An ultrastructural study on the early cellular response to Dirofilaria immitis (Nematoda) in the Malpighian tubules of Aedes aegypti (refractory strains).

Dirofilaria immitis living in Aedes aegypti refractory strains were studied in relation to ultrastructural events in primary cells of Malpighian tubules and to defense mechanisms activated by host-cells. When the microfilaria reaches the Malpighian cells, its intracellular development is blocked by defense mechanisms activated by the host, resulting in lysis of the outermost cuticle of the parasite without melanin involvement. Ultrastructural evidence suggests that lysis is brought about by Malpighian cell products.