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Temporal Risk Assessment for Lyme borreliosis in Denmark
Posted: Fri 3 Aug 2007 10:25
The prevalence of Borrelia burgdorferi sensu lato in Ixodes ricinus nymphs in Denmark was found to be approximately 5%. The mean abundance of infected nymphs varied from 0.3 to 4.4 per 100 m2 according to site. The seasonal occurrence of infected nymphs in a beech forest coincided with seasonal distribution of neuroborreliosis cases. In order to establish a working hypothesis, it was assumed that the availability of habitats and human habitat preferences is one of the factors leading to low number of neuroborreliosis cases in the spring. In addition, this paper gives a description of the neuroborreliosis cases in Denmark in the period 1985-97 and offers a possible explanation for the variation in cases. The explanation is based on an assessment of tick density, which by comparison with the number of neuroborreliosis cases provides information on the infectivity of ticks. The model suggests that high temperatures and low precipitation in the autumn is essential for the transmission of B. burgdorferi sensu lato to reservoir hosts or development of B. burgdorferi sensu lato within ticks, which secures high tick infectivity in the following season.
http://www.ingentaconnect.com/content/t ... awler=true
Re: Temporal Risk Assessment for Lyme borreliosis in Denmark
Posted: Fri 3 Aug 2007 10:28
The Tick Task
In Denmark a few decades ago, the consensus was that no "real" health problems for man or animals were associated with ticks. Basically, two diseases were known: Tick borne encephalitis (TBE) and -Babesiosis. The influence of Babesiosis was and is considered unimportant. Most likely, due to intensive agricultural practices, where the grassland is incorporated in the rotation of field crops. Such practice makes it impossible to accumulate a population of ticks pastures grazed by cattle.
TBE has been known to occur on the island of Bornholm from time to time. In the last 20 years a case per year have been reported now and then (Landspatient registeret, Sundheds-styrelsen, pers).
With the discovery of the Lyme Borreliosis agent: Borrelia burgdorferi sensu lato a new tick-borne disease was introduced. The research performed in United States of America, Europe and Asia demonstrated that the spirochete has a world-wide distribution, and is carried by ticks of the genus Ixodes. Studies of Lyme Borreliosis has revealed the disease to be elusive and difficult to describe. New modes of transmission, new genospecies and new reservoir host have been introduced as a result of numerous studies. These studies have demonstrated that Lyme Borreliosis exist in many different biological systems.