Ixodes dammini is a tick vector for which pathogen in the northeastern United States?

• A. Leptospira interrogans
• B. Borrelia burgdorferi
• C. Treponema pallidum
• D. Rickettsia rickettsii

Answer: (B)

Ixodes dammini, now called Ixodes scapularis or the deer tick, is the primary vector in the northeastern United States for Borrelia burgdorferi, the bacterium that causes Lyme disease. Transmission occurs when an infected tick, typically during a blood meal, injects the bacteria into the human host. The nymphal stage is especially important for human transmission because it is small and often goes unnoticed, increasing the chance of bite exposure. In nature, white-footed mice and other small mammals serve as reservoir hosts that maintain the bacterium in tick populations, supporting ongoing cycles of transmission.

Other pathogens listed are not carried by this tick in this region: leptospira interrogans causes leptospirosis via contact with contaminated water or animal urine; Treponema pallidum causes syphilis through sexual contact; Rickettsia rickettsii causes Rocky Mountain spotted fever and is transmitted by different tick species, not Ixodes dammini.