Evaluation of PCR-ELISA as a tool for monitoring transmission of Wuchereria bancrofti in District of Gampaha,Sri Lanka

Objective:To compare Wuchereria bancrofti(W.bancrofti)infection rates of Culex quinquefasciatus,using dissection and PCR-EUSA in two consecutive time periods(from 2007to 2008 and from 2008 to 2009).Methods:Mosquitoes were collected in 30 sentinel and 15 nonsentinel sites in 15 Medical Officer of Health areas of Gampaha District known for the presence of W.bancrofti transmission in two consecutive time period of 2007 to 2008 and 2008 to 2009.Captured mosquitoes were dissected to determine the W.bancrofti larvae(L_1 L_2,L_3,).PCR was carried out using DNA extracted from mosquito pools(15 body parts/pool)utilizing the primers specific for Wb-Sspl repeat.PCR products were analyzed by hybridization ELISA using fluorescein-labeled wild type specific probes.The prevalence of infected/infective mosquiloes in PCR pools(3 pools/site)was estimated using the PoolSereen^(TM)algorithm and a novel probability—based method.Results:Of 45 batches of mosquitoes dissected,W.bancrofti infected mosquitoes were found in19 and 13 batches,with an infection rate of 13.29%and 3.10%with mean larval density of 8.7 and1.0 larvae per mosquito for two study periods in the Gampaha District.Total of 405 pools of head,thorax and abdomen were processed by PCR-EUSA for each year.Of these,51 and 31 pools were positive for W.bancrofti in the two study periods respectively.The association of dissection based prevalence rates with PCR based rates as determined by the Pearson correlation coefficient were0.176 and 0.890 respectively for the two periods.Conclusions:Data indicate that PCR-EUSA is more sensitive than the traditional dissection techniques for monitoring transmission intensity.

Bancroftiasis among the mumuye of Northeastern Nigeria: Parasitological and clinical studies in Northern Taraba State

The study reports the prevalence of bancroftiasis in three Local Government Areas (LGAs) of Taraba State, Nigeria. Night blood samples collected from one thousand and thirty one individuals were stained with haematoxylin and examined microscopically for the presence of Wu-chereria bancrofti. The overall prevalence of infection in the study area was high (21.2%) but mean microfilaria densities were generally low. Statistically, prevalence rate differed significantly (χ2d.f.2 = 10.498;P χ2d.f.1 = 1.385;P > 0.05) between sexes. Infection also did not statistically differ between age groups (χ2d.f.5 = 13.219;P > 0.05) even though infection rate increased steadily with age and reaching a peak at the 40 - 49 year age group. Lymphoe-dema was the commonest (M = 12.4%, F = 19.2%) clinical manifestation of bancroftian morbidity encountered in the survey. Overall, the findings indicate that bancroftian filariasis is a public health problem in Taraba state and there is an urgent need to establish an elimination programme with a view of halting transmission in the area.

近10年门诊乳糜尿3700例分析

本文对1982～1991年门诊乳糜尿3 700例与防治前1957～1958年资料对比。防治后乳糜尿比重明显增高,占门诊晚期丝虫病患者的86.85％,其中新发病者3041例,占82.18％。提出当前丝虫性乳糜尿发病的特点为短期内发病集中增多,新发病人多,壮、老年发病率高,排出乳糜的程度轻。发作类型、主要临床症状等作为乳糜尿本身所具有的临床表现与防治前基本相同。对乳糜尿在基本控制微丝蚴血症后短期内逐渐集中发病的原因和乳糜尿发病的趋势进行了讨论和分析。

