330 - Adapt mosquito nets for better malaria control
Malaria is the world’s most widespread parasitic disease and is both a cause and a consequence of poverty. It kills between one and three million people every year and the African continent suffers 90% of the deaths caused. The pathogens are parasites of the genus Plasmodium transmitted to humans by mosquitoes of the species Anopheles . As a system for guarding against these insects, insecticide-treated mosquito nets are still the best means of control.
Previous studies have shown the effectiveness of public awareness raising campaigns and free distribution of mosquito nets to encourage people to use them. However, no long-term assessment of their utilization had hitherto been conducted. Research scientists from the IRD and the Centre Muraz/Institut de Recherche en Sciences de la Santé (IRSS )(1) recently showed that this positive effect was waning after only a few months. What are the causes of this decline? The perceived limited usefulness of nets and the daily inconvenience of putting them up in restricted spaces in rooms used differently during daytime and at night.
Malaria is a major public health problem which affects between 300 and 500 million people per year. More than 2 million deaths are recorded every year 90% of which hit Africa where it is the primary cause of mortality of infants between birth and five years of age. There are many obstacles to efforts to push back the disease: genetic and biological diversity among the mosquito vectors and the parasites transmitted, the absence of a vaccine, the emergence of vector resistance to insecticides and parasite resistance to medical treatments.
Promoted by the WHO, insecticide-treated mosquito nets, impregnated using a process developed by IRD researchers and the Muraz Centre in Burkina Faso, have already proved their effectiveness against the main malaria vector, Anopheles mosquitoes. However, this efficiency depends on the correct constant use by the people concerned. Previous studies have shown that the level of education, access to health care, and the economic situation and socio-cultural context influence the use of these nets. Other surveys have brought out the positive effect of awareness-raising campaigns and free distribution. Yet the short or long-term impact of these campaigns had hitherto never been assessed. Research scientists form the IRD and the Muraz Centre / Institut de Recherche en Sciences de la Santé (IRSS) of Burkina Faso (1) recently demonstrated that they do not guarantee sustained use of mosquito nets.
A three-year study by sociologists, in the village of Soumousso in an endemic malaria zone in the south-west of Burkina Faso, revealed that one in every three persons stop using the nets within less than one year. Insecticide-treated nets (ITNs) were distributed at the beginning of the rainy season in May, to all heads of family and their wives. The medical team then explained to the public what malaria is, how it is spread and the crucial role of mosquito nets. They also stressed how fatal the disease could be.
Throughout the three-year survey, day and night time observations were made of the arrangement of space in the household after installation of a mosquito net in 200 houses. Finally, every month they interviewed about 100 men and women aged between 15 and 60 years. After six months, one-third of the people who had benefited from a treated net no longer used it.
Adapt mosquito nets to living space arrangements
Everyday use of the nets therefore appeared to be constricting. Houses only have one or two rooms. During the day, mats are put away along a wall whereas the kitchen utensils, condiments and food are kept in different parts of the room. At night, the objects are placed in corners and the mats are spread in the middle. It is therefore not easy to leave the mosquito net hanging during the day, and there is the added inconvenience of fire risk from the cooking stove.
At night the spatial arrangements are made according to specific social rules: the young men sleep in one space, while younger children and young girls sleep near their mother. Allocation of mosquito nets to the most vulnerable members of the family (pregnant women, the under-fives) can therefore disturb these social models.
One disease, several names
The inhabitants of Soumousso use several terms in Dioula (2) to translate the word “malaria”. In their representations the signs of the illness are attributed to various other diseases: Sumaya , sumaya gwe , or again djakadjio are the most common. Sumaya , for example, in reality translates a straightforward cold with high temperature and headache, common symptoms also of malaria. Confusion also exists about the modes of transmission. Local acceptance takes it that a person can contract sumaya not only from a mosquito bite but also during cold weather, or if people eat certain food and so on. However, those who have had school education know that the disease is transmitted only by bites of female Anopheles .
Mosquitoes are therefore not considered as the sole causes of malaria, and inhabitants do not feel completely protected by the mosquito nets. Moreover, they use them more against the nuisance from insects, not against the disease.
This study shows how sustained use of ITNs is much more complex than that of awareness-raising campaigns had initially anticipated. Understanding of what determines the choice of whether or not to protect oneself is essential for setting appropriate measures in place and encouraging the long-term use of mosquito nets. The research carried out indicates the necessity to create a framework for dialogue between medical care personnel and the people and make mosquito nets more convenient for use by taking account of the way households organize their living space.
1. These studies were conducted jointly with research scientists from the Muraz Centre at Bobo-Dioulasso in Burkina Faso, INSERM, Intelligent Insect Control (IIC) in Montpellier, the Institut Pierre Richet at Abidjan in the Ivory Coast, CIRAD and the Cotonou Centre de Recherche Entomologique (CREC) in Benin.
Rédaction DIC – Gaëlle Courcoux