Integrated seroprevalence-based assessment of Wuchereria bancrofti and Onchocerca volvulus in two lymphatic filariasis evaluation units of Mali with the SD Bioline Onchocerciasis/LF IgG4 Rapid Test.

BACKGROUND: Mali has become increasingly interested in the evaluation of transmission of both Wuchereria bancrofti and Onchocerca volvulus as prevalences of both infections move toward their respective elimination targets. The SD Bioline Onchocerciasis/LF IgG4 Rapid Test was used in 2 evaluation units (EU) to assess its performance as an integrated surveillance tool for elimination of lymphatic filariasis (LF) and onchocerciasis. METHODOLOGY/PRINCIPAL FINDINGS: A cross sectional survey with SD Bioline Onchocerciasis/LF IgG4 Rapid Test was piggy-backed onto a transmission assessment survey (TAS) (using the immunochromatographic card test (ICT) Binax Filariasis Now test for filarial adult circulating antigen (CFA) detection) for LF in Mali among 6-7 year old children in 2016 as part of the TAS in two EUs namely Kadiolo-Kolondieba in the region of Sikasso and Bafoulabe -Kita-Oussoubidiagna-Yelimane in the region of Kayes. In the EU of Kadiolo- Kolondieba, of the 1,625 children tested, the overall prevalence of W. bancrofti CFA was 0.62% (10/1,625) [CI = 0.31-1.09]; while that of IgG4 to Wb123 was 0.19% (3/1,600) [CI = 0.04-0.50]. The number of positives tested with the two tests were statistically comparable (p = 0.09). In the EU of Bafoulabe-Kita-Oussoubidiagna-Yelimane, an overall prevalence of W. bancrofti CFA was 0% (0/1,700) and that of Wb123 IgG4 antibody was 0.06% (1/1,700), with no statistically significant difference between the two rates (p = 0.99). In the EU of Kadiolo- Kolondieba, the prevalence of Ov16-specific IgG4 was 0.19% (3/1,600) [CI = 0.04-0.50]. All 3 positives were in the previously O. volvulus-hyperendemic district of Kolondieba. In the EU of Bafoulabe-Kita-Oussoubidiagna-Yelimane, an overall prevalence of Ov16-specific IgG4 was 0.18% (3/1,700) [CI = 0.04-0.47]. These 3 Ov16 IgG4 positives were from previously O.volvulus-mesoendemic district of Kita. CONCLUSIONS/SIGNIFICANCE: The SD Bioline Onchocerciasis/LF IgG4 Rapid test appears to be a good tool for integrated exposure measures of LF and onchocerciasis in co-endemic areas.

Implementing a community vector collection strategy using xenomonitoring for the endgame of lymphatic filariasis elimination.

BACKGROUND: The global strategy for elimination of lymphatic filariasis is by annual mass drug administration (MDA). Effective implementation of this strategy in endemic areas reduces Wuchereria bancrofti in the blood of infected individuals to very low levels. This minimises the rate at which vectors successfully pick microfilariae from infected blood, hence requiring large mosquito numbers to detect infections. The aim of this study was to assess the feasibility of using trained community vector collectors (CVCs) to sample large mosquito numbers with minimal supervision at low cost for potential scale-up of this strategy. METHODS: CVCs and supervisors were trained in mosquito sampling methods, i.e. human landing collections, pyrethrum spray collections and window exit traps. Mosquito sampling was done over a 13-month period. Validation was conducted by a research team as quality control for mosquitoes sampled by CVCs. Data were analyzed for number of mosquitoes collected and cost incurred by the research team and CVCs during the validation phase of the study. RESULTS: A total of 31,064 and 8720 mosquitoes were sampled by CVCs and the research team, respectively. We found a significant difference (F(1,13) = 27.1606, P = 0.0001) in the total number of mosquitoes collected from southern and northern communities. Validation revealed similar numbers of mosquitoes sampled by CVCs and the research team, both in the wet (F(1,4) = 1.875, P = 0.309) and dry (F(1,4) = 2.276, P = 0.258) seasons in the southern communities, but was significantly different for both wet (F(1,4) = 0.022, P = 0.005) and dry (F(1,4 ) = 0.079, P = 0.033) seasons in the north. The cost of sampling mosquitoes per season was considerably lower by CVCs compared to the research team (15.170 vs 53.739 USD). CONCLUSIONS: This study revealed the feasibility of using CVCs to sample large numbers of mosquitoes with minimal supervision from a research team at considerably lower cost than a research team for lymphatic filariasis xenomonitoring. However, evaluation of the selection and motivation of CVCs, acceptability of CVCs strategy and its epidemiological relevance for lymphatic filariasis xenomonitoring programmes need to be assessed in greater detail.

