Brucella melitensis Biovar 1 and Brucella abortus S19 Vaccine Strain Infections in Milkers Working at Cattle Farms in the Khartoum Area, Sudan.

BACKGROUND: Human brucellosis is a preventable zoonoses that may become persistent, causing, if left untreated, severe localized disease. Occupational exposure to infected animals or animal products and consumption of fresh contaminated dairy are main risk factors. METHODS: One hundred farmworkers employed at two cattle farms one in Khartoum North and one in Omdurman were screened for the presence of specific antibodies and seropositive workers were invited to donate a blood sample for blood culture. Molecular typing was used to characterize Brucella isolates. RESULTS: Ten percent of farmworkers tested seropositive and while Brucella melitensis biovar 1 was isolated from the blood of three individuals, an isolate identical to the B. abortus S19 vaccine strain was isolated from a fourth person. All four bacteremic individuals were employed as milkers and did not have obvious disease. CONCLUSIONS: The isolation of the highly infectious pathogen B. melitensis from seropositive workers is consistent with the notion that the pathogen may persist in the blood without causing overt disease. While vaccination with strain S19 is essential for the control of bovine brucellosis the vaccine strain may be transmitted to the human population and protective measures remain important to prevent exposure also in view of the presence of B. melitensis. To create awareness for this potentially severe disease more information on the prevalence of the pathogen in different risk groups and in livestock in the Sudan is needed.

Brucellosis seroprevalence in Bali cattle with reproductive failure in South Sulawesi and Brucella abortus biovar 1 genotypes in the Eastern Indonesian archipelago.

BACKGROUND: Brucellosis is a major cause of infertility and reproductive failure in livestock. While cattle in the Eastern Indonesian archipelago suffers from reproductive problems information on bovine brucellosis in the region is fragmentary. The control of brucellosis requires a major and prolonged effort and confirmation of the infection by isolation with detailed knowledge of the spread of the infection is essential when planning a control program. RESULTS: Serological investigation of Brucella infection in beef cattle tended under extensive farming conditions revealed a high seroprevalence (19.3%; 95% CI, 17-22) in the compliment fixation tests. The results of a rapid and simple field test correlated well with the Rose Bengal test (kappa, 0.917) and indicated an acceptable sensitivity (87.5%) and specificity (98.1%) compared with the complement fixation test. Reproductive failure was reported for 39.0% of the cows with a loss of calves due to abortion or early death amounting to 19.3%. Past reproductive failure did not, however, correlate with seropositivity in the complement fixation test (RP = 1.21; P = 0.847). B. abortus biovar 1 was freshly isolated from the hygromas of two cows and together with thirty banked isolates collected since 1990 from different parts of Sulawesi and Timor eight related genotypes could be distinguished with one genotype being identical to that of an isolate (BfR91) from Switzerland. The Indonesian genotypes formed together with BfR91 and one African and one North American isolate a distinct branch on the B. abortus biovar 1 dendogram. CONCLUSIONS: Bovine brucellosis appears to be widespread in the Eastern Indonesian archipelago and calls for urgent intervention. The fresh isolation of the pathogen together with the observed high seroprevalence demonstrates the presence and frequent exposure of cattle in the area to the pathogen. The application of a rapid and simple field test for brucellosis could be very useful for the quick screening of cattle at the pen side.

Serological evidence for brucellosis in Bos indicus in Nigeria.

PURPOSE: Nigeria is the largest cattle-rearing nation in Africa with most animals kept under traditional husbandry practices. While bovine brucellosis does not receive much attention, a relatively high seroprevalence is found in samples submitted for laboratory testing. The aim of the study was to provide serological evidence of brucellosis in cattle from some of the main cattle-rearing states of the country and to validate a simple and rapid field test for the serodiagnosis of bovine brucellosis. METHOD: Serum samples collected in various states of Nigeria from cattle because of suspicion of brucellosis were investigated in the Rose Bengal plate test, and results were compared with a newly developed rapid field test for the detection of Brucella-specific antibodies. RESULTS: Serological evidence for the presence of brucellosis in cattle was obtained for all states included in the study and a high herd prevalence was observed. The seroprevalence was also high among trade and slaughter animals. Results of a rapid field test for the serodiagnosis of bovine brucellosis correlated well with the Rose Bengal plate test (agreement, 95.7%; kappa value, 0.80). CONCLUSIONS: The results indicate that bovine brucellosis is an important veterinarian problem in Nigeria. The easy-to-use and robust field test is most promising for field-based surveillance as it provides an immediate result allowing the prompt instigation of control measures.

