Bulletin of the World Health Organization

Reducing vector-borne disease by empowering farmers in integrated vector management

Henk van den Berga, Alexander von Hildebrandb, Vaithilingam Ragunathanc, Pradeep K Dasd

Background and context

Malaria and other vector-borne diseases are a major public health problem in WHO’s South-East Asia Region.1 In the wake of increasing resistance to both drugs and pesticides, there is a need to establish integrated vector management strategies that are less reliant on chemical methods of disease control. These strategies should involve other sectors and local communities in managing the ecosystem to reduce health risks and increase the sustainability of programmes to control vector-borne diseases.2,3

There is an opportunity for integrated vector management strategies to exploit tropical agriculture’s rich experience in integrated pest management strategies. Briefly, integrated pest management that uses the “farmer field school” approach entails providing practical, field-based education to farmers during weekly meetings. During these sessions farmers acquire the skills needed to analyse their ecosystem and make evidence-based decisions to grow healthy crops while relying less on agrochemical inputs.4,5 Special attention is given to developing communication skills and strengthening farmers’ groups. The farmer field schools that address rice farming commonly result in immediate farm-level benefits in terms of reductions in the use of agrochemicals and in developing stable or increased yields; they are a proven entry point for farmer-driven development.6 Farmer field schools were introduced in Sri Lanka in 1995, and were scaled up in 1999–2002, when almost 1000 field schools were held. Technical assistance was provided by the Food and Agriculture Organization (FAO) of the United Nations. An 82% reduction in frequency of insecticide applications and a 23% increase in yield have been attributed to training, and these results proved durable during a period of five years.7,8

A pilot project on integrated pest and vector management that started in Sri Lanka in 2002 has been unique in educating farmers about agriculture and public health by involving farmers in vector-management activities.9 Project funds have been limited and funding sources diverse. The FAO facilitated the project and provided the initial grant of US$ 35 000, which was the only source of external funding during the first three years (Phase I). The United Nations Environment Programme provided US$ 56 500 during 2005–2007 (Phase II), and WHO supported an evaluation mission in 2006.

The project has several institutional partners. The central-level Plant Protection Service of the Department of Agriculture, part of the Ministry of Agriculture, conducts technical coordination. The Department of Agriculture Offices at the district level and the Mahaweli Authority, which governs major irrigation schemes, implement the field schools. The Department of Public Health’s Anti-Malaria Campaign, part of the Ministry of Health, has assisted in curriculum development and monitors mosquito populations.

This paper is based on the findings of an evaluation mission in June 2006, commissioned by WHO’s Regional Office for South-East Asia, to determine the effectiveness, sustainability and replicability of the integrated pest and vector management approach in the context of implementing WHO’s integrated vector management strategy.10 Data were obtained through field visits, discussions with farmers and other stakeholders, and unpublished records and reports.

The problems

At the field level, irrigated agriculture poses several public health risks associated with vectors of human disease and the use of pesticides for agriculture and to protect public health. Paddy fields, irrigation systems and peridomestic environments facilitate breeding of vectors of malaria, lymphatic filariasis, Japanese encephalitis and dengue.1115 Additionally, the use of insecticides may cause acute poisoning and leave toxic residues in food;16,17 resistance may develop in vector populations against the insecticides used for control;18,19 and biodiversity may be degraded, which may contribute to a resurgence of mosquitoes.20,21 Therefore, convergence is needed between integrated pest management strategies and integrated vector management strategies to help farmers improve their agricultural practices while minimizing environmental risks to health. However, the intersectoral collaboration required to jointly address environmental health risks is lacking in most developing countries.

An international workshop facilitated by the United Nations Environment Programme provided the basis for intersectoral project development in Sri Lanka. The triggers were the Stockholm Convention on Persistent Organic Pollutants, the Bahia Declaration of the Intergovernmental Forum on Chemical Safety and World Health Assembly resolution WHA-50.13, all of which call on countries to develop viable alternative strategies for controlling vector-borne diseases, particularly malaria, and to reduce reliance on insecticides through the promotion of integrated pest-management approaches.

