Date: Wed 17 Aug 2016
Source: Statens Serum Institut Epi-News No 28-33 - 2016 [edited]
The period from January 2011 to June 2016 saw a total of 60 recorded cases of leptospirosis [in Denmark] overall that is, notified and/or laboratory-confirmed cases; 10 (17per cent) women and 50 (83 per cent) men aged 13-70 years with a median age of 44 years, figure 1 [figures and tables available at the URL above]. Among the recorded cases, 38 patients aged 13-69 were notified clinically. Among these, 33 (87 per cent) were men aged 16-69 years (median age 44 years). A total of 59 cases were laboratory-confirmed; these included 37 of the 38 clinically notified patients. For a total of 25 people (42 per cent), information was provided about infection in Denmark.
Eight of these had occupational exposure, including 4 following contact with sewage where rats were present, and in a total of 3 cases after direct contact to rats or rat urine, one at a fish farm and 2 at farms, table 1. The 8th person worked putting up animal fencing outdoors and came into contact with stagnant water. The people who were infected in Denmark and had no occupational exposure had most frequently become infected when cleaning their own cellars (6 people) and through contact with stream water (5) in connection with both intentional and unintentional stays in water. Another 4 had come into more direct contact with rats, either by being bitten or in connection with rat prevention.
Also, one patient was a hunter, and another reported having stood barefoot in sewage. A total of 26 people were infected abroad, 16 (61 per cent) of whom had travelled to Asia. Among those who were infected outside Denmark, 10 had been exposed to lake water and rivers; and among these, 3 had been infected doing river rafting. Only one person was believed to have become infected from sewage. For 9 people, cerebral symptoms were reported. Two of the 60 patients (one man and one woman) died due to their leptospira infections. Infection by the leptospira bacterium is renowned for seasonal variation, which depends on the temperature and on rat population density.
As in other years, the majority of leptospirosis cases were seen in late summer and in the autumn (Figure 2) which is when water temperatures peak. The bacterium survives poorly in water below 18 C [64 F] and does not tolerate drying out. In Denmark, Statens Serum Institut performs the laboratory diagnostics for leptospirosis. Diagnostics consist of serology (R-343) through micro-agglutination testing, MAT testing for 15 _Leptospira_ serovars, PCR for the _Leptospira_ species (R-065), and PCR and culture for leptospira (R-1350). The recommended materials for PCR are blood, urine or spinal fluid, if possible obtained before the initiation of antibiotic treatment.
In 38 per cent of cases, the serovar could not be determined. In 15 of these patients, the diagnosis was based on PCR exclusively. An additional 7 patients' sera yielded too many cross-reactions for the serovar to be determined. The most frequently established serovar was _L. interrogans_ serovar Icterohaemorrhagiae (20 per cent), Table 2, which is frequently found naturally in rat urine. Two patients had leptospira DNA detected in their spinal fluids, and serology identified _Leptospira interrogans_ of the serovar Sejroe, table 2. One of these patients recovered, whereas leptospira DNA was detected in the spinal fluid post-mortem in the other case (for a detailed description, see "Case stories"). A total of 46 people contacted hospitals directly, whereas only 6 people were seen by their GP. In 8 cases, the samples were ordered by private medical companies or by other Scandinavian healthcare facilities.
The number of patients who were infected with leptospirosis in the period from January 2011 to June 2016 -- a total of 60 people -- was considerably higher than the number recorded in the corresponding period from 2005-2010, when a total of 42 cases were registered, EPI-NEWS 34b/11. Only about half of the cases recorded in the entire period were notified on Form 1515.
The majority of the cases were reported in 2011, including 5 cases associated with the summer 2011 rainstorm, EPI-NEWS 5/12. The infection course with leptospira from the bloodstream to secretion in the urine and subsequent development of antibodies means that both laboratory methods (serology and PCR) may be needed to increase diagnostic sensitivity and specificity.
It is remarkable that the number of people who were presumably infected through farms or due to contact with sewage or freshwater in the period from January 2011 to June 2016 exceeded the number of people presumably infected at fish farms. Leptospirosis in pigs in Denmark is described by the Knowledge Centre for Agriculture. (byline: R Datcu, Microbiological Diagnostics and Virology; C KjelsÃ¸, Department of Infectious Disease Epidemiology; M M SÃ¸ndergaard, Department of Medicine, Svendborg Hospital; K A Krogfelt, Microbiology and Infection Control)
[The above report on leptospirosis in Denmark, 2011-2016 has been condensed. The full report, including figures and tables, can be found at the source URL. For discussions of leptspirosis, see moderator comments in prior ProMED-mail posts below. - ProMED Mod.ML]
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