Scale-up of integrated malaria vector control: lessons from Malawi

Abstract Problem Indoor residual spraying and long-lasting insecticidal nets (LLINs) are key tools for malaria vector control. Malawi has struggled to scale up indoor residual spraying and to improve LLIN coverage and usage. Approach In 2002, the Malawian National Malaria Control Programme developed guidelines for insecticide treated net distribution to reach the strategic target of at least 60% coverage of households with an LLIN. By 2005, the target coverage was 80% of households and the Global Fund financed the scale-up. The US President’s Malaria Initiative funded the indoor residual spraying intervention. Local setting Malawi’s entire population is considered to be at risk of malaria. Poor vector control, insecticide resistance in malaria vectors and insufficient technical and financial support have exacerbated the malaria burden. Relevant changes Between 2002 and 2012, 18 248 206 LLINs had been distributed. The coverage of at least one LLIN per household increased from 27% (3689/13 664) to 58% (1974/3404). Indoor residual spraying coverage increased from 28 227 to 653 592 structures between 2007 and 2011. However, vector resistance prompted a switch from pyrethroids to organophosphates for indoor residual spraying, which increased the cost and operations needed to be cut back from seven to one district. Malaria cases increased from 2 853 315 in 2002 to 6 748 535 in 2010, and thereafter dropped to 4 922 596 in 2012. Lessons learnt A single intervention-based approach for vector control may have suboptimal impact. Well-coordinated integrated vector management may offer greater benefits. A resistance management plan is essential for effective and sustainable vector control.


Introduction
Malaria remains an important cause of morbidity and mortality. Approximately 214 million malaria cases and 438 000 malaria-related deaths were reported globally in 2015. The highest burden is seen in sub-Saharan Africa, where over 88% of all malaria episodes and 90% of all malaria-related deaths occur. 1 The huge malaria burden in sub-Saharan Africa has been partly attributed to the presence of efficient vectors that maintain high levels of transmission. 2 For vector control, the World Health Organization (WHO) recommends integrated vector management. 3 Important pillars of the integrated vector management framework are insecticide treated nets and indoor residual spraying (hereafter referred to as indoor spraying). 4 In Malawi, malaria control includes early definitive diagnosis of febrile cases by microscopy or use of a rapid diagnostic test, treatment with artemisinin-based combination therapy and the use of long-lasting insecticidal nets (LLINs), indoor spraying and intermittent preventive treatment. 5 This paper describes the approaches used to scale up vector control in Malawi, the challenges encountered, the lessons learnt from this experience, and how these lessons have informed vector control efforts.

Local setting
Malaria is endemic across Malawi and the entire population is considered to be at risk of the disease. 5,6 Transmission of the causative parasite is high -more than one case per 1000 residents -and perennial with substantial seasonal variation in transmis-sion intensity. 5 The main vectors are Anopheles gambiae sensu stricto, A. arabiensis and A. funestus. 7 To improve malaria control in the country, the Malawian National Malaria Control Programme was established in 1984. The programme's tasks are to set policies, institute strategies, coordinate, monitor and evaluate activities, provide technical assistance and mobilize resources for malaria control. The first two national malaria strategic plans (1984-1989 and 1990-1994) that the programme developed had a focus on effective disease management. 8 Since 1997, the programme has been distributing insecticide treated nets to children younger than five years and pregnant women countrywide. 5 The vector control interventions of the programme remained small in scope and scale until 2007 when LLINs were delivered on a large scale. In 2010, the programme scaled up the coverage of indoor spraying.

Approach Policy and guidance
To facilitate reaching the target of 60% household coverage by 2005, set in the 2000-2005 strategic plan, the programme developed guidelines in 2002 for distribution and use of insecticide treated nets. In the following strategic plans, the target was raised to 80% household coverage by 2010 8 and then further raised to 90% of households owning at least one net and net usage to 80% by 2015. Integrated vector management and indoor spraying were introduced in the 2006-2010 strategic plan but were only consolidated during the 2011-2015 strategic plan. 9 Programmatic implementation of integrated vector management began

Delivery mechanisms
The programme ran time-limited, intermittent mass distribution campaigns. Mass campaigns were conducted every three years and aimed at achieving coverage of one net for every 1.8 people. 9 Planning and implementation of campaigns involved trained community health workers, government sister ministries and departments, nongovernmental organizations, private sector and civil societies. Before the campaign, communities were identified and households within these communities were registered and household members counted. Householders received education on how to hang, use and maintain the nets. The campaign used both door-to-door and centralized distribution approaches. If needed, mop-up campaigns followed each mass distribution. Nets were also distributed during the provision of routine health services, particularly to pregnant women and mothers of newborns who were attending clinics associated with the Expanded Programme on Immunization or antenatal care.
Using the pyrethroid lambda-cyhalothrin, the programme piloted indoor spraying in the Nkhotakota district in 2007. The indoor spraying was later expanded to seven districts with the plan of scaling up to 12 of the 28 Malawian districts by 2015. 10 The programme aimed to ensure coverage of at least 85% of all structures in targeted districts. Entomological surveillance and resistance monitoring were done to inform decisions on vector control taken by the programme. 11,12

