Laboratory and Field Evaluation of a New Rapid Test for Detecting Wuchereria bancrofti Antigen in Human Blood

Abstract

Global Program to Eliminate Lymphatic Filariasis (GPELF) guidelines call for using filarial antigen testing to identify endemic areas that require mass drug administration (MDA) and for post-MDA surveillance. We compared a new filarial antigen test (the Alere Filariasis Test Strip) with the reference BinaxNOW Filariasis card test that has been used by the GPELF for more than 10 years. Laboratory testing of 227 archived serum or plasma samples showed that the two tests had similar high rates of sensitivity and specificity and > 99% agreement. However, the test strip detected 26.5% more people with filarial antigenemia (124/503 versus 98/503) and had better test result stability than the card test in a field study conducted in a filariasis-endemic area in Liberia. Based on its increased sensitivity and other practical advantages, we believe that the test strip represents a major step forward that will be welcomed by the GPELF and the filariasis research community.

Semi-Quantitative Scoring of an Immunochromatographic Test for Circulating Filarial Antigen

“…A recently published study used a similar scoring system to evaluate the Alere Filariasis Test Strip that is expected to replace the ICT test in the near future. 25 Although the Test Strip was more sensitive than the ICT test in that study, antigen scores for blood samples that were positive by either test were highly correlated. Note that there is no additional cost associated with scoring filarial antigen tests, and scores can be written directly on the cards.…”

Expanding the MDx toolbox for filarial diagnosis and surveillance

“…The immunochromatography card test (ICT), which detects an adult female antigen, is the tool of choice for determining the areas in which levels of W. bancrofti infection have been reduced to a point where transmission is no longer sustainable and therefore MDA programs can cease [23]. A new rapid antigen test (Alere Filariasis Test Strip) with increased sensitivity and greater stability has become available [24]. Although the filariasis card test has been used for more than 10 years, recent studies have shown false-positive results in patients with high L. loa microfilaremia [25].…”

The Use of Filariae as a Therapeutic Agent for Hypersensitivity Diseases

“…In 1997, a rapid, card-based diagnostic test (BinaxNOW® Filariasis) was developed to detect circulating adult worm antigen (235). Recently, a new antigen test (Alere Filariasis Test Strip) was developed to increase sensitivity of diagnosis (234).…”