New Surveyor tool to monitor the distribution of drug resistant P. vivax

Extensive research efforts over the last 20 years have improved greatly our understanding of drug resistant Plasmodium falciparum parasites. In contrast, drug resistance of the parasites that cause the persistent and debilitating form of malaria due to P. vivax remains poorly understood. Current estimates of the global burden of P. vivax infection vary considerably, but range between 13 and more than 100 million clinical cases each year. Although chloroquine remains the recommended treatment for P. vivax malaria infection in most vivax endemic countries, several countries have been forced to abandon chloroquine due to the emergence of parasites resistant to high levels of the drug. This threat to established antimalarial policy poses new challenges to the scientific community.

To respond to the challenge of resistance, WWARN is pleased to share with you the first interactive online tool that displays the prevalence and degree of chloroquine resistance in P. vivax parasites from many geographic locations and time periods. The P. vivax Surveyor presents a comprehensive review of all of the published antimalarial clinical trials of P. vivax. The map allows you to visualise the locations of research activity and areas where there is evidence of chloroquine resistant P. vivax. 

Chloroquine resistant P. vivax was first reported over 25 years ago, however it is difficult to diagnose and hence its geographical spread is poorly documented. The new Surveyor will help researchers to understand better this vital information.

“The Vivax Surveyor provides the research community with the most comprehensive picture yet of the spatio-temporal trends of chloroquine resistance in P. vivax parasites throughout the world,” says Professor Ric Price, Head of the WWARN Clinical Group. “This interactive tool will help to highlight where and how we need to focus our efforts to understand the spread and emergence of chloroquine resistant vivax malaria parasites.”

The tool summarises data from 231 clinical trials and 26 case reports published since 1950, examining data on P. vivax  clinical response in the majority of endemic countries. The colour code of the pins and the use of filters allows a quick summary of the areas where chloroquine resistant P. vivax parasites have been reported, and allows the output from individual studies to be compared at a glance across the world.

The studies can be visualised on the map by selecting different countries, and treatments, sorting the results into anti-relapse clinical trials, blood stage clinical trials or case reports. Full details of the methodology, including the categorisation of data according to the strength of evidence for chloroquine resistance, are available within the Surveyor tool.

“For certain countries, we know little about the prevalence of P. vivax resistance to antimalarial drugs. This tool can be used to help us to design and prioritise antimalarial clinical studies from which treatment strategies for P. vivax can be optimised,” said Professor Marcus Lacerda, Fundação de Medicina Tropical, Manaus .

We will share more news soon about two new dedicated P.vivax Study Groups, the first of which will focus on assessing the risk of early P.vivax recurrence before day 28 and the risk of late recurrence after day 42 with and without primaquine treatment. The second group will analyse the consequences of symptomatic P.vivax infections on anaemia in patients before and after antimalarial treatment.

The data included in the Vivax Surveyor were derived from updated reviews of P. vivax antimalarial clinical trials published in the Lancet Infectious Diseases and the Malaria Journal. The comprehensive search of databases included PubMed, Embase, Web of Science and the Cochrane Database of Systematic Reviews.

Find more information about emerging strains of drug resistant P. vivax and why elimination of P. vivax is a far greater challenge than it is for P. falciparum.

Related publications:

Battle KE, Gething PW, Elyazar IR, et al. The global public health significance of Plasmodium vivax. Advances in Parasitology.  DOI: 10.1016/B978-0-12-397900-1.00001-3

Price RN, von Seidlein L, Valecha N, et al. The global extent of chloroquine resistant Plasmodium vivax: a systematic review and meta-analysis. Lancet Infectious Diseases; DOI S1473-3099(14)70855-2

Baird JK.  Resistance to therapies for infection by Plasmodium vivax. Clinical Microbiology Reviews. DOI: 10.1128/CMR.00008-09.

John GK, Douglas NM, von Seidlein L, et al. Primaquine radical cure of Plasmodium vivax: a critical review of the literature. Malaria Journal. DOI: 10.1186/1475-2875-11-280

For more information on the Surveyor or the new Studies, please email clinical@wwarn.org