The limits and intensity of Plasmodium falciparum transmission: implications for malaria control and elimination worldwide.
The limits and intensity of Plasmodium falciparum transmission: implications for malaria control and elimination worldwide.
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DOI：
10.1371/journal.pmed.0050038
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发表时间：
2008-02
期刊：
影响因子：
15.8
通讯作者：
Snow, Robert W.
中科院分区：
文献类型：
--
作者：
Guerra, Carlos A.;Gikandi, Priscilla W.;Tatem, Andrew J.;Noor, Abdisalan M.;Smith, Dave L.;Hay, Simon I.;Snow, Robert W.
要利用适当的干预措施组合有效地为疟疾控制分配财政资源，就需要关于疟疾风险地理分布的准确信息。近40年来，对全球恶性疟原虫及其流行范围的循证描述尚未形成。本文旨在确定2007年全球恶性疟原虫的地理分布，并初步描述其在该范围内的传播强度。利用国家报告的病例发病率数据、医学情报和排除传播的生物学规则，利用优势按蚊媒介物种的生物学信息所提供的温度和干旱限制，生成了恶性疟原虫疟疾的全球空间分布。总共收集了4278份空间上独特的恶性疟原虫寄生虫率的横断面调查估计。从人口表面提取的数据显示，2007年有23.7亿人生活在有恶性疟原虫传播风险的地区。在全球，近10亿人生活在不稳定或极低的疟疾风险之下。据报道，几乎所有恶性疟原虫50%以上的发病率都发生在与冈比亚按蚊分布一致的纬度带内。然而，在非洲，寄生虫发病率低的情况也很常见。在非洲以外，恶性疟原虫疟疾流行率基本上是低地方病（不到10%），在调查地区中位数低于5%。这张新地图合理地反映了目前恶性疟原虫的风险程度，并在这些范围内对处于恶性疟原虫疟疾风险中的人口进行了最新总结。对于面临不稳定疟疾传播风险的10亿人来说，消除疟疾在流行病学上是可行的，而且非洲大片地区比以前认识到的更容易控制。在公共领域发布这一信息将有助于将未来的资源集中用于控制和消除恶性疟原虫疟疾。结合广泛的监测和气候数据，以及按蚊的生物学特征，Robert Snow和他的同事们创建了一个全球恶性疟原虫疟疾风险地图。疟疾是发生在世界热带和亚热带地区的一种寄生虫病。每年有5亿疟疾病例发生，100万人因此死亡，其中大多数是生活在撒哈拉以南非洲的儿童。导致这些死亡的主要寄生虫——恶性疟原虫——是通过受感染蚊子的叮咬传播给人类的。这些昆虫注入一种叫做孢子虫的寄生虫的生命阶段，孢子虫侵入并在人的肝细胞中繁殖。几天后，肝细胞释放出侵入红细胞的分裂子（寄生虫的另一个生命阶段）。在这里，它们繁殖，然后爆发，感染更多的红细胞，引起发烧和损害重要器官。受感染的红细胞也会释放配子体，蚊子在吸食人血后就会被感染。在蚊子体内，配子体繁殖并发育成孢子体，从而完成寄生虫的生命周期。疟疾可以用抗疟药物治疗，也可以通过控制传播寄生虫的蚊子（例如，使用杀虫剂）和避免蚊子叮咬（例如，睡在经杀虫剂处理的蚊帐下）来预防。由于疟疾造成如此巨大的全球公共卫生负担，许多国家和国际机构向疟疾流行（总是存在）的国家提供财政资源，用于控制疟疾，并在可行的情况下消除疟疾。这些资源的有效分配需要关于疟疾风险地理分布的准确信息，但疟疾风险地图的编制已经过去了40年。在这项研究中，这是疟疾地图集项目的一部分，研究人员绘制了一个新的全球地图，显示了恶性疟原虫传播风险中等或较高的地区（疟疾流行的稳定传播地区）和传播风险较低的地区（发生零星疟疾爆发的不稳定传播地区）。为了构建他们的恶性疟原虫风险地图，研究人员收集了每年全国报告的疟疾病例数据和样本社区感染人数。他们还收集了有关气候条件的信息，这些气候条件会影响寄生虫的生命周期，从而影响主动传播的可能性。例如，在一定温度以下，受感染的蚊子在寄生虫有时间转化为传染性孢子虫之前就到达了其自然寿命的终点，这意味着疟疾的传播不会发生。通过将这些不同的信息与全球人口数据结合起来，研究人员计算出，23.7亿人（约占世界人口的35%）生活在有一些恶性疟原虫传播风险的地区，其中约10亿人生活在疟疾传播风险较低但仍然存在的地区。此外，半数以上儿童携带恶性疟原虫（恶性疟原虫流行率超过50%）的区域几乎都在非洲，尽管有些非洲区域很少有人感染恶性疟原虫。在非洲以外，恶性疟原虫的流行率一般低于5%。这张新的恶性疟原虫疟疾风险空间分布地图的准确性取决于其组装过程中的假设和输入数据的准确性。尽管如此，通过提供全球恶性疟原虫疟疾风险模式的当代指示，这张新地图应该成为试图控制和消除疟疾的机构的宝贵资源。（更常见但不那么致命的间日疟原虫的类似地图也会有用，但由于可用的信息较少，其生物学更复杂，因此尚未构建。）重要的是，该地图提供了生活在疟疾传播率较低地区的人数的估计，在这些地区，原则上应该有可能利用现有的干预措施来消除这种寄生虫。此外，它还确定了非洲的大片地区，在那里寄生虫可能比以前认为的更容易控制并最终消灭。最后，通过定期更新，该地图将能够监测疟疾控制和消除工作的进展情况。请通过本摘要的在线版本http://dx.doi.org/10.1371/journal.pmed.0050038访问这些网站。MedlinePlus百科全书包含一个关于疟疾的页面（英文和西班牙文）。世界卫生组织提供关于疟疾的信息(英文、西班牙文、法文、俄文、阿拉伯文、美国疾病控制和预防中心提供关于疟疾的信息（英文和西班牙文）遏制疟疾伙伴关系提供关于其全球控制疟疾方法的信息，疟疾地图集项目提供关于全球疟疾风险绘图的更多信息
The efficient allocation of financial resources for malaria control using appropriate combinations of interventions requires accurate information on the geographic distribution of malaria risk. An evidence-based description of the global range of Plasmodium falciparum malaria and its endemicity has not been assembled in almost 40 y. This paper aims to define the global geographic distribution of P. falciparum malaria in 2007 and to provide a preliminary description of its transmission intensity within this range. The global spatial distribution of P. falciparum malaria was generated using nationally reported case-incidence data, medical intelligence, and biological rules of transmission exclusion, using temperature and aridity limits informed by the bionomics of dominant Anopheles vector species. A total of 4,278 spatially unique cross-sectional survey