Filariasis Test Strip Research Articles

Performance characteristics of STANDARD Q Filariasis Antigen test (QFAT) to detect filarial antigens of Wuchereria bancrofti in the field.

Mapping, monitoring, and evaluation of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) rely on high-throughput diagnostics. While the WHO-recommended Filariasis Test Strip (FTS) is widely used to evaluate the programme, its use is limited by some technical and operational issues. We evaluated the performance characteristics of Q Filariasis Antigen Test (QFAT) compared to FTS for detecting Wuchereria bancrofti filarial antigen in the field. The QFAT and FTS kits were tested simultaneously for circulating filarial antigen (CFA) during an epidemiological monitoring survey (EMS) in two blocks of a filariasis endemic district in Karnataka, India, as a part of evaluation of the filariasis elimination programme with three drugs (Ivermectin, Diethylcarbamazine, and Albendazole-IDA). Blocks are considered as the evaluation unit as per the revised national guidelines. Two sentinel and one random site from each block with a sample size of 300 individuals aged ≥20 years were selected for the EMS. The field evaluation of the new kit was carried out in the four sentinel sites. Positive tests with either FTS or QFAT or both were tested for microfilaria (Mf) using night blood samples. The performance of the tests was compared in terms of sensitivity, specificity, and predictive values. The percentage agreement between the tests was verified using Cohen's kappa statistics (k), with a P value of less than 0.05 indicating statistical significance. A total of 1227 individuals were tested for CFA using both the QFAT and FTS tests. The QFAT test detected 299 positive individuals at the end of 10 minutes, while the FTS detected 310 positives. The QFAT showed high sensitivity (95.5%), specificity (99.7%), positive predictive value (99.0%), and negative predictive value (98.5%), and the results were in near perfect agreement with those of the FTS (k = 0.97, P <0.001) when the results were read at 10 minutes. There were 17 discordant results that were positive according to either one of the tests. Both antigen tests were positive for all 68 microfilaria-positive samples. None of the QFAT tests were invalid, while three FTS tests were invalid due to non-flow on the test pad. There was no cross-reactivity of the QFAT with Brugia malayi-positive samples (n = 5). The feedback from the technicians indicates that QFAT tests were easier to perform compared to FTS in the field. The Q filariasis antigen test is a promising tool for detecting the Wuchereria bancrofti antigen. The kits may be further validated for the review of Diagnostic Technical Advisory Group for Neglected Tropical Diseases (DTAG), to be recommended for the Global Programme to Eliminate Lymphatic Filariasis (GPELF).

Results of Integrated Transmission Assessment Surveys for Lymphatic Filariasis and Malaria in Haiti, 2017-2022.

Haiti is endemic for lymphatic filariasis (LF) and malaria, two mosquito-transmitted parasitic diseases targeted for elimination. The World Health Organization recommends a transmission assessment survey (TAS-1) to determine if LF prevalence is significantly beneath putative transmission thresholds (<2% antigen prevalence in Haiti, where Culex is the primary vector for Wuchereria bancrofti) to stop mass drug administration (MDA). Repeated TASs (TAS-2 and TAS-3) are recommended at 2-3-year intervals during post-treatment surveillance. From 2017 to 2022, The Carter Center assisted the Haitian Ministry of Public Health and Population in conducting 15 TASs in 11 evaluation units (EUs) encompassing 54 of the country's 146 districts. Children 6-7 years old were assessed for circulating filarial antigen (CFA) by Filariasis Test Strip: n = 5,239 in TAS-1; n = 11,866 in TAS-2; and n = 1,842 in TAS-3, of whom eight (0.15%), 20 (0.17%), and eight (0.43%) tested positive, respectively. The number of positive results in children was less than the threshold in each EU. When available, participants (n = 16,663) were also tested for malaria by rapid diagnostic test, with 31 (0.19%) children testing positive for Plasmodium falciparum. Integrated TASs provided an efficient means to collect epidemiological data for LF and malaria in Haiti. Results indicated thresholds for stopping and maintaining the halt of MDA for LF have been achieved in all EUs, with the halt of MDA for 571,358 people in four districts and the first TAS-3 surveys conducted in Haiti. Investigations are needed to assess the potential of ongoing LF transmission, especially in areas where CFA-positive samples were detected in TAS-3.

Field laboratory comparison of STANDARD Q Filariasis Antigen Test (QFAT) with Bioline Filariasis Test Strip (FTS) for the detection of Lymphatic Filariasis in Samoa, 2023.

