الفهرس 
• Historical aspects of brucellosisOnly 14 pages are availabe for public view
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Abstract
In Egypt, brucellosis is still an endemic disease in animals and human; in spite of attempts that were adopted in the country to control the disease. Although, human brucellosis is a notifiable disease in Egypt, it is often labeled ”fever of unknown cause”. So, the actual number of cases of brucellosis is unknown and is believed to be far more than the officially reported figures.
In many laboratories, the serological diagnosis of brucellosis is based on a tube agglutination test requiring incubation for two days and therefore causing delay in reporting of results.
The standard tube agglutination test (STAT) is the most widely used serologic test for the confirmation of human brucellosis. The detection of seroconversion or high antibody titers (≥1/160) are considered diagnostic together with a compatible clinical presentation. The lack of seropositivity in patients with strongly suspected clinical picture may be attributed to the performance of tests early in the course of infection.
The isolation of Brucella pathogens from contaminated samples is not always possible. Also, the culture is of low sensitivity especially in chronic infection. As the culture is rarely successful in the absence of identifiable localizing lesions and the serological tests often give inconclusive results.
Rose Bengal Test is a rapid test that uses a suspension of Brucella abortus in an acid buffer. It is able to detect agglutinating and non-agglutinating antibodies. This endows the RBT with a high degree of sensitivity for diagnosing infection with Brucella spp., irrespective of the stage of the disease. This high sensitivity, together with the fact that the technique is simple and rapid (4 min), makes the RBT ideal for screening patients for human brucellosis.
But RBT is believed to give few false negative results and also, give many false positive results when compared with other serological tests in the diagnosis of brucellosis.
This study was designed to analyze the diagnostic yield of (RBT & STAT) in comparison with PCR for the diagnosis of human brucellosis. And to evaluate the sensitivity, specificity, accuracy, the cost and the time consuming of (RBT &STAT) in comparison with PCR for the diagnosis of human brucellosis.
This study was conducted in co-operation between Tropical Medicine Department, Faculty of Medicine, Ain Shams University and Zoonotic Diseases Department of National Research Center and Imbaba Fever Hospital in the period from Mars 2009 to Mars 2010. The current study included 30 cases. All of the studied cases were subjected to the following; full medical history taking, thorough clinical examination, laboratory investigations, serological tests (STAT and RBT) and PCR for diagnosis of brucellosis.
The patients enrolled in our study were selected from Imbaba Fever Hospital. We operated our study on 30 patients that were suspected to be brucellosis, based on history medical taking, clinical manifestations and positive serum tube agglutination test (at titer ≥ 160).
There was male predominance being 19 male patients (63.3%) and 11 female patients (36.7%). Their age ranged between 10 and 53 years (mean 32.5± 13.8 years).
Regarding the clinical presentations of the studied group; in the present study, all studied patients were presented with fever (100%) the most presenting symptoms beside fever were body aches (53.3%) and profuse sweating at night (43.3%).
Concerning the laboratory findings of the studied cases; the most common haematological manifestation in our study was anaemia 29/30 (96.7%). There was a significant negative correlation between STAT titer and Hb level. There was only, 23.3% of the studied cases had hyperbilirubinemia, 43.3% of the studied cases had an increased level of ALT and 36.7% of the studied cases had an increased level of AST and there was a significant positive correlation with ALT and AST. 23.3% of the studied cases had increased level of urea, 3.3% of the studied cases had an increased level of serum creatinine.
The clinical picture of brucellosis alone can not always lead to diagnosis. Since the symptoms are nonspecific and often atypical; therefore, diagnosis needs to be supported by laboratory tests. Although, many serological tests and new automated blood culture techniques have been developed to diagnose brucellosis, there are still significant problems in the diagnosis of the disease. Blood cultures are time-consuming, since the average time required for growth has been reported to be more than 6 days. In addition, handling the organism poses a high risk of contagion for laboratory personnel. Also, the sensitivity of blood cultures ranges from 53 to 90% whereas it is significantly reduced in focal and chronic forms of the disease. So in the presented study we considered PCR is the golden test for diagnosis of brucellosis. As the PCR method is more sensitive and specific than culture and serology for diagnosis of Brucella from peripheral blood in suspected cases.
In the current study, we used 30 suspicious blood samples from Imbaba fever hospital with positive STAT (≥160) for diagnosis of brucella by PCR and RBT.
In our series, 25 samples had positive RBT and 24 samples had positive PCR for brucella. The sensitivity, Specificity and accuracy of RBT were 87.5%, 33.3% and 76.6%, respectively. Specificity and sensitivity values of RBT was less than STAT ≥ 320.The data reviewed in this study suggest that the STAT ≥ 320 has greater diagnostic accuracy than the RBT.
The combination of the 2 tests together was of no statistically significant value, there was no statistically significant association between STAT and or RBT and chronic cases (past history of similar condition). However, the RBT was less costly, easier to perform (i.e. simple and rapid), that making it suitable for national serological surveys, and laboratories with large diagnostic workloads. Unlike the other tests, it can be used under field conditions to detect antibody to Brucella species, would further reduce the laboratory and programs costs relative to the use of PCR.