How does a tick acquire borreliosis? - briefly
Ticks acquire Borrelia bacteria during blood meals from infected reservoir hosts, primarily rodents, while in the larval or nymphal stage. The pathogen enters the tick’s gut from the host’s bloodstream and remains through subsequent molts, enabling later transmission.
How does a tick acquire borreliosis? - in detail
Ticks become carriers of Lyme‑disease spirochetes through a series of well‑defined steps linked to their feeding behavior and developmental stages. During the larval stage, a tick hatches free of infection. The first blood meal, usually taken from small mammals such as the white‑footed mouse, provides the opportunity for acquisition of the pathogen. If the host is infected with «Borrelia burgdorferi» or related species, spirochetes enter the tick’s midgut while it is engorged. The bacteria survive the molting process; transstadial transmission allows them to persist from the larva to the nymphal stage.
The nymph, now infected, seeks a second host. Feeding on larger mammals, including humans, introduces the spirochetes into the new host’s skin. During blood ingestion, the bacteria migrate from the midgut to the salivary glands, a movement triggered by the tick’s physiological changes. Salivary secretion during attachment releases the pathogens into the bite site, where they can establish infection.
Additional mechanisms reinforce pathogen acquisition:
- Co‑feeding: uninfected ticks feeding in close proximity to infected conspecifics on the same host can acquire spirochetes without the host developing systemic infection.
- Transovarial passage: occasional transfer of «Borrelia» from an infected female to her eggs occurs at low frequency, contributing to early‑stage infection in some populations.
Environmental factors influence these processes. High host density, especially of competent reservoirs, raises the likelihood that larvae encounter infected blood. Seasonal activity patterns align larval feeding with peak reservoir infection rates, enhancing transmission efficiency.
In summary, infection of the tick results from ingestion of pathogen‑laden blood during the larval meal, retention of spirochetes through molting, migration to salivary glands in the nymph, and delivery to subsequent hosts during feeding. Co‑feeding and limited transovarial transmission further sustain the pathogen within tick populations.