Date: Wed 19 Sep 2012
From: Marcella Mori <Marcella.Mori@coda-cerva.be> [edited]
On Mon 20 Aug 2012, the Veterinary and Agrochemical Research Centre in Brussels (CODA-CERVA) was contacted by the official Health Inspectorate (Control of infectious diseases) of the Walloon region to investigate an outbreak of leptospirosis in boys attending a scout camp. The camp was located on the banks of the Semois River, in the province of Luxembourg. 10 out of 25 boys participating developed clinical symptoms. The diagnosis of leptospirosis was confirmed by the microscopic agglutination test (MAT) in the 3 boys that were hospitalized.
Contamination from an infected wildlife reservoir was immediately suspected because boy-scouts deemed to have played with a rat, most probably a muskrat considering the dimensions (information is scarce due to the discomfort of the patients). On site investigations were conducted by CODA-CERVA in association with the environmental unit of the Walloon region to collect water samples and muskrats. Animals were captured from 2 nests in the vicinity of the scout camp.
Pathogenic _Leptospira_ spp. was found in the liver and kidney of these animals and antibodies against _Leptospira_ were demonstrated by MAT in the body fluids. Water samples were negative, which could be explained by the absence of stagnant water. The definitive link between the human infections and the infected animals requires further investigations.
Leptospirosis is a pandemic zoonosis and may affect various species, including domestic animals and humans. The natural hosts are wild animals particularly rats where the pathogenicity is not manifested but whose role is expressed as carriers. Those animals are important determinants for leptospirosis and their control can positively impact the wellness at veterinary and public health levels.
In Belgium, leptospirosis is present in domestic animals (particularly dogs and horses) but it is infrequent in humans. The human cases are the result of direct contact with animal reservoirs or contaminated water sources in Belgium or result from recreational activities in (sub)tropical regions.
Combination of both climate change and increased uncontrolled water sports is certainly playing a role in driving favorable conditions for leptospirosis spreading worldwide. Under beneficial weather conditions the rodent population is growing fast. These premises suggest rodent surveillance programs to complement the control of leptospirosis, particularly in regions with opportunities for water sports and recreation.
Dr Marcella Mori
Dr David Fretin
Belgian Reference Laboratory for Leptospirosis in animals
Dr Sylvia Depoorter
Pediatrics Department in AZ-Sint Jan, Brugge
Dr Marjan Van Esbroeck
Belgian Reference Laboratory for Leptospirosis in humans
Institute of Tropical Medicine, Antwerp
Dr Carole Schirvel
Directeur Generale de la Sante,
Direction Surveillance et Protection de la Sante
[ProMED very much appreciates this outbreak report direct from the Belgium authorities. It serves as a warning to people who operate campsites that may be contaminated with bat guano in any country. - ProMed Mod.JW]
[Leptospirosis is a zoonotic spirochetal infection that is distributed throughout the world in warm climates and is transmitted to humans by direct contact of abraded skin or mucous membranes with the urine of infected animals or by contact with wet soil, vegetation, or water that has been contaminated with infected animal urine. These animals are mostly asymptomatic, but chronically infected with one of the several hundred serovars of pathogenic _Leptospira_. Different leptospiral serovars are prevalent in particular geographical regions. In carrier animals with chronic renal infections, leptospiruria persists for long periods or for life. _Leptospira_ bacteria shed in urine may survive in water or moist soil for weeks to months. Many species of wild and domestic animals (including dogs, cattle, swine, and especially rodents) are susceptible to chronic urinary infection with pathogenic leptospira. Outbreaks of leptospirosis frequently follow heavy rainfall, flooding with fresh water, and increasing rodent numbers.
Leptospirosis is an occupational hazard for people who work outdoors or with animals -- for example, farmers, sewer workers, veterinarians, dairy farmers, rice and sugarcane field workers, and military personnel. It is a recreational hazard for those who participate in outdoor water sports such as swimming, rowing, or whitewater rafting in contaminated lakes and rivers.
Because of the relatively nonspecific nature of the clinical presentation of leptospirosis, its diagnosis cannot be made confidently without laboratory confirmation. The United States Centers for Disease Control and Prevention can provide _Leptospira_ Dip-S-Tick (DST) IgM dot-ELISA test kits (PanBio Integrated Diagnostics) to local laboratories for serological testing of suspected leptospirosis cases in support of the response to a disaster. The DST is suitable for in-the-field testing of suspected patients. Confirmatory testing uses the microscopic agglutination test (MAT).
Belgium is a federal state with 3 regions: the Brussels-Capital Region, the Dutch-speaking region of Flanders in the north, and the landlocked French-speaking region of Wallonia in the south (for a map showing these 3 regions of Belgium, see <http://ssy.org.uk/wp-content/uploads/2010/04/belgium.gif
>.) Wallonia consists of the provinces of Walloon Brabant, Hainaut, Liege, Luxembourg, and Namur (<http://www.yurtdisiegitimim.net/sites/default/files/belgium_regions_map.jpg
>). The source of the Semois River, where this leptospirosis outbreak occurred, is in the province of Luxembourg, close to the border with the Grand Duchy of Luxembourg; it flows westerly to France and joins the Meuse River (<http://en.wikipedia.org/wiki/Semois
>). For a map of Semois River see <http://en.wikipedia.org/wiki/File:KaartSemois.jpg
The HealthMap/ProMED-mail interactive map of Belgium is available at
[Muskrat photo at: