S L Hoti1, A Elango, K Radjame, J Yuvaraj, S P Pani. 1. Vector Control Research Centre (Indian Council of Medical Research), Indira Nagar, Pondicherry 605 006, India. vcrc@vsnl.com
Abstract
BACKGROUND: The launching of the global filariasis elimination programme has necessitated the use of highly sensitive and specific diagnostic tests. The Og4C3 monoclonal antibody-based ELISA test has been found to be highly specific and sensitive for the diagnosis of filariasis using night blood samples. However, it requires a serum sample which poses problems of transport and storage. Collection of blood samples on filter paper the will greatly circumvent these problems. Therefore, we evaluated the utility of the Og4C3 assay on filter paper samples collected during daytime. METHODS: Blood samples were collected from 63 microfilariae (mf) carriers during different time periods in a day on filter paper discs as well as venous blood for sera. The mf carriers and chronic (hydrocele n = 20; lymphoedema n = 120) and acute filariasis (adenolymphangitis n = 39) patients were from the endemic areas and the non-endemic normals were from Uthagamandalam district of Tamil Nadu, India. The filarial antigens in the samples were determined using the Og4C3 filarial antigen assay as per the manufacturer's instructions (JCU TrapBio, Australia). The sensitivity of the assay on sera and filter paper samples collected during night and also on filter paper samples collected during different time intervals of the day were compared with those of the membrane filtration technique, which was used as a gold standard. RESULTS: The geometric mean titre of the sera samples collected during night was 11 units/ml for non-endemic normals and 601.2 units/ml for mf carriers. The specificity of the assay on sera samples collected during night was 100% and the sensitivity 96.8% and the positive and negative values were 100% and 95.2%, respectively. The antigen positivity of the filter paper samples collected during morning hours was 93.3% while it was 76.6% and 86.7% for afternoon and evening hours. A significant association was observed between antigenaemia levels and mf density in the blood samples collected during the night. CONCLUSION: The samples collected on filter paper during the day can be used as an alternative to sera samples for detection of filarial antigens employing Og4C3 ELISA. Also, samples collected during morning hours yield a higher positivity. The assay when applied to serum samples will be useful especially when quantitative results are required.
BACKGROUND: The launching of the global filariasis elimination programme has necessitated the use of highly sensitive and specific diagnostic tests. The Og4C3 monoclonal antibody-based ELISA test has been found to be highly specific and sensitive for the diagnosis of filariasis using night blood samples. However, it requires a serum sample which poses problems of transport and storage. Collection of blood samples on filter paper the will greatly circumvent these problems. Therefore, we evaluated the utility of the Og4C3 assay on filter paper samples collected during daytime. METHODS: Blood samples were collected from 63 microfilariae (mf) carriers during different time periods in a day on filter paper discs as well as venous blood for sera. The mf carriers and chronic (hydrocele n = 20; lymphoedema n = 120) and acute filariasis (adenolymphangitis n = 39) patients were from the endemic areas and the non-endemic normals were from Uthagamandalam district of Tamil Nadu, India. The filarial antigens in the samples were determined using the Og4C3 filarial antigen assay as per the manufacturer's instructions (JCU TrapBio, Australia). The sensitivity of the assay on sera and filter paper samples collected during night and also on filter paper samples collected during different time intervals of the day were compared with those of the membrane filtration technique, which was used as a gold standard. RESULTS: The geometric mean titre of the sera samples collected during night was 11 units/ml for non-endemic normals and 601.2 units/ml for mf carriers. The specificity of the assay on sera samples collected during night was 100% and the sensitivity 96.8% and the positive and negative values were 100% and 95.2%, respectively. The antigen positivity of the filter paper samples collected during morning hours was 93.3% while it was 76.6% and 86.7% for afternoon and evening hours. A significant association was observed between antigenaemia levels and mf density in the blood samples collected during the night. CONCLUSION: The samples collected on filter paper during the day can be used as an alternative to sera samples for detection of filarial antigens employing Og4C3 ELISA. Also, samples collected during morning hours yield a higher positivity. The assay when applied to serum samples will be useful especially when quantitative results are required.
Authors: Katherine Gass; Madsen V E Beau de Rochars; Daniel Boakye; Mark Bradley; Peter U Fischer; John Gyapong; Makoto Itoh; Nese Ituaso-Conway; Hayley Joseph; Dominique Kyelem; Sandra J Laney; Anne-Marie Legrand; Tilaka S Liyanage; Wayne Melrose; Khalfan Mohammed; Nils Pilotte; Eric A Ottesen; Catherine Plichart; Kapa Ramaiah; Ramakrishna U Rao; Jeffrey Talbot; Gary J Weil; Steven A Williams; Kimberly Y Won; Patrick Lammie Journal: PLoS Negl Trop Dis Date: 2012-01-17
Authors: Humpress Harrington; James Asugeni; Christopher Jimuru; John Gwalaa; Elmer Ribeyro; Richard Bradbury; Hayley Joseph; Wayne Melrose; David MacLaren; Rick Speare Journal: Parasit Vectors Date: 2013-07-26 Impact factor: 3.876