Serological diagnosis of brucellosis

How it is diagnosed

A presumptive diagnosis can be made by demonstrating elevated or rising titers of specific serum antibodies. Positive serological test results can persist long after recovery in treated individuals, so it is not always possible to distinguish serologically between active and past infection. Positive titers consist of 1:80 in nonendemic regions and 1:160 in endemic areas. A negative serology does not exclude the diagnosis in brucellosis.

Laboratory findings help but do not decide. Nine literature references are set out with the percent of patients having each given feature, and the numbers differ a great deal from one reference to the next: ESR above 20 mm/h in 42 to 77 percent, CRP above 5 mg/L in 23 to 79 percent, ALT above 40 U/L in 10 to 40 percent, leucopenia in 2 to 31 percent, leucocytosis in 3 to 9 percent, lymphocytes above 45 percent in 24 to 68 percent, thrombocytopenia in 3 to 15 percent, anemia in 7 to 70 percent, and pancytopenia in 1 to 3.5 percent. Not one of these findings is present in every patient, and many cells of the table carry no data at all.

So the titer read as positive depends on where the patient lives: 1:160 in endemic areas, against 1:80 in nonendemic regions.