To monitor the progress of lymphatic filariasis (LF) elimination programmes, field surveys to assess filarial antigen (Ag) prevalence require access to reliable, user-friendly rapid diagnostic tests. We aimed to evaluate the performance of the new Q Filariasis Antigen Test (QFAT) with the currently recommended Filariasis Test Strip (FTS) for detecting the Ag of Wuchereria bancrofti, the causative agent of LF, under field laboratory conditions. During an LF survey in Samoa, 344 finger-prick blood samples were tested using FTS and QFAT. Microfilariae (Mf) status was determined from blood slides prepared from any sample that reported Ag-positive by either Ag-test. Each test was re-read at 1 hour and the next day to determine the stability of results over time. Overall Ag-positivity by FTS was 29.0% and 30.2% by QFAT. Concordance between the two tests was 93.6% (kappa = 0.85). Of the 101 Mf slides available, 39.6% were Mf-positive, and all were Ag-positive by both tests. Darker test line intensities from Ag-positive FTS were found to predict Mf-positivity (compared to same/lighter line intensities). QFAT had significantly higher reported test result changes than FTS, mostly reported the next day, but fewer changes were reported between 10 minutes to 1hour. The field laboratory team preferred QFAT over FTS due to the smaller blood volume required, better usability, and easier readability. QFAT could be a suitable and user-friendly diagnostic alternative for use in the monitoring and surveillance of LF in field surveys based on its similar performance to FTS under field laboratory conditions.

Burden, knowledge and perception of lymphatic filariasis in resource - poor communities in north central Nigeria.

A number of vector-borne diseases are known to affect humans in tropical and sub-tropical regions of the world. Lymphatic filariasis is one of such debilitating disease caused by a nematode, Wuchereria bancrofti. The present study assessed the prevalence of lymphatic filariasis by screening individuals with filariasis test strip and clinical examination. A sample of 765 consenting individuals were screened for filarial antigenemia using filariasis test strip and clinical examination and interviewed for knowledge and perception of filariasis using a structured questionnaire. Overall antigenemia prevalence was 8.8% and the disease prevalence varied among villages with Shonga (16.7%) having the highest and Tada (1.6%) the least infected.In relation to age group, 40-49years had the highest (49.3%) while 0-9 years did not record any infection. Among the respondents infected, a greater number (43.3%) believed that the disease was caused by stepping on charm, 45.4% of those unaffected also believed in the same cause. A greater number of the respondents (28.4%) believed that avoiding sexual intercourse with affected individuals can help prevent the disease. A majority(67.2%) of the study participant had a misconception about its preventive measure. Misconceptions on the preventive measures included sacrifice to appease the gods and avoiding sexual intercourse with affected individuals. This study showed filarial antigenemia was above the threshold of 2% in the study area with misconception on the disease transmission and therefore this area warrants strategies to prevent transmission.

Longitudinal study of cross-reactive antigenemia in individuals with high Loa loa microfilarial density reveals promising biomarkers for distinguishing lymphatic filariasis from loiasis.

Circulating Loa loa antigens are often detected in individuals with heavy L. loa infections by diagnostic tests for lymphatic filariasis (LF) caused by Wuchereria bancrofti. This is a major challenge to LF mapping and elimination efforts in loiasis co-endemic areas. However, it also provides an opportunity to identify antigen biomarkers for loiasis. To determine which L. loa antigens might be promising biomarkers for distinguishing true LF from loiasis, we screened for L. loa antigens in a group of individuals with heavy L. loa infections living in the Okola Health District of Cameroon. In this longitudinal study, participants were tested for cross-reactive antigenemia by filariasis test strip (FTS), ELISA, and western blot, and were monitored for FTS status at 6, 9, 12, and 15 months post-enrollment. We then identified specific circulating L. loa antigens by liquid chromatography-tandem mass spectrometry (LC-MS/MS) from baseline and 15-month plasma samples. Among 73 FTS-positive (FTS+) and 13 FTS-negative (FTS-) participants with high L. loa microfilarial loads, 83% maintained their FTS status over the course of the study, while 17% experienced at least one FTS conversion event (from FTS+ to FTS- or vice versa). Cross-reactive antigens were detected in both FTS+ and FTS- sera by western blot, and there was poor agreement in antigen detection by FTS, western blot, and ELISA methods. One protein family, a group of Nas-14 metalloproteases, was detected by LC MS/MS in >80% of tested samples, including FTS- samples. These data identify Nas-14 as a promising loiasis biomarker potentially capable of distinguishing loiasis from lymphatic filariasis.

Integrated Prevalence Assessment of Wuchereria bancrofti and Onchocerca volvulus in Three Co-Endemic Districts of Gambella Region, Ethiopia.

