Performance characteristics and costs of serological tests for brucellosis in a pastoralist community of northern Tanzania.

The control of brucellosis across sub-Saharan Africa is hampered by the lack of standardized testing and the use of tests with poor performance. This study evaluated the performance and costs of serological assays for human brucellosis in a pastoralist community in northern Tanzania. Serum collected from 218 febrile hospital patients was used to evaluate the performance of seven index tests, selected based on international recommendation or current use. We evaluated the Rose Bengal test (RBT) using two protocols, four commercial agglutination tests and a competitive enzyme-linked immunosorbent assay (cELISA). The sensitivity, specificity, positive predictive value, negative predictive value, Youden's index, diagnostic accuracy, and per-sample cost of each index test were estimated. The diagnostic accuracy estimates ranged from 95.9 to 97.7% for the RBT, 55.0 to 72.0% for the commercial plate tests, and 89.4% for the cELISA. The per-sample cost range was $0.69-$0.79 for the RBT, $1.03-$1.14 for the commercial plate tests, and $2.51 for the cELISA. The widely used commercial plate tests performed poorly and cost more than the RBT. These findings provide evidence for the public health value of discontinuing the use of commercial agglutination tests for human brucellosis in Tanzania.

Burden of typhoid fever in Sulaimania, Iraqi Kurdistan.

BACKGROUND: Typhoid fever imposes a high disease burden worldwide, but resource limitations mean that the burden of typhoid fever in many countries is poorly understood. METHODS: The authors conducted a prospective surveillance study at the adult and pediatric teaching hospitals in Sulaimania, Iraqi Kurdistan. All patients presenting with an undifferentiated febrile illness consistent with typhoid were eligible for enrollment. Enrolled patients had blood cultures and Brucella serologies performed. Incidence was calculated with reference to census data. RESULTS: Both typhoid fever and brucellosis were common, and the incidence of typhoid fever was 21 cases/100 000 patient-years. Classic disease symptoms were uncommonly observed. DISCUSSION: Cost-effective surveillance projects to calculate disease burden of typhoid fever are practical and replicable. Typhoid has successfully adapted to the healthcare environment in Sulaimania. Additional work in the region should focus on antibiotic resistance and other enteric pathogens such as Brucella spp.

Evaluation of five serological tests for the diagnosis of porcine brucellosis in French Polynesia.

Porcine brucellosis due to Brucella suis biovar 1 raises important issues for pig breeders in French Polynesia. In this region, the disease is enzootic, spreads silently and engenders economic losses in infected farms as well as sporadic human cases. While serological tests are essential in surveillance and control programmes of animal diseases, to date none of the available tests have been shown to be reliable enough to be used as a gold standard in routine individual diagnosis of porcine brucellosis. Few studies about the estimation of the sensitivity and the specificity of porcine brucellosis screening tests have been published, none of them dealing with French Polynesia. The studied population included 1,595 pigs from French Polynesia. Five tests were evaluated: Rose Bengal test, fluorescence polarisation assay, indirect ELISA, and two competitive ELISAs (C-ELISA). The sensitivity and the specificity of each test were estimated. C-ELISA2 was the most sensitive test (Se C-ELISA2=0.954 [0.889; 0.992] 95% credibility interval (CrI)) while both C-ELISA and Rose Bengal test (RBT) were the most specific ones (Sp C-ELISA1=0.856 [0.806; 0.915] 95% CrI; Sp C-ELISA2=0.849 [0.817; 0.879] 95% CrI; Sp RBT=0.853 [0.812; 0.898] 95% CrI).

Assessment of performance of selected serological tests for diagnosing brucellosis in pigs.

Swine brucellosis due to Brucella suis is considered an emerging zoonotic disease whose control is based on serological testing and the subsequent culling of seropositive animals or the full depopulation of affected flocks. Here we assessed the performance of several serological tests (Rose Bengal Test [RBT], indirect ELISA [i-ELISA], blocking ELISA [b-ELISA], and two competitive ELISAs [c-ELISA]) for diagnosing swine brucellosis caused by B. suis biovar 2. Both frequentistic and Bayesian statistical inference were used. A frequentistic analysis, using sera from known gold standard (GS) populations (i.e., from truly infected or brucellosis free animals), resulted in maximum (100%) diagnostic sensitivity (Se) and specificity (Sp) in the RBT, i-ELISA and b-ELISA tests. However, c-ELISAs resulted in lower diagnostic Se (ranging from 68.5% to 92.6%, according to the different cut-offs selected). A Bayesian analysis of tests yielding the best diagnostic performance with GS sera (RBT, i-ELISA and b-ELISA), but using a large collection of field sera, resulted in similar Se among tests but markedly lower (≈ 80%) than that resulting from the frequentistic analysis using the GS serum populations. By contrast, the estimated Sp in the Bayesian analysis was only slightly lower than 100%, thus similar to that obtained frequentistically. Our results show that adequate diagnostic tests for brucellosis in swine are available, but also emphasize the need for more extensive validation studies before applying these tests under field conditions.

