According to the agency, a Whatcom County man in his 80s was hospitalized with severe disease on Aug. 8.
Health officials say the man was working in brush in Mason County beforehand and was likely bitten by an infected tick.
Anaplasmosis is a disease caused by the Anaplasma phagocytophilium bacteria, which can be carried by blacklegged ticks and western blacklegged ticks. Symptoms include fever, headache, chills, muscle aches, nausea, vomiting or loss of appetite.
These symptoms typically begin one to two weeks after getting bitten.
DOH says human cases have occurred in Washington before, but have always originated from outside the state. Previously, the only locally acquired cases of anaplasmosis were diagnosed in dogs.
"Not all tick bites will cause disease," said State Epidemiologist Dr. Scott Lindquist. "However, people across Washington are at risk for tick-borne illnesses and should take precautions to prevent tick bites."
To protect yourself and your pets from tick bites, DOH recommends you:
- Avoid wooded and brushy areas with tall grass and fallen leaves, where ticks live
- Wear light-colored and long-sleeved clothing to more easily spot ticks and prevent them from attaching to skin
- Use EPA-registered insect repellant
- Always check yourself, family members and pets for ticks after going to possible tick habitats
- Shower after being outdoors to wash off unattached ticks
- If ticks are attached, carefully remove them with fine-tipped tweezers, then clean the area with antiseptic
DOH warns there is no vaccine against anaplasmosis, but bites can be avoided with simple steps. For more information on ticks, visit the DOH webpage.