Addressing the problems

At a project-inception workshop held early in 2002, multisectoral stakeholders agreed upon objectives and a course of action. Subsequently, field-based workshops were held where trainers in integrated pest management and vector specialists learned from each other about vector ecology, agro-ecology and environmental management options. As curriculum development began, surveys on farmers’ knowledge and perceptions were used to tailor the curriculum to meet local needs. Field-testing was done and improvements made to new exercises on sampling methods, identifying mosquitoes, the breeding habitat, the life-cycle of the mosquito, predators of mosquitoes and the disease cycle. The end result was a field school curriculum on integrated pest and vector management that differed from that on integrated pest management.10 The duration of the field school was increased from 16 weeks to 20 weeks; the vector management component focused on the beginning of the season, when most vector breeding occurs.

The field schools were implemented during both the long rainy season and the short rainy season; in recognition of the flight radius of vector mosquitoes, the schools were clustered within villages to achieve area-wide effects. Alumni of the new field schools were guided in techniques of problem analysis and in planning exercises to assist them in taking action.

By mid-2006, the project has held 67 farmer field schools on integrated pest and vector management (with 20–30% of participants being women) involving 1000 families of farmers in 11 locations. The Anti-Malaria Campaign conducted fortnightly mosquito surveys in two locations during the course of the project to monitor its impact. Each location had an intervention and comparison village separated by 2–4 km, in line with the maximum flying range of 2–3 km for Anopheles mosquitoes.13,22

Central-level workshops have been held every season since 2002 to assist in the evaluation and planning of field activities. The project has supported field experimentation by trainers and farmers to study interactions between agricultural practices such as the use of fertilizer and vector breeding. A part-time national expert was recruited in 2005 to assist in coordinating the project.

Field visits and group discussions in 2006 revealed that field school alumni were able to distinguish between beneficial and harmful insects, and to identify larvae and adults of three vector mosquito genera (Anopheles, Culex, Aedes). Alumni had acquired the skills necessary to analyse their agricultural and peridomestic environments and make locally appropriate decisions to manage vectors, pests and crops.

Alumni reported that they applied insecticide less frequently during rice production as a result of becoming more aware of adverse effects. Common vector-control actions that contributed to reducing local risk were eliminating breeding sites, rearing fish for household use, cleaning surroundings, applying mineral oil to bodies of water, covering water containers and using bednets. The field school generated visible enthusiasm and self-confidence among farmers. At one site, field school alumni had reportedly approached the Anti-Malaria Campaign office to learn about vector-borne diseases. Nevertheless, the monitoring and evaluation framework needs to be strengthened to ensure evidence-based recording of the project’s performance.

A separate study by Yasuoka et al. verified an impact on knowledge, agricultural practices and vector-control actions that were attributable to the integrated pest and vector management intervention.23 The study also reported a 60% increase in the use of bednets, also attributable to the intervention, indicating there was an increased awareness about personal protection. The same researchers suggested that the role of farmers in vector management was most important during the short rainy season, when ecosystem management is associated with reduced densities of anopheline mosquitoes, thus providing an opportunity to interrupt local transmission of malaria.24 However, the effect of the intervention on malaria transmission in areas where Anopheles (Cellia) culicifacies is more common remains to be studied. This species is considered to be the major malaria vector in Sri Lanka and has a preference for breeding in temporary pools and semiprotected wells.25,26 Measuring the impact of the intervention on disease burden was beyond the scope of the pilot project owing to the limited scale of field operations. Data on the use of insecticides for public health protection were not available.

Discussion

The integrated pest and vector management strategy has helped farmers to minimize the use of agrochemicals, particularly insecticides; to improve agronomic practices; and to reduce health risks associated with vector-borne diseases and pesticides. Alumni from the farmer field school were motivated to take part in vector-management activities (Box 1). As the local evidence base expands, the curriculum could also emphasize the use of fertilizers, crop rotation and larvivorous fish for vector management.2729 Moreover, there is scope for expanding the curriculum to cover the health effects of pesticides, using exercises in participatory monitoring of signs and symptoms of poisoning,30 and by extending farmers’ knowledge of rice farming to other local crops that are sprayed with insecticides.