estimates of P. falciparum parasite rates were assembled. Extractions from a population surface showed that 2.37 billion people lived in areas at any risk of P. falciparum transmission in 2007. Globally, almost 1 billion people lived under unstable, or extremely low, malaria risk. Almost all P. falciparum parasite rates above 50% were reported in Africa in a latitude band consistent with the distribution of Anopheles gambiae s.s. Conditions of low parasite prevalence were also common in Africa, however. Outside of Africa, P. falciparum malaria prevalence is largely hypoendemic (less than 10%), with the median below 5% in the areas surveyed. This new map is a plausible representation of the current extent of P. falciparum risk and the most contemporary summary of the population at risk of P. falciparum malaria within these limits. For 1 billion people at risk of unstable malaria transmission, elimination is epidemiologically feasible, and large areas of Africa are more amenable to control than appreciated previously. The release of this information in the public domain will help focus future resources for P. falciparum malaria control and elimination. Combining extensive surveillance and climate data, as well as biological characteristics of Anopheles mosquitoes, Robert Snow and colleagues create a global map of risk for P. falciparum malaria. Malaria is a parasitic disease that occurs in tropical and subtropical regions of the world. 500 million cases of malaria occur every year, and one million people, mostly children living in sub-Saharan Africa, die as a result. The parasite mainly responsible for these deaths—Plasmodium falciparum—is transmitted to people through the bites of infected mosquitoes. These insects inject a life stage of the parasite called sporozoites, which invade and reproduce in human liver cells. After a few days, the liver cells release merozoites (another life stage of the parasite), which invade red blood cells. Here, they multiply before bursting out and infecting more red blood cells, causing fever and damaging vital organs. Infected red blood cells also release gametocytes, which infect mosquitoes when they take a human blood meal. In the mosquito, the gametocytes multiply and develop into sporozoites, thus completing the parasite's life cycle. Malaria can be treated with antimalarial drugs and can be prevented by controlling the mosquitoes that spread the parasite (for example, by using insecticides) and by avoiding mosquito bites (for example, by sleeping under a insecticide-treated bednet). Because malaria poses such a large global public-health burden, many national and international agencies give countries where malaria is endemic (always present) financial resources for malaria control and, where feasible, elimination. The efficient allocation of these resources requires accurate information on the geographical distribution of malaria risk, but it has been 40 years since a map of malaria risk was assembled. In this study, which is part of the Malaria Atlas Project, the researchers have generated a new global map to show where the risk of P. falciparum transmission is moderate or high (stable transmission areas where malaria is endemic) and areas where the risk of transmission is low (unstable transmission areas where sporadic outbreaks of malaria occur). To construct their map of P. falciparum risk, the researchers collected nationally reported data on malaria