Status of pesticide management in the practice of vector control: a global survey in countries at risk of malaria or other major vector-borne diseases

Malaria and other vector-borne diseases continue to inflict a major burden on human populations [1‐3]. The control of malaria has been intensified in the last decade, relying to a substantial degree on the action of chemical pesticides to control vector populations or reduce disease transmission. It is critical that these vector control pesticides are used for their acceptable purpose without causing adverse effects on health and the environment. The International Code of Conduct on the distribution and use of pesticides, hereafter referred to as the Code of Conduct, provides voluntary standards for all public and private entities engaged in, or associated with, the distribution and use of pesticides, and serves as a globally-accepted standard for pesticide management [4].

Countries at risk of malaria and/or other vector-borne diseases, however, face major challenges in managing vector control pesticides and other public health pesticides, which include pesticides for use by households and pest control operators [5]. The challenge is greatest under decentralized health systems. Many countries, even those with long-standing vector control programmes [6], lack capacity to regulate availability and use of the pesticides for vector control purposes. Proper management of pesticides throughout their life cycle, from product development to waste disposal, requires legislation, regulatory control, operational guidelines and procedures, criteria, training, safety measures, quality control, informing the public, and evaluation [7].

The state of implementation of the Code of Conduct with a focus on agricultural pesticides has been reported in 1993, 1996 and 2008 [8‐10]. The results suggest that in the past 15 years there has been progress in some areas, such as data collection, labelling, storage and the establishment of poison control facilities. However, little progress was reported in pesticide quality control, removal of hazardous products from the market, integrated pest management, resistance management, monitoring of adverse effects, and safe disposal of pesticide-related waste.

Comparable studies on management of public health pesticides have been lacking. A preliminary study on public health pesticides conducted in 2003 indicated various shortcomings in countries, but the scope of the questionnaire was rather limited and the coverage modest, with 71 responding countries [11]. Based on the experience of the preliminary study, an improved and a more comprehensive study was conducted with the aim to provide an overview of the global status on management of public health pesticides. The purpose was to inform future plans on the optimization and harmonization of public health pesticide registration procedures and post-registration regulation among countries, and to assist countries in developing strategies and action plans for strengthening capacity on pesticide management.

This paper reports on part of the questionnaire, which relates to the practice in vector control (Figure 1); a separate paper reports on legislation and regulatory control [12]. In-depth assessment of specific aspects or quantitative comparison between Regions or countries was beyond the scope of this assessment.

The questionnaire had been developed through a consultative process of the World Health Organization (WHO), with field testing in selected countries and peer review [13]. Countries targeted were those member states of the WHO, territories excluded, which are endemic with or at risk of malaria or one of the other major vector-borne diseases, i.e. lymphatic filariasis, dengue, leishmaniasis, Chagas disease, and Japanese encephalitis. Hence, the study excluded most of the European countries (except for 6 countries), North America, Japan, Australia and New Zealand.

The questionnaire was distributed through six WHO Regional Offices to 142 countries [13]. The questionnaire was translated into three languages; the English version was administered to most countries except where the French or Spanish version was preferred. Focal points for malaria and other vector-borne diseases in WHO representative's offices facilitated the data collection in each country through the ministry of health. The part of the questionnaire addressed in this paper was completed by, either, the director of the vector-borne disease control programme, or the national manager for vector control. Most questions relate to vector control pesticides but a few questions refer more generally to public health pesticides (Table 1).

The questionnaire consisted mostly of logical choices between two options (yes/no), but for a few questions there were more options. Responses were entered into a computer spread-sheet. Some open questions were used to further clarify or verify the practices reported but the responses were not included in the analysis. In several cases where the respondent selected more than one option or failed to respond, that record was excluded from analysis.

In the analysis, all targeted countries were given equal weight, irrespective of country size or disease burden, because the focus of the study was on pesticide management at the national level. Country responses were examined per Region.

In total, 113 countries responded to the questionnaire, showing an 80% response rate (113/142). In terms of human population, these countries represented 94% of the population in all countries targeted, based on demographic data for 2008 [14]. Consequently, the 29 non-responding countries had relatively small populations. Response rates per Region were 65% for the African (30 countries out of 46 targeted), 85% for the American (28/33), 81% for the Eastern Mediterranean (17/21), 83% for the European (5/6), 73% for the South-East Asian (8/11), and 100% for the Western Pacific Region (25/25). The relatively low response rate from the African Region was mainly attributable to logistic issues in some countries.

The aggregated results of the questionnaire show a high variability in the positive responses to each question (Table 1), with 103 to 110 countries responding to individual questions. The aggregated results were used to highlight areas of concern and to suggest steps which could be taken by countries to improve pesticide management. The areas of concern were grouped under seven themes subjected to closer examination in the following sections.