Box 1. Lessons learned

Role of farmers: The farmer field school intervention focusing on integrated pest and vector management motivates and enables rural people to take part in vector-management activities in their agricultural and peridomestic environments. It also helps reduce the agricultural use of insecticides and reliance on pesticides to protect public health.

Curriculum: There is scope to expand the curriculum to cover the health effects of pesticides.

Role for the health sector: Benefits of the intervention for other community-based health programmes that relate to vector-borne disease and the use of pesticides need to be further developed. This could be done, for example, by involving communities in the surveillance of vector populations and local health staff in farmer field school sessions.

Institutional basis: Extending the institutional basis by involving more organizations in integrated pest and vector management will be essential to allow this interdisciplinary approach to progress beyond the pilot stage. A more efficient monitoring and evaluation system needs to be integrated into the project.

The sectors of agriculture and health, despite their differing goals of raising agricultural productivity and reducing health risks, share the objective of enhancing the role of rural communities in providing sound management of the local ecosystem (Fig. 1). This provides a motive for collaboration. Convergence between the activities of the health and agriculture sectors during the project’s first year resulted in effective cross-sector learning and a joint process of curriculum development. In the implementation phase, however, the surveillance activities by the Anti-Malaria Campaign were not integrated with the activities of the field school. Convergence was limited to holding seasonal joint workshops. A lesson learned is that field-level integration requires better synchronization of the Anti-Malaria Campaign’s surveillance with weekly field school activities to allow for interaction and mutual learning; regular district-level forums for local stakeholders are also desirable. Also, finding ways to increase the participation of local health staff needs to be addressed. The Anti-Malaria Campaign plans to adopt the integrated pest and vector management strategy to prevent malaria in areas of low transmission since there is an apparent additive effect between the use of bednets and the strategy.

Fig. 1. How a shared objective contributes to sector-specific goals in agriculture and health
Fig. 1. How a shared objective contributes to sector-specific goals in agriculture and health

The health sector’s current surveillance system, which is constrained by limited resources, could benefit from community participation by developing local capability in monitoring and evaluation. Benefits of community-based surveillance are twofold: it provides better coverage and intervals for data collection, allowing for the more accurate and timely targeting of interventions, and it contributes to a local feeling of project ownership, enhancing preventive community action and personal protection. Increasing the participation of the health sector in integrated pest and vector management initiatives would further improve the performance of community-based health programmes.

Another lesson learned is that potential stakeholders – at the policy level, senior level and district level – need exposure to the strategy (Fig. 1, Fig. 2). Extending the institutional basis by involving more organizations in integrated pest and vector management is essential to achieving greater acceptance of the multisectoral approach. This would allow it to progress from an externally funded pilot programme to one supported by the national budget. For example, the strategy could be used as an interdisciplinary topic for project-based education in secondary schools.

Fig. 2. Present and potential stakeholders of the integrated pest and vector management strategy<sup><sup>a</sup></sup>
Fig. 2. Present and potential stakeholders of the integrated pest and vector management strategya

In addition to its suitability under Sri Lankan conditions, the integrated pest and vector management approach is potentially replicable in other countries and other regions. It is as an adaptive educational approach that may initially focus on situations where vector-borne diseases are associated with irrigated environments for growing rice. The integrated pest and vector management approach could play a key part in meeting the global action goals of the Strategic Approach to International Chemicals Management. ■


References

Affiliations

  • Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH Wageningen, the Netherlands.
  • Environmental Health, WHO Regional Office for South-East Asia, New Delhi, India.
  • Food and Agriculture Organization, New Delhi, India.
  • Vector Control Research Centre, Pondicherry, India.
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