MMWR Surveill Summ. 2014 Dec 5;63(12):1-22.
PROBLEM/CONDITION: Malaria in humans is caused by intraerythrocytic protozoa of the genus Plasmodium. These parasites are transmitted by the bite of an infective female Anopheles mosquito. The majority of malaria infections in the United States occur among persons who have traveled to regions with ongoing malaria transmission. However, malaria is also occasionally acquired by persons who have not traveled out of the country, through exposure to infected blood products, congenital transmission, laboratory exposure, or local mosquitoborne transmission. Malaria surveillance in the United States is conducted to identify episodes of local transmission and to guide prevention recommendations for travelers.
This report summarizes cases in persons with onset of symptoms in 2012 and summarizes trends during previous years.
Malaria cases diagnosed by blood film, polymerase chain reaction, or rapid diagnostic tests are mandated to be reported to local and state health departments by health-care providers or laboratory staff. Case investigations are conducted by local and state health departments, and reports are transmitted to CDC through the National Malaria Surveillance System (NMSS), National Notifiable Diseases Surveillance System (NNDSS), or direct CDC consults. For the first time, CDC conducted antimalarial drug resistance testing on blood samples submitted to CDC by health-care providers or local/state health departments. Data from these reporting systems serve as the basis for this report.
CDC received 1,687 reported cases of malaria with an onset of symptoms in 2012 among persons in the United States, including 1,683 cases classified as imported, one laboratory-acquired case, one nosocomial case, and two cryptic cases. The total number of cases represents a 12% decrease from the 1,925 cases reported for 2011. Plasmodium falciparum, P. vivax, P. malariae, and P. ovale were identified in 58%, 17%, 3%, and 3% of cases, respectively. Twenty (1%) patients were infected by two species. The infecting species was unreported or undetermined in 17% of cases, a decrease of 6 percentage points from 2011. Polymerase chain reaction testing determined or corrected the species for 45 (43%) of the 104 samples submitted for drug resistance testing. Of the 909 patients who reported purpose of travel, 604 (66%) were visiting friends or relatives (VFR). Among the 983 cases in U.S. civilians for whom information on chemoprophylaxis use and travel region was known, 63 (6%) patients reported that they had followed and adhered to a chemoprophylaxis drug regimen recommended by CDC for the regions to which they had traveled. Thirty-two cases were reported in pregnant women, among whom only one adhered to chemoprophylaxis. Among all reported cases, 231 (14%) were classified as severe infections in 2012. Of these, six persons with malaria died in 2012. Beginning in 2012, there were 104 blood samples submitted to CDC that were tested for molecular markers associated with antimalarial drug resistance. Of the 65 P. falciparum-positive samples, 53 (82%) had genetic polymorphisms associated with pyrimethamine drug resistance, 61 (94%) with sulfadoxine resistance, 29 (45%) with chloroquine resistance, 1 (2%) with mefloquine drug resistance, 2 (3%) with atovaquone resistance, and none with artemisinin resistance.
Despite the 12% decline in the number of cases reported in 2012 compared with 2011, the overall trend in malaria cases has been increasing since 1973. Although progress has been made in reducing the global burden of malaria, the disease remains endemic in many regions, and the use of appropriate prevention measures by travelers is still inadequate.
Completion of data elements on the malaria case report form increased slightly in 2012 compared with 2011, but still remains unacceptably low. This incomplete reporting compromises efforts to examine trends in malaria cases and prevent infections. VFRs continue to be a difficult population to reach with effective malaria prevention strategies. Evidence-based prevention strategies that effectively target VFRs need to be developed and implemented to have a substantial impact on the numbers of imported malaria cases in the United States. Although more patients reported taking chemoprophylaxis to prevent malaria, the majority reported not taking it, and adherence was poor among those who did take chemoprophylaxis. Proper use of malaria chemoprophylaxis will prevent the majority of malaria illness and reduce the risk for severe disease (http://www.cdc.gov/malaria/travelers/drugs.html). Malaria infections can be fatal if not diagnosed and treated promptly with antimalarial medications appropriate for the patient's age and medical history, the likely country of malaria acquisition, and previous use of antimalarial chemoprophylaxis. Recent molecular laboratory advances have enabled CDC to identify and conduct molecular surveillance of antimalarial drug resistance (http://www.cdc.gov/malaria/features/ars.html). These advances will allow CDC to track, guide treatment, and manage drug resistant malaria parasites both domestically and globally. For this to be successful, specimens should be submitted for cases diagnosed in the United States and for ongoing specimen collection and testing globally. Clinicians should consult the CDC Guidelines for Treatment of Malaria and contact the CDC's Malaria Hotline for case management advice when needed. Malaria treatment recommendations can be obtained online (http://www.cdc.gov/malaria/diagnosis_treatment) or by calling the Malaria Hotline (770-488-7788 or toll-free at 855-856-4713).