Information technology in morbidity management of human lymphatic filariasis-A promising tool in global programme for elimination of lymphatic filariasis.

BACKGROUND & OBJECTIVES: India is a signatory to the 1997 World Health Assembly resolutions on lymphatic fila- riasis, and other neglected tropical diseases, and supports global elimination of lymphatic filariasis by 2020. The global programme to eliminate lymphatic filariasis (GPELF) has two main components, viz. interrupting transmission of LF through mass drug administration; and managing morbidity and preventing disability. Consorted efforts by the Public Health Department in Tamil Nadu state (India) for elimination of LF was launched in the year 1997 concentrating on both the components of the programme. The data on the prevalence of filarial morbidity and its entire management at present is based on manual reports and registers maintained by the field functionaries. To overcome the constraints in the manual reporting, an attempt was made to develop a web-based reporting system with different modules and user-friendly interface. METHODS: The Vellore and Thiruvannamalai districts were selected as a study area. The study was conducted between 2011 and 2014, which revealed that the entire morbidity management was based on the manual formats. Constraints in the present manual reporting were analysed. PHP and MySQL tools were used to generate user friendly modules. Feedback was collected from field functionaries at different health centre levels, on the adequacy in the modules and effectiveness of the web-based reporting system. RESULTS: The online reporting modules facilitated data entry at the health subcentre level itself. Analysis and retrieval of data was facilitated at all other levels in the public health system. The modules also covered details of surgical interventions, ex-gratia payments and other benefits extended to the lymphoedema patients by the Government. INTERPRETATION & CONCLUSION: The usage and feedback of the web-based reporting system appeared very encouraging and reliable, indicating that it can be implemented in health programmes for disease management. This web-based user-friendly online reporting system can contribute largely to achieve the goals of the GPELF; specially after MDA is withdrawn.

Comparison of antigen and antibody responses in repeat lymphatic filariasis transmission assessment surveys in American Samoa.

BACKGROUND: Current WHO recommendations for lymphatic filariasis (LF) surveillance advise programs to implement activities to monitor for new foci of transmission after stopping mass drug administration (MDA). A current need in the global effort to eliminate LF is to standardize diagnostic tools and surveillance activities beyond the recommended transmission assessment survey (TAS). METHODOLOGY: TAS was first conducted in American Samoa in 2011 (TAS 1) and a repeat TAS was carried out in 2015 (TAS 2). Circulating filarial antigen (CFA) and serologic results from both surveys were analyzed to determine whether interruption of LF transmission has been achieved in American Samoa. PRINCIPAL FINDINGS: A total of 1,134 and 864 children (5-10 years old) were enrolled in TAS 1 and TAS 2, respectively. Two CFA-positive children were identified in TAS 1, and one CFA-positive child was identified in TAS 2. Results of both surveys were below the threshold for which MDA was warranted. Additionally, 1,112 and 836 dried blood spots from TAS 1 and TAS 2, respectively were tested for antibodies to Wb123, Bm14 and Bm33 by luciferase immunoprecipitation system (LIPS) assay and multiplex bead assay. In 2011, overall prevalence of responses to Wb123, Bm14, and Bm33 was 1.0%, 6.8% and 12.0%, respectively. In 2015, overall prevalence of positive Bm14 and Bm33 responses declined significantly to 3.0% (p<0.001) and 7.8% (p = 0.013), respectively. CONCLUSIONS/SIGNIFICANCE: Although passing TAS 1 and TAS 2 and an overall decline in the prevalence of antibodies to Bm14 and Bm33 between these surveys suggests decreased exposure and infection among young children, there were persistent responses in some schools. Clustering and persistence of positive antibody responses in schools may be an indication of ongoing transmission. There is a need to better understand the limitations of current antibody tests, but our results suggest that serologic tools can have a role in guiding programmatic decision making.

