Report of the workshop to review and plan therapeutic efficacy studies to monitor P.falciparum and P.vivax resistance to anti-malarial drugs in the greater Mekong sub-region
Other TitlesMandalay, Myanmar, September 30 - October 2, 2009
AbstractThe Greater Mekong Sub-region (GMS) is known as the global epicentre of P. falciparum resistance to antimalarial drugs. The WHO Mekong Malaria Programme (MMP) in vivo Therapeutic Efficacy Study (TES) Network promotes the use of a single standardized protocol across 6 Mekong countries to monitor the efficacy of first-line antimalarial medicines recommended in the GMS. This Network has been strengthened following a WHO MMP informal consultation in January 2007 in Cambodia acknowledging the decreased sensitivity of P. falciparum to ACTs on the Cambodia-Thailand border. In Sept 2007, representatives and principal investigators (PI) from malaria control programmes of Cambodia, China, Lao PDR, Myanmar, Thailand and Viet Nam as well as partners agreed to use the updated WHO TES protocol and related case management guidelines to monitor drug resistance in 32 sentinel sites across the GMS. Patients' clinical symptoms and parasite counts were monitored during at least 28-days follow-up, adhering to strict standardized entry criteria, cross-checking slides and quality data management, and systematically using polymerase chain reaction (PCR) to differentiate re-infections from recrudescence, including genotyping and use of molecular markers for resistance. Preliminary results were presented by PIs in Mandalay, Myanmar in September 2009. Longer parasite clearance time (PCT) and decreasing efficacy rate (ACPR) of ACTs have been observed in Kawthaung on the south-eastern part of Myanmar bordering Thailand (province of Ranong) where the ACPR to AS+M has been also declining since 2006. Preliminary results also show a longer PCT (beyond day 3) to AS7 monotherapy in Dehong, Yunnan province of China bordering Myanmar, and in Binh Phuoc province in southern Viet Nam bordering Cambodia (province of Snoul). Such worrying results have been further validated. Since artemisinin resistance is not only confined on the Cambodia-Thailand border but might have extended to or spontaneously emerged de novo in the Myanmar-Thailand, China-Myanmar and Cambodia-Viet Nam borders, additional in vivo studies with 7-day artemisinin monotherapies including pharmacokinetic (Pk) assays of AS and molecular fingerprinting of parasite genomes to track artemisinin resistance (gene flow) circulating around the region are planned in 2010-2011 in the six countries. Molecular biology tools and markers are increasingly crucial to be identified / used through samples collected in the GMS. Also noted during the workshop was the increasing complexity to recruit malaria cases through a single sentinel site channel against required sample size in most of Mekong countries. New multi-district sentinel sites approaches will be discussed and piloted to address that situation.
World Health Organization, Regional Office for South-East Asia. (2010). Report of the workshop to review and plan therapeutic efficacy studies to monitor P.falciparum and P.vivax resistance to anti-malarial drugs in the greater Mekong sub-region. WHO Regional Office for South-East Asia. http://www.who.int/iris/handle/10665/206314