Lymphatic filariasis (LF) and onchocerciasis (OV) are among the neglected tropical diseases (NTD) targeted for elimination in Ethiopia. We used a transmission assessment survey (TAS-1) to evaluate the serological status of OV in three co-endemic districts in Gambella simultaneously. During May and June 2019, blood samples were collected from 6- to 7-year-old children who were randomly selected through standard community-based TAS methodology. Children were tested for both circulating filarial antigen (CFA) for LF via filariasis test strip and for Onchocerca volvulus 16 (Ov16) antibody for OV via laboratory-based ELISA. A total of 3,377 children from 150 villages in the three districts were tested; 1,823 (54.0%) were male. All three districts had CFA results below the critical threshold for stopping LF mass drug administration (MDA). In contrast, 40 children (1.2%) were positive for Ov16 antibody, well above the WHO's OV stop MDA threshold of 0.1%. The integrated assessment indicated two programmatic decisions: stop MDA for LF and continue MDA for OV. Accordingly, albendazole MDA was discontinued in the districts but ivermectin MDA continued. This integrated assessment showed that a random sample for TAS can give important information about OV transmission status in co-endemic areas.

The Prevalence of Lymphatic Filariasis Infection among Primary School Children (5-9 Years) of Infected Adults in Ihiala Local Government Area of Anambra State, Nigeria

Aims: To determine the prevalence of Lymphatic flariasis infection among primary school children and of infected adults in Ihiala LGA, Anambra State. Study design: Cross-sectional study. Place and Duration of Study: Department of the Ministry of Health Anambra State and a few selected primary school children in Ihiala Local Government Area between June 2021 and July 2022. Methodology: A total of 150 residents were examined for Lymphatic filariasis. In the Primary Health Centre, a screening for clinical manifestation was done among adults. Sample analysis was done using Filariasis Test Strip while Semi-structured questionnaires were used to collect data on knowledge, attitude and practices (KAP) among residents. Results: Out of 299 blood samples collected from school children and 150 questionnaires distributed to residents to ascertain the awareness of Lymphatic filariasis among residents in the study areas and also to evaluate the efficacy of Ivermectin and Albendazole distributed annually through Mass Drug Administration since 2014, Filariasis Test Strip (FTS) showed 0.0% prevalence of circulating filarial antigen among the school children while the total prevalence of clinical manifestations among residents was 43.33% with higher rate in males (57.33%) than females (42.67%) while forty to 49-year-olds recorded the highest prevalence (13.33%) of clinical manifestations. Statistical analysis was performed with ANOVA using SPSS package and the mean difference is significant at the .05 level that is the P value of the analysis is significant at ≥0.005 level. Conclusion: Our findings on Filariasis Test Strip (FTS) showed 0.0% prevalence of circulating filarial antigen among the school children implying that Lymphatic Filariasis transmissions is low in the study area, suggest the Ivermectin and Albendazole distributed through MDA since 2014 in the endemic areas of Anambra have been effective for Lymphatic filariasis control and should remain the recommended strategy for the elimination of Lymphatic filariasis.

Determinants of Podoconiosis in Bensa District, Sidama Region, Ethiopia: A case control study.

Podoconiosis is one of the neglected tropical diseases (NTD) with the greatest potential for elimination. Despite its public health importance, podoconiosis is a poorly understood disease which led to a widespread misconception about its cause, prevention, and treatment. Even though the exact global burden is still to be measured, it is estimated that at least 4 million people are affected with podoconiosis worldwide, of which more than 1.5 million people are in Ethiopia. The objective of this study was to identify the determinants of podoconiosis in Bensa District, Sidama Regional State, Ethiopia. A community-based unmatched case-control study was used to identify the determinants of podoconiosis. The sample size was estimated using the double population proportion formula. An interviewer-administered structured questionnaire was used for data collection. Blood specimens collected from cases were tested by Filariasis Test Strip to exclude lymphatic filariasis. Data were checked for completeness, coded and entered into Epi-data Version 4.6, and exported to the SPSS version 22 software. Variables with a p<0.2 in the bivariate analysis were further analyzed using multivariable binary logistic regression. Multivariable logistic regression analysis was used to examine determinants that could be associated with podoconiosis with a 95% confidence interval. A total of 459 (153 cases and 306 controls) participants were included with a response rate of 100%. Factors such as the age of participant [AOR = 0.34, 95% CI (0.13-0.87)], being female [AOR = 2.90, 95% CI (1.40-6.10)], age at which shoe wearing started [AOR = 0.7, 95% CI (0.03-0.16)], not wearing shoe daily [AOR = 2.26, 95% CI (1.05-4.86)], wearing hard plastic shoe [AOR = 3.38, 95% CI (1.31-10.89)], and family history with a similar disease (leg swelling) [AOR = 10.2, 95% CI (3.97-26.37)] were significantly associated with the occurrence of podoconiosis. The age of the participants, gender, the age at which shoe wearing started, type of shoe the participants' wear, frequency of shoe wearing, traveling barefoot, and family history with similar disease (leg swelling) were significantly associated with the occurrence of podoconiosis. Sidama regional health bureau along with non-governmental organizations working on the neglected tropical disease should plan modalities on awareness creation and comprehensive health education on shoe wearing and foot hygiene.