cases each year and on the number of people infected in sampled communities. They also collected information about climatic conditions that affect the parasite's life cycle and consequently the likelihood of active transmission. For example, below a certain temperature, infected mosquitoes reach the end of their natural life span before the parasite has had time to turn into infectious sporozoites, which means that malaria transmission does not occur. By combining these different pieces of information with global population data, the researchers calculated that 2.37 billion people (about 35% of the world's population) live in areas where there is some risk of P. falciparum transmission, and that about 1 billion of these people live where there is a low but still present risk of malaria transmission. Furthermore, nearly all the regions where more than half of children carry P. falciparum parasites (a P. falciparum prevalence of more than 50%) are in Africa, although there are some African regions where few people are infected with P. falciparum. Outside Africa, the P. falciparum prevalence is generally below 5%. The accuracy of this new map of the spatial distribution of P. falciparum malaria risk depends on the assumptions made in its assembly and the accuracy of the data fed into it. Nevertheless, by providing a contemporary indication of global patterns of P. falciparum malaria risk, this new map should be a valuable resource for agencies that are trying to control and eliminate malaria. (A similar map for the more common but less deadly P. vivax malaria would also be useful, but has not yet been constructed because less information is available and its biology is more complex.) Importantly, the map provides an estimate of the number of people who are living in areas where malaria transmission is low, areas where it should, in princple, be possible to use existing interventions to eliminate the parasite. In addition, it identifies large regions of Africa where the parasite might be more amenable to control and, ultimately, elimination than previously thought. Finally, with regular updates, this map will make it possible to monitor the progress of malaria control and elimination efforts. Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050038. The MedlinePlus encyclopedia contains a page on malaria (in English and Spanish) Information is available from the World Health Organization on malaria (in English, Spanish, French, Russian, Arabic, and Chinese) The US Centers for Disease Control and Prevention provide information on malaria (in English and Spanish) Information is available from the Roll Back Malaria Partnership on its approach to the global control of malaria More information is available on global mapping of malaria risk from the Malaria Atlas Project
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影响因子：
11.8
作者：
Brooker S;Leslie T;Kolaczinski K;Mohsen E;Mehboob N;Saleheen S;Khudonazarov J;Freeman T;Clements A;Rowland M;Kolaczinski J
通讯作者：
Kolaczinski J
影响因子：
168.9
作者：
Fegan, Greg W.;Noor, Abdisalan M.;Snow, Robert W.
通讯作者：
Snow, Robert W.
DOI：
10.4269/ajtmh.2005.73.553
发表时间：
2005-09-01
影响因子：
3.3
作者：
Gray, EM;Bradley, TJ
通讯作者：
Bradley, TJ
DOI：
10.1002/joc.1276
发表时间：
2005-12-01
期刊：
INTERNATIONAL JOURNAL OF CLIMATOLOGY
影响因子：
--
作者：
Hijmans, RJ;Cameron, SE;Jarvis, A
通讯作者：
Jarvis, A
疟疾风险的全球分布和人口：过去，现在和未来。
影响因子：
56.3
作者：
Hay, SI;Guerra, CA;Tatem, AJ;Noor, AM;Snow, RW
通讯作者：
Snow, RW