Mosquito-borne illness is up in Arizona. This ASU scientist focuses on making new control methods
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Mosquito-borne diseases have become more of a concern in Arizona over the past several years; in 2021, Maricopa County had the biggest outbreak of West Nile Virus of any county in the U.S, ever.
So far this year, the state has reported 81 cases of West Nile, along with 25 cases of dengue, another mosquito-borne illness.
A group of Arizona State University scientists is raising concern about one of the ways we try to control mosquitos: insecticide.
Ndey Bassin Jobe is one of them; she’s a fifth-year Ph.D. candidate at the Center for Evolution and Medicine at ASU. Jobe spoke with The Show about whether the efforts to protect people from diseases like Zika, West Nile and malaria are generally successful, and the impacts they have on the mosquitoes that are carrying those illnesses.
Interview highlights
NDEY BASSIN JOBE: So, many efforts are being put in place, especially to control the adult insects, right. Or arthropods in general. If I give it in the context of, for instance, with mosquitoes, we do use long lasting insecticidal nets, which are the bed nets that people would sleep under to protect them from the mosquito bite. And so they wouldn't be bitten by a mosquito and as a result, get a mosquito-borne disease. Other interventions that are also used are indoor residual spraying, where you spray, a house or room. And so when that happens, these walls are being sprayed with insecticides, and so when the adult mosquitoes comes into the room, when they rest on these walls, they get in contact with insecticides. And the goal for that is basically to make sure these adult vectors basically die, they're controlled. But of course, over the years, we've seen a lot of improvement that has happened when it comes to these diseases as a result of the interventions that are being put in place. But we've also seen that there's a lot of insecticide resistance that has been happening. Lots of insects being resistant to these chemical interventions that we use, especially with mosquitoes in the mosquito field.
MARRK BRODIE: Well, so what's the answer then? I mean, if mosquitoes, for example, are becoming resistant to the insecticides that are being used to try to control their population, what do we move on to next?
JOBE: Of course, there, there are other non-chemical based interventions that we can use. But then first, I think with insecticides, it's not like we're saying that insecticides shouldn't be used at all. I think if insecticides have been very effective in controlling the adult mosquito populations. And so we can continue, of course, to use insecticides. It's just the way we use them. We need to start thinking our strategies. How do we ensure that these insecticides are effective? In terms of the new active ingredients that we start making, which are the new classes of insecticides that we are like trying to develop to bring into the market, how do we ensure that those ones would last long before resistance develops in, in, in the vectors? And of course, there's other resistance management strategies that are being used in order to ensure that these insecticides continue to be effective for a long time. But then of course, we can also use other non-chemical based interventions. I personally, I'm very interested in non-chemical based interventions. And within my Ph.D. program, I've been working on new tools, which includes like using electricity to repel mosquitoes, which has been something that has been really exciting and we've been, we've been seeing exciting results with that. And so I think what we need to then move to our scientists and people in the science world, of course, people that are interested in insect work and medical entomology would be to start thinking about new tools that are perhaps not chemical based that we can use to control these mosquitoes. But then also to, to think about the current strategies and tools that we have such as the insecticides and how we can have them to continue, to continue to last longer.
BRODIE: I would imagine that if you're using, for example, electricity to repel mosquitoes, you don't run into the problem of mosquitoes becoming resistant to that electricity? Like, if you, it sounds like the goal here is to maybe use insecticide in places where you really need to use it. But use other things, you know, other techniques of controlling mosquitoes where, you know, maybe you don't need to use the insecticide, which will keep the mosquitoes from becoming resistant to that kind of control.
JOBE: Yeah, exactly. Exactly. Like what we have realized, like we just one of the things that we've talked about in, in our recent publication, is the fact that for instance, in malaria control, we've been over using insecticides. It's not, it's not just in malaria control, but we of course know that insecticides do work. And so it's overly deployed, overly used, right? We are very much dependent on, on using insecticides. And so because of that constant use and us using it at very high amounts and constantly using it, resistance obviously emerges over time. So yeah, I think like using it when it's necessary. And of course, like coming up with strategies in which we're ensuring that there's not that over-usage of it. We are not constantly pressurizing these insects and, and and leading to that selection pressure when it comes to resistance is very important.
BRODIE: Are there particular parts of the world where there's more of a problem with mosquitoes that are resistant to insecticides than others or is it pretty much a problem everywhere?
JOBE: It is a problem everywhere. But I can definitely tell you that it is a huge problem in Sub-Saharan Africa. For malaria, for instance, 95% of the cases are coming from Sub-Saharan Africa. So there we do have a huge problem. But then in general, even here in the United States, in Arizona, in particular, we do have mosquitoes. We do not have a malaria problem, of course, in Arizona because we do not have any anna mosquitoes. But we do have a West Nile virus issue and things like that.
BRODIE: What kind of timeline are you looking at in terms of maybe being able to deploy some of these non-insecticide methods of, of trying to take care of mosquitoes?
JOBE: If I think about, for instance, the electric field work that I do, I think it will take a couple of years for sure. Just because it's in it's very infant stages, like using electricity to control insects is something that is quite new, relatively new, right? So we're still in the early stages, we're still doing more research to see like how we can make sure the technology works effectively but not just to work effectively, but also like how best to make sure it is safe for humans, right? We're talking about electricity. You want to make sure that if we incorporate it in our houses and in entry points and houses that it's also safe for humans. But also how do we make it affordable, especially for people that need it the most like people in Saharan Africa, people in communities that do not have much money to invest in such technologies, right? How do we make it accessible to them?
