How do ticks transmit piroplasmosis? - briefly
During a blood meal, a tick ingests piroplasm‑infected erythrocytes, the parasites multiply and migrate to the salivary glands, and are injected into the next host when the tick feeds again.
How do ticks transmit piroplasmosis? - in detail
Ticks serve as the primary vector for piroplasmosis, a disease caused by intra‑erythrocytic parasites of the genera Babesia and Theileria. Transmission proceeds through a series of tightly coordinated biological events within the arthropod host.
During a blood meal on an infected mammal, the tick ingests parasitized erythrocytes. In the midgut, parasites differentiate into gametes, undergo sexual fusion, and develop into motile ookinetes. These penetrate the midgut epithelium, forming sporoblasts that mature into sporozoites. The sporozoites remain within the tick through its successive developmental stages—a process known as transstadial passage. In many Babesia species, the parasite does not pass to the next generation of ticks (no transovarial transmission), whereas certain Theileria species are capable of infecting the ova, allowing vertical spread.
As the tick molts from larva to nymph and later to adult, sporozoites migrate to the salivary glands. When the tick attaches to a new vertebrate host, sporozoites are expelled with saliva directly into the bloodstream. Once in the host, they invade erythrocytes, initiate asexual replication (merogony), and cause the clinical manifestations of piroplasmosis.
Key steps in the vector‑borne cycle:
- Acquisition of infected blood by feeding tick.
- Gametogenesis and fertilization in the midgut.
- Formation of sporozoites and their migration to salivary glands during molting.
- Release of sporozoites into a naïve host during subsequent feeding.
- Intracellular multiplication within host erythrocytes.
Understanding each phase clarifies how tick biology underpins the spread of piroplasmosis and informs strategies for interrupting the transmission cycle.