August 5, 2011

New Tick-borne Bacterium Infecting Humans

(Ivanhoe Newswire)--A new tick-borne bacterium is on the move and infecting people across the country.

Ehrlichiosis is an infectious disease transmitted through the bite of a tick. In the United States, this disease is mainly found in the southern central and southeast states but this new bacterium, not yet named, has been identified in more than 25 people and found in deer ticks in these two states. Doctors at the Mayo Clinic, the Center for Disease Control and Prevention, the University of Minnesota, the University of Wisconsin, and state and local health departments say that this disease can cause feverish symptoms in humans who contract it.

Ehrlichia infect and kill white blood cells and can cause fever, body aches, headache, and fatigue. If the disease goes untreated and becomes severe in multiple organs such as the lungs, kidneys, and brain, patients may require hospitalization but rarely the disease results in death. Bobbi Pritt, M.D., a Mayo Clinic microbiologist and director of the Clinical Parasitology and Virology Laboratories was quoted saying, "Before this report, human ehrliochosis was thought to be very rare or absent in Minnesota and Wisconsin. Therefore, physicians might not know to look for Ehrlichia infections at all." Risk factors for ehrlichiosis include: living near an area with a lot of ticks, owning a pet that may bring ticks into the home, and walking in tall grasses.

Thousands of blood samples from across the United States have been screened by the Mayo Clinic and the bacterium has only been detected in specimens collected from Wisconsin and Minnesota. Although thousands of ticks have been analyzed from across the country, only those from the two states have been identified as being carriers. Doctors caution people to apply insect repellant and wear pants and long-sleeved shirts when active outdoors to avoid tick bites.

Unfortunately traditional blood antibody tests can provide misleading results that fail to accurately identify this new species. A new specific antibody test for this bacterium has been developed by the Center for Disease Control but is not yet widely available. In its replacement, a molecular blood test that detects DNA from the Ehrlichia species is the preferred method for detecting the disease in symptomatic patients. Physicians should also consider testing these patients for other tick-borne diseases such as Lyme, babesiosis and anaplasmosis, all prevalent in Minnesota and Wisconsin.

SOURCE: New England Journal of Medicine,  August 4, 2011