Assessment of antigenemia among children in four hotspots of filarial endemic districts of Nepal during post-MDA surveillance

BackgroundSixty-three out of 77 districts reported lymphatic filariasis (LF) endemic in Nepal. Mass drug administration (MDA) with diethylcarbamazine (DEC) and albendazole (ALB) treatment program was continued for 6 to 11 rounds in these districts. Nepal government has stopped the MDA program based on the transmission assessment survey (TAS) report of 2014 and 2018 indicating Wuchereria bancrofti antigenemia prevalence < 2%. But the persistence of low levels of the circulating filarial antigen (CFA) in some foci of four endemic districts of Central Nepal, i.e., 0.4% in Dhading, 0.7% in Mahottari, 0.21% in Lalitpur and 1.2% in Bara district could responsible for enhancing the risk of infection resurgence. Hence the present study was designed to assess antigenic prevalence using Filariasis Test Strip (Alere, Scarborough ME) in children born after MDA in hotspot areas of four endemic districts of Central Nepal.ResultsThe present study covers 70% children of the eligible population. The result revealed significantly high CFA prevalence in hotspots of Mahottari district belonging to the Terai region and Dhading district belonging to the hilly region, i.e., 13% and 10%, respectively, compared to baseline prevalence and TAS report. While in Lalitpur district and Bara district CFA prevalence was still found to be less than 2%. A higher number of MDA rounds covered in hotspots were found significantly associated with the low antigenic prevalence of W. bancrofti. Whereas median treatment coverage and inter-quartile range (IQR) in study districts were not found significantly associated with CFA prevalence. Although the clinical manifestation of hydrocele (1%) was found in all four study districts, it was not due to the W. bancrofti infection.ConclusionsTwo hotspot regions, one each from the Terai (Mahottari) and hilly (Dhading) districts were found highly prevalent with CFA and significantly associated with the number of MDA rounds but were not associated with treatment coverage and IQR. Higher CFA prevalence was observed in hotspots where baseline prevalence was high together indicating that rounds of MDA program need to be extended further in these hotspot regions of endemic districts.

Morbidity hotspot surveillance: A novel approach to detect lymphatic filariasis transmission in non-endemic areas of the Tillabéry region of Niger

The Niger Lymphatic Filariasis (LF) Programme is making good progress towards the elimination goal and scaling up morbidity management and disability prevention (MMDP) activities. Clinical case mapping and the increased availability of services has prompted patients to come forward in both endemic and non-endemic districts. The latter included Filingué, Baleyara and Abala districts of the Tillabéry region, and in 2019, 315 patients were found during a follow-up active case finding activity, suggesting it may have low transmission.The aim of this study was to assess the endemicity status in areas reporting clinical cases, ‘morbidity hotspots’, in three non-endemic districts of the Tillabéry region. A cross-sectional survey was conducted in 12 villages in June 2021. Filarial antigen was detected using the rapid Filariasis Test Strip (FTS) diagnostic, and information obtained on gender, age, residency length, bed net ownership and usage, and presence of hydrocoele and/or lymphoedema. Data were summarised and mapped using QGIS software.A total of 4058 participants between 5 and 105 years old were surveyed, with 29 (0.7%) participants found to be FTS positive. Baleyara district had significantly higher FTS positive rates than the other districts. No significant differences were found by gender (male 0.8%; female 0.6%), age group (<26 years 0.7%; ≥26 years 0. 7%), and residency length (<5 years 0.7%; ≥5 years 0.7%). Three villages reported no infections; seven villages <1%, one village 1.1% and one village 4.1%, which was on the border of an endemic district. Bed net ownership (99.2%) and usage (92.6%) was very high and there was no significant difference between FTS infection rates.The results indicate that there are low levels of transmission in populations, including children, living in districts previously classified as non-endemic. This has implications for the Niger LF programme in terms of delivering targeted mass drug administration (MDA) in transmission hotspots, and MMDP services, including hydrocoele surgery to patients. The use of morbidity data may be a practical proxy to trigger mapping of ongoing transmission in low endemic areas. Continued efforts to study morbidity hotspots, post-validation transmission, cross-border and cross-district endemicity are needed to meet the WHO NTD 2030 roadmap targets.

