The epidemiology of malaria in the Papua New Guinea highlands: 2. Eastern Highlands Province

The epidemiology of malaria in Eastern Highlands Province (EHP) is characterized by generally very low-level or no local malaria transmission but a considerable risk of epidemics. In non-epidemic situations, parasite prevalence was under 5% in all but one area, Lufa Valley, where P. vivax was the most common parasite (prevalence rate of 58%). During epidemics, however, 23% (range 8-63%) of people were infected, with P. falciparum the predominant parasite. Mixed infections were very common (12%) but P. malariae and P. ovale were rare. Outside epidemics, malaria was only a minor source of febrile illness and enlarged spleens and anaemia (haemoglobin level < 7.5 g/dl) were virtually absent. However, epidemics were associated with a high incidence of relatively severe morbidity, both in terms of fevers and moderate to severe anaemia. Epidemic prevention, surveillance and response therefore are priorities in malaria control in EHP.     

澜沧江下游航运区疟疾学调查

目的 了解澜沧江下游航运区疟疾流行情况和恶性疟原虫对氯喹、青蒿琥酯的敏感性。 方法 居民带虫普查、IFA检测、疟史访问、发热病人血检、媒介按蚊、社会经济等调查和恶性疟原虫对氯喹、青蒿琥酯敏感性测试。 结果 各种人群累计平均疟原虫率为8.36％(226／2 704),其中间日疟占58.85％,恶性疟占40.27％,混合疟占0.88％。发热病人疟原虫检出率为30.03％(106／353)。居民、搬运工人和船员的疟史率,2001年分别为38.39％、8.82％和1.06％。主要媒介微小按蚊占捕获10种244.只按蚊总数的10.66％,叮人率为0.75只／人工·h。恶性疟原虫对青蒿琥酯和氯喹的抗性率各为8.70％和96.15％;半数抑制量(ID50)分别为13.44和91.25nmoL／L。 结论 目前澜沧江下游航运区疟疾呈不同程度流行状态,防治工作薄弱,急待加强。氯喹仍不宜治疗恶性疟,青蒿琥酯的敏感性有所下降,应引起重视。     

海南抗疟四十年

海南省历史上是著名的高疟区,抗疟前疟疾遍布全省农村,8种按蚊查获疟原虫自然感染,4种人疟原虫均有发现,居民原虫率山区74％,丘陵区34％,平原区12％。1959年开始全面抗疟,采取杀虫剂滞留喷洒灭蚊为主,经过30多年的防治,疟区已大面积缩小,疟疾发病率由1955年的1036.5/万降至1992年的11.5/万,成效卓著。目前疟疾分布局限于山区和一些近山丘陵区,以大劣按蚊为主要媒介,存在灶点和上山感染是其流行特征;次要媒介为微小按蚊,常可引起外来人群和新建居民点的点状暴发;平原区已无疟疾发生。全省每年约有4万疟疾病例,其中1/3病例为抗氯喹恶性疟,防治技术难题尚未完全解决,疟疾仍然是全省需要优先解决的公共卫生问题之一。     

Imported malaria in Australia.

OBJECTIVE: To obtain information on imported malaria in Australia. DESIGN AND SETTING: Patients with malaria diagnosed by microscopy by laboratories in southeast Queensland and northern New South Wales between October 1987 and December 1988 were included in this study. The chi 2 test was used to analyse data. PATIENTS: Blood films, details of prophylactic regimens and clinical history were received from 146 patients. MAIN OUTCOME MEASURES: This study was to determine the percentage of patients infected with each malaria species, where they contracted their infections, whether they had taken appropriate prophylactic agents and to determine the relationship between parasitaemia and previous exposure, symptoms and prophylaxis. RESULTS: One hundred patients (68.5%) had Plasmodium vivax malaria and 33 patients (22.6%) had Plasmodium falciparum malaria, with 3 (2.1%) infected with both of these malaria species. Ten cases (6.8%) were presumptively diagnosed as infections but diagnosis by microscopy was uncertain. Seventy-four per cent of the P. vivax infections and 85% of the P. falciparum infections were contracted in Papua New Guinea. Patients presented with a range of blood parasite concentrations that did not correlate with their symptoms, previous infection with malaria (P greater than 0.25) or the regular taking of prophylactic drugs (P greater than 0.1). Only 41% of the patients took any prophylactic drugs; the figure for temporary visitors to malarious areas was 54%. Only 11.6% of patients were taking the recommended drugs for the malarious areas they visited or were resident in. CONCLUSIONS: Constant monitoring of malarial infections is needed to ensure that appropriate advice is given to the traveller. Our study supports the dogma that malaria should be suspected in all patients who have been to malarious areas, regardless of previous malarious attacks, prophylaxis, treatment or the time which has elapsed since leaving the area.     