Impact of two follow-up schemes on morbidity management and disability prevention (MMDP) programme for filarial lymphedema in Matara, Sri Lanka.

Alleviating morbidity due to lymphatic filariasis (LF)-especially in elderly patients who are rather ignorant-is presently the biggest challenge for the national filariasis campaign. We introduced two follow-up schemes and compared each other to address three key programmatic issues (1) locating patients, (2) educating patients, family members on practice of lymphoedema self-care (3) well sustained daily self-care. Hundred and seven lymphoedema patients were introduced to the new Community Home Based Care (CHBC) programme as a part of MMDP programme at their homes. Twenty seven of 107 patients were selected by purposive sampling and followed-up under two schemes, 14 in Daily follow-up (DFU) scheme and 13 in Monthly follow-up (MFU) scheme. Impact was assessed using a KAP score, number of entry lesions (EL) and number of ADL episodes, limb volume, its appearance, changes in the quality of life and gained benefits. Visiting patients in their homes to introduce lymphoedema care programme was a success. KAP scores of the more important activities on lymphoedema care were significantly higher in DFU scheme. Number of patients (51.9%; 14/27) who had EL/s at baseline reduced significantly to 18.5% (5/27) at one year follow-up. The mean numbers of ADL episodes/year reduced significantly in both schemes. Six photographs of 27 showed obvious improvement in lymphoedema and its grade. Mean volume of lymphoedema reduced significantly in both schemes at one year no significant difference between schemes. Benefit score at one year revealed that the patients in DFU scheme received significantly higher amount of benefits compared to MFU scheme. In conclusion daily instruction has significantly motivated the patient and his/her family bringing a new hope.

Twelve-month longitudinal parasitological assessment of lymphatic filariasis-positive individuals: impact of a biannual treatment with ivermectin and albendazole.

OBJECTIVE: Mass drug administration (MDA) for the control of lymphatic filariasis (LF), in Ghana, started in the year 2000. While this had great success in many implementation units, there remain areas with persistent transmission, after more than 10 years of treatment. A closer examination of the parasite populations could help understand the reasons for persistent infections and formulate appropriate strategies to control LF in these areas of persistent transmission. MATERIALS AND METHODS: In a longitudinal study, we assessed the prevalence of microfilaraemia (mf) in two communities with 12 years of MDA in Ghana. In baseline surveys 6 months after the National MDA in 2014, 370 consenting individuals were tested for antigenaemia using immunochromatographic test (ICT) cards and had their mf count determined through night blood surveys. 48 ICT positives, of whom, 17 were positive for mf, were treated with 400 µg/kg ivermectin + 400 mg albendazole and subsequently followed for parasitological assessment at 3-month intervals for 1 year. This overlapped with the National MDA in 2015. RESULTS: There was a 68% parasite clearance 3 months after treatment. The pre-treatment mf count differed significantly from the post-treatment mf counts at 3 months (P = 0.0023), 6 months (P = 0.0051), 9 months (P = 0.0113) and 12 months (P = 0.0008). CONCLUSION: In these settings with persistent LF transmission, twice-yearly treatment may help accelerate LF elimination. Further large-scale evaluations are required to ascertain these findings.

Partnering for impact: Integrated transmission assessment surveys for lymphatic filariasis, soil transmitted helminths and malaria in Haiti.

