The Meningitis Environmental Risk Information Technologies (MERIT) project is a joint effort of the World Health Organization (WHO) and partners to utilize more effectively existing knowledge of the epidemiology of meningococcal meningitis to improve current control strategies; to improve the understanding of the relationship between bacterial meningitis and environmental parameters; to use this understanding to provide more timely warnings of the onset of meningitis epidemics; and to use this knowledge to improve the efficacy of meningitis prevention and control strategies. This effort is designed to coincide with the implementation of the forthcoming group A conjugate vaccine for the control of meningococcal disease in Africa, which is likely to radically change the epidemiology of meningitis epidemics across the continent [1] and require a reassessment of the control activities to facilitate the optimal utilization of resources.
Meningitis control activities currently rely on the early identification of epidemics followed by a rapid deployment of polysaccharide vaccines [2]. Although the efficacy of these interventions is debated [3, 4]; it is widely recognized that there is only a short lead-time for vaccination once an epidemic is underway. This constraint is because current vaccines lack immunological memory and confer no significant herd immunity nor do they produce long-lasting protection; or protect very young children [5]. Given the association of the epidemics with a dry and dusty environment and their higher incidence in the so-called Meningitis belt [6], recent research has focused on developing maps that identify the areas at high risk of epidemics [7] and climate-driven early warning systems that could provide longer lead-times for initiating response [8, 9].
Although not the number one killer disease in Africa, meningitis is one of the most feared diseases and of major public health importance in West Africa. What's most frightening about the disease is the speed at which it develops and the severity of the after-effects:
The geographical distribution of meningitis epidemics also appears to be changing. In the late 1980s and 1990s many countries experienced new epidemic waves and some outbreaks were reported from less usual places, prompting the suggestion of an extension outside the usual boundaries [12, 13]. Although it is likely that these waves resulted from the spread of new clones throughout the continent [14]; it is also possible that environmental changes affecting the region may have contributed. For example, a review of epidemics occurring from January 2000 to April 2004 identified epidemics in districts of Somalia, Cameroon and other countries that had suitable environmental characteristics but had never been affected by meningitis epidemics in the past [13].
The technology for the development of a vaccine for the main strains causing epidemic meningitis in Africa has been established for 20 years [10]. However, until now the cost has been prohibitive and their use limited. This has changed with the development and production of new low cost conjugate vaccines by the WHO – PATH Meningitis Vaccine Project (MVP)* . Currently in phase two trials and demonstration projects, implementation of these vaccines will start in 2009. It is currently envisaged that the total annual production of vaccines will be 40 million doses. Given this projection it would require about a decade to protect the populations (350 million) living in areas that experience epidemics. Demonstration of efficacy for similar vaccines in Europe depended on the availability of enhanced surveillance systems in which the case numbers were reported, by age cohorts).
The Integrated Disease Surveillance and Response Strategy (IDSR) was adopted by WHO African Regional Office (WHO AFRO) in 1998 in response to the meningitis epidemics of 1996/1997 in West Africa, which affected more than 250,000 people were affected and killed 25,000. Its aim is for all WHO AFRO Member countries to have an effective IDSR system by 2008, capable of generating information for timely action to reduce mortality, disability and morbidity.
The definition of epidemic thresholds and the routine use of geographical information systems (GIS) based surveillance, analysis and mapping applications, such as the WHO OpenHealth, public health information system, is enhancing the decision making process and the communication of epidemic information. Maps of districts which have crossed alert and epidemic thresholds are now routinely distributed throughout the region by the WHO Multi Disease Surveillance Centre (MDSC) in Burkina Faso (Fig 1).
Despite these and other improvements meningitis surveillance systems still fall short of the sensitivity required to demonstrate incidence changes in vaccinated and non-vaccinated cohorts and complementary approaches are needed to demonstrate the impact of the vaccines as well as improve the targeting of limited resources.
Figure 1 Map of Epidemic thresholds
In 1998, with sponsorship from the UK’s Meningitis Research Foundation, Médécins sans Frontières (MSF)and the National Oceanic and Atmospheric Administration (NOAA), the Meningitis Forecasting for Africa Project was initiated. This was a first effort to forecast future meningitis epidemics. It provides an ongoing framework for future efforts to provide early warning of epidemics in Africa and highlights the need for environmental monitoring alongside improved disease surveillance [11, 15]. Assessment of the contribution of low absolute humidity and dust as risk factors was an objective of this project [7] and is the basis for collaborative efforts to develop environmental models capable of predicting meningitis epidemics [8]. They highlight the need for a better understanding of the epidemiological and environmental phenomena and improved epidemiological and environmental data sets, as well as skill in environmental prediction. Currently most seasonal and inter-annual climate forecasting systems focus on predicting the onset of the rainy season rather than the dry, dusty conditions associated with meningitis epidemics. There is also going evidence that the geographical distribution of epidemics is changing in response to climate and environmental changes [16].
A major impediment to the implementation and widespread use of new techniques to improve the timeliness of health interventions is the capacity of the public health sector to utilize this information. For example, it is only in recent years that operational malaria control products have been adopted by decision-makers in Africa, despite over 30 years of research [16 17]. While common to many disciplines, accelerating the transition of research to operations depends in large measure on close cooperation between the research and operational communities from the start. MERIT aims to reduce the time required to transition research by ensuring that program focuses on service delivery.
Quantifying the expected benefit of better surveillance and more timely warnings is a critical step towards ensuring that the capacity and capability exists within the public health sector to use the information effectively.
The goal of the project is to reduce the suffering and death from bacterial meningitis in the Meningitis Belt of Africa by helping public health practitioners and other key stakeholders to increase the effectiveness of current and new meningitis vaccination strategies and programs.
The MERIT project objectives are:
A large number of groups are working on meningitis disease, but with little or no coordination and, in particular, without direct connection to WHO’s operational activities. At the outset, it is recognized that a more coherent approach to medical, epidemiological and related environmental research would accelerate the benefits of more rapid detection and intervention to those at risk from the disease. The MERIT project aims to bring these groups together provide this coherence and to increase the impact of this community on disease reduction. In particular, it will provide an opportunity for health and climate scientists to work together.
Hitherto, the climate community and especially providers of earth observing systems have tended to oversell environmental solutions to health problems that are, at best, climate-sensitive rather climate-driven. The development of the Group on Earth Observations (GEO) and its focus on societal benefits provides an opportunity for a constructive engagement with the health sector and a mechanism to ensure the sustainability of the climate component of any effective health surveillance system. The MERIT project is part of the work plan of the health societal benefit area of GEO.
MERIT has also been adopted by the Health and Climate Foundation (HCF), as a health and climate capacity building project for Sub-Saharan Africa. The MERIT project is a pathfinding activity to demonstration that greater cooperation between the health and climate communities can improve health outcomes.
The International Federation of the Red Cross and Red Crescent Societies (IFRC) is using MERIT to help define longer term commitments to public education and outreach programmes designed to increase the capacity of the families to cope with meningitis disease.
*The Meningitis Vaccine Project (MVP) is a partnership between the World Health Organization (WHO) and the Program for Appropriate Technology in Health (PATH). Created in 2001 with core funding from the Bill & Melinda Gates Foundation, its goal is to eliminate epidemic meningitis as a public health problem in Sub-Saharan Africa.