Infection of cattle in Kenya with Brucella abortus biovar 3 and Brucella melitensis biovar 1 genotypes.

Brucella melitensis biovar 1 was isolated from bovine milk samples from a herd in central Kenya, and Brucella abortus biovar 3 was isolated from aborted fetus materials and vaginal discharge fluids from cattle in central and eastern provinces of Kenya. All infections including those with B. melitensis were in cattle with reproductive problems kept in mixed herds indicating that cross infection occurs from small ruminants. Multiple-locus variable-number tandem repeat analysis genotyping revealed a close molecular homology of the B. melitensis isolates with an isolate from Israel and a close homology of the B. abortus isolates with an isolate from Uganda indicating that these genotypes have a wide geographic distribution. Infection of cattle with B. melitensis may complicate the control of brucellosis in this country.

Application of a point-of-care test for the serodiagnosis of typhoid fever in Nigeria and the need for improved diagnostics.

INTRODUCTION: There is an urgent need for affordable point-of-care diagnostics for the differentiation of febrile illnesses and the confirmation of typhoid in endemic countries. METHODOLOGY: Blood samples were collected from febrile patients with clinical suspicion of typhoid and screened for typhoid fever using the Widal and Typhi Dri Dot tests, while stool and blood samples were screened for Salmonella Typhi using the culture method as well as PCR as a confirmatory test. RESULTS: A high proportion of febrile patients from Lagos with clinical suspicion of typhoid fever reacted positively in a simple and rapid latex agglutination assay for typhoid fever, indicating that this illness is a common and presumably under-diagnosed health problem in this metropolis. Seropositivity was 19.2% in the rapid test compared with 22.9% in the classical Widal test. The confirmation of typhoid in these seropositive patients appeared cumbersome because of negative blood cultures and low DNA yield in molecular testing. A review of the literature revealed that in Nigeria seroprevalence rates can be high in the normal population and that pathogens other than S. Typhi are often isolated from the blood of seropositive febrile patients. CONCLUSION: The simplicity and the relatively high specificity (97.8%) of the rapid test as determined in a study performed in Indonesia calls for a further validation of this promising test for use in Africa.

Validation of the Dri-Dot Latex agglutination and IgM lateral flow assays for the diagnosis of typhoid fever in an Egyptian population.

Laboratory confirmation of typhoid fever is essential for appropriate medical treatment. Blood culture is a standard test for diagnosis of typhoid fever, but well-equipped diagnostic facilities to perform culture are seldom available in endemic areas. We retrospectively compared 2 diagnostic field tests, a latex agglutination Dri-Dot assay and an IgM Lateral Flow assay, to blood culture, in patients with clinically diagnosed typhoid fever. Sensitivity of the Dri-Dot was 71.4%, and specificity was 86.3% for samples collected at time of first diagnosis. Sensitivity and specificity of IgM Lateral Flow were 80% and 71.4%, respectively. A major limitation of these serologic tests is the limited sensitivity at the early stage of the disease. Performing both tests in parallel increased sensitivity to 84.3%, but decreased specificity to 70.5%. There was a trend towards improved diagnostic performance using either assay over a longer duration of illness. These rapid, point-of-care assays for typhoid fever provide easy-to-interpret results in typhoid-endemic countries and may be most useful in patients presenting 1 week after symptom onset.

The evaluation of a user-friendly lateral flow assay for the serodiagnosis of human brucellosis in Kazakhstan.

