Leptospirosis--current risk factors connected with human activity and the environment

Leptospirosis is a widespread although recently neglected zoonosis recognized worldwide. The disease seems to be underestimated, especially in countries located in the temperate climatic zone. The presented article concerns the main characteristics of leptospirosis and describes formerly known and recently observed environmental, occupational and recreational risk factors significant in the spreading and pathogenesis of the disease. The aspects of epidemiology significant in the temperate climatic zone are emphasized. The majority of cited articles present cases of the disease reported from Europe or North America. Climatic changes (warming) and extreme weather events such as floods are potential risk factors of leptospirosis. Also, some socio-economic phenomena, such as the intensive migration of people resulting in the transfer of the infections acquired in tropical countries, or worsening of economic status in the cities, increase the probability of disease. Apart from the danger connected with rodents, which are the main vectors of leptospires, occurrence of the disease in dogs and cats can generate a higher risk of infection for humans. Infections may also be acquired during various types of agricultural work and during recreational activities, such as swimming. The results of recent investigations show that ticks are also potential vectors of leptospires. The more frequent emergence of leptospirosis in countries located in the temperate climatic zone emphasize the need to verify knowledge related to the risk of its appearance, and to consider this disease during diagnostic processes.