Evaluating insecticide treated plastic sheeting for malaria control in complex emergencies

Millions of people around the world live in countries affected by conflict, where access to effective health care and basic food supplies may be very limited. Under such conditions, disease and malnutrition thrive, often leading to death. In the acute phase of emergencies, preventable diseases such as malaria contribute significantly to the death toll. High malaria mortality rates do not always imply an increase in mosquitoes among affected populations; high mortality can also stem from a failure to deploy effective malaria prevention efforts in a timely fashion.

The opportunity to reduce malaria-related mortality during the early stages of an emergency is often missed because of the long lead times needed to deploy the current mainstay techniques and tools. Current mainstay approaches to malaria prevention include Insecticide Treated Nets (ITNs – see [cross-reference]), Indoor Residual Spraying (IRS) and intersectoral approaches that help to motivate communities to participate in their own malaria prevention practices. However, there are numerous obstacles to overcome if these tools and methods are to have a measurable impact in complex emergency situations. Although they are very effective under stable conditions, it is questionable whether such methods are practical in emergency situations, and even whether they can be deployed correctly by the end-user.

More needs to be done; ready-to-use, easily available and context-specific malaria prevention tools are essential to improve humanitarian response capacity to malaria among the world’s most vulnerable populations. This article looks at one such approach: Insecticide Treated Plastic Sheeting (ITPS). ITPS uses the same impregnation technology which has worked well for ITNs. In all other respects, it is identical to the standard plastic sheeting currently used for shelter by millions of people in emergency situations throughout the world.

Evaluating ITPS

Development of ITPS began at the end of the 1990s. Since then, it has undergone a stepped evaluation. Phase I involved small-scale laboratory testing. In Phase II, small-scale field trials were carried out. In Phase III, beginning in October 2002, the tool was used operationally on a large scale in a real-time emergency situation, in Liberian refugee camps in Sierra Leone. The aim of Phase III was to measure whether ITPS had an impact on disease reduction by looking at clinical/parasitological indicators and entomological findings. The evaluation also looked at safety issues and user perceptions, all in an environment which contained many of the confounding factors typical in emergencies.

The evaluation of ITPS as a product has proceeded fairly quickly because the insecticide (Deltamethrin) has been endorsed by the World Health Organisation Pesticide Evaluation Team (WHOPES). However, validation of the insecticide does not imply that the approach itself has been endorsed. The patent for the overall product is not on the insecticide incorporated into the plastic sheeting itself, but rather on the impregnation technology (migration-inhibiting molecules and UV filters) that enable the sheeting to release insecticide slowly over time. Therefore, complete endorsement of the tool is only likely after the results of tests relating to user and ecological safety are known.

The Sierra Leone work has now finished and, while final analysis was still pending when this article was written, crude trends suggest promising results. If further research is encouraging, there would need to be a transition from evaluation to monitored deployment (Phase IV evaluation), with a view to ITPS becoming a standard shelter material in emergency situations. It is of great importance in this key stage of activity that the patent timeframes are reviewed by coordinating bodies, donor agencies and implementing organisations, in partnership with the manufacturer, since this may have implications for how ITPS is used in the future. If these issues are not addressed immediately, this is likely to obstruct the transition from evaluation to officially endorsed distribution within camps.

ITPS: a universal tool?

It cannot be assumed, from a single field evaluation, that ITPS will be effective in all complex emergency situations. Many factors, both specific and general, will need further scrutiny.

Field-level analysis should focus on sharing information between sectors on how ITPS could be used within the field site, or whether current mainstay prevention tools and interventions are more cost-effective and sustainable. Decisions on whether ITPS is suitable for a particular situation will need to be based on several factors, including plastic positioning, the surface area the plastic covers, the level of malaria transmission (e.g. seasonal or intense perennial), whether the tool has been successful in similar settings, whether there is any known history of mosquito resistance to the insecticide in the ITPS, the likely duration of the emergency (i.e., whether it is likely to allow for optimum release of the impregnated insecticide) and whether there are specific phases in the emergency (acute, transitional, chronic) to which specific funds might be allocated, allowing for different malaria prevention strategies.

Clearly, ITPS may not be appropriate in all emergency scenarios. For example, irrespective of how intense the malaria transmission may be in a given emergency, the extra costs of deploying ITPS would be wasted if camp planning teams envisaged using plastic only as an outside covering on top of thatched roofing. Mosquito contact with the plastic would be minimal, and there would probably be no significant effect on the level of malaria infections within the beneficiary population. In natural disasters or political emergencies where preparatory time is minimal, it may be more feasible to stick to existing shelter responses and deploy alternative malaria prevention measures than to modify shelter planning to accommodate ITPS. In this scenario, ITPS effectively loses its key selling point, which is its ‘dual-purpose’ ability to combine shelter with effective malaria control.

