Controlling the controller: suppressing microsporidia in their mosquito hosts

What is it about?

Microsporidia are natural parasites of mosquitoes and promising allies in the fight against malaria. But studying them inside live hosts is difficult, and manipulating their infections even more so. In our new study, we tested whether Dexrazoxane, a known anti-microsporidian drug, could suppress infections of Vavraia culicis in Anopheles gambiae — the main mosquito vector of malaria. We found that Dexrazoxane significantly reduced parasite spore loads in infected mosquitoes, especially when they were reared individually. However, it did not block infection altogether, meaning the parasites could still enter the host — but struggled to proliferate. This result echoes findings in C. elegans and suggests that Dexrazoxane primarily targets parasite replication. The likely mechanism? Inhibition of DNA topoisomerase II, not iron chelation — which also explains why mosquito larvae exposed to the drug failed to develop into adults.

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Photo by Cameron Webb on Unsplash

Photo by Cameron Webb on Unsplash

Why is it important?

While this makes Dexrazoxane unsuitable as a larvicide due to potential environmental harm, its ability to partially suppress microsporidia in adult mosquitoes opens new doors. By controlling parasite load without clearing infection, Dexrazoxane may become a powerful tool for studying interactions between microsporidia and other pathogens like Plasmodium. It also raises the possibility of resource-based interference between co-infecting parasites, a promising line of inquiry for future control strategies.

Perspectives