Community sensitization and mobilization
During World Malaria Day, the malaria commemoration week and the mass distribution campaigns, the programme conducted public awareness and social mobilization campaigns to create awareness, promote behavioural change and community participation and engagement. The mass media and interpersonal communication channels were used to disseminate advocacy, behavioural change and information and education communications. To ensure that the materials for both electronic and print media addressed current needs, the materials were updated between every round of the campaign. Unfortunately, the periodic educational communications were hampered by socioeconomic and political factors, cultural aspects, irregular reviews, and limited funds for production of materials. In addition, the lack of formative research on effective methods to conduct communication further compromised the dissemination of information. 9,13 In 2002, A. arabiensis was reported to be resistant to dichlorodiphenyltrichloroethane (DDT), but still susceptible to pyrethroids and organophosphates. 14 However, in 2010, this species showed resistance to pyrethroids. 10 Since 2010, A. funestus has also been shown to be resistant to pyrethroids and carbamates across the country, which led the programme to switch from pyrethroids to organophosphates for indoor spraying in 2011. 15 The programme reduced the indoor spraying to only one district (Salima) in 2014 due to the exorbitant cost of organophosphate insecticides. 10

Challenges and lessons learnt
The vector control implementation faced several challenges ( Table 1 ). The suboptimal LLIN coverage and use of nets coupled with alleged abuse of LLINs, are probably some of the explanations why the programme has not been as effective as anticipated. Another explanation could be that indoor spraying had to be scaled back due to insecticide resistance. The community sensitization, participation and ownership were sporadic resulting in refusals or low compliance with existing interventions. 9,13 Supplementary interventions such as larval source management were not deployed due to lack of technical capacity. The technical design for the procurement of commodities and equipment was inadequate, including lack of consensus among stakeholders on using DDT for indoor spraying in selected areas with susceptible vectors and suboptimal information sharing regarding entomo- Table 1

. Challenges and risks encountered in integrated vector management and recommendations for improvement in Malawi, 2002-2012 Key element Challenges and risks Recommendation
Advocacy, social mobilization and legislation Inconsistent community sensitization and mobilization, and low compliance, ownership and involvement in malaria vector control activities.
Conduct IEC/BCC campaigns, reinforce/mobilize community engagement and empowerment for participation and adopting relevant policies and ensuring legislation on vector control. Irregular IEC/BCC reviews and planning meetings, limited funds for production of IEC materials, IEC messages are available in limited languages. BCC has been focusing on creating awareness but not on behaviour change.
To create awareness and promote behaviour change, collaborate with the Health Education Unit, community radio stations and use the World Malaria Day and SADC malaria weeks. Low coverage and use of vector control interventions, occurrence of net misuse and low LLIN availability at ANC clinics and EPI services due to stock outs.
PMI to continue to fund national mass and print media campaigns to increase awareness, promote correct and nightly ITN use, and proper care and repair. Follow-up to ensure that ITN supplies are available at all facilities. Collaboration within the health sector and with other sectors Lack of consensus among stakeholders on the use of DDT for IRS, LSM and disposal mechanism for old LLINs.
Establish a national steering committee on IVM to ensure broader stakeholder engagement and strengthened intraand inter-sectoral collaboration. Minimal collaboration between academic/scientific institutions and health ministry on entomological resources, including insecticide resistance and vector bionomics.
Establish a multidisciplinary decision-making body for entomological resources to make technical recommendations and give advice on vector control.
Poor financial resources hindering the scale-up of some interventions.
Strengthen cooperation among stakeholders and advocate for political commitment to mobilize resources.

