A colourimetric dipstick colloidal dye immunoassay for rapid diagnosis of active cases of canine dirofilariasis
Wan Omar Abdullah*, Low Kiat Cheong1, Vivian Jacob Gomes1, Sulaiman Osman1 and Yusof Suboh1
Department of Medical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor;
1Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur
(Received 27 October 1997 / Accepted 16 June 1998)
Abstract.
The application of dispersed dye particles as label in immunological assay was investigated as an alternative to enzyme labeled immunoassay (ELISA). Dipsticks prepared from the antibody (Ab) coated nitrocellulose membrane mounted on acetate strips served as capture matrix. Ab absorbed to a commercial brilliant pink colloidal dye particles served as antigen (Ag) detecting reagent. The dipstick developed was compared with plate ELISA for detecting antigenemic cases of Dirofilaria immitis infection in dogs. Evaluation statistics of the dipstick assay varied according to the cutoff value of the ELISA titers. The overall specificity and sensitivity of ELISA was 96.67% and 98.57% respectively. The dipstick performed with a specificity of 85.71 % and a sensitivity of 94.12% when the ELISA titre was 160. There was high level of agreement between these two assay formats ranging from 89.47% to 92.60%. Dipstick assay detected 1% of the occult dirofiliariasis as with the plate ELISA. As the dipstick assay is simpler, rapid, inexpensive, equally sensitive and specific its use in detecting active cases of D. immitis infections in dogs is recommeded especially under field condition. The dipstick immunoassay format would enable veterinary practitioners to quickly diagnose and appropriately treat most cases of the disease.
Keywords: colourimetric, dipstick, inununoassay, dirofilariasis
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