Finding and eliminating the reservoirs: Engage and treat, and test and treat strategies for lymphatic filariasis programs to overcome endgame challenges

Many lymphatic filariasis (LF) endemic countries, including Ghana, have successfully implemented mass drug administration (MDA) and made significant progress towards the elimination of the disease as a public health problem. Unfortunately, the existence of individuals who seldom or never take part in MDA pose a threat to this success, as they may serve as reservoirs of infection, re-infecting their communities. In this study we implemented strategies to identify and treat these individuals, while also assessing their level of infection, to inform programme actions. The study was undertaken in the Ahanta West hotspot district in Ghana, which has received more than 17 rounds of MDA. Through the community registers used in recording participation in MDAs, we identified and offered treatment to individuals who were ineligible or inadvertently missed the last MDA in April 2021 (Engage and Treat – E&amp;amp;T), or testing using the filariasis test strip followed by treatment to community members who for various reasons chose not to participate in the last MDA (Test and Treat – T&amp;amp;T). During the study, 23,879 individuals ranging from 5 to 98 years were reached, of whom 78% were not captured in the MDA register. Among the E&amp;amp;T group, 75.06% willingly received and swallowed the treatment drugs. The remaining 24.94% were offered testing followed by a re-engagement to receive the drug in the T&amp;amp;T group. Overall, 22,830 (95.61%) of participants were treated by either strategy. Of the participants in the T&amp;amp;T group, 516 (8.66%; 95% CI= 7.96 – 9.41) were positive by the FTS. The highest antigen prevalence was detected among children 5 to 10 years, with 16.59% (95% CI= 12.02 – 22.06) and 22.54% (95% CI= 17.11 – 28.74) among females and males, respectively. Mapping of the data revealed that most infections are in a few select communities. Of the 516 FTS positives, 27.33% reportedly missed MDA once, 18.41% missed MDA twice and 54.26% missed all of the last three MDAs. The main reasons for missing MDA included absence (25.49%), travel (21.24%), being unaware of MDA (20.27%), refusals to take the drug (10.65%), illnesses (7.07%) and fear of adverse events (6.13%). This study demonstrates that greater sensitization and engagement strategies, with a test and treat strategy reserved for the most hesitant individuals, could significantly increase the number of individuals who receive treatment and therefore help districts reach their elimination targets by reducing the remaining reservoir or infection. NTD programmes require new tools to help them identify, engage and treat these individuals, as part of their overall monitoring and evaluation strategy.

Integrated transmission assessment surveys (iTAS) of lymphatic filariasis and onchocerciasis in Cross River, Taraba and Yobe States, Nigeria

BackgroundIntegrated transmission assessment surveys (iTAS) have been recommended for evaluation of the transmission of both lymphatic filariasis (LF) and onchocerciasis as the prevalence of both diseases moves toward their respective elimination targets in Nigeria. Therefore, we conducted an iTAS between May and December 2017 in five local government areas (LGAs), also known as implementation units (IUs), in states of Cross River, Taraba and Yobe in Nigeria.MethodsThe TAS comprised two phases: the Pre-iTAS and the iTAS itself. Three states (Cross River, Taraba and Yobe), comprising five LGAs and 20 communities that have completed five rounds of combined treatment with ivermectin and albendazole for LF and 12 total rounds of ivermectin, were selected for inclusion in the study. All participants were tested with the Filariasis Test Strip (FTS; Alere Inc.) and the Biplex rapid Diagnostic Test (RDT; identifying filaria antigens Ov16/Wb123; Abbott diagnosctics Korea Inc.). Pre iTAS included 100 children ages 5-9 in each 4 communities and 300 individuals ages 10 and older in a subset of two communities. For the iTAS, only LGAs where antigenemia prevalence in all sampled communities during the Pre-iTAS was < 2% for LF were selected.ResultsOf the five LGAs included in the study, four met the cutoff of the Pre-iTAS and were included in the iTAS; the Ikom LGA was excluded from the iTAS due to antigenemia prevalence. A total of 11,531 school-aged children from 148 schools were tested for LF and onchocerciasis across these four LGAs, including 2873 children in Bade, 2622 children in Bekwara, 3026 children in Gashaka and 3010 children in Karim Lamido. Using the FTS, all samples from Bade and Karim Lamido were negative, whereas 0.2% of the samples from Bekwara and Gashaka were positive. Using the Biplex RDT, LF prevalence in Bade, Bekwara, Gashaka and Karim Lamido was < 0.1%, 0.5%, 0.4% and < 0.1%, respectively. Moreover, all samples from Bade and Karim Lamido were negative for onchocerciasis, whereas 3.1% and 1.8% of the samples from Bekwara and Gashaka were positive, respectively.ConclusionThis study has provided additional information on the current burden of onchocerciasis and LF in the four IUs sampled where mass drug administration (MDA) for both infections has been ongoing for years. The study identifies that LF-MDA can be safely stopped in all four of the IUs studied, but that MDA for onchocerciasis needs to continue, even though this may pose a challenge for LF surveillance. Based on the preliminary results from all four sites, this study has fulfilled the primary objective of determining the programmatic feasibility of an iTAS as a tool to simultaneously assess onchocerciasis and LF prevalence in areas co-endemic for the two infections that have completed the recommended treatment for one or both infections, and to make decisions on how to proceed.Graphical

