First locally acquired human case of tick-borne disease anaplasmosis hospitalizes Washington resident

OLYMPIA – The Washington State Department of Health (DOH) is reporting the first locally acquired human case of the tick-borne disease anaplasmosis in a Washington resident discovered on August 8. A Whatcom County man in his 80s was hospitalized with severe disease, and is now in recovery, after working in the brush in Mason County where he was likely bitten by an infected tick.   

Human cases of anaplasmosis have been identified in Washington before, though all previous cases involved travel outside of the state. Until now, only dogs have been diagnosed with locally acquired anaplasmosis in Washington. 

Anaplasmosis usually causes mild to moderate symptoms in people, including fever, headache, muscle aches, and nausea, vomiting or loss of appetite. Symptoms typically begin 1 to 2 weeks after being bit by an infected tick. The disease is treatable with antibiotics. If treatment is delayed, or if a person has other pre-existing medical conditions, anaplasmosis can cause severe illness. 

In Washington, the disease is spread by the western blacklegged tick which are mainly found in the western part of the state as well as along the eastern slopes of the Cascades. Western blacklegged ticks infected with Anaplasma spp. bacteria, which causes the disease, have previously been found in Washington at very low levels.

“Not all tick bites will cause disease,” said Scott Lindquist, MD, MPH, State Epidemiologist for Communicable Diseases. “However, people across Washington are at risk for tick-borne illnesses and should take precautions to prevent tick bites.”

DOH recommends the following to protect people and pets against tick bites:

• When possible, avoid wooded and brushy areas with tall grass and fallen leaves, which are where ticks typically live.
• When in tick habitats, wear light-colored clothing and long-sleeved shirts and pants, so that ticks can be more easily spotted and to help prevent them from attaching to skin.
• Apply EPA-registered insect repellants to clothing and skin, following label instructions.
• Carefully check yourself, family members, and pets for ticks after being in potential tick habitats.
• Shower soon after being outdoors to wash off any unattached ticks.
• If ticks are found, promptly remove them with fine-tipped tweezers, then clean the area with antiseptic.