RBT

This test is a simple spot agglutination test using antigen stained with rose Bengal and buffered to a low pH, usually 3.65 ± 0.05. Serum samples (25–30 µL of each) were placed on a WHO hemagglutination plate. Equal volume of antigen was placed near serum spots. The serum and antigen were mixed thoroughly to produce an oval zone approximately 2 cm in diameter. The mixture was agitated gently for 4 min at ambient temperature on a rocker. The agglutination was read after the 4-min period. Any visible reaction was considered to be positive. A control serum that gives a minimum positive reaction was tested before each day’s tests to verify the sensitivity of test conditions.