According to estimates from routine surveillance data, in 2009 approximately 225 million cases of malaria occurred globally. This estimate is less in comparison to other published figures, like those from the Malaria Atlas Project (MAP), in particular estimates of malaria cases outside Africa. In PLoS Medicine, Richard Cibulskis and his team at the WHO in Geneva, Switzerland publish a critique of different estimation methods of the worldwide incidence of malaria.
Malaria incidence rates in any country are a crucial component of public health planning. Furthermore, these figures are a vital key to accurately estimate the global burden of Malaria, which in turn is essential for monitoring the progress towards the United Nations’ Millennium Development Goals.
Cibulskis and his team calculated their estimate by analyzing routine surveillance reports that have been compiled by national health ministries, and carried out a statistical analysis to establish the range of uncertainty of their estimates.
When comparing the pros and cons of surveillance-based with cartographic-based, i.e. relying on surveys, malaria incidence estimation methods, they found that even though existing malaria surveillance systems currently fail to recognize at least 90% of incidences, accurate surveillance displays spatial as well as temporal benefits in comparison to population survey data and should therefore be the ultimate aim for malaria control programs.
The researchers proclaim:
“To strengthen surveillance requires a critical evaluation of all the types of error we have identified in this paper. Only with investigations of this kind can we confidently assess malaria burden and trends, and the return on investments in control programs.”
Ivo Mueller, Laurence Slutsker, and Marcel Tanner, who was not involved in the study, point out the importance of using complementary methods to estimate the number of malaria cases in an accompanying comment and demand a renewed focus on efficient malaria surveillance, saying:
“Both methods used in the research article] have their unique strengths and weaknesses, and rather than seeing them as competing approaches, they should be synergistically combined. Ultimately, good quality and up-to-date information on malaria burden will become even more important for both monitoring and operational purposes as malaria control activities are further intensified.”
Written by Petra Rattue