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Photo of Sipho Ngxongo Fighting Malaria

Sipho Ngxongo, a regional director for the Department of Health, directs efforts to combat malaria in the province of KwaZulu-Natal. Frontiers viewers learned more about the strategies to combat malaria when Sipho answered viewers' questions as part of an Ask the Scientists panel following the premier of the Scientific American Frontiers Special Special Science Safari. Here are viewers' questions and his answers:

QWhy can't we simply vaccinate people against malaria the way we vaccinate against so many other diseases?

A lot of work is being undertaken by researchers on the malaria vaccine. They have been working on this for years. We are still waiting for an effective vaccine. There is none yet on the market.

Q After spraying the homes with insecticide, are there any fumes left? If so, how long do they last? Are they dangerous to the people who live in the houses?

There are no fumes left after spraying. Only deposits of the insecticide are left on walls and roofs after spraying. These are not dangerous to man. The residual effect of these deposits is about 12 months. Hence houses are sprayed once in a year.

Q If sleeping nets would save lives, why don't you think people use them? On the show it said people aren't used to them -- could you educate them about their advantages?

Bednets are new in South Africa. They have been used in other countries with success. The malaria control program is introducing them Obviously there is a need to educate the public on their use and their advantage. There is also a need for the study of the knowledge, attitude and practices in the community (KAP studies) before their introduction. The malaria control program in collaboration with the Medical Research Council is busy doing this.

QCan the mosquitoes ever become immune to the insecticides? If it happens, can it be stopped? How?

Yes, the mosquitoes can become resistant or immune to the insecticides used, especially if spraying is not done properly. For example, the application of an insecticide that is below the strength on walls or roofs results in mosquitoes resting on such a wall or roof picking up a sublethal dose thus building resistance to the insecticide. This is a common problem in most malarious countries. The only solution to this problem is the replacement of this insecticide with an effective alternative one.

QDon't the insecticides cause cancer or other illnesses? If not, do they cause other side effects?

There is no proof that insecticides used in malaria control cause cancer. Some insecticides are hazardous and some irritative on the mucous membrane. The ones chosen for malaria control in South Africa are not toxic to man and other mammals. Before any insecticide is chosen for malaria control it undergoes a lot of testing to insure that it is safe. The other characteristic that is becoming important is that it must be environmentally friendly.

Q Is there any way to permanently get rid of the mosquitoes in the particular region of Africa you are focused on?

Getting rid of mosquitoes in the whole of Africa can be a mammoth task that is not likely to be achieved as nature tends to reproduce itself. Furthermore mosquitoes are not a problem unless they have been infected by the malaria parasite from man. The mosquito is only a vehicle in transmitting this parasite from an infected man to the healthy person. Getting rid of the parasites will help. However, this is also a big job that will require an intensive campaign by all countries. Most countries do not have resources just to keep malaria under control let alone mounting a campaign of such a magnitude.

QWhere does the funding for malaria eradication programs come from?

In South Africa the malaria control programs are funded by the government while in other countries donor agencies play a major role in funding.

QIf exposed to malaria and cured, can the person be reinfected at a later time?

Any person who has contracted malaria and cured of the disease is susceptible to reinfection a later time. There are many cases of people who were infected three months ago or a year ago who are falling victims of malaria again. This reflects low immunity or no immunity at all. People living in endemic areas built some immunity. If they become infected, such infection does not become severe. People living in non-malarious areas do not have immunity. If they fall victims the infection becomes severe and they can die if not treated in time.


Scientific American Frontiers
Fall 1990 to Spring 2000
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