ITPS is likely to be more effective in the acute phases of an emergency, when other malaria prevention tools and methods are not feasible (for instance when the shelter is too small to accommodate a hanging bed-net, or when the effectiveness of IRS is limited because of inappropriate wall structures). Shelters will be temporary, but likely to be constructed from plastic sheeting, and therefore there would be ample surface area coverage and proper placement to allow for a mass reduction in the mosquito and fly population (especially if temporary communal latrine structures are covered with ITPS), and hence a reduction in disease transmission. As the emergency continues, affected populations are likely to start building their own structures, and these may not use ITPS in areas of mosquito contact. This, combined with the fact that insecticide levels may have fallen to the point where there is no effect on mosquitoes and flies, means that ITPS is not an acceptable form of malaria prevention. This is obviously very important in planning at the field level, as ITPS should not necessarily be seen as appropriate for the entirety of the emergency, or as a substitute for the more conventional malaria control methods and tools that have proved effective in chronic settings.

Next steps, and planning

For the future, there could be a four-stage process, combining further research and planning with Pre-Implementation Situational Planning and Pre-Distribution Modalities. There needs to be a concerted effort from actors in different sectors to optimise the latter stages of evaluation; in parallel, a steering framework committee should focus on usage guidelines and the ‘Software Elements’ (for instance pre-distribution sensitisation outlines) which will be required for the successful application of ITPS in large-scale emergency situations.

Step 1: Further research and evaluation

• Further Phase III and Phase IV field testing (especially in a situation in which malaria transmission differs from Sierra Leone). Further research would be optimised through effective collaboration from different academic institutions to avoid duplicating work, whilst at the same time including different monitoring components, such as disease reduction, safety, ecological monitoring and cultural acceptance.

Step 2: Planning (can run concurrently with Step 1)

• Formation of an inter-agency ITPS Steering Committee (comprising academics, NGOs in health, shelter and water and sanitation, UNHCR, WHO and ICRC representatives). The committee’s remit would be to standardise structural specifications for ITPS to meet international (SPHERE, UNHCR, ICRC) minimum standards; prepare guidelines for the ethical and equitable use of ITPS in emergency situations; review logistical planning; and mediate between public and private organisations (the manufacturer) to ensure that ITPS is available for large-scale use in emergencies.
• Product endorsement by WHOPES.

Step 3: Pre-implementation situational planning at the onset of an emergency (based on fulfilment of Steps 1 and 2)

• Review emergency type and local malaria transmission.
• Review proposed communal, dwelling and latrine structures to ascertain prospective ITPS usage and effective placing (for example, will ITPS be used in places mosquitoes will land or rest?).
• Estimate the degree of beneficiary acceptance (for instance, is there a history of plastic usage within the community?).
• Review donor and organisational purchasing and logistical frameworks.

Step 4: Pre-distribution modalities (based on fulfilment of Steps 1 and 2, and if Step 3 calls for ITPS usage)

• Intersectoral briefing sessions to review and finalise ITPS coverage for communal, dwelling and latrine structures.
• Pre-plan distribution and storage arrangements.
• Distribution of ITPS product and usage guidelines, and promotion of ITPS through camp meetings and focus group discussions.
• Ensure that there are adequate safety briefings and protection for users (gloves to reduce exposure to the insecticide).

There is still a lot to do before ITPS can be deployed to control malaria in emergency settings. Some may view the stepped approach outlined above as an impediment, delaying the point at which ITPS could be used to save lives. The contrarian view would be that it is better, based on field evidence, to target ITPS in the most effective way within emergency situations, whilst minimising the timescales for deployment and distribution by having a preformatted agenda. This may in the future limit the overall usage of ITPS, while leaving adequate financial resources in place for other preventative measures or case-management strategies that may be better matched to a given emergency situation. It is clear that alternative malaria control tools need to be developed that complement, or be used instead of, ITPS if the malaria burden in all emergency situations is to be challenged effectively.

Matthew Burnsis a malaria consultant. He was the Research Coordinator for the Field Evaluation of ITPS in Sierra Leone, under the Center for International Emergency, Disaster and Refugee Studies at the Bloomberg School of Public Health, Johns Hopkins University. He is also a PhD candidate in the faculty of Medical Entomology at Wageningen University in Amsterdam. His email address is: Simulium98@yahoo.com.

References and further reading

Kate Graham, ‘New Tools to Control Malaria in Refugee Camps’, Journal of the Royal Society for the Promotion of Health, vol. 124, no. 6, November 2004, pp. 253–55.

Richard Allan, Matthew Burns and Mikkel Vestergaard Frandsen, ‘Cash and Crisis – Motivating the Private and Public Sector to Establish Common Goals’, International Aid and Trade Journal, June 2003, pp. 90–91.

Richard Allan, Matthew Burns, Caroline Lynch and Mikkel Vestergaard, ‘Waging War on Malaria’, PATH Canada Journal, May 2003, www.pathcanada.org/english/malaria_news12.cfm.

M. Rowland and F. Nosten, ‘Malaria Epidemiology and Control in Refugee Camps and Complex Emergencies’, Annals of Tropical Medicine and Parasitology, 95(8), 2001, pp. 741–54.