BACKGROUND: Since 2001, Haiti's National Program for the Elimination of Lymphatic Filariasis (NPELF) has worked to reduce the transmission of lymphatic filariasis (LF) through annual mass drug administration (MDA) with diethylcarbamazine and albendazole. The NPELF reached full national coverage with MDA for LF in 2012, and by 2014, a total of 14 evaluation units (48 communes) had met WHO eligibility criteria to conduct LF transmission assessment surveys (TAS) to determine whether prevalence had been reduced to below a threshold, such that transmission is assumed to be no longer sustainable. Haiti is also endemic for malaria and many communities suffer a high burden of soil transmitted helminths (STH). Heeding the call from WHO for integration of neglected tropical diseases (NTD) activities, Haiti's NPELF worked with the national malaria control program (NMCP) and with partners to develop an integrated TAS (LF-STH-malaria) to include assessments for malaria and STH. METHODOLOGY/PRINCIPLE FINDINGS: The aim of this study was to evaluate the feasibility of using TAS surveys for LF as a platform to collect information about STH and malaria. Between November 2014 and June 2015, TAS were conducted in 14 evaluation units (EUs) including 1 TAS (LF-only), 1 TAS-STH-malaria, and 12 TAS-malaria, with a total of 16,655 children tested for LF, 14,795 tested for malaria, and 298 tested for STH. In all, 12 of the 14 EUs passed the LF TAS, allowing the program to stop MDA for LF in 44 communes. The EU where children were also tested for STH will require annual school-based treatment with albendazole to maintain reduced STH levels. Finally, only 12 of 14,795 children tested positive for malaria by RDT in 38 communes. CONCLUSIONS/SIGNIFICANCE: Haiti's 2014-2015 Integrated TAS surveys provide evidence of the feasibility of using the LF TAS as a platform for integration of assessments for STH and or malaria.

The significant scale up and success of Transmission Assessment Surveys 'TAS' for endgame surveillance of lymphatic filariasis in Bangladesh: One step closer to the elimination goal of 2020.

BACKGROUND: Bangladesh had one of the highest burdens of lymphatic filariasis (LF) at the start of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) with an estimated 70 million people at risk of infection across 34 districts. In total 19 districts required mass drug administration (MDA) to interrupt transmission, and 15 districts were considered low endemic. Since 2001, the National LF Programme has implemented MDA, reduced prevalence, and been able to scale up the WHO standard Transmission Assessment Survey (TAS) across all endemic districts as part of its endgame surveillance strategy. This paper presents TAS results, highlighting the momentous geographical reduction in risk of LF and its contribution to the global elimination target of 2020. METHODOLOGY/PRINCIPAL FINDINGS: The TAS assessed primary school children for the presence of LF antigenaemia in each district (known as an evaluation unit-EU), using a defined critical cut-off threshold (or 'pass') that indicates interruption of transmission. Since 2011, a total of 59 TAS have been conducted in 26 EUs across the 19 endemic MDA districts (99,148 students tested from 1,801 schools), and 22 TAS in the 15 low endemic non-MDA districts (36,932 students tested from 663 schools). All endemic MDA districts passed TAS, except in Rangpur which required two further rounds of MDA. In total 112 students (male n = 59; female n = 53), predominately from the northern region of the country were found to be antigenaemia positive, indicating a recent or current infection. However, the distribution was geographically sparse, with only two small focal areas showing potential evidence of persistent transmission. CONCLUSIONS/SIGNIFICANCE: This is the largest scale up of TAS surveillance activities reported in any of the 73 LF endemic countries in the world. Bangladesh is now considered to have very low or no risk of LF infection after 15 years of programmatic activities, and is on track to meet elimination targets. However, it will be essential that the LF Programme continues to develop and maintain a comprehensive surveillance strategy that is integrated into the health infrastructure and ongoing programmes to ensure cost-effectiveness and sustainability.

Evaluating the Burden of Lymphedema Due to Lymphatic Filariasis in 2005 in Khurda District, Odisha State, India.