Serum samples from all patients with culture-confirmed brucellosis including those with chronic disease from Kazakhstan tested positive in the serum agglutination test for titers > or = 1:25 and reacted in the Brucella immunoglobulin M/immunoglobulin G lateral flow assay (LFA) confirming the high sensitivity of these assays. The strong reactivity in the LFA observed for the majority (92.1%) of the samples from the patients with culture-confirmed brucellosis together with the user-friendliness of the assay procedure makes the LFA ideal for the confirmation of brucellosis in endemic areas in Kazakhstan. The Rose Bengal test lacked sensitivity in particular for patients with chronic brucellosis therefore limiting its value as a quick screening assay. The study emphasizes the importance of the LFA as a useful, rapid, and easy-to-perform tool in the diagnostic testing of brucellosis.

Comparison of a flow assay for brucellosis antibodies with the reference cELISA test in West African Bos indicus.

Brucellosis is considered by the Food and Agricultural Organisation and the World Health Organisation as one of the most widespread zoonoses in the world. It is a major veterinary public health challenge as animals are almost exclusively the source of infection for people. It is often undiagnosed in both human patients and the animal sources and it is widely acknowledged that the epidemiology of brucellosis in humans and animals is poorly understood, particularly in sub-Saharan Africa. It is therefore important to develop better diagnostic tools in order to improve our understanding of the epidemiology and also for use in the field for disease control and eradication. As with any new diagnostic test, it is essential that it is validated in as many populations as possible in order to characterise its performance and improve the interpretation of its results. This paper describes a comparison between a new lateral flow assasy (LFA) for bovine brucellosis and the widely used cELISA in a no gold standard analysis to estimate test performance in this West African cattle population. A Bayesian formulation of the Hui-Walter latent class model incorporated previous studies' data on sensitivity and specificity of the cELISA. The results indicate that the new LFA is very sensitive (approximately 87%) and highly specific (approximately 97%). The analysis also suggests that the current cut-off of the cELSIA may not be optimal for this cattle population but alternative cut-offs did not significantly change the estimates of the LFA. This study demonstrates the potential usefulness of this simple to use test in field based surveillance and control which could be easily adopted for use in developing countries with only basic laboratory facilities.

Brucellosis in household members of Brucella patients residing in a large urban setting in Peru.

During home visits and using a point-of-care test for brucellosis, we screened the household members of adult patients found to have brucellosis by investigation at the Hospital Nacional Daniel Alcides Carrión in Callao, Peru. A total of 206 household members of 43 patients were screened, and 15 (7.3%) household members in 10 (23.3%) households tested seropositive. Brucellosis was diagnosed in 14 of them, all but 4 presenting with acute or subacute uncomplicated disease. Regardless of attempts to control brucellosis in Peru, the disease continues to be reasonably common among household members of brucellosis patients. Household members presumably remain the single most important identifiable risk group in an urban setting, and screening them provides an effective means for their early diagnosis. Although contact with livestock was rare, the consumption of unpasteurized dairy products was reported by almost all patients with brucellosis, their household members, and hospitalized non-brucellosis patients.

Simple, rapid, and affordable point-of-care test for the serodiagnosis of typhoid fever.

We developed a point-of-care test for the serodiagnosis of typhoid fever in the format of an immunochromatographic lateral flow assay. The flow assay for typhoid fever is based on the detection of Salmonella enterica serotype Typhi lipopolysaccharide-specific immunoglobulin M (IgM) antibodies. The assay was evaluated on serum samples collected in a hospital in South Sulawesi, Indonesia, where typhoid fever is endemic, and the results were compared with culture and Widal test. The sensitivity of this typhoid fever IgM flow assay for samples collected at 1st diagnosis from patients with culture-confirmed typhoid fever was determined to be 59.3%. The sensitivity ranged from 41.2% to 89.5%, depending on the duration of illness. A specificity of 97.8% was calculated based on results obtained for patients with clinical suspicion of typhoid fever that was later excluded. The assay is ideal for use as a point-of-care test in health care centers that lack the expertise and facilities to perform culture or the less specific Widal test. Because of its simplicity, the assay may also be used as a field test in remote areas.

Laboratory evaluation of a simple and rapid latex agglutination assay for the serodiagnosis of typhoid fever.