Podoconiosis: Clinical spectrum and microscopic presentations

Podoconiosis is a skin Neglected Tropical Disease (skin NTD) that causes lymphoedema, and affects barefooted subsistence farmers in some tropical countries. The clinical presentation and histopathologic correlates of podoconiosis have been understudied. Here, we systematically document the clinical and histopathologic spectrum of podoconiosis. This is a cross-sectional study in Durbete, Ethiopia from February 2018 to October 2019. Dermatologists performed a patient history, physical examination, filariasis test strip, and skin biopsy for histopathologic examination. The results were summarised and a descriptive statistical analysis and Wilcoxon rank sum test with continuity correction was done. We recruited 289 patients for the study, 178 (61.6%) had stage 1 or 2 podoconiosis, and 111(38.4%) stage 3 to 5 podoconiosis. 188 (64.1%) had a family history of podoconiosis. In 251 (86.9%) patients, both legs were affected by podoconiosis and in 38 (13.1%) only one leg was affected. 220 (77.5%) patients had warty lesions, 114 (39.4%) had nodules. The median number of episodes of Acute Dermato-Lymphangio-Adenitis (ADLA) reported by the patients in the last three months was 2 (interquartile range (IQR) 1-4). Increased episodes of ADLA were significantly associated with stage 3-5 podoconiosis (P = 0.002), while burning pain in the feet was more common in stage 1 or 2 podoconiosis. Stage 3-5 disease was histopathologically characterised by epidermal and dermal thickening, verrucous acanthosis, inflammatory cell infiltrates (predominantly lymphoplasmacytic), dilated and ectatic and a reduced number of lymphatic vessels, eccrine ductal hyperplasia, and sclerosis such as thickened collagen bundles. We provide a detailed description of the different clinical patterns, associated clinical findings and the histopathologic spectrum of podoconiosis at different stages of the disease. Our observations should serve as a guide to classifying patients with podoconiosis for prognostic assessment and treatment decision.

IgG4 antibodies against Bm14 as an evaluation tool of mass drug administration in a co-endemic area of Brugia timori and Wuchereria bancrofti

To evaluate the success of mass drug administration for lymphatic filariasis, WHO has recommended two rapid tests, Brugia Rapid (BR) to detect the presence of IgG4 antibodies against Brugia sp and Filariasis Test Strip (FTS) to detect antigens of Wuchereria bancrofti. As a country co-endemic for Brugia sp. and W. bancrofti, Indonesia needs a single diagnostic tool that can detect the exposure to both species. This study aimed to evaluate the efficacy of mass drug administration by measuring Bm14-specific IgG4 levels in blood samples of the population living in a co-endemic area of B. timori and W. bancrofti in Southwest Sumba Regency. A total of 132 plasma samples obtained before and one year after DEC-albendazole administration, which have been previously tested with BR and FTS, were examined for IgG4 against Bm14 using enzyme-linked immunosorbent assay. The results showed that before treatment all 32 individuals (100%) with BR+/ FTS+ were also positive for Bm14-specific IgG4, while in BR+ or FTS+ group there were >90% samples detected positive. At one year after treatment, positive results for Bm14-specific IgG4 were still detected in 96.9% samples with BR+/ FTS+, 78.8% samples with BR+/ FTS- and 82.9% samples with BR-/ FTS+. On the other hand, the BR-/ FTS- group also had high rate of Bm14-specific IgG4 positivity either before treatment (62,5%) and at one year after treatment (43.8%). The lowest decrease of Bm14-specific IgG4 positivity at one year after treatment was shown in the double positive group (3.1%), while the highest was in the double negative group (18.7%). The measurement of IgG4 against Bm14 has the potential as a sensitive diagnostic tool to evaluate the success of MDA in the areas co-endemic for B. timori and W. bancrofti.

Brugia malayi Glycoproteins Detected by the Filariasis Test Strip Antibody AD12.1.