河南省淮滨县恶性疟流行病学调查报告

1984年6～10月在淮滨县18个乡开展了发热病人血检工作,结果在11个乡发现恶性疟,这些乡分布在淮河两岸,发病季节高峰在9月;居民带出率10月比6月高3～18倍,婴儿感染率为3.5%。证明1984年该地属暴发流行。通过调查,嗜人按蚊的地理分布及在人帐内的组成比与恶性疟的分布及发病率密切相关。结合其生态特征,证明嗜人按蚊是当地恶性疟的主要媒介。     

Outpatient treatment of malaria in recently arrived African migrants

OBJECTIVE: To describe the clinical features and management of African migrants recently arrived in Western Australia and subsequently diagnosed with malaria. DESIGN, PARTICIPANTS AND SETTING: Retrospective case record analysis of African migrants aged > or = 16 years with malaria referred to Royal Perth Hospital (RPH) from the WA Migrant Health Unit (MHU) between 1 March 2003 and 30 September 2005. MAIN OUTCOME MEASURES: Demographic variables; clinical and laboratory variables; Plasmodium species; antimalarial medications used and their efficacy. RESULTS: 57 (3.5%) of 1609 adult African migrants screened at the MHU were diagnosed with malaria and referred for treatment. 52 were infected with P. falciparum, two with P. ovale, one with P. malariae, and one with both P. falciparum and P. malariae; the malaria parasite could not be identified in one individual. No patients had severe malaria by World Health Organization criteria. Most patients (53/57) were treated as outpatients with oral antimalarial therapy; four patients without severe malaria were admitted to hospital for treatment and observation. Atovaquone-proguanil was the antimalarial medication most commonly used (in 52/57), and treatment was well tolerated in most patients. Post-treatment follow-up was possible in 50 patients; all 27 of those who were followed for 4 weeks or longer were cured. Cure could not be concluded in patients with shorter follow-up periods. All follow-up blood films were negative for malarial parasites. CONCLUSIONS: Outpatient treatment of malaria in recently arrived adult African migrants appeared to be safe and efficacious in our cohort.     

青蒿琥酯片预防疟疾效果观察

为了观察青蒿琥酯片预防疟疾的效果,1991～1992年选择疟疾高发区——三亚市高峰乡福万水库和电站作为试验压,以户为单位将试验区人口分为青蒿琥酯片试验组和安慰剂对照组,进行对照观察。1992年以1991年分组为基础,两组互相对换服药,增加人员以户为原则分别编入两组内。1991年试验组与对照组人数分别为77人与56人,1992年分别为75人与79人。试验组每周一次口服青蒿琥酯片100mg,1991年连服13周,1992年连服16周。结果:1991年试验组无发病,对照组发病率为8.93％(P<0.01);1992年试验组发病率为4.0％,对照组为13.92％(P<0.05);两年合计发病率试验组为1.97％,对照组为11.85％(P<0.01)。观察结果提示,虽然青蒿琥酯是一个速效而半衰期甚短的抗疟药,但是每周口服100mg对于疟疾的预防有一定的作用,且未发现任何副反应。对于短期进入疟区作业的人群,采用该方案是可行的。     

Two cases of severe falciparum malaria in KMCTH

Malaria is the most important parasitic disease of man. It is the protozoan infection of RBCs transmitted by bite of blood feeding female anopheline mosquito. Until the 19th century malaria was found throughout Europe, North America and Russia. Since then, it has been eradicated from these areas but in tropics though initial efforts of eradication had been successful, there has been resurgence of disease accompanied by increasing resistance of the anopheline vector to insecticide and of the parasite to antimalarial drugs. We report two cases of falciparum malaria in which there was co-existent vivax malarial infection. These two cases were both exposed to highly endemic zone for malaria.     

