyme disease cases reported in the first quarter of 2023 (n=152) was higher than in the same time period in 2022 (n=139). The total number of acute cases was similar in the first quarter 2023 (n=83) compared to to the same period in 2022 (n=89). It should be noted that diagnosis for acute Lyme disease presenting with erythema migrans is made clinically and testing is not recommended. The number of laboratory-confirmed cases presented in this report are therefore likely an underestimate of the true burden of acute Lyme disease.

Figure 3 shows how the number of cases continues to peak during the summer months (third quarter), which corresponds to the peak period of exposure to ticks in the UK – the spring and summer months.

Figure 3. Laboratory confirmed cases of Lyme disease in England by quarter, Q1 2019 to Q1 2023

Of the total cases reported in the first quarter, 83 (54.6%) were acute (including 10 with neurological Lyme disease) and 69 (45.4%) were longstanding. Of the acute cases, 31 were male (aged 15 to 84 years, median 43) and 52 were female (aged 12 to 87, median 46). Table 3 shows the age group and sex distribution.

Table 3. Laboratory confirmed acute cases of Lyme disease in England by age group and sex, Q1 2023

Age group (years)	Male	Female	Total
0 to 14	0	2	2
15 to 24	6	8	14
25 to 34	4	4	8
35 to 44	7	11	18
45 to 54	7	10	17
55 to 64	4	9	13
65 to 74	1	6	7
Over 75	2	2	4
Total	31	52	83

The regions that reported the most acute cases in the first quarter of 2023 were the South East (n=238), London (n=18) and the South West (n=16) (Table 4). Only 1 of the acute cases in the first quarter of 2023 reported foreign travel, specifically to eastern Europe.

Table 4. Laboratory confirmed acute cases of Lyme disease in England by region, Q1 2022 to Q1 2023

UKHSA Centre	Q1 2022	Q2 2022	Q3 2022	Q4 2022	Total 2022	Q1 2023	Total 2023
East Midlands	4	1	1	3	9	1	1
East of England	4	12	23	15	54	2	2
London	22	31	69	38	160	18	18
North East	2	2	16	7	27	4	4
North West	12	20	28	14	74	12	12
South East	18	59	132	42	251	23	23
South West	16	54	107	36	213	16	16
West Midlands	6	0	22	2	30	3	3
Yorkshire and Humber	5	8	21	12	46	4	4
Total	89	187	419	169	864	83	83

Toxoplasmosis

Data for toxoplasmosis in England was obtained from the Toxoplasma Reference Unit (TRU), Public Health Wales, Swansea. There were a total of 63 confirmed toxoplasmosis cases reported in the first quarter of 2023, an increase compared to 54 in the same quarter of 2022.

Figure 4. Laboratory confirmed cases of toxoplasmosis in England by quarter, Q1 2019 to Q1 2023

Of the total confirmed cases, 26 were male (aged 16 to 79 years, median 39) and 39 were female (aged 0 to 69 years, median 31.5). Table 5 shows the age group and sex distribution.

Table 5. Laboratory confirmed cases of toxoplasmosis in England by age group and sex, Q1 2023

Age group (years)	Male	Female	Total
Under 15	5	0	5
15 to 24	3	7	10
25 to 44	9	15	24
45 to 64	7	11	18
Over 64	2	2	4
Unknown	0	2	2
Total	26	37	63

Psittacosis

Data for psittacosis was obtained from the Respiratory and Vaccine Preventable Bacteria Reference Unit (RVPBRU) in Colindale and from cases reported by local laboratories through the Second Generation Surveillance System (SGSS).

It is recognised that it is difficult to diagnose infection retrospectively through serological assays and, as such, following an external review, the surveillance case definitions for psittacosis were reviewed. As of 1 January 2023, a confirmed case of psittacosis is defined by a positive 16S rRNA PCR result or culture isolation only. This case definition has been applied to all retrospective data presented in these reports from 2023.

It should be noted that the existing PCR assay is unable to differentiate between Chlamydia psittaci (C. psittaci) and Chlamydia abortus (C. abortus). However, as there are currently no other reliable methods of psittacosis identification, the numbers presented in these reports will reflect laboratory confirmed cases with a positive PCR result for C. psittaci / C. abortus.

There were 3 reports of psittacosis in the first quarter of 2023, compared to 0 reports in the same quarter of 2022. Of these, 2 cases were male and 1 was female. All cases were aged over 40 years of age. Figure 5 shows the number of laboratory-confirmed cases of psittacosis between 2019 and 2023.

Figure 5. Laboratory confirmed cases of psittacosis in England by quarter, Q1 2019 to Q1 2023

Other zoonotic organisms

There were 15 reports of Capnocytophaga spp. infection in the first quarter of 2023. This is similar to the number reported in the same quarter of 2022 (n=17). Of the cases reported this quarter, 8 were further speciated to C. canimorsus. Of those speciated, 3 were male and 5 were female, and cases were reported in the North East (1), the South East (2), the South West (3), the West Midlands (1) and Yorkshire and Humber (1). Capnocytophaga spp. are frequently carried in the mouths of companion animals (cats and dogs) or humans, and may be associated with an animal or human bite or opportunistic infections in those with impaired immune systems.

There were 5 reports of Mycobacterium marinum infection in the first quarter of 2023. This is the same as the number reported in the same quarter in 2022. Of the cases reported this quarter, 4 were male and 1 was female.

There were 2 reports of Erysipelothrix rhusiopathiae infection in the first quarter of 2023. This is similar to the number reported in the same quarter of 2022 (n=3). Of the cases reported this quarter, one was male and one was female.

There were 3 reports of toxigenic Corynebacterium ulcerans infection in the first quarter of 2023. This is the same as the number of cases reported in the same quarter of 2022 (n=3). Of the cases reported this quarter, 1 was male and 2 were female, and all cases were aged above 55 years. Two cases reported known contact with companion animals. In England, contact with companion animals remains the most frequently reported exposure for individuals with confirmed toxigenic C. ulcerans infections, however, the animals may not show evidence of infection and it is not always possible to confirm the carriage of C. ulcerans in animals.

There were 8 reports of Taeniasis in the first quarter of 2023. This is an increase compared to 5 cases reported in the same quarter in 2022. Of the cases reported this quarter, 5 were further speciated to T. saginata.

There were no reports of Toxocariasis in the first quarter of 2023.