A potential new treatment could transform the fight against scabies, with QIMR Berghofer researchers developing a single-dose therapy for the debilitating skin condition that kills both scabies mites and their eggs.
Scabies is caused by microscopic mites that burrow into the skin, causing intense itching, rash and secondary bacterial infections. At least 400 million people are infected worldwide each year. More than just an itch, when the skin is broken, bacterial infections associated with the condition can lead to serious complications including rheumatic heart disease, renal disease and sepsis.
The topical therapy developed by the Scabies Research Group at QIMR Berghofer combines abametapir, an ingredient in lice treatment, and flavesone, an ingredient found in manuka oil. Both compounds kill mites and eggs, but abametapir is particularly effective against eggs while flavesone is especially effective against mites. Together, the compounds target multiple stages of the parasite's life cycle through different, non-neurotoxic mechanisms.
To assess the combined treatment, researchers tested it on an animal model that closely replicates human scabies infection. Animals with established severe scabies received a single topical application, which was washed off after four hours. Researchers measured mite survival, egg viability, itch reduction and drug exposure within the skin for 42 days. Results were compared with the current standard two-dose oral treatment of ivermectin and with no treatment.
The findings were striking.
A single treatment eradicated all live mites and eggs and significantly reduced itching, outperforming ivermectin treatment.
Senior Researcher Professor Katja Fischer said the results address one of the biggest shortcomings of existing scabies treatments.
"Current therapies often require multiple treatments because they do not kill eggs," Professor Fischer said. “Our combination therapy is designed to target the parasite at multiple life stages, and in this study a single application eliminated every live mite and egg we could detect."
Fellow researcher Dr Deepani Fernando said the findings point to a simpler and potentially more effective approach to scabies control.
"A treatment that eliminates both mites and eggs in a single application could make management easier for patients, healthcare providers and disease control programs," Dr Fernando said.
"Because the two compounds work through different mechanisms, this approach may also help address worries about treatment resistance."
The researchers are keen to progress the treatment to human clinical trials but say further funding will be required.