问题/状况：人类疟疾是由疟原虫属的红细胞内原生动物引起的。这些寄生虫通过受感染的雌性疟蚊叮咬传播。美国大多数疟疾病例发生在前往疟疾持续传播地区的旅行者中。然而，也有一些人在没有出国旅行的情况下通过接触受感染的血液制品、先天性传播、实验室暴露或当地蚊媒传播而获得疟疾。在美国进行疟疾监测是为了确定当地传播的病例，并为旅行者提供预防建议。
本报告总结了 2012 年发病的患者病例，并总结了前几年的趋势。
通过血液涂片、聚合酶链反应或快速诊断检测诊断的疟疾病例，由医疗保健提供者或实验室工作人员向当地和州卫生部门报告。地方和州卫生部门进行病例调查，并通过国家疟疾监测系统 (NMSS)、国家法定疾病监测系统 (NNDSS) 或直接向 CDC 咨询向 CDC 报告报告。CDC 首次对医疗保健提供者或地方/州卫生部门提交给 CDC 的血液样本进行了抗疟药物耐药性检测。这些报告系统的数据是本报告的基础。
CDC 收到了 1687 例 2012 年在美国发病的疟疾病例报告，其中 1683 例为输入性病例，1 例为实验室获得性病例，1 例为院内感染病例，2 例为隐匿性病例。报告病例总数比 2011 年的 1925 例下降了 12%。在 58%的病例中发现了恶性疟原虫、间日疟原虫、三日疟原虫和卵形疟原虫，分别在 17%、3%和 3%的病例中发现了两种疟原虫。在 17%的病例中，感染的物种未报告或未确定，比 2011 年下降了 6 个百分点。聚合酶链反应检测确定或纠正了 104 份用于耐药性检测的样本中的 45 份（43%）的物种。在 983 名报告旅行目的的美国平民中，有 604 名（66%）是探亲访友。在已知旅行地区用药预防和旅行地区信息的 983 例病例中，有 6 例（6%）患者报告他们按照并坚持了 CDC 针对他们旅行地区的药物预防方案。有 32 例报告发生在孕妇中，其中只有 1 人坚持了预防措施。在所有报告的病例中，2012 年有 231 例（14%）被归类为严重感染。其中，有 6 人死于疟疾。从 2012 年开始，有 104 份血液样本提交给 CDC 进行与抗疟药物耐药性相关的分子标记物检测。在 65 份恶性疟原虫阳性样本中，有 53 份（82%）存在与乙胺嘧啶耐药相关的遗传多态性，61 份（94%）与磺胺多辛耐药相关，29 份（45%）与氯喹耐药相关，1 份（2%）与甲氟喹耐药相关，2 份（3%）与阿托喹酮耐药相关，无与青蒿素耐药相关。
尽管 2012 年报告的病例数量比 2011 年下降了 12%，但自 1973 年以来，疟疾病例的总体趋势一直在增加。尽管在减少全球疟疾负担方面取得了进展，但这种疾病在许多地区仍然流行，旅行者使用适当的预防措施仍然不足。
与 2011 年相比，2012 年疟疾病例报告表中数据元素的完成情况略有增加，但仍远不能令人满意。这种不完整的报告损害了检查疟疾病例趋势和预防感染的努力。探亲访友者仍然是难以接触到有效疟疾预防策略的人群。需要制定和实施基于证据的预防策略，以对美国输入性疟疾病例的数量产生重大影响。尽管更多的患者报告服用了预防疟疾的药物，但大多数患者没有服用，而且即使服用了药物，也没有坚持服用。正确使用疟疾预防药物将预防大多数疟疾疾病，并降低严重疾病的风险（http://www.cdc.gov/malaria/travelers/drugs.html）。如果不及时诊断和用适当的抗疟药物治疗，疟疾感染可能会致命，这些药物应根据患者的年龄和病史、可能获得疟疾的国家以及之前使用抗疟药物预防情况来选择。最近的分子实验室进展使 CDC 能够识别和进行抗疟药物耐药性的分子监测（http://www.cdc.gov/malaria/features/ars.html）。这些进展将使 CDC 能够跟踪、指导治疗并管理国内和全球的耐药疟原虫寄生虫。要取得成功，应提交在美国诊断的病例标本以及全球正在进行的标本采集和检测。临床医生应咨询 CDC 疟疾治疗指南，并在需要时致电 CDC 疟疾热线寻求病例管理建议。疟疾治疗建议可在线获取（http://www.cdc.gov/malaria/diagnosis_treatment）或致电疟疾热线（770-488-7788 或免费拨打 855-856-4713）。
