What is a tick that causes anaplasmosis? - briefly
The bacterium Anaplasma phagocytophilum is transmitted primarily by the black‑legged (deer) tick, Ixodes scapularis in eastern North America and Ixodes pacificus on the West Coast, with Ixodes ricinus serving as the main vector in Europe. These ticks acquire the pathogen while feeding on infected wildlife and pass it to humans during subsequent blood meals.
What is a tick that causes anaplasmosis? - in detail
The bacterium Anaplasma phagocytophilum is transmitted primarily by the black‑legged tick, scientifically known as Ixodes scapularis in the eastern United States and Ixodes pacificus along the West Coast. Both species belong to the family Ixodidae and are commonly called deer ticks or western black‑legged ticks.
These arachnids undergo a three‑stage life cycle—larva, nymph, and adult—each requiring a blood meal from a vertebrate host. Larvae acquire the pathogen rarely, but nymphs often become infected after feeding on small mammals such as the white‑footed mouse (Peromyscus leucopus). Infected nymphs are the principal vectors to humans because they are small, active during the spring and early summer, and frequently bite unnoticed. Adult ticks maintain the bacterium in wildlife reservoirs and can also transmit it to humans, though adult bites are less common.
Key biological characteristics:
- Morphology: Six legs as larvae, eight legs as nymphs and adults; reddish‑brown body with a distinctive black dorsal shield in adults.
- Habitat: Moist, wooded areas with leaf litter; questing behavior places them on vegetation at heights matching host shoulder level.
- Seasonality: Larvae peak in late summer; nymphs in late spring to early summer; adults in fall and early winter.
- Host range: Small mammals, birds, reptiles, and large mammals (including deer and humans).
Transmission dynamics:
- Infected nymph attaches to a human host, inserts its hypostome, and secretes saliva containing anti‑coagulant and immunomodulatory compounds.
- A. phagocytophilum is released into the bloodstream during feeding, invades neutrophils, and proliferates intracellularly.
- Clinical onset typically occurs 5–14 days after the bite, presenting with fever, headache, myalgia, and leukopenia.
Prevention measures focus on reducing exposure to the vector:
- Apply EPA‑registered repellents containing DEET or picaridin to skin and clothing.
- Wear long sleeves and pant legs; tuck trousers into socks in endemic areas.
- Conduct thorough tick checks after outdoor activities; remove attached ticks promptly with fine‑tipped tweezers, grasping close to the skin and pulling steadily.
- Maintain yard hygiene by clearing leaf litter, trimming low vegetation, and creating a barrier of wood chips between lawns and forested zones.
Understanding the ecology of Ixodes species and their role in the life cycle of A. phagocytophilum is essential for accurate diagnosis, effective treatment, and implementation of targeted public‑health interventions.