Rapid and accurate prevalence mapping of lymphatic filariasis (LF) is necessary to eliminate this disfiguring and disabling neglected tropical disease. Unfortunately, rapid tests such as the filariasis test strip (FTS) for Wuchereria bancrofti, the causative agent of LF in Africa, can cross-react with antigens circulating in some persons infected by the African eye worm, Loa loa, rendering the test unreliable in eleven co-endemic nations. The intended target of the FTS is a heavily glycosylated W. bancrofti circulating filarial antigen (Wb-CFA). Previously, we determined that the FTS monoclonal antibody, AD12.1, which detects a carbohydrate epitope on Wb-CFA, also detects multiple L. loa proteins in cross-reactive sera from persons with loiasis. Since the carbohydrate epitope recognized by AD12.1 is present on glycoproteins of other parasitic nematodes, including Brugia species, it is unclear why reactive glycoproteins are not detected in infections with other filarial parasites. To gain a better understanding of the proteins recognized by the FTS diagnostic antibody, we used proteomics and lectin array technology to characterize filarial glycoproteins that are bound by the AD12.1 antibody using Brugia malayi as a model. Distinct but overlapping sets of AD12 glycoproteins were identified from somatic and excretory/secretory worm products. One of the identified proteins, Bm18019 was confirmed as a secreted AD12-reactive glycoprotein by in-gel proteomics and immunoassays. Based on lectin binding patterns, Brugia AD12-reactive glycoproteins express glycans including core fucose, galactose, N-acetylglucosamine and galactose (β1-3)N-acetylgalactosamine in addition to the epitope recognized by AD12.1. None of the lectins that bound B. malayi AD12 glycoproteins had affinity for the Wb-CFA, highlighting a key difference between it and other AD12 glycoproteins. B. malayi somatic and excretory/secretory proteins are similar to L. loa antigens found in FTS-positive human sera, bolstering the hypothesis that circulating L. loa AD12 antigens result from worm tissue damage or death. The difference in glycan and protein composition between the Wb-CFA and other AD12 glycoproteins can be used to differentiate LF from cross-reactive loiasis.

Comparison of Immunochromatographic Test (ICT) and Filariasis Test Strip (FTS) for Detecting Lymphatic Filariasis Antigen in American Samoa, 2016.

Circulating filarial antigen (Ag) prevalence, measured using rapid point-of-care tests, is the standard indicator used for monitoring and surveillance in the Global Program to Eliminate Lymphatic Filariasis. In 2015, the immunochromatographic test (ICT) was replaced with the filariasis test strip (FTS), which has higher reported sensitivity. Despite differences in sensitivity, no changes in recommended surveillance targets were made when the FTS was introduced. In 2016, we conducted lymphatic filariasis surveys in American Samoa using FTS, which found higher Ag prevalence than previous surveys that used ICT. To determine whether the increase was real, we assessed the concordance between FTS and ICT results by paired testing of heparinised blood from 179 individuals (63% FTS-positive). ICT had 93.8% sensitivity and 100% specificity for identifying FTS-positive persons, and sensitivity was not associated with age, gender, or presence of microfilariae. Based on these findings, if ICT had been used in the 2016 surveys, the results and interpretation would have been similar to those reported using FTS. American Samoa would have failed Transmission Assessment Survey (TAS) of Grade 1 and 2 children with either test, and community prevalence would not have been significantly different (4.1%, 95% CI, 3.3–4.9% with FTS vs. predicted 3.8%, 95%, CI: 3.1–4.6% with ICT).

Assessment of Etiology of Elephantiasis and Its Associated Risk Factors in Jeldu District, West Shoa, Ethiopia.

Elephantiasis is the main cause of tropical lymphoedema in Ethiopia. The aim of the current study was to assess the etiology of elephantiasis and its associated risk factors. Cross-sectional community-based study was carried out from March to May 2020 in seven purposively selected villages of Jeldu district. Identified suspected cases of elephantiasis in those villages were interviewed, clinically observed, and serologically examined using filariasis test strip kits at their respective houses during day time. A midnight blood sample was obtained from all FTS positive cases for microscopic examination of Wuchereria bancrofti larva, microfilariae. From a total of 105 identified elephantiasis cases, 69.5% were podoconiosis cases and 30.5% were LF cases. Among 32 serologically positive cases, only 15.6% cases were found positive by parasitological blood diagnosis. Considerable cases of podoconiosis (37%) were at age range 26–40 years, whereas smallest cases (16.4%) were at 10–25 years. Among cases of podoconiosis and LF, 77 subjects have been developed overt chronic leg(s) swelling; 85.7% of them showed bilateral swelling below knee and 14.3% of them showed unilateral swelling with stage II swelling 41.1%. Regarding risk factors, odds of podoconiosis was greatly lower in participants who washed their legs daily when compared to those who washed their legs sometimes (P=0.002). Odds of LF was higher in people who used bed nets/IRS and they were more protected than those who did not use bed nets/IRS (P=0.03). Odds of LF was high in cases farming besides rivers and/or perform irrigation work (P=0.003). The highest silicon concentration 4.65 mg/10 gm in Urgaha is coinciding with the highest podoconiosis cases (23.3%) of the village. Family history was a significant risk factor for the disease (P ≤ 0.001). Age (26–40 years), sex, and leg hygiene were also strong risk factors. Both etiologies of elephantiasis, LF and podoconiosis, are geographically overlapped in Jeldu district.

