Life cycle of one-host ixodid (hard) ticks.

描述：

Life cycle of one-host ixodid (hard) ticks.

The adult of a one-host ixodid (hard) tick is considered the diagnostic stage, as identification to the species level is best achieved with adults. Few ixodids of public health importance have this type of life cycle, but one example is Rhipicephalus annulatus, which can serve as a vector for babesiosis. Rhipicephalus microplus, a major tick parasite of cattle in much of the world, also has a 1-host life cycle (Merck Veterinary Manual online).

One-host ixodid ticks remain on the same host for the larval, nymphal, and adult stages, only leaving the host prior to laying eggs. Vertical transmission of Babesia via transovarial transmission has been demonstrated for some species of ticks. Gravid females lay eggs in the environment (1). The eggs hatch into six-legged larvae (2). Larvae seek out and attach to the host and after two molts, develop into adults (3a-3c). Although humans may serve as incidental hosts for species normally found on other animals, they usually do not host all three stages. Females drop from the host to lay eggs (4) and the cycle repeats.

From Centers for Disease Control Parasites and Health website.