Dot-IGSS和Dot-ELISA检测班氏微丝蚴血症者血清特异性抗体的比较研究

以马来丝虫成虫可溶性抗原作为靶抗原，采用斑点免疫金银染色（Dot－IGSS）和斑点酶联免疫吸附试验（Dot－ELISA）检测班氏微丝蚴血症者血清特异性抗丝虫抗体。Dot－IGSS和Dot－ELISA的检测阳性率分别为100％（50／50）和90％（45／50）。两法均为阳性反应的45份血清的滴度为1∶100－1∶2560．其平均滴度在Dot－IGSS为1∶184，在Dot－ELISA为1∶150。两法检测滴度相同者30例，Dot－IGSS滴度高于Dot－ELISA的13例，低于Dot－ELISA的2例。Dot－IGSS和Dot－ELISA所检测抗体滴度呈直线相关（r=0．8433）。与Dot－ELISA相比，Dot－IGSS具有操作简便、容易判断结果等优点，还具有更高的敏感性和特异性，且不使用酶反应底物。建议将Dot－IGSS作为丝虫病免疫学诊断和血清流行病学调查的方法。

嗜人按蚊对班氏丝虫易感性的实验观察

本文报告嗜人按蚊对班氏丝虫人工感染的易感性,并和中华按蚊、致倦库蚊和东乡伊蚊的易感性进行比较。在用一名微丝蚴密度为190条/20cmm的班氏微丝蚴血症者血液感染的188只嗜人按蚊、202只中华按蚊、280只致倦库蚊和129只东乡伊蚊中,L_3阳性率分别为35.64％、9.41％、30.0％和65.89％;而在用另一名微丝蚴密度为83条/20cmm的班氏微丝蚴血症者血液感染的188只嗜人按蚊、134只中华按蚊、289只致倦库蚊和176只东乡伊蚊中,L_3阳性率分别为18.09％、3.73％、13.84％和39.77％。结论认为,嗜人按蚊对班氏丝虫人工感染的易感性明显高于中华按蚊,明显低于东乡伊蚊,而与致倦库蚊的易感性处在同一水平上。

山东省晚期丝虫病的流行病学分析

目的了解和掌握山东省晚期丝虫病的发病与流行状况。方法对山东原班氏丝虫病流行区基本消灭前后晚期丝虫病发病及流行病学调查情况进行了对比分析。结果防治前后晚期丝虫病病人的主要临床表现为象皮肿、鞘膜积液和乳糜尿。防治前32．00％的象皮肿和31．00％的鞘膜积液患者在40岁以上，而乳糜尿病人73．00％低于40岁，防治后象皮肿和鞘膜积液患者90．00％以上高于40岁，乳糜尿66．70％超过40岁，且女性高于男性。象皮肿、鞘膜积液和乳糜尿从基本消灭前的1．38％、6．14％和0．21％，基本消灭后分别下降到0．20％、0．34％和0．19％。结论基本消灭丝虫病后，象皮肿和鞘膜积液明显下降，但乳糜尿仍有一些新病例出现，所以乳糜尿的监测和治疗应作为晚期丝虫病防治的主要对策。

检测IgG、IgM抗体对考核丝虫病疗效的观察

用马来丝虫成虫冰冻切片抗原作IEST,对海群生治疗后18个月的班氏微丝蚴血症和症状体征阳性者进行了复查,结果显示治后IgG和IgM的总GMRT,均分别低于治前IgG和IgM的总GMRT;IgG和IgM的治后转阴率分别为15.1%和80.3%,差异具有显著性(P<0.01)。表明IgG抗体水平在治后18个月虽有下降。但仍有较高的抗体阳性率,而IgM抗体已大部转阴,转阴速度较快,提示在丝虫病防治后期检测IgM抗体的转阴率,可以作为考核疗效和疫情监测的一种方法。

