Department of Entomology, The Pennsylvania State University, University Park, 16801, USA.
Acta Trop. 2012 Mar;121(3):227-39. doi: 10.1016/j.actatropica.2011.02.016. Epub 2011 Mar 5.
The Greater Mekong Subregion (GMS), comprised of six countries including Cambodia, China's Yunnan Province, Lao PDR, Myanmar (Burma), Thailand and Vietnam, is one of the most threatening foci of malaria. Since the initiation of the WHO's Mekong Malaria Program a decade ago, malaria situation in the GMS has greatly improved, reflected in the continuous decline in annual malaria incidence and deaths. However, as many nations are moving towards malaria elimination, the GMS nations still face great challenges. Malaria epidemiology in this region exhibits enormous geographical heterogeneity with Myanmar and Cambodia remaining high-burden countries. Within each country, malaria distribution is also patchy, exemplified by 'border malaria' and 'forest malaria' with high transmission occurring along international borders and in forests or forest fringes, respectively. 'Border malaria' is extremely difficult to monitor, and frequent malaria introductions by migratory human populations constitute a major threat to neighboring, malaria-eliminating countries. Therefore, coordination between neighboring countries is essential for malaria elimination from the entire region. In addition to these operational difficulties, malaria control in the GMS also encounters several technological challenges. Contemporary malaria control measures rely heavily on effective chemotherapy and insecticide control of vector mosquitoes. However, the spread of multidrug resistance and potential emergence of artemisinin resistance in Plasmodium falciparum make resistance management a high priority in the GMS. This situation is further worsened by the circulation of counterfeit and substandard artemisinin-related drugs. In most endemic areas of the GMS, P. falciparum and Plasmodium vivax coexist, and in recent malaria control history, P. vivax has demonstrated remarkable resilience to control measures. Deployment of the only registered drug (primaquine) for the radical cure of vivax malaria is severely undermined due to high prevalence of glucose-6-phosphate dehydrogenase deficiency in target human populations. In the GMS, the dramatically different ecologies, diverse vector systems, and insecticide resistance render traditional mosquito control less efficient. Here we attempt to review the changing malaria epidemiology in the GMS, analyze the vector systems and patterns of malaria transmission, and identify the major challenges the malaria control community faces on its way to malaria elimination.
大湄公河次区域（GMS）由六个国家组成，包括柬埔寨、中国云南省、老挝、缅甸、泰国和越南，是疟疾威胁最严重的地区之一。自十年前世界卫生组织湄公河疟疾规划启动以来，GMS 的疟疾情况已大大改善，表现为年疟疾发病率和死亡率的持续下降。然而，随着许多国家向消除疟疾迈进，GMS 国家仍面临巨大挑战。该地区的疟疾流行病学具有巨大的地理异质性，缅甸和柬埔寨仍然是高负担国家。在每个国家内部，疟疾的分布也不均匀，例如“边境疟疾”和“森林疟疾”，分别在国际边境和森林或森林边缘地区发生高传播。“边境疟疾”极难监测，迁徙人口频繁引入疟疾对邻国消除疟疾的国家构成重大威胁。因此，邻国之间的协调对于从整个地区消除疟疾至关重要。除了这些操作上的困难，GMS 的疟疾控制还面临着一些技术挑战。当代疟疾控制措施主要依赖于有效的化学疗法和媒介蚊虫的杀虫剂控制。然而，恶性疟原虫对青蒿素类药物的耐药性传播和潜在的青蒿素耐药性出现使耐药性管理成为 GMS 的一个高度优先事项。这种情况因假冒和劣质青蒿素类药物的流通而进一步恶化。在 GMS 的大多数流行地区，恶性疟原虫和间日疟原虫共存，在最近的疟疾控制历史中，间日疟原虫对控制措施表现出显著的弹性。由于目标人群中葡萄糖-6-磷酸脱氢酶缺乏症的高流行率，唯一用于根治间日疟的注册药物（伯氨喹）的使用严重受阻。在 GMS，截然不同的生态、多样化的媒介系统和杀虫剂耐药性使得传统的蚊虫控制效率降低。在这里，我们试图回顾 GMS 中不断变化的疟疾流行病学，分析媒介系统和疟疾传播模式，并确定疟疾控制界在消除疟疾的道路上面临的主要挑战。