Recent advances in management of lymphedema

There has been a paradigm shift in the management of lymphedema with a better understanding of the functioning of lymphatics with the introduction of “lymphosome concept” and with the recent advances in super-microsurgical techniques. The most frequently used intraoperative imaging modality now is indo cyanine green lymphangiography. In endemic countries, any patient with lymphedema without prior history of trauma or, oncosurgical or radiotherapy interventions must undergo Alere filariasis test strip. Patients in early stages of disease can benefit from complex decongestive therapy and physiologic surgical procedures such as lymphovenous anastomosis or vascularized lymph node transfers. However, in advanced disease, excisions or debulking through radical reduction with preservation of perforators will be required. The localized adipose tissue deposits in lymphedema can be removed by liposuction. At present, there is still no cure for lymphedema, but emerging research in tissue engineering, lymphangiogenic growth factors, and immunomodulatory therapy may provide better management options for lymphedema in future.

Lymphatic Filariasis Transmission Assessment Survey in Burkina Faso in Connection with 4 Districts

RésuméObjectifDans le cadre d'une étude d'impact de la chimiothérapie préventive contre la filariose lymphatique au Burkina Faso, le Programme national de lutte contre les maladies tropicales négligées (PNMTN) a conduit une enquête d'évaluation de la transmission dans les districts sanitaires de Léo, Sapouy, Boromo et Dédougou. L'objectif principal était d'évaluer le niveau de transmission de la filariose lymphatique dans ces 4 districts sanitaires répartis en 2 unités d'évaluation (UE) (Boucle du Mouhoun 3 et du Centre-Ouest 2) après au moins 9 ans de traitement médicamenteux de masse.MéthodologieIl s'est agi d'une enquête transversale à visée descriptive réalisée en milieu communautaire sur un échantillon d'enfants de 6 à 7 ans sélectionnés par sondage en grappe.RésultatsSur 1649 enfants enquêtés dans l'UE Centre-Ouest 2, quatre étaient positifs au Filariasis Test Strip (FTS), soit une proportion de porteurs d'antigène filarien circulant (signant la présence de stades adultes vivant de Wuchereria bancrofti ) de 0,24%. Dans l'UE BMH3, aucun des 1716 enfants enquêtés n'était positif au FTS.ConclusionCes résultats montrent que la transmission de la filariose lymphatique est interrompue dans ces districts sanitaires, où les traitements de masse à l'albendazole et l'ivermectine peuvent donc être interrompus.

Monitoring migrant groups as a post-validation surveillance approach to contain the potential reemergence of lymphatic filariasis in Togo

BackgroundIn March 2017, Togo was declared the first country in sub-Saharan Africa to eliminate lymphatic filariasis as a public health problem, but post-validation surveillance has been lacking. In some areas of the country, migrant groups from neighboring countries that are still endemic for LF pose a risk of reintroduction of LF to Togo. The objective of this study was to identify the risk posed by migrant groups by measuring their prevalence of LF infection and investigating any positive case using Togo’s case investigation algorithm to prevent resurgence of LF and sustain Togo’s elimination success.MethodA cross-sectional study was conducted in 2018 in the northernmost region of the country. Three migrant populations were identified: (i) nomadic Peuhls, (ii) Togolese members of local communities who migrate annually to neighboring countries for seasonal labor, and (iii) refugees from Ghana who came to Togo because of a communal conflict in Ghana. A questionnaire was designed to collect data on demographics and history of LF and MDA; all participants were tested for circulating filariasis antigen (CFA) using the filariasis test strip (FTS). Any CFA-positive case was confirmed with nocturnal microfilaremia.ResultsRefugees, seasonal economic migrants and nomadic Peuhls represented 42.1%, 31.4% and 26.5% of the study participants, respectively. The overall prevalence of CFA was 4.2% (58/1391) with the highest prevalence in the nomadic Peuhl group (11.9%), but only one of them (0.07%) was confirmed positive with nocturnal microfilaremia. Using the case investigation algorithm, no other positive case was identified in the positive case’s surroundings.ConclusionThis study demonstrates that nomadic Peuhls, with a CFA prevalence of 11.9%, pose a potential risk for reintroduction of LF into Togo while Ghanaian refugees and seasonal economic migrants do not appear to pose a significant risk. Periodic monitoring of migrants, especially the nomadic Peuhl population, is a potential post-validation surveillance approach that could be used to promptly detect any LF cluster that may arise.Graphical