Colorado tick fever (CTF) is a viral infection (Coltivirus) transmitted from the bite of an infected Rocky Mountain wood tick ("Dermacentor andersoni"). It should not be confused with the bacterial tick-borne infection, Rocky Mountain spotted fever. CTF is transmitted to humans most commonly by the bite of an infected adult wood tick, and while there is no evidence of natural person-to-person transmission, rare cases of transmission by blood transfusion have been reported. In general, adult ticks are approximately the size of a sesame seed and nymphal ticks are approximately the size of a poppy seed. The Lyme disease bacterium, "Borrelia burgdorferi", is spread through the bite of infected ticks. Symptoms include: