CANINE HEARTWORM DISEASE - WHAT HAS CHANGED?

摘要

In 1975, organisms were observed with the electron microscope in intra-uterine microfilariae and developing embryos of Dirofilaria immitis and Brugiapahangi. Research on these organisms then stalled until 1995 when it was shown with molecular methodsthat the organisms in Dirofilaria immitis were related to the Rickettsia-like Wolbachia endosymbionts of arthropods. In 1999, it was shown that tetracycline had negative effects on the embryogenesis of D. immits, and that long-term treatment of cattle infected with Onchocerca ochengi using tetracycline resulted in the death of the adult filarial worms, apparently associated with the death of their endosymbiotic bacteria. Long-term tetracycline or doxycycline chemotherapy does have negative effects on the larvae and adults of human parasitic filarioid nematodes, Brugia and Onchocerca; however, the required long-term and regular administration of these compounds appears to provide no significant advantage over periodic treatment with microfilaricidal ivermectin for control through the prevention of transmission.