Abstract
Some evidence indicated that human babesiosis caused by Babesia duncani has spread widely in North America. However, current therapeutic regimens (atovaquone + azithromycin) for human babesiosis are suboptimal with frequent recrudescence and side effects, and furthermore, there is no specific treatment for human babesiosis caused by B. duncani. Here, we screened 97 essential oils and identified 10 essential oils (garlic, black pepper, tarragon, palo santo, coconut, pine, meditation, cajeput, moringa, and stress relief) at a low concentration (0.001%; v/v) that showed good inhibitory activity against B. duncani in the hamster red blood cell culture model. Among them, garlic oil and black pepper oil performed best, as well as their potential active ingredients diallyl disulfide (DADS) and β-caryophyllene (BCP), respectively. Interestingly, further subculture study indicated that B. duncani could relapse after treatment with current therapeutic drugs atovaquone or azithromycin even at high concentrations. In contrast, the combination of garlic oil or DADS and azithromycin showed eradication of B. duncani at low concentrations without regrowth. These results are encouraging and suggest that the garlic-derived sulfur compound DADS and β-caryophyllene (BCP) may be promising drug candidates for evaluation of their ability to cure persistent B. duncani infections in the future.
Highlights
Human babesiosis is an emerging tick-born disease caused by members of the genus Babesia, which are similar to Plasmodium parasites that cause malaria as both of them are intraerythrocytic protozoan parasites
We found 10 essential oils including garlic, black pepper, tarragon, palo santo, coconut, pine, meditation, cajeput, moringa, and stress relief that showed more than 50% inhibitory effects at 0.001% against B. duncani (Table 1)
The results indicated that some essential oils have anti-Babesia activity ex vivo, and garlic and black pepper essential oils had the most potent activity against B. duncani in this study
Summary
Human babesiosis is an emerging tick-born disease caused by members of the genus Babesia, which are similar to Plasmodium parasites that cause malaria as both of them are intraerythrocytic protozoan parasites. Babesia microti, and Babesia duncani cause the most human babesiosis cases worldwide [1]. The clinical symptoms of babesiosis patients can range from flu-like mild to malaria-like severe symptoms, and patients who undergo immune disease (e.g., acquired immune deficiency syndrome (AIDS)), immunosuppressive therapies, and splenectomy can suffer more severe manifestations, and even death [1]. Cases of human babesiosis in the USA have been increasing in the past two decades, and babesiosis was added to the list of nationally notifiable diseases by the Centers for Disease Control and Prevention (CDC) in 2011 [4]. In the United States, B. microti and B. duncani are commonly recognized and identified in humans
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