Ali Afify


Mosquito repellents are used worldwide to prevent mosquito bites and mosquito-borne diseases. In order to develop more efficient and safer mosquito repellents, we first need to understand how currently used repellents work, or how they affect the mosquito’s sense of smell. At the Potter lab, we developed a method (calcium imaging) to visualize how sensory neurons on the antennae of the malaria mosquito respond to repellents. We found that natural repellents, such as lemongrass oil and eugenol, are able to activate some of these neurons. To our surprise, man-made repellents such as DEET did not activate any of these antennal neurons. This suggests that the malaria mosquito can smell natural repellents but not man-made repellents. We found that man-made repellents work in another way: They make neurons on the mosquito antennae respond less (or not at all) to the odors on our skin by decreasing the volatility of these odors. This means that instead of directly repelling the malaria mosquitoes away, man-made repellents prevent chemicals on our skin from evaporating and reaching the mosquitoes, rendering us invisible to them. We further showed that other species of mosquitoes, such as the yellow fever mosquito and the southern house mosquito, are directly repelled by DEET. This suggests that confusion in the field about how DEET works could be due to its species-specific effect. Our findings can help inform mosquito repellent choice by species, and streamline the discovery of improved insect repellents.

Questions & Answers

Why did you choose Johns Hopkins for your work? Johns Hopkins is one of the best research universities in the world. In addition, the lab was a perfect fit for me, and proved to be an excellent choice. What does receiving this award mean to you personally and professionally? Do you have any connection with the particular award you received? The award means a lot to me, and I hope it will help my career in the future. I do not have any connection with the particular award I received, but I am honored to receive an award named after a great scientist like Alfred Blalock. What contributed to your project's success? The work environment in the Potter lab is the main contributor to my project’s success. I continuously receive great support from my mentor and colleagues, and I really appreciate every one of them. What thoughts do you have about Young Investigators’ Day itself, as a celebration of the roles students and fellows play in research at Johns Hopkins? I think it is a great way to recognize the excellent research done by young investigators at Johns Hopkins. We tend to doubt ourselves sometimes, and it really helps when we feel that our work is recognized. Things like the Young Investigators' Day can make us feel appreciated, and hopefully will inspire future young investigators who are just starting their projects at Johns Hopkins. What has been your best/most memorable experience while at Johns Hopkins? I think it was when my paper was finally published after more than three years of work. What are your plans over the next year or so? I plan to stay in academia. I want to find a faculty position one day. Tell us something interesting about yourself. I love writing; the best time during my Ph.D. was when I was writing my thesis. I could not stop there, so I used the few months after graduation to write a novel, and I enjoyed every moment in the process.