Which organism transmits Lyme disease?

• A. Dirofilaria immitis
• B. Heartworm
• C. Lice
• D. Tick

Answer: (D)

Lyme disease is transmitted by a tick. The bacteria Borrelia burgdorferi is carried by hard ticks, especially Ixodes species (like the black-legged tick, Ixodes scapularis, in many regions). The tick acquires the bacteria when feeding on an infected host, and after it attaches to a new host and feeds for a sufficient period (often 24–48 hours), the bacteria pass into the host through the tick’s saliva, causing infection. Prompt removal of ticks reduces the chance of transmission, since shorter attachment means less opportunity for the bacteria to move into the host. Mosquitoes and lice are not vectors for Lyme disease; mosquitoes transmit other pathogens (like heartworm in dogs), and lice transmit different diseases.