Antibodies to the causative agent of brucellosis in serum

In norm or rate AT to the activator brucellosis in a blood are absent.

The diagnostic titer for the agglutination reaction is 1: 160 and higher.

The most reliable serological test of AT determination for the causative agent of brucellosis in serum is the standard test tube

of glutinizing( Wright's reaction), with it determine the content of AT, reacting mainly with lipopolysaccharide Ag Brucella. The increase of AT titers by 4 times and more in blood serum samples obtained with an interval of 1-4 weeks allows to identify the etiologic factor of the disease. In most patients, the specific AT titers are increased on the 3-5th day from the onset of the disease. It is believed that AT's titer is not less than 1: 160 with its subsequent increase. Elevated titre of AT is revealed in 97% of patients in the first 3 weeks of the disease. The highest AT titer is usually observed 1-2 months after the onset of the disease, in the future it begins to decline rapidly. A standard test of tube agglutination reveals AT to B. abortus, B. suis, B. melitensis, but not to B. canis. Elevated titre of AT can persist in 5-7% of patients within 2 years after the infection. Therefore, Wright's reaction can not be used for differential diagnosis of brucellosis with other infectious diseases in the presence of a history of brucellosis within the last 2 years. The cause of false positive results can be a skin test for brucellosis, vaccination against cholera, as well as infections caused by cholera vibrio, Yersinia, Francisella tularensis. In some cases, false-negative results of the agglutination reaction in patients with brucellosis are possible, which is explained by the effect of the prozone, or by the so-called blocking of AT.In chronic localized forms of brucellosis, titres may be negative or lower than 1: 160.Against the background of the treatment, the titers of the AT class IgG decrease rapidly and within a year approach zero. In case of relapse, the level of Ig Ig increases again. The presence of a single increase in the titre of AT IgG more than 1: 160 is a reliable objective indication of the current or recently transferred infection. After treatment and patient discharge from the hospital, serology is recommended for the first year after 1, 2, 3, 6, 9 and 12 months, and during the second year - quarterly.

RPHA is more sensitive and specific for the detection of brucellosis in the blood serum. Often, hemagglutinins are detected when the agglutination reaction gives a negative or doubtful result.

RSK allows to identify complement-binding ATs to brucellae that appear in the blood after agglutinins. The maximum titres of AT in the DSC are recorded by the 4th month of the disease, later their titer decreases, but in a small amount they are detected within 1 year. There are no significant advantages of RSK in comparison with the agglutination reaction.