Macrocyclic lactone resistance in Dirofilaria immitis
Catherine Bourguinat1, Kathy Keller, Aron Bhan
1Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec H9X3V9, Canada.
Veterinary Parasitology
|May 17, 2011
Summary
Macrocyclic lactone (ML) resistance in heartworm (Dirofilaria immitis) is confirmed. Genotyping revealed a high frequency of a specific genetic polymorphism linked to ML insensitivity in surviving microfilariae.
Area of Science:
- Veterinary Parasitology
- Molecular Entomology
- Antiparasitic Drug Resistance
Background:
- Heartworm (Dirofilaria immitis) infections pose a significant threat to canine health.
- Macrocyclic lactones (MLs) are widely used for heartworm prevention and treatment.
- Emerging resistance to MLs necessitates investigation into resistance mechanisms.
Observation:
- Microfilariae were isolated from a canine that remained microfilaremic despite multiple adulticidal and high-dose ML treatments.
- Genotyping focused on two P-glycoprotein single nucleotide polymorphic sites associated with reduced ML sensitivity.
- A specific genetic polymorphism (GG-GG), previously linked to in vitro ML insensitivity, was analyzed.
Findings:
- The GG-GG genotype was present in 45.3% of microfilariae surviving repeated high-dose ML treatments.
- This indicates a strong association between the GG-GG genotype and ML resistance in D. immitis.
- Phenotypic and genotypic evidence confirms ML resistance in this heartworm population.
Implications:
- The findings highlight the growing challenge of ML resistance in heartworm treatment protocols.
- Understanding the genetic basis of resistance is crucial for developing effective diagnostic and therapeutic strategies.
- This research underscores the need for vigilant monitoring of anthelmintic resistance in veterinary medicine.
Related Concept Videos
01:21Antiprotozoal Agents
Leishmaniasis is a widespread parasitic disease caused by several Leishmania species. It affects millions of people each year and remains a major public health problem in endemic regions. First-line treatment relies on pentavalent antimonials, including meglumine antimoniate and sodium stibogluconate. Even so, how these drugs work has not been fully clear, especially their interaction with parasite-specific biochemical pathways. One key target is trypanothione reductase (TR), an enzyme that...
01:15Anthelminthic Agents
Anthelmintic drugs differ significantly from antiparasitic therapies targeting protozoa, primarily due to differences in parasite biology. Whereas most protozoal treatments act on proliferating cells, anthelmintics are typically directed against mature, nonproliferative helminths. The therapeutic approach considers the helminth's reliance on neuromuscular coordination, glucose metabolism, and microtubular integrity for survival, reproduction, and localization within the host. Most anthelmintics...
01:30Leishmaniasis
Leishmaniasis is a protozoal disease caused by species of the genus Leishmania and transmitted through the bite of infected female sandflies. The parasite exists in two principal morphological forms during its life cycle. A sandfly acquires intracellular amastigotes from an infected reservoir host, such as a dog. Within the sandfly, these forms differentiate into motile, flagellated promastigotes. During a subsequent blood meal, promastigotes are injected into the human host, where they...