BACKGROUND: Over 1.1 billion people worldwide are at risk for lymphatic filariasis (LF), and the global burden of LF-associated lymphedema is estimated at 16 million affected people, yet country-specific estimates are poor. METHODOLOGY/PRINCIPAL FINDINGS: A house-to-house morbidity census was conducted to assess the burden and severity of lymphedema in a population of 1,298,576 persons living in the LF-endemic district of Khurda in Odisha State, India. The burden of lymphedema in Khurda is widespread geographically, and 1.3% (17,036) of the total population report lymphedema. 51.3% of the patients reporting lymphedema were female, mean age 49.4 years (1-99). Early lymphedema (Dreyer stages 1 & 2) was reported in two-thirds of the patients. Poisson regression analysis was conducted in order to determine risk factors for advanced lymphedema (Dreyer stages 4-7). Increasing age was significantly associated with advanced lymphedema, and persons 70 years and older had a prevalence three times greater than individuals ages 15-29 (aPR: 3.21, 95% CI 2.45, 4.21). The number of adenolymphangitis (ADL) episodes reported in the previous year was also significantly associated with advanced lymphedema (aPR 4.65, 95% CI 2.97-7.30). This analysis is one of the first to look at potential risk factors for advanced lymphedema using morbidity census data from an entire district in Odisha State, India. SIGNIFICANCE: These data highlight the magnitude of lymphedema in LF-endemic areas and emphasize the need to develop robust estimates of numbers of individuals with lymphedema in order to identify the extent of lymphedema management services needed in these regions.

The health and economic benefits of the global programme to eliminate lymphatic filariasis (2000-2014).

BACKGROUND: Lymphatic filariasis (LF), also known as elephantiasis, is a neglected tropical disease (NTD) targeted for elimination through a Global Programme to Eliminate LF (GPELF). Between 2000 and 2014, the GPELF has delivered 5.6 billion treatments to over 763 million people. Updating the estimated health and economic benefits of this significant achievement is important in justifying the resources and investment needed for eliminating LF. METHOD: We combined previously established models to estimate the number of clinical manifestations and disability-adjusted life years (DALYs) averted from three benefit cohorts (those protected from acquiring infection, those with subclinical morbidity prevented from progressing and those with clinical disease alleviated). The economic savings associated with this disease prevention was then analysed in the context of prevented medical expenses incurred by LF clinical patients, potential income loss through lost-labour, and prevented costs to the health system to care for affected individuals. The indirect cost estimates were calculated using the human capital approach. A combination of four wage sources was used to estimate the fair market value of time for an agricultural worker with LF infection (to ensure a conservative estimate, the lowest wage value was used). RESULTS: We projected that due to the first 15 years of the GPELF 36 million clinical cases and 175 (116-250) million DALYs will potentially be averted. It was estimated that due to this notable health impact, US$100.5 billion will potentially be saved over the lifetimes of the benefit cohorts. This total amount results from summing the medical expenses incurred by LF patients (US$3 billion), potential income loss (US$94 billion), and costs to the health system (US$3.5 billion) that were projected to be prevented. The results were subjected to sensitivity analysis and were most sensitive to the assumed percentage of work hours lost for those suffering from chronic disease (changing the total economic benefit between US$69.30-150.7 billion). CONCLUSIONS: Despite the limitations of any such analysis, this study identifies substantial health and economic benefits that have resulted from the first 15 years of the GPELF, and it highlights the value and importance of continued investment in the GPELF.

Can community-based integrated vector control hasten the process of LF elimination?

Community-based integrated vector control (IVC) using polystyrene beads (EPS) and pyrethroid impregnated curtains (PIC) as an adjunct to mass drug administration (MDA) was implemented for lymphatic filariasis elimination, in the filaria endemic villages of Tirukoilur, south India. In all the villages, MDA was carried out by the state health machinery, as part of the national filariasis elimination programme. Thirty-six difficult-to-control villages were grouped as, viz, MDA alone, MDA + EPS and MDA + EPS + PIC arms. Implementation and monitoring of IVC was carried out by the community. After 3 years of IVC, higher reductions in filariometric indices were observed in both the community and vector population. Decline in antigenaemia prevalence was higher in MDA + IVC as compared to MDA alone arm. Vector density dropped significantly (P < 0.05) in both the IVC arms, and nil transmission was observed during post-IVC period. Almost 53.8 and 75.8 % of the cesspits in MDA + EPS and MDA + EPS + PIC arms were closed by the householders, due to the enhanced awareness on vector breeding. The paper presents the key elements of IVC implementation through social mobilization in a LF prevalent area. Thus, community-based IVC strategy can hasten LF elimination, as it reduced the transmission and filariometric indices significantly. Indices were maintained at low level with nil transmission, by the community through IVC tools.