Integrated approach
Lack of consistence in timely deployment and scaling up of key vector control interventions to achieve universal coverage.
Update guidelines and policies for LLINs distribution and IRS implementation and ensure their universal access. Implementing evidence-based, cost-effective and sustainable interventions. Supplementary interventions, such as using larvicides and biological control, have not been implemented.
Develop requisite competences for deploying supplementary tools where feasible and mobilize the needed resources. Limited collaboration with other vector borne disease control programmes, such as lymphatic filariasis programme.
Strengthen collaboration with other vector control programmes and explore synergies for targeting different vectors. Evidence-based decisionmaking Absence of comprehensive malaria transmission data and minimal use of existing entomological data for decisionmaking for vector control.
Develop and implement a vector and epidemiological surveillance plan/system, establish sentinel sites and strengthen operational research and monitoring and evaluation to guide the scale-up of interventions. Emergence and spread of pyrethroid and carbamate resistance in malaria vectors have the potential to diminish the effectiveness of IRS and LLINs.
Conduct well-coordinated and intensive surveillance for insecticide resistance data to inform evidence-based response. Irregular insecticide resistance monitoring and management with limited documentation.
Develop and implement an insecticide resistance monitoring and management plan/strategy to facilitate vector resistance mapping and rational decision-making. Limited LLIN durability monitoring to inform replacement and innovation, nominal data preference of conical to rectangular-shaped nets that could affect use and retention of ITNs.
In Chikhwawa, ITN durability study suggests a high proportion of nets were heavily damaged and need replacement. Specific questions on net shape preference were included in the 2014 MIS to address concerns. There is inadequate information sharing between stakeholders for timely decision-making.
There is a need to establish a forum for research dissemination by all partners.

Capacity building
The number of entomologists is limited and only minimal capacities for entomological laboratory, infrastructure and logistics exist for vector management activities.
Build requisite institutional capacity for planning and implementing effective malaria vector control.
Delays in disbursement of funding from the Global Fund, primarily due to issues related to government financial management systems for procurement and implementation.
PMI to continue to work with the National Malaria Control Programme to strengthen partnerships that exist between the programme and stakeholders around ITN procurement and distribution. Limited technical expertise on IVM. Inadequate experience in LSM and lack of compliance with vector control distribution guidelines.  The main lessons learnt are summarized in Box 1 . While vector control seemed to be effective in 2011 and 2012 -by reducing the number of malaria cases -without investment in insecticide treated nets and indoor spraying, the malaria burden could worsen in the country. Accordingly, the programme developed a new integrated vector management strategy for 2015-2019, which established functional multidisciplinary coordination mechanisms and advocated for appropriate vector control interventions among key stakeholders. 12 This strategy prioritizes: (i) adoption of a policy for universal coverage with LLINs -that is, to ensure that every sleeping space in every household is covered by an LLIN; (ii) indoor spraying with insecticides other than pyrethroids and carbamates, and that the selection of insecticides is based on epidemiological and entomological data; (iii) where feasible, supplementing indoor spraying and LLINs with focal larval source management, preferably using biological larvicides; and (iv) determining the diversity of vectors and establishing a rational insecticide resistance management strategy. 12 In Malawi, insecticides' resistance limits the choice of insecticides for indoor spraying and threatens the continued effectiveness of insecticide treated nets. 14,15 Strengthened entomological monitoring, including insecticide resistance management, would be critical for evidence-based, cost-effective, operationally scaled-up and sustainable vector control. Therefore, the programme aims to develop and implement a resistance monitoring and management plan and a vector surveillance plan. 12 Despite the challenges, there is now a strong political commitment to vector control in Malawi. This includes wide-ranging partner support, increased social mobilization and advocacy by stakeholders, a high demand for LLINs by community members and the possibility of expanding indoor spraying through public-private sector partnerships, including consensus to pilot DDT-based indoor spraying by the programme in non-tobacco growing districts. 9 However, successful integrated vector management demands for adequate financial and technical resources, strengthened operational research for evidence-based, effective targeting, deployment and monitoring of interventions. The programme will evaluate improvement in housing and introduction of larvivorous fish in earmarked areas amenable with the interventions, novel models of LLIN and repellents, and determine residual and/or outdoor transmission of malaria. 12 In Malawi, a functioning vector control needs adequate financial resources and an integrated vector management strategy. Scale-up of vector control in similar settings will need to be carefully considered and adapted to the local situation in the context of the integrated vector management approach. ■

Resumen
Ampliación del control integrado de vectores de la malaria: lecciones de Malawi Situación La fumigación de interiores con acción residual y los mosquiteros tratados con insecticidas de larga duración (LLIN, por sus siglas en inglés) son herramientas importantes para el control de vectores de la malaria. Malawi ha luchado por aumentar la fumigación de interiores con acción residual y por mejorar la cobertura y uso de los LLIN. Enfoque En 2002, el Programa de Control Nacional contra la Malaria de Malawi desarrolló directrices para la distribución de mosquiteros tratados con insecticidas con el fin de alcanzar el objetivo estratégico de que como mínimo el 60% de los hogares dispusieran de un LLIN. En 2005, la cobertura objetivo era un 80% de los hogares y el Fondo Mundial financió la ampliación. La Iniciativa del Presidente de los Estados Unidos de América contra la Malaria financió la intervención de la fumigación de interiores con acción residual. Marco regional Se considera que toda la población de Malawi corre el riesgo de sufrir malaria. Los escasos controles de vectores, la resistencia de los insecticidas en los vectores de la malaria y el apoyo técnico y financiero insuficiente han multiplicado las tasas de malaria.