Malaria control: the power of integrated action
Challenges and opportunities for IVM
Management: the critical "m" in IVM
The greatest hurdle to the promotion of IVM may not lie in any technical weaknesses, but rather in good management.
IVM requires the overhauling of ‘vertical’ management structures that relied solely on one form of vector control – namely, residual spraying – dating back to the malaria eradication era. In contrast, IVM involves:
- making regular assessments of local disease transmission problems;
- agreeing on decision-making criteria and on procedures to meet targets and thresholds for transmission reduction; and
- making use of the full range of vector control tools available.
Responsibilities must be allocated for various essential functions to the optimal level in the overall system (e.g. national, provincial, district, community levels). In parallel, decision-making on resources needed to finance operations must also be allocated to the optimal level. Rigorous audits through an independent quality control programme should ensure that management functions are carried out effectively.
Regulation is important to ensure that other sectors comply with standards and norms that reduce the overall environmental conditions in which vectors thrive. Sanctions and incentives are important means of enforcement, as are adequate inspection mechanisms for which capacity will need to be strengthened. Health impact assessment of new infrastructure projects can help avoid the transfer to the health sector of hidden costs resulting from development activities in other sectors.
In some cases, inspection may extend to the household level. In Singapore, for example, households were fined when breeding grounds for Aedes aegypti, the primary vector of dengue fever, were found on their premises. (See related policy briefing on Better environmental management for control of dengue.) Anne Marie, can we create an interactive link here?)
Intersectoral cooperation and IVM
IVM management strategies demand close cooperation among health, environment, water, agriculture, land use, and other sectors, as well as the overarching planning sector, from the local to the national and even regional levels. For instance, dam construction, watershed and water resource development, and irrigation schemes often represent major economic development and infrastructure investments, involving a range of national and local development actors, as well as possibly multiple countries. Therefore, a good understanding of how health and environment objectives may be incorporated into good design at the outset will be critical to the successful execution of a project that helps – rather than harms – vector-borne disease control.
Intersectoral cooperation is often extremely difficult – ministries and sectors typically work on their own programmes, and within their own budget guidelines, in parallel rather than in synergy. They may represent different political and economic interests and compete for limited resources. Collaboration will only occur systematically and regularly when the combined benefits of collaboration – social, political, legal, and economic – are greater than the benefits of competition.
At the same time, promoting greater intersectoral collaboration in vector management can have many other long-term co-benefits. Greater cooperation among health, environmental, and economic sectors is badly needed to effectively address the root causes of most environmental health risks and impacts – be they vector-borne disease, water management, agriculture, or household energy. Intersectoral collaboration therefore represents an important emerging approach to the control of a range of disease conditions.
For IVM, there are particular benefits in strengthening collaboration with the equivalent in the agriculture sector – integrated pest management (IPM). IPM not only has a long history of success, involving an evolution from a purely economics-based tool to an ecosystem management tool, but there are also a significant number of settings where IVM and IPM can achieve synergies by pooling resources and knowledge. IPM's great strength lies in the methods it developed and tested for promotion at the local level. Farmer Field Schools (FFS) have demonstrated their value as an environment for rural communities to learn – hands-on – about the ecosystem upon which their livelihoods depend. Such forums can also be used to disseminate knowledge about IVM. (For more on farmer field schools, see Priority Risks: agrochemicals; directory of resources).
Community-level awareness/action and IVM
Since integrated vector management involves making good vector control and disease control decisions in relation to local conditions community support, awareness and action are essential. For example, environmental management strategies may require a capital investment from communities as well as recurrent maintenance and monitoring by local farmers and other actors. Local technical capacities must be sufficient to support the precise and timely use of biological predators and biological or chemical larvicides, as well as the monitoring of local vector ecosystems and feedback into management strategies.
A range of social, economic, and livelihood concerns will influence community support for various IVM approaches, and must be considered as part of the total strategy picture. For instance, farmers must be guaranteed a steady supply of irrigation water if they are to agree to the periodic drainage of their fields. Conversely, older and often-successful environmental-modification measures (such as the drainage of wetlands and swamps) may today be regarded as unacceptable by environmental groups.
Nevertheless, however, the development of grass-roots technical capacities for vector management is highly compatible with the recent trend towards decentralization in government in general, and can result in greater local community empowerment overall. In general, therefore, implementing IVM strategies requires the active commitment and cooperation of local communities, technical skills at the local level, and government support/oversight. At the same time, engendering such cooperation in vector control efforts can yield important benefits in terms of local empowerment, participatory decision-making, and effective use of local knowledge and resources (23).
Applying IVM in rural versus urban settings
In tropical Africa, where malaria is most widespread, some environmental management strategies will work best in areas of relatively low and more seasonal transmission (such as urban locales and their periphery), at certain altitudes, and also at the northern and southern fringes of malaria distribution. Here, breeding sites may be fewer, more easily identifiable, and more amenable to control (15). For instance, environmental management may have potential in urban centres and port cities of Africa south of the Sahara, where large populations are aggregated on relatively small surfaces and where urban development has already degraded major vector breeding grounds (24).
At the same time, there are historical examples where environmental management has also been used successfully in highly endemic areas, such as Zambia (formerly Northern Rhodesia) to achieve impressive reductions in death and disease tolls and significant economic benefits (25,26). (See Section 5, Cost-effectiveness of IVM.)
Decision-making mechanisms that are most effective in implementing IVM may be very different in rural as compared to urban settings. For example, in urban areas, and where the public sector wields sufficient authority, use of formal regulatory mechanisms (e.g. inspections, incentives, and sanctions) may be effective in implementing IVM policies. By contrast, in more remote rural areas implementation of IVM may be more linked to effective advocacy and grass-roots community participation.
Chemical insecticides and IVM
IVM stresses a ‘hierarchy of solutions’ whereby options for improved environmental management and use of biological larvicides and control methods should be explored in light of local vector ecology and epidemiology, at least before decisions on the use of chemical insecticides are made. However, in areas of more intense malaria transmission as measured by the entomological inoculation rate (EIR), environmental management strategies may fail to reduce malaria vector densities to a level sufficiently low to affect actual disease transmission. Chemicals that reduce mosquito longevity can thus play a powerful role in interrupting the cycle of disease transmission. For those reasons, chemical control methods are likely to remain a very key component of IVM strategies in many settings. Personal protection via insecticide treated nets (ITNs), or indoor residual spraying of homes (IRS) will be critical. In general, each approach can and should reinforce the effectiveness of the other. For instance, chemical treatments often have an amplified impact on disease transmission, due to the drastic shortening of the mosquito's life cycle, which in turn limits their capacity to incubate the parasite and reinfect more victims. On the other hand, environmental management can reduce the overall ‘pressure’ to use chemicals with very long-term health and environmental impacts, such as persistent organic pollutants (POPs), which are now regulated by the Stockholm, Basel, and Rotterdam Conventions (27). In turn, less reliance on chemicals and drugs delays the build-up of vector and parasite resistance, improving their long-term efficacy in cases where they must be used. Chemical campaigns may also be costly and difficult to sustain. IVM thus may help maximize cost-effectiveness and extend the useful life of insecticides and drugs.