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Prevention within the household

Hear from Dr James Logan and Dr Jo Lines about the control methods that can be employed in and around the house.
So what can you do if you are living in an area in a region with Zika or other vector borne diseases in terms of the household. How can protect your household? How can you protect yourself and your family within that household? And there are actually many things that you can do to help reduce the number of mosquitoes around and also help reduce the number of bites that you get as well. Now obviously repellents is something that we’ve covered in more detail and in another step, but repellents is a very good idea and there are four main active ingredients one is DEET, PMD, Icaridin, and IR3535.
So choosing a very good repellent and making sure that you apply it frequently will provide protection, even inside your house, so any mosquitoes that enter inside the house are then much less likely to bite you. If you have disease in the area that it’s a very very good idea. Screening your house is a good idea as well, because that creates a physical barrier. It stops the mosquitoes from actually entering into your house, and in fact there is evidence to suggest that screening of households can actually reduce dengue transmission and it’s one of the few vector control interventions for dengue that has any evidence really or a lot of evidence that it actually works in terms of reducing disease transmission.
So it’s definitely something that should be done. And you know so with screening we talk about screening doors and screening windows and also eaves so any gaps in any sort of household where a mosquito can enter should be screened over. And the screens can also be treated with an insecticide which can make them more effective, so that’s a very good thing to do. As well as screening your house with with netting, you should also just be aware that you know keeping your windows and doors shut will have an effect, because again it creates a physical barrier and it will stop the mosquitoes from entering, particularly at times when they’re active.
Bed nets can also be used against Zika; conventionally, bed nets are not something that are recommended for Aedes mosquitoes and that’s because they bite outdoors and they also bite during the day so you might think it’s no good for an Aedes mosquito and they’re much better placed for controlling malaria because the vectors bite at night.
But in fact a lot of people do sleep during the day, so if you are in a hot country quite a lot of people will take an afternoon nap, they’ll have a sleep in the afternoon, and pregnant woman certainly will sometimes do that as well, children will school sleep during the day, people who work night shifts will sleep during the day, and people who just go to bed early or get up late will be sleeping at times when these mosquitoes are active. So we should never dismiss bed nets when it comes to Zika and other viruses transmitted by Aedes.
</em> There’s not a lot of evidence out there because people haven’t looked in great detail to see how well bed nets work, but they should be recommended, particularly if you’re sleeping during the day. Plus, what you have to remember is that in a lot of countries where Zika is either present now or might be present in the future, there are other diseases that are spread by mosquitoes that bite at night and indoors and so even if you’re not doing it for Zika or for for Aedes specifically, there will be other reasons to use a bed net. So a bed net is always a good idea and if it’s treated with insecticide, even better.
A lot of people tend to like to use mosquito coils and these are coils that contain an insecticide. Normally you have to light the coil and and it burns essentially. These produce a smoke which repel the insects and can kill them or knock them down, because it contains an insecticide. They can have some effect– they can be quite useful particularly outdoors.
We wouldn’t recommend them being used indoors, one is that they are a fire hazard, so it is you know it’s not a flame as such, but it is burning, so it is a potential fire hazard and also the smoke that it produces that you would inhale then in an enclosed space is perhaps not the best thing to be doing long term. But certainly in an outdoor situation where there’s lots of ventilation, these things could potentially be quite useful and can reduce the number of bites that you can get. In a hot country, quite often people will use a fan or air conditioning. And you know a lot of people tend to think that this might have an effect with mosquitoes.
Mosquitoes tend not to like to fly in high airflows or in cold temperatures. Now whether you can get a fan a strong enough and a temperature in your room that’s cold enough to stop a mosquito from flying is is doubtful. But certainly having a fan on and particularly blowing over you perhaps while you’re while you’re asleep at night may have some impact. There’s absolutely no evidence really that it will affect or reduce disease transmission or reduce the number of bites, but it keeps you cool and it and it may have an effect so it’s definitely worth doing if you have that or you have access to a fan.
At a community level, when it comes to Aedes control we tend to promote clean up campaigns, and what that means is that we try to get rid of all the potential breeding sites within an area. What we’ve already learned about is that Aedes mosquitoes will breed pretty much anywhere in any kind of man made container whether that’s an old tin of food that’s been discarded, a bucket, a place where you might wash your clothes, it can be pretty much anywhere. The campaigns really are based around getting rid of all those breeding sites, cleaning it up, getting rid of the rubbish in backyards and in front yards and that sort of thing.
And that’s really important when it comes to controlling Aedes– there’s some evidence that it can reduce the numbers and it’s certainly something that should be done and that you can do at the household level as well. Aedes mosquitoes tend not to fly very far, so in theory you could potentially have an effect around your own household but where you have to be aware of of course is that there are there is a possibility of mosquitoes coming in from your neighbours, for example. So these community clean up campaigns work much better when you have a whole community engaging in this and actually doing the clean up campaign.
But it’s certainly worth at the household level, at your individual level, to make sure that you minimise the number of breeding sites available for these mosquitoes and that will help to keep the numbers down. And then the last community level intervention that is used quite commonly is space spraying. So these fogging devices, or ULV Ultra-Low Volume devices, putting out a fog or smoke of insecticide laden particles that are really meant to kill the mosquitoes that are on the wing this evening.
You want to do it in the evening when there’s a temperature inversion so that the fog stays close to the ground for half an hour, an hour, as long as possible and that tends to be very popular because yes you immediately notice there are no mosquitoes– for at least a few hours, everybody notices. So it’s popular but it’s also mainly cosmetic, because actually the epidemiological benefit is very short lived. I’m not saying it doesn’t work, but the epidemiological benefit will fade within a week. Why?
Because ok you’ll kill the mosquitoes that are there but others are coming it’s not a long term solution so it’s the kind of thing that you would certainly want to try to do in epidemic conditions. If there’s a thing raging tonight, even tonight there are infected mosquitoes biting people who are going to suffer, you may want to do that. The effectiveness of that does tend to vary from place to place.
They say that perhaps it works better in Southeast Asia than in Latin America because the houses and walls in Latin America tend to be solid and high to keep the sun out, whereas in Southeast Asia, the buildings are more porous and people want the breeze to come through the house. So along with the breeze will come the fog or the smoke with the insecticide to penetrate the middle of the house where as in Latin America with the solid walls it’s harder for the smoke in the street to get inside. It’s been alleged that that may be the key difference.
What can you do to protect yourself and your family when you’re at home?
In the video, Dr James Logan discusses some of the practical interventions you can employ to prevent mosquitoes from entering your home, repel or kill them if they already have, and how community clean-up campaigns can help to reduce mosquito numbers. Dr Jo Lines then discusses fogging and the hypothesis that the effectiveness of this control method can vary in different regions of the world due to a variety of factors, such as building construction and materials.
What kind of things have you done to prevent mosquitoes from entering your house? Have you heard of or been involved in a community clean-up campaign?
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Preventing the Zika Virus: Understanding and Controlling the Aedes Mosquito

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