Distribution and movement of infective-stage larvae of Dipetalonema viteae (Filarioidea) in the vector tick, Ornithodoros tartakowskyi (Argasidae).

Histological sections and dissection of infected ticks, Ornithodoros tartakowskyi, showed that in the resting tick the 3rd-stage larvae of Dipetalonema viteae were distributed in clumps throughout the hemocoel. In the biting tick, larvae moved anteriorly and congregated especially in the capitulum; and the forward migration occurred even though no blood was ingested. This suggests that the act of biting and not the ingestion of blood is the critical factor in migration. The larvae may reach the buccal cavity through 4 possible avenues: 1) the junction of the pharynx with the buccal cavity; 2) the esophagus; 3) the salivary ducts; and 4) the roof of the hypostome. Developing forms produce direct injury to muscle fibers, and the migrating larvae further disorganize the muscles, affecting to some extent the normal activities of the ticks.