淡色库蚊和致倦库蚊对广东株班氏丝虫易感性的研究

本文用南京株和合肥株淡色库蚊以及广东株致倦库蚊分别人工感染广东株周期型班氏丝虫，并对其易感性进行比较。用一名微丝蚴密度为２４条／６０μｌ的班氏丝虫微丝蚴血症者血液感染南京株淡色库蚊３３４只，合肥株淡色库蚊１３９只和致倦库蚊２４１只，Ｌ３阳性率分别为１２．５７％、５．７６％和５．８０％。结果表明上述三株库蚊均对广东株班氏丝虫易感，以南京株淡色库蚊的易感性为最高，合肥株淡色库蚊与致倦库蚊的易感性处于同一水平上，这提示在丝虫病的防治后期和监测工作中应加强对来自原疫区的外来人口的监测，及时发现和消除输入性传染源，以巩固丝虫病防治成果。

广东省班氏丝虫病防治后期人群和媒介感染情况观察

目的 探索人群微丝蚴率降至 1%以下 ,终止防治措施后人群和媒介感染情况。方法 终止防治措施后 ,1988～ 2 0 0 0年在原广东省班氏丝虫病流行区抽查 30 %以上流行镇 ,重点村居民夜间采血 12 0 μl血检微丝蚴 ,在血检点捕集致倦库蚊解剖 ,观察自然感染情况 ;选定 10个县原丝虫病流行较严重的村 ,纵向观察人群和媒介感染情况。结果 1988年人群微丝蚴率为 0 33% (5 75 /172 6 31) ,此后人群微丝蚴率和致倦库蚊自然感染率逐年下降 ,1997年后无微丝蚴血症者 ;1992～ 2 0 0 0年共解剖致倦库蚊 2 4 8115只 ,无发现自然感染幼丝虫 ;1988～ 1995年纵向观察 ,1988年人群微丝蚴率和蚊自然感染率分别为 0 14 %和 0 0 7% ,1994年后两者均为 0。结论 班氏丝虫病经防治后 ,人群微丝蚴率降至 1%以下则可阻断传播 ,10年后人群微丝蚴血症消失。

广州市花都区消灭丝虫病的研究

目的:总结和分析丝虫病的防治方法和效果,探讨消灭丝虫病的有效途径。方法:用回顾性调查方法,对花都区丝虫病的流行趋势、防治措施、防治效果进行分析和总结。结果:60年代调查花都丝虫病流行区平均微丝蚴率为7.47%,传播媒介为致倦库蚊。经过反复查治,1980年流行区人群微丝蚴率降至0.04%,达到基本消灭丝虫病标准,此后进行20多年的流行病监测,人群和蚊媒均未发现丝虫感染。1995年经省卫生厅审评,确认花都区已阻断丝虫病的传播,达到部颁消灭丝虫病标准。结论:花都区丝虫病防治在科学决策指导下,进行了传播媒介、治疗方法、防治策略及技术措施的一系列研究,确定以针对传染源为主导的防治策略及措施,使花都区丝虫病流行趋于终止。

Scrotal Filariasis, the Importance of Filarial Dance Sign in Scrotal Ultrasound

Objective: To study the value of the filarial dance sign as a diagnostic sign in scrotal ultrasonography in human Bancroftian filariasis. Methods: We studied 3 patients with scrotal pain, with high-resolution ultrasonography (HRUS) of scrotum including power and color Doppler study. All patients underwent peripheral blood smear. Results: Multiple cystic spaces containing motile echogenic twisted tubular structures were observed in the 3 patients. Peripheral blood smears in the 3 patients confirmed the presence of microfilaria. Mild hydrocele in two patients. Conclusions: HRUS is a useful technique for diagnosing scrotal filariasis in symptomatic patients and is very useful in the follow-up treatment.

