Recombinant antigens used as diagnostic tools for lymphatic filariasis.

Lymphatic filariasis (LF) is a parasitic disease caused by the worms Wuchereria bancrofti, Brugia malayi, or Brugia timori. It is a tropical and subtropical illness that affects approximately 67 million people worldwide and that still requires better diagnostic tools to prevent its spread and enhance the effectiveness of control procedures. Traditional parasitological tests and diagnostic methods based on whole protein extracts from different worms are known for problems related to sample time collection, sensitivity, and specificity. More recently, new diagnostic tools based on immunological methods using recombinant antigens have been developed. The current review describes the several recombinant antigens used as tools for lymphatic filariasis diagnosis in antigen and antibody capture assays, highlighting their advantages and limitations as well as the main commercial tests developed based on them. The literature chronology is from 1991 to 2021. First, it describes the historical background related to the identification of relevant antigens and the generation of the recombinant polypeptides used for the LF diagnosis, also detailing features specific to each antigen. The subsequent section then discusses the use of those proteins to develop antigen and antibody capture tests to detect LF. So far, studies focusing on antibody capture assays are based on 13 different antigens with at least six commercially available tests, with five proteins further used for the development of antigen capture tests. Five antigens explored in this paper belong to the SXP/RAL-2 family (BmSXP, Bm14, WbSXP-1, Wb14, WbL), and the others are BmShp-1, Bm33, BmR1, BmVAH, WbVAH, BmALT-1, BmALT-2, and Wb123. It is expected that advances in research with these antigens will allow further development of tests combining both sensitivity and specificity with low costs, assisting the Global Program to Eliminate Lymphatic Filariasis (GPELF).

Acute disease episodes in a Wuchereria bancrofti-endemic area of Papua New Guinea.

Acute disease episodes of Bancroftian filariasis were monitored prospectively in a rural area of Papua New Guinea. The frequency and duration of episodes were recorded for the leg, arm, scrotum, and breast. A very high incidence of acute disease was observed; 0.31 episodes per person-year in the leg alone. Incidence generally increased with age, except in the breast, where episodes were concentrated in the reproductive age range. Males had slightly higher incidence than females in the leg and arm. Chronic disease was strongly associated with acute disease incidence in all locations. Microfilaremia had a statistically significant association with acute disease in the leg, arm, and breast, but not the scrotum. This study again demonstrates the high burden of acute manifestations of lymphatic filariasis, and provides new information on risk factors, which may lead to better understanding of etiology and control prospects.

Human filariasis: infection rate as the uniform measurable criterion for filarial endemicity.

The endemicity classification based on filariasis infection rate is suggested. Based on the filariometric data collected from 60 villages in Orissa, areas are classified into low, high, hyper and holo endemic levels. Suggested endemicity levels are found to correlate very well with the filariometric indices. The mean mf rates were found to be 2.7, 6.8, 12.0, and 16.0, and disease rates 4.9, 10.2, 18.9 and 35.1 respectively at four endemicity levels. It is suggested that the proposed classification may uniformly be used in mapping areas for endemicity so as to help direct public health control interventions in a judicious manner.