Assessment of clinical pathology and pathogen exposure in sea otters (Enhydra lutris) bordering the threatened population in Alaska.

Northern sea otter (Enhydra lutris kenyoni) abundance has decreased dramatically over portions of southwest Alaska, USA, since the mid-1980s, and this stock is currently listed as threatened under the Endangered Species Act. In contrast, adjacent populations in south central Alaska, USA, and Russia have been stable to increasing during the same period. Sea otters bordering the area classified in the recent decline were live-captured during 2004-2006 at Bering Island, Russia, and the Kodiak Archipelago, Alaska, USA, to evaluate differences in general health and current exposure status to marine and terrestrial pathogens. Although body condition was lower in animals captured at Bering Island, Russia, than it was at Kodiak, USA, clinical pathology values did not reveal differences in general health between the two regions. Low prevalences of antibodies (<5%) were found in Kodiak, USA, and on Bering Island, Russia, to Toxoplasma gondii, Sarcocystis neurona, and Leptospira interrogans. Exposure to phocine herpesvirus-1 was found in both Kodiak, USA (15.2%), and Bering Island, Russia (2.3%). Antibodies to Brucella spp. were found in 28% of the otters tested on Bering Island, Russia, compared with only 2.7% of the samples from Kodiak, USA. Prevalence of exposure to Phocine distemper virus (PDV) was 41% in Kodiak, USA, but 0% on Bering Island, Russia. Archived sera from southwest and south-central Alaska dating back to 1989 were negative for PDV, indicating exposure occurred in sea otters in Kodiak, USA, in recent years. Because PDV can be highly pathogenic in naïve and susceptible marine mammal populations, tissues should be examined to explore the contribution of this virus to otter deaths. Our results reveal an increase in exposure to pathogens in sea otters in Kodiak, Alaska, USA, since the 1990 s.

Mapping brucellosis risk in communities in the Republic of Armenia.

We describe the geographical patterns and identified factors associated with serological evidence of brucellosis in ruminants in Armenian communities during 2006 and 2007. The data comprised the two first complete years of the current national test-and-slaughter control programme for cattle, sheep and goats. Overall, 29% and 21% of the 858 communities involved in this study reported brucellosis in their respective cattle and small ruminant populations. The national brucellosis control data showed a widespread and uneven distribution of brucellosis throughout the Republic of Armenia for both cattle and small ruminants. The geographical areas of greater risk of communities having seropositive animals were different for cattle and small ruminant populations but most of the associated factors were similar. Several areas where the likelihood of disease occurrence was predicted poorly by the statistical models were also identified. These latter findings are indicative of either less than perfect testing and reporting procedures or unexplained epidemiological factors operating in those particular areas. The analyses provided valuable insights into understanding the brucellosis epidemiology at the community level which operates in small ruminant and cattle populations, and identified priority areas for implementing targeted risk-based surveillance and disease control interventions.

Feral swine contact with domestic swine: a serologic survey and assessment of potential for disease transmission.

Feral swine (Sus scrofa) are present in 38 of the 50 United States, and their populations continue to expand. Domestic swine are widely regarded as vulnerable to diseases harbored by feral swine. Our objectives were to determine antibody prevalence for selected pathogens in Texas feral swine populations and identify contact events between feral and domestic swine. Overall prevalence of antibodies against brucellosis and pseudorabies virus was 11% and 30%, respectively. Antibodies to porcine reproductive and respiratory disease virus were detected in 3% of feral swine from southern Texas. All samples tested negative for antibodies to classical swine fever virus. To determine the frequency of contact events between feral swine and domestic swine in neighboring facilities, we analyzed movement data from 37 adult feral swine that were trapped < or =10 km from domestic swine facilities and equipped with geographic positioning system collars. Seven of the 37 feral swine had contact (relocated within 100 m) with domestic swine. We found that contact between feral swine and domestic swine occurred predominantly at night. Additionally, we analyzed 60 consecutive days of experimental track plots around pens that contained domestic swine and empty control pens, and found greater visitation by feral swine to the domestic swine pens. Our data demonstrate that feral swine have direct contact with domestic swine, which presents opportunity for disease transmission.

