Diagnosis of recent and relapsed cases of human brucellosis by PCR assay

Peripheral blood specimens from 50 healthy control subjects and 165 seropositive patients having compatible signs and symptoms that were clinically diagnosed to have brucellosis were tested by blood culture, and by PCR. The PCR assay used genus-specific primers from the conserved region of the 16S rRNA sequence, which showed high specificity for the Brucella spp.Diagnosis of Brucella was established by PCR in 120 cases (72.7%). All of them were seropositive and 20 were positive by culture. Forty-eight of 58 (82.8%) of the relapsed cases two months after completing the treatment with an increase in the previous serological titers were positive by PCR. The assay has 85.7% positive predicative value, 100% sensitivity and specificity since it correctly identified all cases that were positive by blood cultures, 95.8% by serology and none of the control group was positive.Results showed that PCR assay can be applied with serology for the diagnosis of brucellosis suspected cases and relapses regardless of the duration or type of the disease without relying on the blood cultures, especially in chronic cases.Brucellosis continues to be an important zoonosis of economic significance and human suffering. It affects human populations in many developing countries including the Middle East, and Latin America where it is still endemic [1]. The World Health Organization reports an annual incidence of human brucellosis of less than one to 78 cases per 100,000 population in the Middle East, with six countries reporting an annual total incidence of more than 90,000 cases [2]. Four Brucella spp. namely, Brucella abortus, B. canis, B. suis and especially B. melitensis are able to cause human infections [3]. Brucellosis is usually transmitted to humans by ingestion of unpasteurized dairy products or by direct contact with infected animals. Occupational disease is contracted by exposure of abattoir workers and veterinarians to infected animals especially aborted fetuses, fluids, membranes