皖北中华按蚊传播疟疾密度阈值的研究

目的研究皖北中华按蚊传播疟疾密度阈值,为当地疟疾监测、预警与防制提供合理的评价指标。方法选取安徽北部中华按蚊分布区疟疾发病率较高的亳州市蒙城县立仓镇路楼村为调查点,于2005年8～9月现场调查媒介按蚊的叮人率、经产蚊比例、人血指数,调查人群疟疾发病率、原虫率以及疟疾患者发病至接受治疗的平均间隔期,收集观察期间的平均气温数据。根据基本繁殖率概念计算以媒介按蚊临界叮人率为指标的传播疟疾密度阈值。结果中华按蚊的人血指数为0.1771,平均经产蚊比例为0.51,当地中华按蚊的实际叮人率为11.1877、临界叮人率为7.6340,实际叮人率是临界叮人率的1.47倍。结论安徽北部试点中华按蚊的实际叮人率需要降低47%以上,才能阻断当地中华按蚊引起的疟疾传播。     

海口市按蚊调查和疟疾再传播风险评估

目的 了解海口市当前的按蚊的种类、分布及季节消长情况,为评估疟疾再传播风险提供科学依据。方法 采用灯光诱捕法（诱蚊灯法）、动物诱捕法（动物帐诱法）、人诱捕法（人诱停落法）,从海口市4个区中随机抽取13个乡镇所辖自然村进行按蚊种类及分布调查;并选取1个自然村为固定监测点,研究媒介按蚊季节消长规律。结果 在13个调查点共捕获按蚊9种1 684只。棋斑按蚊占61.82%,中华按蚊占34.80%,迷走按蚊占2.61%,乌头按蚊均占0.24%,须喙按蚊占0.18%,美彩按蚊占0.12%,带足按蚊占0.12%,嗜人按蚊占0.06%,多斑按蚊占0.06%;在固定监测点1~12月共捕获按蚊7种1 421只。其中中华按蚊、棋斑按蚊、迷走按蚊所占比例分别为44.76%、39.55%、15.20%。按蚊数量从4月份开始增多,9月达到高峰,4—11月捕获数占全年93.31%;中华按蚊全年都有活动。结论 海口市当前主要按蚊种类为棋斑按蚊、中华按蚊。中华按蚊分布广、密度高,全年均有活动;嗜人按蚊仅在局部地区发现,且密度较低,未发现历史上主要的传疟媒介微小按蚊。海口市属于高再传播风险地区。     

红河州1953-2016年疟疾流行、防治和消除历程及措施

目的 了解云南省红河州疟疾流行概况与防治历程,分析消除疟疾的措施、效果和经验.方法 对红河州1953-2016年疟疾防治疫情数据、报表和相关文件进行分析和总结.结果 红河州气候炎热,疟疾媒介按蚊复杂,调查发现有22种按蚊;在中华按蚊、微小按蚊、溪流按蚊、印神按蚊、巴拉巴按蚊和雷氏按蚊按蚊中均检测到过疟原虫子孢子自然感染,其中主要媒介微小按蚊子孢子自然感染率高达0.62％(8/1 291),历史上是疟疾高度地方性流行区,64年来累计报告疟疾病例409 251例,死亡788例,病死率0.19％.1953年发现病例最多,共报告43 071例,发病率2 661.1/10万.经过64年的积极防治,2008年疟疾发病率控制在5/10万以下,2011年发现最后1例当地感染病例后,再无本地感染疟疾,2015年11月通过省级考核评估,实现消除疟疾.结论 红河州原为我国主要边境高疟区,防治和消除措施成功有效,按国家规划实现了消除疟疾目标.加强境外输入性疟疾监测和管理,是巩固消除疟疾成果的重要策略.     

