LEPRESNOR - Role of zoonotic Leptospira spp. in Norway from a One Health perspective and their host-pathogen interactions

LEPRESNOR - Role of zoonotic Leptospira spp. in Norway from a One Health perspective and their host-pathogen interactions

Scanning electron microscopic image of Leptospira interrogans strain RGA. Image source: Public Health Image Library CDC/Rob Weyant.

Leptospirosis is a zoonosis caused by bacteria called Leptospira. We want to clarify the role of possible maintenance hosts for the disease in Norway and understand the pathogens' virulence mechanisms better.



Leptospirosis is considered the most widespread zoonotic disease in the world with a notable (re-)emergence during the past decade. The World Health Organization (WHO) recognizes leptospirosis outbreaks to be driven by climate and environment since warmer and wetter conditions favor the spread of the infection. Leptospira have a broad host range and leptospirosis may present with a broad spectrum of clinical symptoms. While maintenance hosts like rats generally remain asymptomatic, in humans, who are dead-end hosts, clinical manifestations are highly variable ranging from mild influenza-like symptoms to severe multisystemic illness with potentially fatal outcome. At-risk population include for example farmers, agricultural workers, fishermen, pest exterminators, water sports people, sanitary workers, sewage workers, animal caretakers and abattoir staff. In livestock, the clinical signs of leptospirosis include reduced fertility, stillbirth and abortion. Acute disease in dogs may present with acute kidney injury and liver impairment and respiratory, sometimes also gastrointestinal, signs. Leptospires colonize the kidneys of their host and can therefore be shed via urine into the environment, contaminating water sources.

The diagnosis of leptospirosis is difficult in both the clinic and the laboratory and the global disease burden is thus likely underestimated. In Sweden and Denmark, urban rats were identified as a source for leptospirosis with prevalence rates ranging from 24% to up to 89%, respectively, in recent years. It is believed that leptospirosis does not play a role in Norway but currently, no comprehensive data on leptospirosis in Norway are available to support that and the epidemiological situation including potential maintenance hosts is unknown.  


Our network collaborates on different subprojects:

- Ph.D. student Silje is working on identifying the role of Leptospira in cattle, rodents and shrews in Norway. Moreover, she is studying host-pathogen interactions of Leptospira borgpetersenii serovar Hardjo type hardjobovis in a bovine caruncular epithelial cell line (BCEC-1). Her project will shed light on the current epidemiological situation in Norway and understand the mechanisms that Leptospira use to cause reproductive disease in cattle by harming the placenta.

- Our project linked to the HUNT One Health project aims at screening metagenomic data from livestock and pets for the presence of pathogenic Leptospira spp. and, subsequently, will select the Leptospira-positive samples for further testing by qPCR and multilocus sequence typing. All samples and data were obtained in the Nord-Trøndelag region of Norway.

- The collaborators on the INSPIRED project aim at deciphering host-pathogen interactions in maintenance versus dead-end host in an in vitro approach (mouse and human kidney cell line). They use two strains belonging to different serovars of L. borgpetersenii which were obtained from a mouse population and are linked to human infection. Since isolating leptospires from clinical material is challenging, our success at culturing two different strains isolated from the same mouse population whereof one led to human infection is a unique possibility to study their behavior in the two hosts.