Malaria and Lymphatic Filariasis Co-Transmission in Endemic Health Districts in Burkina Faso

Introduction: Lymphatic filariasis (LF) and malaria are two vector-borne diseases which parasites can simultaneously infect human or mosquito. In Burkina Faso, studies mainly focused on the control of these diseases independently. Hence, there is a lack of information on their co-transmission of to both human and vector. The present study aimed at providing baseline data from endemic areas in Burkina Faso towards a successful integrated management of both diseases. Methods: The study was carried out in six sites distributed in the East, Center-East and South-West regions of Burkina Faso. Data were collected in August 2014 and September 2015. The infection rates in human and vector populations, vector diversity, trophic and resting behavior were investigated. To determine the disease prevalence nocturnal finger- prick blood sample and microscopic observations were performed. Vectors collected by human landing catches and pyrethrum spray collections. Biochemical and molecular analyses were performed to identify Anopheles gambiae sensu lato sibling species, and to determine vector infection rate and their blood meal origins. Results: Results indicate residual transmission of LF and malaria in human and vector populations. A low co-infection rate (<1%) with Wuchereria bancrofti and Plasmodium falciparum was noted in both human and mosquito. Anopheles gambiae s.l. , An. funestus s.l. and An. nili were by order the main potential vectors encountered. It was in majority parous females and exhibited endophagic and exophagic behavior. Parasite’s co-infection was found with An. coluzzii and An. nili only. Conclusion: The present study has provided basic information on the (co-)transmission of both diseases in the study areas. These results will be useful for further investigations towards the development and implementation of a better integrated strategy to control these diseases.

斑氏丝虫感染Scid小鼠模型的建立

采用人工感染法,对严重联合免疫缺陷小鼠(Scid 小鼠) 进行夜现周期性斑氏丝虫实验感染研究。结果表明,斑氏丝虫经人工感染后能在Scid 小鼠体内发育成熟并产生微丝蚴,且虫体回收率较高为6～30% ,平均14-8% 。感染的10 只小鼠均在外周血中检获出微丝蚴,及解剖收集到成虫,感染成功率高达100% 。作者认为Scid 小鼠由于T、B淋巴细胞功能缺如,不能产生相应的抗丝虫感染抗体,是一种易于感染成功、潜伏期短、微丝蚴密度及成虫回收率高的较理想的实验动物。

Historic accounts of Mansonella parasitaemias in the South Pacific and their relevance to lymphatic filariasis elimination efforts today

There are two species of filarial parasites with sheathless microfilariae known to commonly cause parasitaemias in humans:Mansonella perstans and Mtinsonella ozzardi.In most contemporary accounts of the distribution of these parasites,neither is usually considered to occur anywhere in the Eastern Hemisphere.However,Sir Patrick Manson,who first described both parasite species,recorded the existence of sheathless sharp-tailed Mansonella ozzardilike parasites occurring in the blood of natives from New Guinea in each and every version of his manual for tropical disease that he wrote before his death in 1922.Manson's reports were based on his own identifications and were made from at least two independent blood sample collections that were taken from the island.Pacific region Mansonella perstans parasitaemias were also later(in 1923) reported to occur in New Guinea and once before this(in 1905) in Fiji.Although Mansonella-parasilaernias are generally regarded as benign,they are thought to be of public health importance because they can affect the epidemiological monitoring of other filarial diseases.In this article,we reviewed the historic literature concerning Pacific-origin Mansonella-parasitaemias in an attempt to explain how,despite repeated reports of Pacificregion Mansonella-parasilaemias,by as early as the 1970 s,the WHO had arrived at the presentday view that Wuchereria bancrofti is the only cause of filarial parasitaemias in Papua New Guinea.We have also evaluated the evidence supporting the contemporary existence of Pacificarea parasitaemia-causing Mansonella parasites and assessed the relevance such parasites could have for present-day lymphatic filariasis elimination efforts in the region.

