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Home Topics Infectious Diseases Infections A-Z Leptospirosis Epidemiological Data ›  Leptospira infections in 2012

Leptospira infections in 2012

  • The risk of acquiring leptospirosis in the UK remains relatively low compared with many other European countries.
  • Leptospirosis has changed over the years from being a predominantly occupational infection, to one that arises mainly from recreational exposures, especially where water sports and overseas travel are involved.
  • Occupational exposures still occur in those working with livestock or where there are exposures to rodents or their urine.
  • The risk of acquiring Leptospira infection is enhanced with exposure to inland surface waters at home or overseas and where water-borne and adventure sports are involved, and the risk of skin abrasions is high.
  • Overseas travel to South East Asia and Central America, engaging in water-related activities such as swimming, white water rafting or wading in inland waters, especially following periods of heavy rainfall, enhances the risk of acquiring the disease. Other perhaps less obvious activities such as jungle trekking must also be considered a high risk activity for travellers.

Seventy two cases of human Leptospira infection (0.13/100,000 total population) were identified in England and Wales during 2012, of which twenty two (31%) were acquired overseas. The data below include confirmed cases of leptospirosis from the UK Leptospira Reference Unit, Hereford, supplemented by laboratory reports made directly to Public Health England (formerly the Health Protection Agency).

Indigenous cases
Infections acquired in England & Wales were reported in 50 people (0.09/100,000 population) (45 males and 5 females), with ages ranging from 12 to 73 years (mean= 42.54) [Table 1.] and with no identifiable regional foci. There was one fatality, in a 60 year old female from a travelling family and who had rural, water-borne and rodent exposures.

Occupational infections
Eighteen infections were known to have been occupationally acquired. Six were livestock or arable farmers (one was also a part time sewage worker), two were fish farmers, one a wildlife park worker, one a butcher living on a farm and one an abattoir slaughterman. Two infections were in watersports instructors. Other occupational infections were reported in a local authority worker who collected roadkill including foxes and badgers, a sewage worker, a professional gardener, a builder clearing out a pool and a pub manager cleaning out flood water. The only animal contacts mentioned specifically by this group of workers were rats, cattle, mice, foxes and badgers.

The serovars identified in these occupational infections were L. Australis (1), L. Autumnalis (1), L. Ballum (1), L. Hardjo (3), L. Icterohaemorrhagiae (6), L. Saxkoebing (1) and for five cases the infecting serovar was not determined [Figure 1.]. Two of the three cases with L. Hardjo infection reported cattle contact. Back to List

Non-occupational infections
Twenty-five infections were acquired through known recreational or non-occupational activities. Recreational watersports on or in canals and rivers resulted in ten infections, of which canoeing or kayaking, in six, was the most commonly reported activity. Six infections followed swimming or immersion in inland waters and three after fishing. Four infections were acquired in the garden or allotment. Four infections followed rural exposures, one of which was in a member of a travelling family with a variety of rural exposures, who died. One infection was reported following an attempted drowning. One infection followed a domestic rat infestation. The source of infection was not given for a further seven infections.

Serovars identified in recreational infections include L. Australis (3), L. Autumnalis (1), L. hardjo (1), L. Saxkoebing (3), L. Sejroe (1), L. Icterohaemorrhagiae (10). In thirteen cases the infecting serovar was not identified.

Figure 1 shows the range of serovars in indenously acquired infections. Back to List

Overseas cases

Twenty-two infections were acquired overseas, twenty males and two females, ages ranged from 20 to 56 years (mean=33.3 years) [Table 1.]. None of these infections resulted in a fatality although several had severe clinical presentations. Countries visited include Thailand (8), France (4), Brunei (2), Borneo and Sarawak (1), South East Asia and the Pacific Basin (1), Bolivia and Central America (1), Vietnam and Laos (1), Sri Lanka (1), Costa Rica (1), Dominican Republic (1) and Mexico (1).

 

Twelve overseas infections were associated with water sports or water-related activities and four were identified in military personnel, although it is not known if these were acquired during military training or whilst on R & R.  Four infections were acquired following white water canoeing, swimming in fresh water pools or rivers or other unspecified water sports.  Three infections were acquired during exposures in France, including lake swimming, river canoeing and fishing from a river bank. The risk activity was not specified for five cases, although all had visited high risk areas including Thailand and other South East Asian countries, or Central and Southern America. 

 

Leptospira serovars identified in overseas infections included L. Australis (2), L. Autumnalis (1), L. icterohaemorrhagiae (4), L. Mini (1), L. Pyrogenes (2), L. Saxkoebing (3), L. Tarrasovi (1). In eight patients the infecting serovar was not identified [Figure 1.]. Back to List

 

Symptoms and complications reported following infection

Symptoms and clinical presentations were recorded for all cases, and included renal and hepatic failure, meningitis and conjunctivitis [Table 2.]. Concurrent renal and hepatic failure was reported in five (7%) infections, all were UK acquired.  Renal failure only was reported in a further 19 (26%) cases. In addition to this, abnormal liver function test results were noted for 35 (49%) people during treatment; 24 (33%) developed jaundice, of whom 13(18%) had both jaundice and abnormal liver function tests. Meningitis occurred in two (3%) people and conjunctivitis occurred in two (3%) patients. Other presentations included cardiovascular collapse, myocarditis, pulmonary haemorrhage, renal impairment, and septic shock. Several patients were severely unwell requiring supportive therapy. Back to List

Regional and temporal distributions

Of the 50 indigenous cases, nine were submitted by laboratories in the South West health region, nine from the North West, nine from the South East, seven from East Anglia and Lincolnshire, and five each from laboratories in London and the West Midlands; two each from the East Midlands and Wales and one from North-east England.

