Serological and immunological tests are also available. Common tests include Gram staining, blood cultures, serological tests, genotyping, and polymerase chain reaction. Anti-gliadin antibodies were one of the first serological markers for coeliac disease. Blood is tested using serological tests, typically ELISAs, to detect antibodies against proteins. Paired acute and convalescent samples are preferred for serological diagnosis of leptospirosis in animals. Detection of antibodies (serological tests) can be used both for diagnosis and for population surveillance. Hence, new serological tests check for anti-citrullinated protein antibodies ACPAs . It is done by serological methods like latex agglutination or slide agglutination. Diagnosis relies on viral isolation from tissues, or serological testing with an ELISA. This phenomenon is also seen in serological tests for Brucellosis. Diagnosis can be made by identifying clinical signs, serological tests, or parasitological tests. Serological tests are not helpful in diagnosis. Serological or cutaneous tests are not available. In such instances, RF may serve as one of several serological markers for autoimmunity. Serological testing is typically used to obtain a definitive diagnosis.