Wuchereria bancrofti Circulating Filarial Antigen (CFA) for Lymphatic Filariasis Rapid Diagnostic Test LFA IVD Development
Lymphatic filariasis (LF), commonly known as elephantiasis, is a parasitic neglected tropical disease (NTD) caused by filarial nematode worms transmitted to humans through the bites of infected mosquitoes. Three filarial species cause human lymphatic filariasis: Wuchereria bancrofti (responsible for approximately 90% of all LF cases worldwide), Brugia malayi, and Brugia timori. The WHO estimates 51 million people are currently infected with LF globally, with approximately 863 million people living in 44 endemic countries at risk of infection. After years of annual mass drug administration (MDA) campaigns, global LF infection prevalence has declined from approximately 120 million in 2000 to the current level, representing one of the most successful public health achievements in NTD control. However, the disease remains endemic across sub-Saharan Africa, South Asia, Southeast Asia, and Pacific island nations.
W. bancrofti adult worms (males: 40 mm; females: 80–100 mm in length) reside in the human lymphatic vessels, causing progressive lymphatic vessel damage. This damage leads to lymphedema (irreversible swelling of legs, arms, breasts, and genitals) and hydrocele (fluid accumulation in the scrotum, the most common clinical manifestation of W. bancrofti in males) — the hallmarks of clinical elephantiasis. The adult worms reproduce to produce microfilariae (first-stage larvae, MW approximately 2–8 μm by 130–320 μm), which circulate in peripheral blood showing nocturnal periodicity (peaking between 10 PM and 2 AM). The mosquito becomes infected when it ingests microfilariae during a blood meal; within the mosquito, microfilariae develop into infective third-stage larvae (L3) that are transmitted to humans during subsequent feeding. The WHO Global Programme to Eliminate Lymphatic Filariasis (GPELF) aims to eliminate LF as a public health problem by 2030 through annual MDA with albendazole combined with ivermectin (in areas co-endemic for onchocerciasis) or diethylcarbamazine (DEC) in areas without onchocerciasis.
For IVD assay development, the detection of circulating filarial antigen (CFA) — antigens released into peripheral blood by adult W. bancrofti worms — is the WHO-recommended diagnostic method for W. bancrofti infection. CFA-based rapid tests (immunochromatographic assays, ICA) detect W. bancrofti adult worm antigens in whole blood or serum collected at any time of day (unlike microfilaremia detection, which requires nighttime blood collection). The WHO-recommended diagnostic tools for W. bancrofti in LF elimination programs are the Filariasis Test Strip (FTS, manufactured by Alere/Abbott) and the Binax NOW Filariasis ICT card — both based on anti-W. bancrofti monoclonal antibody pairs detecting CFA in patient blood. Sekbio's FIL Ag (Catalog A104201, Lot A24090201) is a W. bancrofti antigen preparation for use in LFA development — supporting anti-W. bancrofti antibody selection, validation, positive control preparation, and ELISA antigen coating for CFA rapid test development.
W. bancrofti circulating filarial antigen preparation for lymphatic filariasis rapid test LFA development, antibody validation, and positive control manufacturing.
| Catalog No. | Lot No. | Antigen | Parasite Species | Application | Storage |
|---|---|---|---|---|---|
| A104201 | A24090201 | Filariasis Antigen (FIL Ag) | Wuchereria bancrofti | LFA / ELISA / Antibody validation / Positive control | −20°C |
Contact info@sekbio.com for FIL Ag specification sheet (concentration, purity, antigen characterization), MOQ, pricing, and OEM supply terms for LF elimination program diagnostic test manufacturers.
Characterized W. bancrofti CFA for WHO GPELF-compatible rapid test development targeting 51 million LF patients across Africa, South Asia, and Southeast Asia.
The fundamental advantage of CFA-based rapid tests over microfilaremia detection is sample collection time independence. W. bancrofti microfilariae show nocturnal periodicity — concentrated in peripheral blood between 10 PM and 2 AM. Collecting blood at night from entire communities for LF surveillance is operationally impractical. CFA — released continuously by adult worms regardless of time of day — is detectable in blood samples collected at any hour. Sekbio's FIL Ag supports development of CFA-based LFA tests that enable daytime community screening in mass drug administration monitoring programs, transmission assessment surveys (TAS), and point-of-care clinical diagnosis without the nighttime scheduling constraint of microfilaremia-based diagnosis.
CFA detection directly identifies active W. bancrofti adult worm infection — not historical exposure. This is critical for WHO GPELF transmission assessment surveys (TAS) used to determine whether MDA can be safely stopped in a program unit: TAS requires detecting residual W. bancrofti transmission, not measuring accumulated antibody titers that may persist for years after successful MDA eliminates active infection. Antibody-based LF serology (IgG4 or total IgG anti-filarial antibody tests) cannot distinguish between active current infection and past resolved infection — making them less specific for elimination endpoint assessment. CFA-positive results confirm current W. bancrofti adult worm infection, directly relevant to transmission assessment decisions. Sekbio's FIL Ag supports this high-specificity CFA detection approach.
