By: Manuel F. LLuberas MS, IDHA
Malaria is a threat to more than 40% of the world’s population. Of the more than 300 million acute annual cases, between 1.1 and 2.7 million people die each year. The vast majority of malaria cases are in sub-Saharan Africa, where children under five and pregnant women are most at risk and where the disease accounts for approximately 10% of the total disease burden. According to the World Health Organization (WHO), malaria constitutes nearly 25% of all childhood mortality. Malaria’s cost to human and social wellbeing is enormous. It is a major cause of poverty, which in turn exacerbates the malaria situation. Malaria has slowed economic growth in the continent by 1.3%, with a further compounding effect of reducing the gross domestic product by about 32% of what it would have been had the Global Malaria Eradication Campaign been completely successful in the late fifties.
Nonetheless, the end of the sixties recorded small victories, when the Global Malaria Eradication Campaign reported that malaria had been eradicated from all developed countries where the disease was endemic and large portions of Latin America and Asia were freed from the risk of infection. The impact this large-scale vector control campaign using DDT had over malaria was such that in 1970, the Committee on Research on the Life Sciences of the Committee on Science and Public Policy of the National Academy of Sciences was quoted as saying “To only a few chemicals does man owe as great a debt as to DDT. In little more than two decades, DDT has prevented 500 million human deaths due to malaria that otherwise would have been inevitable.” Over thirty years later, this statement remains valid, though the current figure could easily be well into four times what was quoted.
Countries where malaria is emerging or re-emerging as a vector-borne disease are forced to take active steps to develop and implement active control measures. Unfortunately, malaria control is affected by a number of challenges and as a result of changes in public health policy, demographic and social changes, shift in emphasis from prevention to emergency response, insecticide and drug resistance, genetic changes in pathogens and several other factors. Fortunately, effective prevention strategies through properly timed and implemented integrated vector management continue to reverse this trend and stop the spread of malaria and other vector-borne disease.
Chemical control is an important component of integrated vector management. However, the depleting arsenal of low-risk and cost-effective insecticides and lack of funding for searching for alternatives are posing a serious risk to public health, the magnitude of which has not been appreciated by the majority of national and international organizations. Moreover, wrong public perception of pesticides, mostly generated from non-public health uses, impedes the development of public-private partnerships for the development of new public health pesticide products and effective management of vector control.
The success of the integrated vector control programs against malaria vectors in the Zambian Copper Belt in the 1930s and 1940s and those of the Global Malaria Eradication Campaign of the 1960s that eradicated malaria from the United States and many other countries provide us conclusive evidence that strategically-sound and well-coordinated and designed vector management initiatives can bring about enormous tangible benefits and improved health and socioeconomic development. Unfortunately, many of these programs have fallen victims of their own successes and were discontinued or cancelled when they were viewed as unnecessary or no longer needed.
The effects of properly planned and executed integrated vector management programs can be seen once again in portions of southern Africa. In Mozambique, for instance, after “three years of sustained effort of implementing malaria vector control in the LSDI area, the overall prevalence of the disease decreased dramatically attaining the 5 year objective” of reducing malaria to less than 20% "after only three years.”
In two districts of the Copper Belt area of Zambia (Chingola and Chililabombwe), for instance, the malaria incidence in the second half of the 1990s saw a continuation of high malaria rates representative of prior decades (see Table 1.). During this period, while the National Malaria Control Program (NMCP) relied almost exclusively on the use of impregnated mosquito nets and therapeutic drugs against the disease, the Zambian Central Board of Health reported more than 2 million malaria cases in a population of just over ten million citizens and an estimated annual death toll of over 50,000 lives for the rest of the country. While public health authorities worked feverishly fighting malaria focusing on drug therapy and the promotion of mosquito net use, they were also drafted press releases attempting to explain why malaria continued. At the same time, a few private corporations in the Copper Belt area quietly restructured their RBM-based programs to include indoor residual spraying, or IRS. These programs began operating in an integrated fashion, erecting physical and chemical barriers against the vectors and the plasmodia while simultaneously seeking the support of country leaders and enlisting the assistance of the general population and the media.
By the end of the rainy season of 2003-2004 the IRS campaign Copper Belt had reduced the malaria incidence rates in Chililabombwe and Chingola by approximately 73% as compared to the same period in 2000. In fact, the program saw the “lowest malaria figures in 10 years” according to the Malaria Control Program Technical report for 2004 of the Konkola Copper Mines –see Table 2. Moreover, the programs have been instrumental in reducing the rate of absenteeism and increasing productivity in several copper mines.
The success of malaria control program in the Copper Belt region inspired the national malaria control program to adopt the Copper Belt model and implement it at national level. Together, Zambia’s public and private sector, including H.D. Hudson Manufacturing Company, have joined hands to fight malaria with very positive and tangible results. The results of this partnership are so encouraging (publications are in progress) that several countries in southern Africa are considering using it as the template for collaboration.
In addition to the obvious challenges inherent to this type of collaboration, the introduction of residual insecticide applications brought with them challenges and opportunities unfamiliar to many. This was especially evident when DDT was added to the vector control arsenal. In light of the restrictions and limitations imposed by the Stockholm Convention on Persistent Organic Pollutants of December 2000 (POPs), specific information pertaining to the procurement, handling, transport, use and disposal of DDT, empty shipping containers and DDT-contaminated rinse water were incorporated in the indoor residual spray team training conducted prior to the beginning of each malaria control season. The goal of this training was to ensure that all team members and supervisors understood the POPs Convention’s implications and were able to answer basic inquiries from the general population benefiting from their activities. In addition, steps and procedures were instituted to enhance personal and environmental safety precautions, minimize the chances of inadvertent or accidental release of DDT in unwanted areas and reduce the risk of unauthorized use of the insecticide.
The integrated malaria vector control programs implemented in Zambia and other parts of southern Africa have provided tangible proof that a properly timed and managed, integrated vector management program with an indoor residual spray component is effective in bringing malaria to a manageable level. These programs provide hope to the countries where they have been implemented and to the surrounding countries also afflicted by this devastating disease that have not been able to implement their own programs.
The long history of the hostilities between man and vector provide us with many powerful examples of the successes of properly managed and oriented vector control programs. Vector management professionals need to be proactive in promoting their activities and dispelling the myths and common misconceptions associated with the use of insecticides for vector control. Only then we will be able to reduce the impact of these dreadful diseases. das com a malária.