Assessment of diagnostic enzyme-linked immunosorbent assay kit and serological markers in human brucellosis.

This study was performed to evaluate commercial brucella immunoglobulin G and M enzyme-linked immunosorbent assay (IgG and IgM ELISA) kits for the diagnosis of human brucellosis and to suggest a candidate prognostic marker for human brucellosis. We determined the serum levels of brucella IgG, IgM, C-reactive protein (CRP), soluble CD14 (sCD14), and neopterin in patients with brucellosis and compared them with those of normal healthy persons, patients with tuberculosis, and patients with other diseases. It was found that the sensitivity of ELISA to diagnose brucellosis was high when both IgG and IgM ELISA were used together. This study showed that serum CRP, sCD14, or neopterin levels were significantly high during the course of human brucellosis. The above markers, alone or in combination, might have the potential to evaluate treatment outcomes in human brucellosis. The markers that can predict the variability of agglutination titer was also determined. It was found that the titer value alone does not fully represent disease status.

[Dot immunoassay with colloidal silver particles as a marker of specific antigen for testing human sera for brucellosis]. / Dot-immunoanaliz s chastitsami kolloidnogo serebra v kachestve markera spetsificheskogo antigena dlia issledovaniia syvorotok krovi liudei na brutsellez.

Whether the dot immunoassay is suitable for the detection of Brucella antibodies in human sera by using a colloidal silver-labeled Brucella specific antigen as a diagnostic tool is assessed. The antigen was the B. abortus 19BA protein polysaccharide complex isolated by Brucella acetic acid hydrolysis. The dot immunoassay is easy-to-use, cost-effective, highly sensitive, and therefore of more informative value in detecting Brucella antigens than routine serological tests (Huddleson test, Wright agglutination test, passive hemagglutination test, long-term complement fixation test, and Coombs test). It requires no use of expensive equipment and reagents.

[Diagnosis of brucellosis in an endemic area. Evaluation of routine diagnostic tests]. / El diagnóstico de la brucelosis en un área endémica. Valoración de las pruebas diagnósticas habituales.

BACKGROUND: The use of classic methods of diagnosis of brucellosis was analyzed, particularly serologic methods whose use in endemic areas and risk groups has been questioned in the literature. METHODS: Prospective analysis of these methods was performed in a group of 171 patients suspected as having brucellosis proceeding from an endemic area, with progressions of risk and frequent antecedents of brucellosis. The results obtained were compared in 119 patients in whom brucellosis was confirmed (80 with positive cultures and 39 with clinic-serologic diagnosis) and in 52 in whom the diagnosis was excluded. RESULTS: The hemocultures provided a sensitivity of 70% with a mean delay in growth of 13.6 days. The rise of Bengal test showed sensitivity of 95% and specificity of 75%. The most adequate cut-off point for seroagglutination was of 1/160 and for the Coombs test 1/320 with sensitivities of 93 and 92% and specificities of 97 and 100%, respectively. CONCLUSIONS: The routine serologic tests offer good results for the diagnosis of brucellosis in endemic areas upon use of adequate cut-off points and permitting therapeutic decisions to be taken prior to knowledge of the results of the cultures. The rose of Bengal test is valid for initial selection of this type of population.

Assessment of interferon production in patients with chronic nonviral diseases by whole blood or whole bone marrow techniques.

Hundred and fifty-four samples of heparinized blood from patients with chronic toxoplasmosis, chronic brucellosis, lung diseases, psychiatric affective disorders, healthy individuals and neonates, were obtained. The experimental material included also 14 bone marrow samples from patients with hematological diseases or lung cancer. The whole cell populations were treated with several classical IFN inducers and supernatants were assayed for IFN activity in human lung adenocarcinoma cell line A 549 using VSV or EMC viruses as challenge. The response of WBC to NDV or PHA + PMA was high and remarkably stable in majority of cases except listed below. The levels of IFN induced by LPS were low. The response of WBMC to IFN inducers closely resembled the response of WBC. Low IFN levels in samples of stimulated WBMC from some hematological patients were connected with low cellularity. WBC from psychiatric patients with affective disorders weakly responded to stimulation with NDV. This suggested an existence of deficiency of IFN alpha production connected with affective disorders. Also WBC from cord blood failed to react to PHA + PMA and were poorly responsive to NDV.