Human Lyme Borreliosis and Puumala hantavirus infection incidence follow rodent abundance variations in Northern Europe

Date:
August 11, 2021
Source:
University of Jyva"skyla" - Jyva"skyla"n yliopisto
Summary:
A recent study shows the association between bank vole abundance
variations and the incidence of Lyme Borreliosis and Puumala
hantavirus infections. The study showed that the abundance
variations of the reservoir hosts of wildlife originated pathogens
have importance in estimating the risks these pathogens pose to
humans. The results of the work can be taken into account in the
risk communication by health authorities.



FULL STORY ==========================================================================
A recent study shows the association between bank vole abundance
variations and the incidence of Lyme Borreliosis and Puumala hantavirus infections. The study, carried out by the University of Jyva"skyla",
the University of Oulu, National Institute for Health and Welfare and
and Natural resources institute Finland, showed that the abundance
variations of the reservoir hosts of wildlife originated pathogens have importance in estimating the risks these pathogens pose to humans. The
results of the work can be taken into account in the risk communication
by health authorities. The paper was published in Scientific Reports in
9th August 2021.


==========================================================================
Bank vole is the most common rodent species in Northern Europe and the reservoir host for Puumala hantavirus and Borrelia bacteria causing
Lyme Borreliosis.

The study quantifies the associations between the time series of bank vole abundance as well as Lyme Borreliosis and Puumala hantavirus infection incidence in Central Finland and Northern Savo regions.

The study shows that the 3-year abundance fluctuations of bank vole
are reflected into Puumala hantavirus and Lyme Borreliosis infection
incidence.

Puumala infection incidence followed the bank vole abundance fluctuations
with a couple of months time lag. Hence, the infections are common when
bank voles are abundant.

The relationship between bank vole abundance fluctuations and the
incidence of Lyme borreliosis was complex. Lyme borreliosis incidence
followed the vole abundance variations with longer, approximately one
year lag.

One year lag is expected based on the lifecycle of Borrelia -bacteria:
A tick larva acquires Borrelia -bactreria while feeding on an infected
vole and moults to an infectious nymph and an adult typically one and
two years later, respectively.

In Finland, two tick species circulate Borrelia-bacteria. Typically,
Ixodes ricinus -tick bites human as a nymph, which explains the one-year
lag between bank vole abundance and Lyme borreliosis incidence.Ixodes persulcatus -tick often bites human as an adult. The study identified
also a two-year time lag between bank vole abundance and Lyme borreliosis incidence, which may have resulted from bites of adult I. persulcatus
ticks.

The study also showed that the strength of the association between Lyme Borreliosis and approximately one year earlier bank vole abundance changed
over ther study period. Also the bank vole population dynamics changed
over the study period, which may have affected the infestation of ticks
on voles and thus the circulation of Borrelia -bacteria between voles
and ticks, consequently affecting the proportion of ticks carrying the
bacteria and thus the human infection incidence.

========================================================================== Story Source: Materials provided by University_of_Jyva"skyla"_-_Jyva"skyla"n_yliopisto. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Mahdi Aminikhah, Jukka T. Forsman, Esa Koskela, Tapio Mappes,
Jussi Sane,
Jukka Ollgren, Sami M. Kivela", Eva R. Kallio. Rodent
host population dynamics drive zoonotic Lyme Borreliosis and
Orthohantavirus infections in humans in Northern Europe. Scientific
Reports, 2021; 11 (1) DOI: 10.1038/s41598-021-95000-y ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210811131528.htm

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