班氏和马来丝虫实验感染东乡伊蚊体内发育及影响因素的研究

周期型班氏和马来丝虫微丝蚴实验感染东乡伊蚊,感染后逐日解剖媒蚊,观察两种丝虫在蚊体内发育。在温度26～28℃,相对湿度80℃～85％下,班氏幼虫于感染后12、36、60小时穿过胃臂进入胸肌,进胸率分别为59.4％(170/286)、95.6％(289/302)和82.9％(34/41)。平均感染率分别为70.1％和79.3％。于14.5和9.5天发有成感染期幼虫并进入头部和喙。同时观察两种丝虫形状大小和内部构造,与在致倦库蚊和中华按蚊体内发育相似。作者认为,东乡伊蚊在实验室易于饲养,传代好,蚊卵保存于4℃冰箱6个月以上,实为两种丝虫的良好实验感染媒介。

Lessons from lymphatic filariasis elimination and the challenges of post-elimination surveillance in China

Background:The Global Programme to Eliminate Lymphatic Filariasis(GPELF)was launched in response to the call proposed at the 50th World Health Assembly.The goal of the GPELF is to ensure that all the countries where the disease is endemic would have been transmission-free or would have entered post-intervention mass drug administration(MDA)surveillance by 2020.However,several countries are still not on track to discontinue MDA as planned.Thus,issues remain regarding the achievement of stated goals and how to effectively monitor the disease in the post-control and post-elimination phases.Main text:China was once a lymphatic filariasis(LF)endemic country with heavy disease burden.There were three milestones in the LF control phase of China,including:the proposal that the major focus of the control strategy should be on infectious sources;the three regimens of diethylcarbamazine(DEC)administration according to LF endemic extent;and the establishment of the threshold for LF transmission interruption.It has been ten years since China entered the post-elimination stage(declaration of LF elimination in China was in 2007).Two schemes and a diagnostic criterion were issued to guide all levels of disease control and prevention workers that conduct LF surveillance,as well as those caring for chronic filariasis patients.Regular training courses are held to maintain LF control skills in grass-root institutions.The Notifiable Diseases Reporting System,which included LF in 2004,plays an important role in LF post-elimination surveillance.Until now,no resurgence of LF cases has been detected,except for LF residue foci being found in Fuchuan County of the Guangxi Zhuang Autonomous Region.To confirm that transmission is no longer achievable after a decade since the declaration of LF elimination in China,it is expected within the next two years a transmission assessment survey,conducted in previous LF-endemic areas.Conclusions:DEC-fortified salt can help accelerate the progress of GPELF before the sprite phase.Sophisticated diagnostic criteria,systematic surveillance regimes,the Direct Network Report system,and regular trainings can effectively prevent the recrudescence of LF during surveillance phases.

Mapping and modelling the impact of mass drug adminstration on filariasis prevalence in Myanmar

Background:Lymphatic filariasis(LF)is endemic in Myanmar and targeted for elimination.To highlight the National Programme to Eliminate Lymphatic Filariasis(NPELF)progress between 2000 and 2014,this paper describes the geographical distribution of LF,the scale-up and impact of mass drug administration(MDA)implementation,and the first evidence of the decline in transmission in five districts.Methods:The LF distribution was determined by mapping historical and baseline prevalence data collected by NPELF.Data on the MDA implementation,reported coverage rates and sentinel site surveillance were summarized.A statistical model was developed from the available prevalence data to predict prevalence at township level by year of measurement.Transmission assessment survey(TAS)methods,measuring antigenemia(Ag)prevalence in children,were used to determine whether prevalence was below a level where recrudescence is unlikely to occur.Results:The highest baseline LF prevalence was found in the Central Valley region.The MDA implementation activities scaled up to cover 45 districts,representing the majority of the endemic population,with drug coverage rates ranging from 60.0%to 98.5%.Challenges related to drug supply and local conflict were reported,and interrupted MDA in some districts.Overall,significant reductions in LF prevalence were found,especially after the first 2 to 3 rounds of MDA,which was supported by the corresponding model.The TAS activities in five districts found only two Ag positive children,resulting in all districts passing the critical threshold.Conclusion:Overall,the Myanmar NPELF has made positive steps forward in the elimination of LF despite several challenges,however,it needs to maintain momentum,drawing on international stakeholder support,to aim towards the national and global goals of elimination.