A latex agglutination assay for the serodiagnosis of typhoid fever was evaluated on samples collected from patients with clinical suspicion of typhoid fever in South Sulawesi, Indonesia, where the disease is endemic. The latex assay is very easy to use, gives a rapid result and may be used as a point-of-care diagnostic test. For acute phase samples collected on average 6 days after the onset of illness, the sensitivity is 42.5% for culture-confirmed patients with typhoid fever and the specificity is 96.9%. The sensitivity improved with the duration of illness from 30.8% for samples collected during the first 4-5 days of illness to 45.5% for samples collected between days 7 and 9, and to 84.6% for the samples collected more than 9 days after the onset of illness. Testing of follow-up samples may further improve sensitivity by demonstrating seroconversion.

Evaluation of brucellosis by PCR and persistence after treatment in patients returning to the hospital for follow-up.

Polymerase chain reaction (PCR) was applied to confirm the diagnosis of brucellosis and to study its clearance in response to the standard treatment regimen with doxycycline and rifampin at hospitals in Callao and Lima, Peru. The PCR confirmed the diagnosis in 23 (91.7%) patients with brucellosis including 12 culture-confirmed cases. For patients treated at the hospital in Callao, PCR was positive for all samples collected during and at the conclusion of treatment and for 76.9% of follow-up samples collected on average 15.9 weeks after completion of treatment. For patients treated at the hospital in Lima, PCR tests were positive for 81.8% of samples collected during treatment, for 33.3% of samples collected at the conclusion of treatment, and for > or = 50% of samples collected at first, second, and third post-treatment follow-up. Thus, Brucella DNA may persist in the serum weeks to months after completion of the standard treatment regimen.

Rapid latex agglutination test for the serodiagnosis of human brucellosis.

We developed and evaluated a user-friendly latex agglutination assay for the serodiagnosis of human brucellosis. The assay was obtained by coating colored latex beads with Brucella lipopolysaccharides and drying of the activated beads onto white agglutination cards. Individual cards were sealed in a protective foil to secure stability of the dried reagent and to obtain a test in a single assay format. The latex agglutination assay is simply performed by suspending the dried latex reagent in a drop of serum and looking for macroscopic agglutination of the latex beads by visual inspection. Results are obtained within 30 s after mixing the sample with the test reagent. The sensitivity of the assay was determined to be 89.1% (95% confidence interval [CI], 76-96) for the initial serum samples collected from patients with culture-confirmed brucellosis and the specificity is 98.2% (95% CI, 96-99). The assay is ideal for use as a field test in remote areas and as point-of-care test in hospitals and health care centers that lack the expertise and facilities to perform the more demanding classic serologic tests.

Prevalence of Brucella antibodies in rural and suburban communities in three provinces of Turkey: need for improved diagnosis and prevention.

OBJECTIVE: To determine the seroprevalence of Brucella-specific antibodies in rural and suburban communities in different provinces of Anatolia. METHOD: Cross-sectional seroepidemiological study on serum samples collected in communities in two relatively developed provinces in west Anatolia with an official low prevalence of brucellosis and in one province in southeast Anatolia with a high prevalence. RESULT: The seroprevalence of brucellosis in the two provinces in the west Anatolia appears to be high and ranged from 2.9 to 8.5% in Rose Bengal test and from 0 to 5.6% in Wright serum agglutination test at a titer equal or higher than 1:100. The seroprevalence in communities in the province in southeast Anatolia was lower and this might well be attributed to vaccination of livestock in the year preceding the survey. CONCLUSION: Adherence to traditional farming practices and lifestyle, and a preference for fresh dairy contribute to the high seroprevalence of brucellosis. Vaccination of livestock is of utmost importance and the consumption of fresh milk and dairy products prepared from unpasteurised milk should be halted. Better access to laboratory testing is needed for the confirmation and management of brucellosis.

Comparison of Brucella immunoglobulin M and G flow assays with serum agglutination and 2-mercaptoethanol tests in the diagnosis of brucellosis.

The diagnostic value of Brucella IgM/IgG flow assays was evaluated in comparison with serum agglutination and 2-mercaptoethanol tests by testing a selection of serum samples submitted to the laboratory because of clinical suspicion of brucellosis. All 39 admission and 11 follow-up samples that agglutinated in the serum agglutination test tested positive in the flow assay, whereas all 20 serum agglutination negative samples with clinical suspicion of brucellosis, 23 control samples from healthy individuals and 20 control samples from cases with chronic hepatitis tested negative in the flow assay. The Brucella IgM and IgG flow assays were slightly more sensitive than the agglutination tests in discriminating between specific IgM and IgG antibodies. The Brucella IgM and IgG flow assays are easy-to-perform and quick assays that can be used for the diagnosis of brucellosis. The flow assays are very useful, especially in rural settings where brucellosis is widespread and where well-equipped laboratories to perform the laboratory tests are not readily available.

