Abstract
Lymphatic filariasis (LF), commonly known as elephantiasis is caused by Filaria parasite i.e. Wuchereria bancrofti, Brugia malayi, B. timori and transmitted by mosquitoes. There are about 40 million people in tropical and subtropical areas suffer from severe disfigurement and disability caused by the disease. It is estimated that more than million Myanmar migrant workers have settled in Thailand and some of them also carry Wuchereria bancrofti. Moreover, Thailand was certified by WHO for successful elimination of lymphatic filariasis and now is in surveillance phase to prevent reemergeing of the disease. Since microfilariae detection by thick blood smear staining technique need night blood collection. Thus, convenience and effective diagnositic tool is needed for the management of filarial infection both at the level of the individual treatment and disease control in populations in regions endemic for filariasis. In the present study, two recombinant proteins iPGM and SXP were produced. Then prototype two test kits, an enzyme-linkedimmunosorbentassay (ELISA) based test kit (FilariaDIAG test kit) and a chromatographic rapid test kit (FilariaDIAGRAPID), were developed, using iPGM recombinant protein and SXP recombinant protein as antigen. Efficacy of the developed test kits were validated in both laboratory condition and in field. Sensitivity of the rapid test kit using recombinant protein SXP antigen shows 97.9% sensitivity, 98.9% specificity, 95.8% positive predictive value and 99.4% negative predictive value when using microfilaria detection by thick blood smear staining as gold standard. The rapid test kit using recombinant protein iPGM antigen reveals sensitivity, specificity, positive predictive value and negative predictive value of 72.3%, 68.8%, 51.6% and 90.5% respectively. For the ELISA based test kit (FilariaDIAG test kit) showed sensitivity, specificity, positive predictive value and negative predictive value of 98.1%, 98.9%, 96.3% and 99.4% accordingly. For field validation, the prevalence of bancroftian filariasis in 509 Myanmar live in Thai-Myanmar boarder in Masod and Phoppha district, Tak province was 1.2% (6/509) while the prevalence of bancroftian filariasis in 363 Myanmar live in Thai-Myanmar boarder in SopMye district, Mahongsorn province was 1.9% (7/363). For prevalence of brugian filariasis in Thai people live in Tak Bai, Sugnai-Padee and Sugai-kolok Narathiwat province (endemic areas of B. malayi) was 0.57% (3/525). Using the ELISA based test kit (FilariaDIAG), antifilarial IgG4 was detected in 1.2% (6/509) of sera collected from Myanmar live in Thai-Myanmar boarder in Masod and Phoppha district, Tak province and in 1.9% (7/363) of sera collected from Myanmar live in Thai-Myanmar boarder in SopMye district, Mahongsorn province. In conclusion, the 2 prototype test kits are useful as tools for screening and surveillances of lymphatic filariasis in B. malayi-endemic areas as well as in Myanmar workers.
