Vector control considerations in Sudan and Ethiopia: an expert opinion

PROFESSOR DIA-ELDIN ELAIEM: Unlike the general assumption that there is no vector control for leishmaniasis in Sudan, there is vector control. Because the disease is so important and there is a lot of political pressure on the Ministries of Health to do something about it, they are employing a very elaborate vector control programme, which consists of three basic tools. A residual insecticide is spraying at indoor sites two times a year, bed-nets distribution– and that’s the long-lasting insecticide-impregnated bed-nets, and they replace it every other year or every three years– and in addition to that, they are doing fogging also with insecticides when there is peak activity of sandflies. This is what is happening in Sudan.

In Ethiopia, they are not having a specific policy for vector of visceral leishmaniasis. The only thing that they are approving is the bed-net distribution. But they are practicing also residual spraying of insecticides in malaria areas. So maybe that can work both ways. But the actual endemic areas of VL in Ethiopia are not targeted by residual insecticide spraying like in Sudan.

There is significant challenges in the vector control of visceral leishmaniasis in Sudan and also in Ethiopia. And these challenges are basically due to lack of knowledge about the places where you find the vector at densities, where you can attack them. And therefore, most of the programme in Sudan is based on little information. And so for example, residual spraying at indoor sites, that will never work for visceral leishmaniasis because sand flies that transmit this specific parasite, called visceral leishmaniasis, is not found inside the rooms. It does not come inside the rooms and does not rest on the walls inside the rooms. It’s not like the mosquito.

It is not like the other sandflies that cause cutaneous leishmaniasis or transmit the parasite that causes cutaneous leishmaniasis. So therefore, all this spraying is not working. There is lack of evaluation. And that is serious because they don’t know what happened before and after. Absolutely, there is no numbers at all. The third real serious problem is for the bed-net distribution. A bed-net is a good tool, because since biting happens at outdoor sites, people use it at outdoor sites. But unfortunately, they leave it in the sun, and the UV light destroys the pyrethroid insecticide. So there is this fundamental knowledge we don’t have yet. But even more basic knowledge we don’t know.

For sure, leishmaniasis in Sudan and Ethiopia still needs a lot of studies. And there is a lot to be learned about the epidemiology of the disease. So there is this fundamental knowledge we don’t have yet. But even more basic knowledge we don’t know– where the vector is found, where people are contracting the infection outside or inside. And all these are so essential for a real sound vector control programme. We need to know exactly the timing of the bites– in terms of season and in terms of the night. And there is a great deal of variation that happens from one week to another week. So there is a lot of intra-seasonal variation.

There is a lot of also variation in the biting rate throughout the night or the early evening. So how can you make a decision about fogging with insecticide, ULV fogging, when you don’t know when the vector is flying around. So all this has to be done. There is a number of new tools that are ready– almost. A number are already there and they are available in the market. And these can be distributed with the help of NGOs or from government because they may be a little bit expensive for people to purchase. But the repellents are available. And so there are some now available long-lasting repellents that can work for 12 hours throughout the night.

There is neem oil as a repellent, and it has been tested. And there is publication that it works against Phlebotomus orientalis, the vector of visceral leishmaniasis in Sudan and Ethiopia. We need to produce that– it’s very extremely cheap– and encourage people to use it to reduce the biting. These are available. We tried to impregnate small bands with permethrin that can last for six months at least and also socks. That also works, and that could be distributed and help. In Ethiopia, the target population are seasonal workers and labourers. They travel all the time, and they work all night long during the transmission season. And so they are very mobile.

And you cannot ask them to use a bed-net because they don’t have beds. They sleep on plastic sheets, what we call sleep mats. But all this relies on health education because it’s all about compliance. Whenever there is something that you need as a personal protection tool, you need to make people believe in it. It’s not understanding – believe that it will work. Health education is a very essential component. We cannot wait until we develop our tools, and we do our programmes, and at the end we come and do health education. We have to start with health education right now. And we have to start by educating the health professionals and educating the village at the village level.

And we have to have assessment tools that they really understand.