Factors associated with the performance and cost-effectiveness of using lymphatic filariasis transmission assessment surveys for monitoring soil-transmitted helminths: a case study in Kenya.

Transmission assessment surveys (TAS) for lymphatic filariasis have been proposed as a platform to assess the impact of mass drug administration (MDA) on soil-transmitted helminths (STHs). This study used computer simulation and field data from pre- and post-MDA settings across Kenya to evaluate the performance and cost-effectiveness of the TAS design for STH assessment compared with alternative survey designs. Variations in the TAS design and different sample sizes and diagnostic methods were also evaluated. The district-level TAS design correctly classified more districts compared with standard STH designs in pre-MDA settings. Aggregating districts into larger evaluation units in a TAS design decreased performance, whereas age group sampled and sample size had minimal impact. The low diagnostic sensitivity of Kato-Katz and mini-FLOTAC methods was found to increase misclassification. We recommend using a district-level TAS among children 8-10 years of age to assess STH but suggest that key consideration is given to evaluation unit size.

A TaqMan-based multiplex real-time PCR assay for the simultaneous detection of Wuchereria bancrofti and Brugia malayi.

With the Global Program for the Elimination of Lymphatic Filariasis continuing to make strides towards disease eradication, many locations endemic for the causative parasites of lymphatic filariasis are realizing a substantial decrease in levels of infection and rates of disease transmission. However, with measures of disease continuing to decline, the need for time-saving and economical molecular diagnostic assays capable of detecting low levels of parasite presence is increasing. This need is greatest in locations co-endemic for both Wuchereria bancrofti and Brugia parasites because testing for both causative agents individually results in significant increases in labor and reagent costs. Here we describe a multiplex, TaqMan-based, real-time PCR assay capable of simultaneously detecting W. bancrofti and Brugia malayi DNA extracted from human bloodspots or vector mosquito pools. With comparable sensitivity to established singleplex assays, this assay provides significant cost and labor savings for disease monitoring efforts in co-endemic locations.

Monitoring and evaluation of lymphatic filariasis interventions: an improved PCR-based pool screening method for high throughput Wuchereria bancrofti detection using dried blood spots.

BACKGROUND: Effective diagnostic tools are necessary to monitor and evaluate interruption of Lymphatic Filariasis (LF) transmission. Accurate detection of Wuchereria bancrofti (Wb) microfilaria (mf) is essential to measure the impact of community treatment programmes. PCR-based assays are specific, highly sensitive tools allowing the detection of Wuchereria bancrofti DNA in human blood samples. However, current protocols describing the pool screening approach, use samples of less than 60 µl of blood, which limits the sensitivity of the pool-screen PCR assay. The purpose of this study was to improve the pool-screen PCR protocol to enhance its sensitivity and usefulness for population scale studies. FINDINGS: DNA extractions were performed with the DNeasy kit, the PCR with the Wb LDR primers and the SYBR-Green dye. Improvements of our pool-screen real-time PCR (qPCR) assay allowed the detection of as little as one Wb microfilaria diluted in a pool of at least 12 blood samples of 60 µl each. Using this assay, mf burdens can be predicted using a standard curve derived from mf spiked dried blood samples. The sensitivity achieved is equivalent to the detection of a single LF positive individual carrying a mf burden as low as 18 mf/ml, in a pool of blood samples from at least 12 individuals. CONCLUSIONS: Due to its sensitivity, rapidity and cost-effectiveness, we suggest this qPCR pool-screening assay could be used as a diagnostic tool for population- scale filariasis elimination monitoring and evaluation.