湖南省疟疾防治后期流行病学特征及监测结果分析

目的分析疟疾防治后期流行病学特征及监测结果,为制订防治策略提供依据。方法收集1980～2004年湖南省各县、市疟疾疫情资料、发热病人血检、荧光抗体检测以及媒介资料进行回顾性研究。结果全省疟疾发病率由1980年的89.27/10万至2004年下降为0.19/10万,发热病人血检阳性率由1980年的2.73%至2004年下降为0.06%;近3年本地居民未查见带虫者;1990年以来湖南省感染病例逐年减少,输入疟疾为主,分别占病例总数的6.51%和93.49%;中华按蚊为唯一的传疟媒介。结论当前湖南省疟疾以输入病例为主,年发病率已连续9年控制在1/10万以下,疟疾疫情相对稳定。     

云南景谷县2007～2012年疟疾媒介按蚊监测结果分析

目的了解景谷县传疟媒介按蚊种群数量、媒介密度、季节消长情况,为科学合理地开展传疟媒介防制工作提供依据。方法2007-2012年在景谷县媒介监测点,采用人工小时法、人诱捕法两种方法调查测定蚊虫数量、密度和季节消长。结果景谷县共捕获按蚊13种4975只,其中中华按蚊3753只,占捕蚊总数的75．44％,平均密度为1．482只从工小时,为按蚊优势种,生长高峰期在4-10月,密度高峰在7月,微小按蚊季节消长不明显,密度最高峰在9月份。对各年捕蚊平均密度进行比较,平均密度呈逐年下降。结论蚊媒监测能随时掌握主要传疟媒介的种群数量、分布和季节消长,为疟疾防治及制定有效的蚊媒防制方案提供科学依据。     

海南历史上著名疟区南桥疟疾现状的调查

通过寄生虫学和血清学调查显示,经过30多年的防治,南桥的疟疾已有较明显的下降,但部分居民点疟疾传播仍较严重,这些黎、苗族农民居民点和农场居民点平均原虫率高达10.4%和8.5％,疟疾荧光抗体阳性率高达32.6%和20.6％,个别农场居民点甚至发生暴发流行。当地农民上山种植并住宿者高达30％,致使发生当前持续传播方式—“上山感染”。调查群众疟防知识贫乏,缺乏蚊帐,基层卫生组织薄弱,病人治疗不彻底等与疟疾流行密切相关。应将疟防策略从生物医学模式转变到新的社会生态医学模式上来,把疟疾控制纳入到初级卫生保健中去。     

Cross-sectional characterization of malaria in Sanma and Shefa Provinces, Republic of Vanuatu: malaria control implications

Endemic malaria still exists in the Republic of Vanuatu, an 80-island archipelago that sits astride the southeast margin of the Southeast Asian-Melanesian malaria band (Buxton Line 170 degrees E, 20 degrees S). The annual parasite incidence has decreased dramatically over the past decade, which has been attributed to an intensive insecticide-treated bednet distribution program and implementation of a revised Plasmodium falciparum treatment policy that employs combination chloroquine + sulfadoxinelpyrimethamine as a first-line therapy. Standard malariometric surveys were conducted at 10 locations in 2 provinces, screening 2351 adults and children towards the end of the peak transmission season. Spleen rates were consistent with mesoendemic malaria. Examination of blood slides revealed a mean slide-positive rate of 22% (range 4% to 33%). P. falciparum predominated, accounting for 73% of infections, followed by P. vivax (25%). Among 396 individuals with P. falciparum, the gametocyte rate was 54%, with 37% presenting gametocytes alone without asexual stages. Only 8% and 4% of persons with asexual stage P. falciparum and P. vivax parasitaemia, respectively, were symptomatic. These data suggest that malaria transmission has increased in some locations in Vanuatu over the past decade and this report underscores the importance of appropriate bednet use and vector control in this setting as well as the impact of adding sulfadoxine/pyrimethamine and removing primaquine from the national malaria treatment formulary.     

