On July 15, 2015, the Centers for Disease Control and Prevention (CDC) published a new study in the journal, “Emerging Infectious Diseases,” on the prevalence of Lyme disease in the United States. The study reveals the geographic regions deemed high risk for Lyme disease exposure are increasing at a remarkable rate.
In the US, high-risk regions remain the most concentrated in the upper Midwest and the Northeast. However, these same regions have more high-risk areas than ten years earlier. At present, 17 states have geographical areas where exposure to Lyme disease remains high and is expanding.
Symptoms, Treatment, and Complications
Lyme disease is a tick-borne illness: One caused by a poppy seed-sized tick infected with Borrelia burgdoferi. A bite from a tick transmits the disease from the tick to the animal or human host. As per the Mayo Clinic online, people who either live in or spend any amount of time in a region that is heavily wooded or grassy have a higher likelihood of receiving a bite from a tick infected with Borrelia burgdoferi.
The symptoms of Lyme range from the presence of a small bite mark that later becomes red, inflamed, and erythema migrans, a bulls-eye patterned rash serving as a hallmark indicator of the disease, appears as a red outer ring around the initial bite. Additional symptoms include a headache, body aches, fatigue, chills, fever, weakness, and flu-like conditions. The disease is treatable with a course of antibiotics However, if left untreated, can result in neurological issues, debilitating fatigue, and joint pain. The most severe symptoms include inflammation of the eye and liver, heartbeat irregularities, cognitive impairments, Lyme arthritis, and temporary paralysis.
The condition was first identified in the state of Connecticut, which remains high-risk, and other high-risk states include New Hampshire and Massachusetts. Nearly half of the states of Vermont and Maine are also high-risk. Additional states witnessing an increase in high-risk regions include Midwest Minnesota, Michigan, Iowa, the Eastern seaboard of New York, Pennsylvania, and Virginia.
Lyme disease reports across the nation range from 20,000 to 30,000 reports annually. Nevertheless, researchers surmise the number is considerably higher as they question the number of unreported incidents. In fact, the actual number of people who contract the disease may be ten times higher than current figures.
Incidents on the Rise
Since the early 1990s, territorial and state-based health departments have monitored and reported incidents of human-contracted Lyme disease to the CDC’s National Notifiable Diseases Surveillance System (NNDS). According to reports collected by the NNDS, the main areas where the prevalence of Lyme disease is high include the north central, mid-Atlantic, and Northeastern states.
According to Dr. Kiersten Kugeler, an epidemiologist with the CDC’s Division of Vector-Borne Diseases in Fort Collins, Colorado, the areas marked as high-risk are increasing in size and in every direction. In fact, in some regions, the increase of Lyme disease incidents reaches levels as high as 320%; specifically, in northeastern states, Lyme disease prevalence was present in 43 counties between 1993 and 1997, compared to 183 counties between 2008 and 2012. The high-risk areas in the north central states witnessed a 250% increase in all of the identified high-risk counties as well. Moreover, a decade ago, 130 counties were high risk, but that totaled has doubled to 260 counties where Lyme disease reports are prevalent.
Disease Prevalence and Transmission
At this time, the cause for the expansion of high-risk areas remains unknown, but researchers surmise it may be due to development of environmental changes causing deer and the parasitic ticks to move from one area to another. In all areas, the potential for encountering infected ticks is greatly influenced by the characteristics of the landscape and human behavior, all of which have an impact on the abundance of ticks as well as small mammals in the region. It is possible environmental changes are increasing the likelihood of tick survival, and the fact that birds and animals can carry the parasite to other areas where survival is likely might be a contributing factor in the spread of the disease and its continued transmission to humans.
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