Anaplasmosis is an infectious disease caused by the bacterium Anaplasma phagocytophilum, which is transmitted to humans through the bite of infected ticks. It primarily affects white blood cells, leading to symptoms such as fever, chills, headache, and muscle aches. The disease is most commonly reported in the northeastern and north-central regions of the United States. Diagnosis is typically made through blood tests that detect the presence of the bacteria or antibodies. Treatment usually involves antibiotics, such as doxycycline, which are effective in clearing the infection. Early detection and treatment are crucial to prevent complications.