Anaplasmosis in Uganda. I. Use of Dried Blood on Filter Paper and Serum Samples for Serodiagnosis of Anaplasmosis-a Comparative Study

The suitability of blood collected on filter papers in comparison with corresponding conventional serum samples in the diagnosis of bovine anaplasmosis was studied using the complement fixation test, DOT-ELISA, Western immunoblot and rapid card agglutination test. Dried blood on Whatman filter paper no. 1 was eluted in PBS 0.05% Tween 20 giving an initial dilution of 1:10. The reactivity of the eluted samples in both DOT-ELISA and Western immunoblotting were similar to those obtained with the corresponding straight serum sample dilutions. Filter paper samples gave lower reactivity in the remaining tests when compared with corresponding serum samples. There was no significant difference in the reactivity between the eluates from filter papers stored at temperatures ranging between 15.5 and 24 degrees C and those kept refrigerated. Storage at 15.5 to 24 degrees C did not significantly affect reactivity for up to six months. Eluates from filter papers stored for six months at 15.5 to 24 degrees C continued to give similar reactivity as those from freshly prepared filter papers in both DOT-ELISA and Western blot, and in the rapid card agglutination test. It is concluded that collecting blood on filter papers is a suitable technique for large scale seroepidemiological studies on anaplasmosis and offers many advantages in developing countries where transport and cold chain facilities are a major constraint.