ENSURE: Enhanced surveillance for control and elimination of malaria in the Philippines

Malaria remains a problem in many parts of the world. Even in countries where the level of infection is low, malaria can still cause death and there is the constant threat that drug and insecticide resistance may undermine any ongoing control attempts such that malaria comes back.

A major complication for control programmes when infections are rare is identifying where transmission is actually occurring. This is because the current methods used to diagnose malaria are not sensitive enough to detect all infections and miss a substantial proportion. Although these infections that are missed may not cause illness, they can still lead to infections in mosquitoes and therefore maintain malaria transmission in the area. It is an expensive process for many poorer countries to try and actively find all these cases, and so more flexible approaches need to be used to identify where infections are happening so that they can be targeted effectively.

The Philippines is a prime example of a low transmission setting. The country has recently experienced a reduction in annual malaria cases (from over 36,000 local cases in 2000 to fewer than 5,000 in 2014), but despite this progress, 54 out of the 81 provinces remain endemic of malaria, putting 14 million people at risk of the disease. Novel approaches and more sensitive methods are needed to detect if and where any remaining transmission might occur. With drug resistant parasites circulating in some countries in South East Asia, targeting transmission in the Philippines through an integrated surveillance system is particularly important and probably the most effective approach to address this issue.

In this project, we will combine existing systems that monitor malaria in people who attend local clinics in the Philippines with more sensitive diagnostic methods to see who is infected and who has recently been exposed to malaria. We will use the data from the clinics and cutting edge mapping techniques with tablet computers to identify where people live, so that we can see where infections are occurring. We will give this information to the Philippines National Malaria Control Programme so that they can target the area for control. We will perform these activities regularly at health facilities and continually update the maps. This will allow us to identify new areas of infection and check that targeted areas remain low.

We will work closely and continually with the control programme and health facility staff to see if the approach we are promoting is acceptable and how it might be improved. The goal is to develop an approach that can be easily absorbed into the existing health system using more modern approaches, and ultimately to help the Philippines eliminate a deadly and costly disease - and potentially to help other countries and regions achieve the same.

The project also aims to build human capacity in the Philippines in serological and molecular surveillance, data analysis, epidemiology, spatial studies and health systems research. The international collaboration provides a unique opportunity to develop and evaluate malaria burden measurement tools, allowing for novel strategies in a region of diverse and complex epidemiology, in which the rapid advances being made on elimination require great input in research and innovation.

Malaria surveillance in low transmission settings is hampered by poor diagnostics. Whilst the majority of infections missed are probably of little consequence clinically, being asymptomatic and low parasite density, they can infect mosquitoes and maintain transmission. This is of concern in areas of southeast Asia where there is the threat of artemisinin drug resistance; elimination of all parasites is widely considered the best way to stop the spread of resistance. Sensitive molecular methods can identify low density infections and, when combined with serological approaches, detect antibodies in those who have been exposed to infection. Together these two methods can more accurately identify areas where active transmission is ongoing and/or specific groups most at risk, such as migrant workers.

Collection of samples through large scale community surveys is not practicable for most control programmes; sensible operational approaches are needed. One option is through health facilities which represent an ideal source of contact with local populations. We have previously demonstrated that facility-based surveys generate malariometric data that correlate well with data collected from the local community and schools.

In this study we will use molecular and serological analysis of samples collected from regular surveys of facility attendees in three areas of the Philippines to generate data on infection and exposure in the community. We will combine these data with routinely collected epidemiological data, which we will embellish using enhanced tablet computer-based maps to create iteratively improved maps of areas where transmission is occurring.

We will work closely with the malaria control programme on laboratory and facility aspects to ensure successful implementation, training and include improvements or changes identified as work progresses. The ultimate goal is to develop an approach that can be easily absorbed into the existing health system.

Malaria remains one of the most important global health challenges. The economic and societal burden of malaria is great, and malaria and poverty are closely linked. In countries such as the Philippines, where persistent and coordinated control methods have achieved remarkable success in reducing the prevalence of malaria, there still exists a reservoir of subpatent and residual infections which continues to drive transmission and undermine progress made.

In the short term, participants in the study (health facility attendees) and indirect participants (health facilities staff) will benefit from increased awareness of malaria via their exposure to the study and consent procedures, despite the decreasing number of cases. This is important for Bataan and Occidental Mindoro, two of the three study sites, which were once priority provinces for malaria control. This will encourage them to use control methods (e.g. bed net). If found to be infected, in addition to being treated at the health facility, they will also benefit from enhanced interventions in and around their home. The community will benefit from better understanding and planning for malaria control including any emergence of drug resistance.

In the medium term, beneficiaries of the research will be the Philippines national public health officials, policy makers and malaria control programmes, and their counterparts in other countries/regions at similar stages of pre-elimination. The outcomes of the research will be used directly by these groups in developing national and regional policy and guidelines for disease surveillance and targeted control activities, and will help them to reach new targets of disease/transmission reduction. In addition, people working on the project will develop technical skills: laboratory, integrating data across disciplines, communication, advocacy, analysis and management, which could be transferred to other sectors, thus creating a highly competent and skilled workforce with the potential to provide economic gains for the country beyond the scientific research community.

In the longer term, the beneficiaries of the research will ultimately be the Philippines general population. In addition to malaria, filiariasis, schistosomiasis and leprosy are other diseases targeted for elimination in the Philippines. If the methods are shown to be effective at targeting reservoirs of infection and eliminating these pockets of transmission, they can be rolled out nationally and used to reduce and ultimately eliminate disease transmission in the Philippines. The Philippines population could be 'free' of a life threatening and debilitating disease, enhancing the health, well-being and quality of life of the nation. Reducing the burden of malaria could contribute to economic prosperity via the improved health and productivity of its population, and potentially through increased tourism and national mobility. If the study results can be generalised to other settings, then these long term impacts could be realised on a much wider, global scale.