The WHO Global Programme to Eliminate Lymphatic Filariasis (GPELF) requires large-scale use of CFA rapid tests for transmission assessment surveys (TAS) — the critical endpoint evaluation conducted after 5+ years of MDA to determine if transmission has been interrupted. Each TAS covers a program evaluation unit (PEU) of 100,000–200,000 people, with approximately 1,500–3,000 children tested per TAS. Globally, hundreds of TAS surveys are conducted annually across 44 LF-endemic countries. This creates substantial annual demand for high-quality, WHO-recommended CFA rapid test kits — driven entirely by program procurement rather than individual clinical demand. Sekbio's FIL Ag supports IVD manufacturers developing CFA rapid tests for this program market. Visit our Products page for our full NTD diagnostic antibody and antigen portfolio.
Beyond use in LFA development, Sekbio's FIL Ag (A104201) serves as: (1) Positive control antigen in CFA rapid test kit QC — spiked into buffer or negative blood matrix to validate test strip performance at each lot release; (2) Immunogen/screening antigen for anti-W. bancrofti antibody development — used to immunize mice for monoclonal antibody generation or to screen hybridoma supernatants for anti-filarial antibody candidates; (3) ELISA coating antigen for anti-filarial antibody ELISA validation and serology research; (4) Calibration standard for quantitative CFA ELISA assays measuring infection intensity in epidemiological studies. This versatility makes FIL Ag a valuable reagent across the LF diagnostic product development pipeline.
Beyond program elimination monitoring, CFA rapid tests have direct clinical utility for individual patient management of LF-related clinical manifestations — particularly hydrocele (scrotal swelling affecting males in W. bancrofti endemic areas, the most common clinical presentation). Before performing hydrocelectomy (surgical correction), confirming active W. bancrofti infection with a CFA rapid test guides clinical decision-making — ensuring patients receive antifilarial drug treatment (DEC + doxycycline for microfilariae and adult worm killing) in addition to surgical correction, rather than surgery alone. CFA rapid tests built on Sekbio's FIL Ag can be deployed in urology and surgical clinics in endemic countries for pre-operative LF antigen screening. Contact info@sekbio.com for clinical use case guidance.
Sekbio's ISO 13485-certified facility provides quality-documented antigen supply for LF diagnostic test manufacturers targeting WHO GPELF procurement channels. The primary purchasers of LF CFA rapid tests are national NTD programs, WHO/PAHO regional offices, UNICEF supply division, and international NTD donors (USAID, UKAID, The END Fund). These institutional buyers require WHO prequalification, CE marking, or equivalent regulatory approvals — and ISO 13485-certified raw material supply chains. Sekbio's certification supports regulatory documentation for LF diagnostic kit OEM partners. Contact our team to discuss FIL Ag supply agreements, specification requirements for WHO prequalification submissions, and antigen characterization data packages.
W. bancrofti CFA for WHO TAS rapid test development, MDA monitoring, clinical diagnosis, and LF elimination program surveillance across Africa, South Asia, and the Pacific.
WHO GPELF Transmission Assessment Surveys (TAS) use CFA rapid tests to determine whether W. bancrofti transmission has been interrupted after MDA — the critical program decision gate for stopping MDA and beginning post-MDA surveillance. TAS-1 (after 5 rounds of MDA) assesses school-age children (6–7 year olds) as sentinels for new infection: if CFA prevalence in this cohort is below the WHO threshold (2% positive by FTS/ICT), MDA can be stopped. Countries with the largest ongoing TAS programs include Nigeria (the world's largest LF endemic country by burden), Tanzania, Mozambique, Cameroon, Ghana, India, Bangladesh, Indonesia, and Papua New Guinea. CFA rapid tests for TAS require high sensitivity (to detect residual low-level infection), high specificity (to avoid false positive results that would delay program stopping decisions), and field robustness for rural community-based deployment.
Before and during MDA campaigns, CFA prevalence surveys measure baseline infection levels and track MDA impact over successive annual treatment rounds. Pre-TAS surveys (conducted after 3–4 MDA rounds when CFA prevalence is expected to have declined but has not yet been formally assessed) use CFA rapid tests in sentinel site surveys to generate early evidence of program effectiveness. These programmatic surveys create sustained annual demand for CFA rapid test kits in all 44 LF-endemic countries. Sekbio's FIL Ag supports IVD manufacturers developing high-throughput CFA test strip production for program procurement at volumes of hundreds of thousands to millions of tests per year. Contact our team for volume pricing and supply capacity discussion.
