Altitudinal patterns of tick and host abundance: a potential role for climate,ch

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Altitudinal patterns of tick and host abundance: a potential

role for climate,change in regulating tick-borne diseases?

 

Oecologia. 2009 Aug 15; [Epub ahead of print]

 

Altitudinal patterns of tick and host abundance: a potential role for

climate change in regulating tick-borne diseases?

 

Gilbert L.

 

Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen, AB31 8QH,

UK, l.gilbert.

 

The impact of climate change on vector-borne infectious diseases is

currently controversial. In Europe the primary arthropod vectors of

zoonotic

diseases are ticks, which transmit Borrelia burgdorferi sensu lato (the

agent of Lyme disease), tick-borne encephalitis virus and louping ill virus

between humans, livestock and wildlife. Ixodes ricinus ticks and reported

tick-borne disease cases are currently increasing in the UK. Theories for

this include climate change and increasing host abundance. This study aimed

to test how I. ricinus tick abundance might be influenced by climate change

in Scotland by using altitudinal gradients as a proxy, while also taking

into account the effects of hosts, vegetation and weather effects. It was

predicted that tick abundance would be higher at lower altitudes (i.e.

warmer climates) and increase with host abundance. Surveys were conducted

on

nine hills in Scotland, all of open moorland habitat. Tick abundance was

positively associated with deer abundance, but even after taking this into

account, there was a strong negative association of ticks with altitude.

This was probably a real climate effect, with temperature (and humidity,

i.e. saturation deficit) most likely playing an important role. It could

be

inferred that ticks may become more abundant at higher altitudes in

response

to climate warming. This has potential implications for pathogen prevalence

such as louping ill virus if tick numbers increase at elevations where

competent transmission hosts (red grouse Lagopus lagopus scoticus and

mountain hares Lepus timidus) occur in higher numbers.

 

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PMID: 19685082 [PubMed - as supplied by publisher]