Predictive value of the eosinophil counts in the biological diagnosis of lymphatic filariasis in French Polynesia.

SETTINGS: Lymphatic filariasis is common in many tropical and subtropical areas and is a major public health issue in south Pacific islands. In endemic areas, most infected individuals are asymptomatic but may harbor microfilariae or filarial antigens in their peripheral blood. Microscopy remains the reference diagnostic tool for the identification of microfilariae but is weakly sensitive. The diagnosis of Wuchereria bancrofti infection was dramatically altered by the development of filarial antigen tests, which are easy to perform but expensive for routine use. Lymphatic filariasis is responsible for acquired eosinophilia and blood eosinophil count is commonly used as a screening tool in endemic areas. METHOD: We retrospectively analyzed all the results of eosinophil counts, antigen and microfilariae detection performed in our laboratory over a 24-month period. We calculated the prevalence of antigenemia for various eosinophilic cut offs. RESULTS: The prevalence of antigenemia was estimated at 25.78% with eosinophilia defined as a count eosinophilic PMN above 500 per mm(3). DISCUSSION: Our prevention strategy against lymphatic filariasis is based on annual mass drug administration, vector control, and systematic treatment of antigenemic and microfilaremic patients. Antigenemic and microfilaremic detection cannot be routinely performed because of their cost. Current treatments used for lymphatic filariasis are safe and cheaper than antigenic detection. A possible additional strategy to decrease the prevalence of antigenemia would be the systematic treatment of patients with hypereosinophilia.

Using the AD12-ICT rapid-format test to detect Wuchereria bancrofti circulating antigens in comparison to Og4C3-ELISA and nucleopore membrane filtration and microscopy techniques.

Lymphatic filariasis (LF) continues to be a major source of permanent disability and an impediment to socio-economic development in 73 countries where more than 1 billion people are at risk and over 120 millions are infected. The global drive to eliminate LF necessitates an increasing demand for valid, reliable and rapid diagnostic tests. This study aimed to assess the performance of the AD12 rapid format immunochromatographic test (ICT) to detect Wuchereria bancrofti circulating antigens, against the combined gold standard: TropBio Og4C3-ELISA (enzyme-linked immunosorbent assay) which detects circulating filarial antigen (CFA) and the nucleopore membrane filtration and microscopic examination. This prospective case-control study involved 647 asymptomatic migrant workers from filariasis-endemic countries. Of these specimens, 32 were positive for microfilaremia using the membrane filtration and microscopy, 142 positive by ELISA (of which 32 had microfilaremia), and 128 positive by the ICT (of which 31 had microfilaremia). The performance of the ICT was calculated against 32 true-positive and 90 true-negative cases. For the detection of CFA, the ICT had a sensitivity of 97% (95% confidence interval [CI] 91-103), specificity 100% (95% CI 100-100), Positive Predictive Value (PPV) 100% (95% CI 100-100), Negative Predictive Value (NPV) 99% (95% CI 97-101); and the total accuracy of the test was 99% (95% CI 98-101). The agreement between ICT and ELISA in detecting W. bancrofti antigens was excellent (kappa = 0.934; p = 0.000). In conclusion, the AD12-ICT test for the detection of W. bancrofti-CFA was sensitive and specific and comparable to the performance of ELISA. The ICT would be a useful additional test to facilitate the proposed strategies for control and elimination of LF. Because it is rapid, simple to perform, and does not require the use of special equipment, the ICT may be most appropriate in screening programs and in monitoring the possible risk of introducing the disease to the non-endemic countries.

Current practices in the management of lymphatic filariasis.