These results show the global situation on the management of pesticides in the practice of vector control, serving as baseline for future initiatives to strengthen the management of vector control pesticides. The survey is exceptional in its high coverage of populations at risk of malaria and other major vector-borne diseases.

The study had several limitations. It was assumed that respondents represented institutional memory, but their actual period in office could have limited the accuracy of their responses. The questionnaire did not allow for qualified statements and in-depth interpretation of results. Moreover, the choice to count all countries as equal, rather than weighting country responses according to population size or disease burden, may have introduced a bias; e.g. if large countries have better developed pesticide management systems than small countries. This problem was partly circumvented by examining the country responses per Region; e.g. with the South-East Asian Region consisting of few but large countries, or with the African Region consisting mostly of highly endemic countries.

It is encouraging to observe that several basic conditions of policy and coordination for pesticide management have been established in many countries, which are: the use of the Code of Conduct, a national IVM policy, a national vector control unit, and statistics on pesticide usage. These conditions are indicative of a country's strategy or prospect for improving pesticide management in the practice of vector control.

Nevertheless, the results have exposed some major gaps in pesticide management globally, in particular in the areas of procurement, training, pesticide application, safety and disposal. Also, the authors have noticed that there are different perceptions of the IVM concept in the Regions.

Regarding pesticide procurement for vector control programmes, national guidelines are absent in half of the countries, after-sales stewardship commitment of the manufacturer not required in almost half of the countries, and quality control not required by some countries. Positive aspects are that procurement is mostly through the ministry of health and is often conducted through public tenders. These are conditions through which procurement procedures could potentially be improved, for example by incorporating stewardship commitments on training of applicators on low-risk and appropriate use and safe disposal of waste.

Training on decision making and implementation of vector control is another area of concern, which will be most acute in situations where decision making has been decentralized to the district level. In some countries, none of those responsible had received any training on vector control or public health pesticide management. In its handbook on IVM, the WHO proposes ways to improve the efficacy, cost-effectiveness, ecological soundness and sustainability of vector control [16]. Means to achieve this are an increasing emphasis on local evidence, adoption of a multi-disease approach, and combining vector control interventions wherever appropriate. Processes through which this could be achieved are the integration within the health sector, collaboration between sectors and participation of communities. Clearly, training investment is required, including on pesticide management, to generate skills of analysis, decision making and facilitation at the national, district and village level.

All chemical pesticides are inherently toxic to humans, and precaution is required to minimize exposure and adverse health effects. Applicators and handlers of pesticides may have a particularly high exposure risk if not protected, especially in tropical climates where use of protective equipment is often lacking owing to personal inconvenience. Further study is needed to determine the coverage, quality, use and maintenance of personal protective equipment in relation to the degree of hazard of pesticides used.

Health monitoring of vector control pesticide applicators is not being given due attention in most countries, highlighting another gap. Under the Code of Conduct, governments are obliged to carry out health surveillance programmes of occupationally exposed workers, and to investigate and document poisoning cases. Furthermore, certification schemes for pesticide applicators and national scheme for quality control of equipment for vector control pesticide application were missing in the majority of countries.

Public awareness programmes, lacking in the majority of countries, are needed wherever pesticides are applied in or around houses to promote people's compliance with the interventions. Furthermore, safe disposal of pesticide-related waste was inadequately addressed in the majority of countries; while governments and industry are obliged under the Code of Conduct to cooperate on this topic with the industry to provide stewardship support.

Since 2002, the WHO, through its Pesticide Evaluation Scheme, has expanded its support to member states in the low-risk and judicious use of public health pesticides and their sound management. The survey results show that WHO's recommendations and standards were adopted by most countries, indicating an important advisory and technical support role of the Organization in the management of vector control pesticides globally [12].

The gaps identified in this study highlight the need for further action. Foremost, awareness-raising is needed for policy makers and programme managers about the urgency of good pesticide management and evidence-based decision making within malaria vector control programmes. The WHO has begun to assist a number of countries in conducting an analysis on the national situation on public health pesticide management, and in preparing national action plans to address shortcomings [19, 20]. Nevertheless, countries need to mobilize resources and build capacity to implement those plans. International agencies should assist countries in developing policies and adopting international guidelines, facilitate regional collaboration (e.g. on insecticide resistance monitoring) and offer support for capacity building on pesticide management as component of IVM.

Given the gaps in pesticide management identified in this study, the effectiveness and safety of vector control pesticide use are clearly being undermined in many countries. This inevitably results in wastage of resources, sub-optimal effectiveness of interventions and adverse effects on human health and the environment. The urgency of the situation is emphasized by the recent rise in pesticide use for malaria vector control in countries that have scaled up interventions [1]; a development that has not necessarily been accompanied by investment in pesticide management. Therefore, capacity building on pesticide management and evidence-based decision making within the context of an IVM approach should be incorporated in any malaria vector control programme and should become a condition for support on vector control given by donors and funding agencies.