 

Sera from all cases were received throughout the year, with (76%) received from indigenous cases in the last six months of the year [Figures 2 and 3.], this probably reflects greater opportunities for outdoor recreational activities during the summer and autumn months. Overseas cases were primarily reported between June and September 2012. Monthly cumulative totals for all cases are given in Figure 3. Back to List

Diagnostic methodologies

The Leptospira Reference Laboratory, in conjunction with the PHE Rare and Imported Pathogens Laboratory (RIPL), has developed a specific PCR for rapid detection of leptospires. The UK is now one of the few countries to use this methodology for human diagnostics as an adjunct to conventional serological methods.

The assay was designed for use in the early acute stage of leptospirosis, one to seven days after onset of symptoms when IgM antibodies may not be detectable and the alternative testing algorithm is isolation of leptospires from blood cultures. This approach is impractical for rapid diagnosis due to the prolonged length of time required, six weeks, for leptospira isolation.

The testing algorithm included serum samples taken within the first 5 days after onset of symptoms from patients demonstrating symptoms compatible with leptospirosis, with disease risk factors including occupational, recreational, water or animal exposures or overseas travel.

Of the 25 patients positive by PCR, 22 were positive by PCR and negative by serology and a further 3 patients PCR positive with equivocal IgM results on examination of the initial serum sample. Follow up sera confirmed the PCR results serologically in all cases with identification of presumptive infecting serogroup on convalescent samples by Microscopic Agglutination Test (MAT) where possible. Nineteen patients were negative by PCR and for a further twenty nine patients PCR was not used.

The use of PCR in these patients allowed an early presumptive diagnosis of leptospirosis and the initiation of appropriate clinical management after discussion with the Clinical Consultant at the LRU. Back to List

Commentary

During 2012 there was an increase compared with 2011 in both home and overseas acquired Leptospira infections. Nearly a third (22, 31%) were acquired overseas, predominantly in the Far East and Central and South America. The majority of these overseas infections were linked to exposure to inland waters with the presence of cuts or abrasions often acting as a portal of entry for leptospires. The increase in overseas acquired cases is a timely reminder to all who venture to exotic parts of the world for unusual and challenging recreational adventures that leptospirosis remains one of the most common waterborne infections throughout the world, especially in countries which have hot tropical or semi-tropical climates with monsoons. These countries all have large domestic and free living animal populations and a high incidence of human leptospirosis. Visitors to these countries frequently have exposures to inland surface waters in rivers and jungle, and engage in activities such as white water rafting, endurance events, jungle trekking, potholing and caving and eco-tourism which put them at high risk of acquiring leptospirosis. The number of cases acquired during holidays in tropical countries remains significant and clinicians should consider leptospirosis in the differential diagnosis for patients with a febrile illness and a history of travel overseas.

For further information on travel associated leptospirosis and appropriate precautions, see the NaThNaC website.

Despite a number of infections being caused by more virulent serovars of serogroup Icterohaemorrhagiae, infections with this serogroup are less common among imported cases [Figure 3.]. Infections with serovar Hardjobovis in serogroup Sejroe are now infrequently reported, but continue to be associated with exposure to dairy cattle. There were no reports of canine serovars, specifically L. Canicola, nor were there any reports in 2012 of infection associated with pet rodents. The low number of cases with serogroup Hardjobovis may reflect associated dairy control measures, and the absence of serogroup Canicola is a reflection of the importance of continued vaccination of dogs.

Continued determination of Leptospira serovars in UK residents ensures that changes in the epidemiology of the infection, should they occur, are closely monitored and recorded. 

Table 1

Leptospira cases by age group (UK & Overseas acquired) 2012

Age Group

Indigenous

Overseas

Total

10-14

2

-

2

15-24

6

5

11

25-34

8

9

17

35-44

7

-

7

45-54

17

6

23

55-64

5

2

7

65-74

5

-

5

Total, all ages

50

22

72

Table 2

Clinical presentations and findings, Leptospirosis cases, 2012

Presentation*

Indigenous

Overseas

Total

FLI

15

12

27

Headache

19

13

32

Myalgia

23

11

34

PUO

 26

15

41

Lethargy

11

11

22

Malaise

15

12

27

Vomiting

13

5

18

Diarrhoea

7

7

14

Conjunctivitis

2

0

2

Abnormal LFTs

26

9

35

Jaundice

20

4

24

Hepatic Failure

5

0

5

Renal failure

19

5

24

Meningitis

0

2

2

Respiratory Failure

0

0

0

Nausea

0

0

0

Haemorrhage

3

0

3

Cough

1

0

1

*Patients may have had several symptoms or findings during the course of their illness and treatment

Figure 1

Leptospirosis 2012, Figure 1

Figure 2

Leptospirosis 2012, Figure 2

Figure 3

Leptospirosis 2012, Figure 3


Last reviewed: 16 July 2013