Lymphatic filariasis is a major cause of acute and chronic morbidity in 81 countries. The availability of safe treatment regimens along with rapid diagnostic tools resulted in a global program to eliminate the disease. The two main objectives of the global elimination program are to interrupt transmission of the parasites and to provide care for those with the disease. The strategy for transmission interruption is preventive chemotherapy through mass drug administration. This article reviews the current treatment regimens for lymphatic filariasis and discusses the challenges posed by co-endemicity with other diseases. The role of integrated vector management as a supplementary strategy for mass drug administration and new strategies for treatment and morbidity control through antibiotic targeting of the Wolbachia endosymbionts are also discussed.

Immuno-parasitological assessment of bancroftian filariasis in a highly endemic area along the River Sabaki, in Malindi district, Kenya.

Lymphatic filariasis is endemic in the coastal areas of Kenya, with four major foci identified in the early 1970s. The prevalence and intensity of Wuchereria bancrofti infection, together with antifilarial antibody responses, were assessed in a historically highly endemic focus along the River Sabaki, in Malindi district. The prevalences of microfilaraemia and antigenaemia (detected by Og4C3 ELISA) were >20% and >40%, respectively, and both increased steadily with age. The high prevalences of antifilarial IgG1 (86%) and IgG4 (91%) responses indicate that most people living in this setting are exposed to W. bancrofti infection. The children investigated had higher levels of antifilarial IgG1 than the adults. The results of this study, based on a battery of currently available parasitological and immunological methods, provide an epidemiological update on lymphatic filariasis on the northern Kenyan coast. They show that the River Sabaki area is still an important focus for bancroftian filariasis and highlight the importance of implementing an elimination programme, to interrupt the transmission of W. bancrofti in all areas of endemicity in Kenya. The detailed baseline data collected in the River Sabaki area make the communities studied ideal as sentinel sites for epidemiological monitoring and the evaluation of the impact of mass drug administrations to eliminate lymphatic filariasis.

Epidemiology of episodic adenolymphangitis: a longitudinal prospective surveillance among a rural community endemic for bancroftian filariasis in coastal Orissa, India.

BACKGROUND: The epidemiological knowledge on acute condition of lymphatic filariasis is essential to understand the burden and issues on management of the disease. METHODS: A one year long longitudinal prospective surveillance of acute adenolymphangitis (ADL) was carried out in rural population of Orissa, India. RESULTS: The annual incidence of ADL per 1000 individuals is 85.0, and is slightly higher (P > 0.05) in male (92.0) than in female (77.6). A steady rise in the incidence of ADL episodes along with the age is recorded. The distribution indicates that persons with chronic disease are more prone to ADL attacks. The average number of episodes per year is 1.57 (1.15 SD) per affected person, and is gender dependent. Duration of the episode varies from 1 to 11 days with mean duration of 3.93 (1.94 SD) days. The chronic disease is the significant predictor for the duration of the episode. The data show that fever and swelling at inguinal regions are most common symptoms. CONCLUSION: The incidence, frequency and duration of ADL episodes in this community are similar to that of other endemic areas. As the loss due to these ADL episodes is substantial, it should be considered while further estimating the burden due to lymphatic filariasis. The disability and loss caused by chronic forms of filariasis is higher, and the additional incapacity caused by the ADL episode, majority of which occur among chronic filariasis patients, further poses the burden on individuals and their families. Hence, morbidity management measures to prevent ADL episodes among endemic communities are to be implemented.

Ultrasonographic examination of Haitian children with lymphatic filariasis: a longitudinal assessment in the context of antifilarial drug treatment.

To assess the clinical findings associated with detection of adult Wuchereria bancrofti worms on ultrasound, 186 schoolchildren in a filariasis-endemic area of Haiti underwent physical and ultrasonographic examinations. The filaria dance sign (FDS) of adult W. bancrofti was detected in the inguinal and crural lymphatics of 28 (15%) children. FDS detection was more common in older children (P = 0.003) and in those with a history of inguinal lymph node inflammation (P = 0.002) or crural lymphadenopathy on physical exam (P = 0.01). Twenty-five FDS-positive children were reexamined after three annual cycles of mass treatment for lymphatic filariasis (LF). The total number of adult worm nests detected by ultrasound decreased from 29 to 4 (P