Brucellosis is not a major cause of febrile illness in patients at public health care facilities in Binh Thuan Province, Vietnam.

OBJECTIVE: To determine the presence of brucellosis among patients with acute febrile illness at health care facilities in Binh Thuan province, Vietnam. METHOD: A retrospective seroepidemiological study on serum samples collected at 13 not adjacent health care facilities using the Rose Bengal test as a rapid screening test and the Brucella IgM/IgG flow assay as a simple confirmatory test. RESULT: The seroprevalence in the Rose Bengal test among 406 patients presented with acute undifferentiated fever was 14.8%. Seven of the 64 Rose Bengal test positive samples reacted weakly (1+) positive in the Brucella IgM/IgG flow assay. No seroconversion was observed. CONCLUSIONS: Brucellosis is not a major cause of morbidity in Binh Thuan province.

Application of a user-friendly Brucella-specific IgM and IgG antibody assay for the rapid confirmation of Rose Bengal-positive patients in a hospital in Iran.

The Brucella IgM/IgG flow assay was used for the confirmation of brucellosis in patients from an area endemic for brucellosis and who had a Rose Bengal (RB)-positive serum sample collected at the time of first presentation for diagnosis. The flow assay confirmed the result of the RB test in 46.6% of the positive admission sera, with the majority (62.5%) of the flow assay-positive samples staining moderately strong to very strong (> or =2+). In comparison, Wright and 2-ME at the routinely used cut-off titre values of 1:320 for Wright and 1:160 for 2-ME tested positive in 37.7% of the RB-positive samples. A relatively large number of RB-positive samples agglutinated at or around the cut-off value in the Wright and 2-ME tests and 66.7% of the RB-positive samples tested positive in these confirmatory tests when using one titre step lower threshold values. The relatively high number of samples with low antibody levels supports the argument for testing follow-up samples from patients with an RB-positive sample in order to confirm the diagnosis by showing seroconversion or a rise in antibody levels.

Use of the Brucella IgM and IgG flow assays in the serodiagnosis of human brucellosis in an area endemic for brucellosis.

The clinical utility of two complementary tests for brucellosis, the Brucella IgM and IgG flow assays, was evaluated in a hospital in eastern Turkey. The results show that the flow assays are convenient diagnostic tests for use in endemic areas. A positive result in the flow assays was obtained in 91% and 97% of the admission sera from adult and pediatric patients with brucellosis, respectively, and the sensitivity at admission was 100% for culture-confirmed brucellosis. The assay system performed equally well in diagnosing patients at different stages of illness including patients with acute, subacute, or chronic disease and with relapse. The results of the flow assays correlated well with those of a serum agglutination test at a cut-off > or =1:160. The agreement was 92%. Application of the flow assays on serum samples collected during a village survey for brucellosis after an outbreak demonstrated their diagnostic potential as field tests.

Immunochromatographic Brucella-specific immunoglobulin M and G lateral flow assays for rapid serodiagnosis of human brucellosis.

To fulfill the need for a simple and rapid diagnostic test for human brucellosis, we used the immunochromatographic lateral flow assay format to develop two assays, one for the detection of Brucella-specific immunoglobulin M (IgM) antibodies and one for the detection of Brucella-specific IgG antibodies. The diagnostic values of these tests were examined. The tests are shown to detect acute, persistent, and relapsing disease and can be used to monitor treatment. The sensitivity of Brucella IgM and IgG flow assays calculated for the combined assay results is 96%, and specificity amounts to 99%. The flow assay requires neither specialized training nor equipment, the assay is very easy to perform and to read, and the components are stable without a requirement for refrigeration and well standardized. Together these characteristics indicate that the Brucella IgM and IgG flow assays are ideal for use in clinical settings in rural and suburban areas in which brucellosis is endemic.