Ticks that carry Lyme disease live in almost half of US counties – study
[ http://www.theguardian.com/us-news/2016 ... -across-us ]
Black-legged tick inhabits twice as many counties as in 1998, CDC reports, with 320% increase in number of north-eastern counties seen as high risk for disease
Oliver Milman @olliemilman Monday 18 January 2016 14.00 GMT Last modified on Tuesday 19 January 2016 22.41 GMT
Ticks that can carry the debilitating illness Lyme disease [ http://www.theguardian.com/lifeandstyle ... t-outdoors ] have significantly spread across the US over the past 20 years and are now found in nearly half of all American counties, including areas where they have never previously been documented, a new analysis has found.
The black-legged tick is now established in twice the number of counties it inhabited in 1998, according to the US Centers for Disease Control,[ http://www.cdc.gov/ ] and has expanded its range in the north-eastern states and the upper midwest. Following its onward march, or hop, across the Ohio river valley, western New York and the shores of Lake Michigan since the 1990s, there has been a tripling in the incidence of Lyme disease in the US.
The tick, which has a variant species present on the west coast of the US, can burrow into humans and transmit Lyme disease, which causes fever, headache and other flu-like symptoms. Further problems include impaired memory, dizziness, heart palpitation and inflammation of the brain and spinal cord. Around 300,000 people are diagnosed with Lyme disease each year.
The CDC said there has been a 320% increase in the number of counties in the north-east US considered high risk for Lyme disease since the 1990s. Overall, more than 45% of all American counties now host the ticks, up from from 30% in 1998, according to the research published in the Journal of Medical Entomology. [ https://jme.oxfordjournals.org/content/ ... jme.tjv237 ]
Reforestation and an increased population of deer, which host the ticks, have contributed to the increase in distribution. Temperature and rainfall also influence the fate of the tick, with a warming climate helping their spread.
MORE:
[ http://www.theguardian.com/us-news/2016 ... -across-us ]