WWARN supports the battle against vivax malaria in Latin America
Plasmodium vivax (P. vivax), the most common malaria-causing parasite, accounts for approximately 80% of the malaria disease burden in the Amazon region of South America (World Malaria Report, 2013). It is now recognised as a major cause of death and because of relapse from its liver phase illness can sometimes last in patients for years. Despite this impact, it remains a relatively neglected form of malaria both in terms of research funding and resources.
This issue is confounded by the fact that chloroquine, the current widely used antimalarial treatment against P. vivax, is becoming less effective at killing the parasite in patients. Chloroquine-resistant P. vivax malaria is already suspected in parts of Bolivia, Brazil and Peru and further treatment failure is reported in Colombia and Guyana.
Many of the techniques used to track malaria resistance in other regions around the world have been focused on the spread of antimalarial resistant forms of Plasmodium falciparum. In contrast, there is no publically available data on chloroquine resistance from many Latin American countries, resulting in a significant gap in the availability of data or analysis on the extent of malaria drug resistance in the region.
Map showing sites of recent in vivo studies of chloroquine treatment for Plasmodium vivax infections in South America (published between 2000-2013). Triangles indicate study sites where treatment failures have been reported, while squares indicate sites with no treatment failures observed over 28 days of follow-up.
WWARN’s Latin America team are now looking at how they can use their expertise to contribute to regional efforts to map and understand chloroquine response to P. vivax malaria in South America.
Colleagues are collaborating with researchers throughout Latin America to collate and analyse data to develop a full picture of the overall problem of chloroquine resistant strains of P. vivax across the region.
Tools such as the WWARN Explorer and the Parasite Clearance Estimator have been successful at helping us understand more about the character and frequency of P. falciparum antimalarial resistance. The WWARN Regional team expect these that tools could be adapted to track the spread and extent of P. vivax chloroquine resistance.
“Mapping and containing cholorquine resistance in Latin America poses a major challenge for regional researchers,” says Dr Ligia Antunes Gonçalves, WWARN Latin America Liaison Scientist. “We are trying to work in partnership with local laboratories to help generate high quality data that will enable us to fully characterise the spread of chloroquine drug resistance in the region.”
WWARN invites researchers in Latin America to become involved in the collaboration, by both sharing data and helping to improve the design of new studies of malaria resistance within the region. WWARN is also interested in finding support from within the community to adapt WWARN’s existing tools for P. vivax. These topics will be addressed during the upcoming National Malaria Research Meeting in São Paulo, Brazil, in October 2015, during which WWARN will hold a regional workshop.
To express your interest in supporting this effort or to ask further questions, please contact Lígia Gonçalves on email ligia.goncalves(at)wwarn.org
Find out more about chloroquine resistance in this paper:
Lígia Antunes Gonçalves et al. ‘Emerging Plasmodium vivax resistance to chloroquine in South America: an overview’. Memórias do Instituto Oswaldo Cruz (2014). Vol. 109. DOI: 10.1590/0074-0276130579.
Other useful resources
Marques MM, Costa MR, Santana Filho FS, Vieira JL, Nascimento MT, Brasil LW, Nogueira F, Silveira H, Reyes-Lecca RC, Monteiro WM, Lacerda MV, Alecrim MG. Plasmodium vivax chloroquine resistance and anemia in the western Brazilian Amazon. Antimicrob Agents Chemother (2014), 58(1):342-7. DOI: 10.1128/AAC.02279-12. PMID: 24165179
Llanos-Cuentas A, Lacerda MV, Rueangweerayut R, Krudsood S, Gupta SK, Kochar SK, Arthur P, Chuenchom N, Möhrle JJ, Duparc S, Ugwuegbulam C, Kleim JP, Carter N, Green JA, Kellam L. Tafenoquine plus chloroquine for the treatment and relapse prevention of Plasmodium vivax malaria (DETECTIVE): a multicentre, double-blind, randomised, phase 2b dose-selection study. Lancet (2014) 383(9922):1049-58. DOI: 10.1016/S0140-6736(13)62568-4 PMID: 24360369