双氢青蒿素、防2对间日疟和抗药性恶性疟的预防效果

目的：评价双氢青蒿素及防2对间日疟和抗药性恶性疟的预防效果，指导高危人群预防服药。方法：在云南省边境的勐腊县、景洪市和孟连县发病率≥8％的村子，随机分成双氢青蒿素(A、B)组、防2(C)组和空白对照(D)组进行预防服药控制疟疾现场研究。结果：A组带虫率从服药前的10．40％(54/591)降到药后的6．95％(37/533)，下降33．17％；B组下降84．70％；C组下降49．82％；空白对照组带虫发病率较观察前上升68．00％。结论双氢青蒿素每15d顿服6片，连续2月，对间日疟和抗药性恶性疟有一定的预防效果；防2对间日疟有一定的预防效果。     

普洱市2007-2011年按蚊种类和数量监测结果分析

目的了解普洱市传疟媒介按蚊种类、种群数量、季节消长现况,为控制疟疾流行提供科学依据。方法2007-2011年选择普洱市所辖10个县（区）内利于疟疾传播媒介按蚊孳生繁殖的老疫区作为监测点,采用流动捕蚊、叮人率、季节消长三种方法进行调查。结果2007-2011年通过三种方法调查结果,在监测区内共捕获按蚊21种47 308只,其中中华按蚊29 408只,占捕获总数的62.163%,为优势蚊种;该地区主要传疟媒介微小按蚊904只,占捕获总数的1.911%,分布于所辖10县（区）。结论微小按蚊在普洱市作为传疟媒介的地位仍然值得重视,应继续加强传疟媒介监测,警惕媒介按蚊密度升高而导致疟疾疫情回升。     

The epidemiology of malaria in the Papua New Guinea highlands: 1. Western Highlands Province

Despite a resurgence of malaria in many Papua New Guinea highlands and highlands fringe areas after the cessation of control activities in the early 1980s the malaria situation in these areas has received little attention. A series of cross-sectional surveys were therefore carried out to provide accurate and up-to-date information on the prevalence of malaria and the risk of epidemics and to propose adequate malaria control strategies. Studies in 24 villages in Western Highlands Province found the prevalence of malarial infections to be strongly correlated with altitude, ranging from 1.6% at altitudes of 1500-1800 m to over 30% in villages below 900 m. Malaria outbreaks were observed at the end of the rainy season. All four human malaria species were present with P. falciparum infections clearly dominating. The relative importance of P. vivax increased with altitude, while both P. malariae and P. ovale were rare. Many infections were of low density. While malaria is an important source of febrile illness in endemic areas below 1500 m altitude, only few observed or reported fevers are due to malarial infections in higher, nonendemic areas. Rates of enlarged spleens, mean haemoglobin levels and the prevalence of anaemia (Hb <7.5 g/dl) were strongly linked to the level of malaria found in each community and were associated with both altitude and concurrent malarial infection. Based on the survey results, areas of different malaria epidemiology are delineated and options for control in each area are discussed.     

Identification of Anopheles aquasalis as a possible vector of malaria in Guyana, South America

Adult female mosquitoes were collected in Mahdia, Guyana, to determine the incidence of malaria in Anopheles species found during the month of June 2000. Centers for Disease Control miniature white (incandescent) light traps, model 512, and miniature black (ultraviolet) light traps, model 912, were used to capture female mosquitoes. Numbers of mosquitoes collected were compared between white and black light traps and between traps set outside and inside of buildings. Adult female Anopheles mosquitoes were identified and an ELISA dipstick test for Plasmodium vivax and Plasmodium falciparum was performed on each mosquito. An aquasalis, An oswaldoi, and An braziliensis were attracted to white light traps. An triannulatus and An darlingi were collected from black light traps. Approximately the same numbers of all female Anopheles mosquitoes 28/45 (62%) were caught inside buildings as outside. Numbers of female non-anopheles mosquitoes captured in light traps varied between the traps set outside of buildings and inside of buildings with bright light traps collecting 91/122 (75%). A total of 45 Anopheles mosquitoes were captured and 122 non-anopheles species. Of the two known vectors of malaria in Guyana, An darlingi mosquitoes were not infected with P vivax but An aquasalis was found to be a carrier. The findings of this study suggest a need for further surveying and identification of current malaria vectors in Guyana.