A Prime Climate for Lyme Disease

Lyme disease and climate change potentially connected as prevalence grows in northern states

(RxWiki News) As summer activities approach, Lyme disease-carrying ticks may put a damper on outdoor activities in parts of the country where they previously weren't a big concern.

A new study revealed that as of 2007, the presence of Lyme disease had increased in certain parts of the United States, particularly in the northernmost states.

"Check for ticks if you think you've been around them."

According to the Centers for Disease Control and Prevention (CDC), Lyme disease is transmitted to people through bites from infected ticks. Initial symptoms can include headache, fatigue, rash and fever, and if untreated, the infection can begin to affect the heart, joints and nervous system.

The presence of Lyme disease has traditionally been more prevalent in temperate parts of the US, due to the tick’s reliance on long and warm seasons of spring and autumn to complete their life cycles, wrote the authors of this new study.

However, according to the authors, it has been suggested that the geographic range of the Lyme disease-carrying ticks could have expanded in recent years.

Led by Ashleigh R. Tuite, MPH, of the The Dalla Lana School of Public Health in Toronto, researchers utilized data from the CDC's National Notifiable Diseases Surveillance System to estimate incidences of Lyme disease in all 50 states and the District of Columbia (DC) during the years 1993 to 2007.

After analyzing the data, the authors estimated that the incidence of Lyme disease in the US increased by around 80 percent between the years 1993 and 2007, but that this increase was not uniform across the whole nation.

For example, the authors estimated that the incidence of Lyme disease in Colorado was 0.008 cases per 100,000 person-years (the lowest rate) but 75 cases per 100,000 person-years in Connecticut (the highest rate).

Overall, 21 states and DC showed an increase in the presence of Lyme disease, 14 states had a decrease and there was no major change in 15 other states.

There seemed to be a connection between states with increasing incidence and the factors of latitude and population density. The authors reported that overall, northernmost states were the areas to see the increases while southern states saw declining or stable Lyme disease rates.

The authors suggest that climate change and human encroachment on natural areas could potentially be connected to these increased rates in certain parts of the country. However, more research is needs to be done.

The authors suggested that public health organizations consider if the existing methods for monitoring Lyme disease are flexible and sensitive enough to cope with a changing presence of Lyme disease.

The study was published online on April 16 in CMAJ, the journal of the Canadian Medical Association. No conflicts of interest were reported.

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Review Date: 
April 15, 2013