In clinical settings — district hospitals, health centers, and outpatient departments in LF-endemic areas — CFA rapid tests provide point-of-care diagnosis for patients presenting with lymphedema, hydrocele, acute dermatolymphangioadenitis (ADLA) episodes, or tropical pulmonary eosinophilia. Confirming active W. bancrofti infection guides clinical management: CFA-positive patients benefit from antifilarial drug treatment (DEC + doxycycline combination, targeting both microfilariae and adult worms via Wolbachia endosymbiont killing) in addition to morbidity management interventions (lymphedema management, hydrocelectomy, lymphedema physiotherapy). Sekbio's FIL Ag enables CFA rapid test development for both programmatic and clinical diagnostic use cases across the LF disease management continuum.
Following successful MDA program completion and TAS-passing, LF elimination programs enter a post-MDA surveillance phase — monitoring for potential W. bancrofti resurgence due to population movement, mosquito vector resurgence, or program lapses. WHO recommends periodic TAS-2 and TAS-3 surveillance surveys (every 2–4 years) using CFA rapid tests to confirm sustained transmission interruption. This ongoing surveillance demand ensures a long-term market for LF CFA rapid tests even as active MDA programs wind down in countries approaching elimination certification. IVD manufacturers developing CFA rapid tests with Sekbio's FIL Ag are positioning for both the current high-volume MDA monitoring market and the emerging post-elimination surveillance market. Visit our Products page for our complete infectious disease diagnostics portfolio.
Technical and commercial questions from IVD R&D engineers developing LF rapid diagnostic tests for WHO GPELF elimination programs.
Lymphatic filariasis (elephantiasis) is a parasitic NTD caused by Wuchereria bancrofti (90% of cases), Brugia malayi, and B. timori — transmitted by mosquitoes. WHO estimates 51 million infections in 44 endemic countries. Circulating filarial antigen (CFA) refers to W. bancrofti adult worm antigens released into blood — detectable at any time of day (unlike microfilariae, which show nocturnal periodicity). CFA detection by LFA rapid test is the WHO-recommended diagnostic for W. bancrofti infection, used in program TAS surveys and clinical diagnosis.
FIL Ag A104201 (Lot A24090201) is a W. bancrofti antigen preparation used for: (1) Anti-W. bancrofti antibody generation and validation (immunogen and ELISA screening antigen); (2) Positive control antigen in CFA rapid test kits; (3) ELISA coating antigen for antibody selection and quality control; (4) Calibration standard for quantitative CFA assays. The antigen supports the full CFA rapid test development pipeline from antibody selection through kit manufacturing. Contact info@sekbio.com for detailed antigen specifications and characterization data.
CFA detection (using Sekbio's FIL Ag-based assays) offers several advantages over microfilaremia: (1) No time-of-day restriction — CFA is present in blood 24 hours/day; (2) Higher sensitivity in low-burden settings — CFA may be detectable even when microfilaremia is below microscopy detection threshold; (3) No species specificity concern — W. bancrofti CFA is specific to W. bancrofti infection; (4) Practical for community-based surveys — daytime blood collection is operationally feasible. These advantages make CFA rapid tests the WHO-recommended diagnostic for LF elimination program TAS, replacing nighttime blood film microscopy.
W. bancrofti CFA is antigenically distinct from Brugia malayi/timori antigens. Existing CFA rapid tests (FTS, ICT) do not detect brugian filariasis — B. malayi/timori require different diagnostic approaches (anti-Brugia antibody ELISA or PCR). Cross-reactivity with other helminths (Loa loa, intestinal helminths) should be characterized for each specific antibody-antigen assay configuration. Contact info@sekbio.com for cross-reactivity characterization data for FIL Ag A104201.
Contact info@sekbio.com for FIL Ag (A104201) MOQ, concentration, purity specifications, format, pricing, and OEM supply availability. Sekbio's ISO 13485-certified manufacturing supports quality-documented antigen supply for WHO prequalification-track LF diagnostic test development. We serve LF diagnostic IVD manufacturers targeting GPELF program procurement markets in Nigeria, Tanzania, India, Bangladesh, Indonesia, Papua New Guinea, and other LF-endemic countries.
Primary sample types for W. bancrofti CFA rapid tests: Whole blood (fingerstick, collected at any time of day — the standard for field TAS surveys; avoids centrifugation); Serum or plasma (for higher antigen concentration relative to whole blood — suitable for laboratory ELISA format). The WHO-recommended Filariasis Test Strip (FTS) uses 75 μL of whole blood or serum, delivering results in 10 minutes. Daytime whole blood fingerstick collection enables community-scale TAS surveys without nighttime operations — a critical field practicality advantage. Contact info@sekbio.com for LFA format development support and sample type optimization guidance using FIL Ag A104201.
Request FIL Ag A104201 specification sheet and discuss OEM supply for WHO GPELF-compatible lymphatic filariasis CFA rapid test development.