Validation of FPA and cELISA for the detection of antibodies to Brucella abortus in cattle sera and comparison to SAT,CFT, and iELISA

The fluorescence polarisation assay (FPA) is a recently described test for the serological diagnosis of Brucella infection. It has many methodological advantages over older, more established tests and can be performed in a fraction of the time. To validate the FPA, serum samples from 146 confirmed (by culture) Brucella-infected cattle were tested in conjunction with serum samples from 1947 noninfected cattle. The competitive ELISA (cELISA) was validated using these positive reference samples and 1440 negative samples, while data for the indirect ELISA (iELISA) was generated from 6957 negative samples plus the positive sera. Published diagnostic specificity (DSp) data for the complement fixation test (CFT) and serum agglutination test (SAT) was used in conjunction with the test results on the positive sera to obtain diagnostic specificity plus diagnostic sensitivity (DSn). After selection of a cutoff for the FPA and cELISA, the diagnostic specificity and sensitivity total for each test were compared. The results, with 95% confidence intervals, were: FPA (195.7+/-2.79), iELISA (195.0+/-2.70), cELISA (194.9+/-3.48), CFT (191.7+/-4.45), and SAT (180.4+/-6.33). The data presented supports the use of the FPA in diagnosis of brucellosis and questions the use of the SAT and CFT for either screening or confirmatory testing.     

Brucellosis and its associated risk factors to humans and domestic ruminants in Kagera Ecosystem,Tanzania

BackgroundBrucellosis is an important disease for both veterinary and public health. A study was conducted to understand the seroprevalence of brucellosis and its associated risk factors in pastoral areas of Kagera, Tanzania.MethodsSera from 156 patients with malaria-like symptoms were analyzed using the commercial rapid agglutination test (specific for B.abortus and B.melitensis detection) and Fluorescence Polarization Assay (FPA). Sera from 426 cattle, 206 goats and 197 sheep were analyzed using Rose Bengal Plate (RBPT) and Competitive ELISA (c-ELISA) tests.ResultsIn humans, overall brucellosis, B. abortus, and B. melitensis sero-prevalences were 7.7% (95%CI: 3.8–12.2%), 1.9% (95% CI: 0.4–4.5%), and 5.8 % (95%CI: 2.6–10.6%), respectively. At animal level, seropositivity was 5.9% (95%CI: 4.0–8.6%), 2.5% (95%CI: 0.8–5.7%) and 0.5% (95%CI: 0.01–2.8%) in cattle, goats and sheep, respectively. At herd level, seropositivity was 18.2% (95%CI: 12.0–25.8%) in cattle and 6.9% (95%CI: 2.2–15.3%) in small ruminants. Brucellosis was associated with assisting in parturition without wearing protective gears (OR= 5.6; p= 0.02) in humans, herds of 50–200 animals (OR= 4.2, p= 0.01) and cattle (OR=3.5; p=0.01). The knowledge of brucellosis among pastoralists (OR=0.1; p<0.01) was a protective factor.ConclusionBrucella infections could be occurring in pastoralists and domestic ruminants in Kagera. Community health education is necessary for the control of brucellosis in Tanzania.     

Validation of the Indirect MAP1-B Enzyme-Linked Immunosorbent Assay for Diagnosis of Experimental Cowdria ruminantium Infection in Small Ruminants

The major antigenic protein 1 fragment B (MAP1-B) enzyme-linked immunosorbent assay (ELISA) for the diagnosis of Cowdria ruminantium infections was validated to determine cutoff values and evaluate its diagnostic performance with sheep and goat sera. Cowdria-infected populations consisted of 48 sheep and 44 goats, while the noninfected populations consisted of 64 sheep and 107 goats. Cutoff values were determined by two-graph receiver-operating characteristic (TG-ROC) curves. The cutoff value was set at 31 and 26.6% of the positive control reference samples for sheep and goat sera, respectively. The test’s diagnostic performance was evaluated with measurements of the area under the concentration-time curve (AUC) of the ROC curves and by the valid range proportion (VRP). The AUCs were 0.978 for sheep sera and 0.989 for goat sera. The VRP for both sheep and goat sera was approximately 1.0. The intermediate range (IR), which defines results that are neither positive nor negative, was 0 for goat sera and 2.81 for sheep sera. In an ideal test, the AUC and VRP would be 1.0 and the IR would be 0. In this study these parameters were close to those of an ideal test. It is concluded that the MAP1-B ELISA is a useful test for the diagnosis of C. ruminantium infection in small ruminants.     

Application of the fluorescence polarization assay for detection of caprine antibodies to Brucella melitensis in areas of high prevalence and widespread vaccination

The screening Rose Bengal test (RBT), the buffered plate agglutination test (BPAT), and the confirmatory complement fixation test (CFT) are currently approved by the World Organization for Animal Health (OIE) for diagnosis of goat brucellosis. However, RBT (at 3% or 8% cell concentration) is known to be affected by vaccinal antibodies. In the present study, Mexican and Canadian OIE tests were compared with the fluorescence polarization assay (FPA), alone or in combination, using indirect and competitive enzyme-linked immunosorbent assays as classification variables for goat sera obtained from an area of high prevalence and widespread vaccination. The relative sensitivities and specificities were, respectively, 99.7% and 32.5% for RBT3, 92.8% and 68.8% for RBT8, 98.4% and 84.8% for Canadian CFT, 83.7% and 65.5% for Mexican CFT, and 78.1% and 89.3% for FPA. The use of FPA as the confirmatory test in combination with other tests significantly increased the final specificities of the screening tests alone; BPAT, RBT3, and RBT8 plus FPA resulted in final specificities of 90%, 91.2%, and 91.3%, respectively, whereas for the combinations RBT3 plus Mexican CFT, RBT8 plus Mexican CFT, and BPAT plus Canadian CFT, specificities were 65.5%, 63.2%, and 91.7%, respectively. We suggest that FPA may be routinely applied as an adaptable screening test for diagnosis of goat brucellosis and as a confirmatory test for screening test series. Some advantages of FPA are that its cutoff can be adjusted to improve its sensitivity or specificity, it is a low-cost and easy-to-perform test of choice when specificity is relevant or when an alternative confirmatory test is not available, and it is not affected by vaccination, thus reducing the number of misdiagnosed and killed goats.     

A rapid, automated colorimetric assay for measuring antibody binding to cell surface antigens

An automated, colorimetric procedure is described for detecting antibodies specific for cell surface antigens. The procedure entails (a) coating the wells of 96-well microplates with either protein A or anti-immunoglobulin antibodies and (b) preincubating either the microplate or target cells with the test antibody. Target cells which react with the test antibody bind to the wells of the microplate and bound cells are quantitated by staining with the dye Rose Bengal. A microplate spectrophotometer is used to measure absorbance in each well of the plate, providing a rapid, automated measure of antibody titre. The assay is simple to perform, uses readily available reagents and gives comparable sensitivity to rosetting assays. With these features, and the capacity for handling large numbers of trays quickly, this method has obvious advantages in screening for antibody activity in culture supernatants of hybridoma clones.     

An inhibition enzyme-linked immunosorbent assay for the detection of antibody to Rift Valley fever virus in humans, domestic and wild ruminants

This paper describes the development and validation of an inhibition ELISA based on gamma-irradiated tissue culture-derived antigen for the detection of antibody to Rift Valley fever virus (RVFV) in humans, domestic and wild ruminants. Validation data sets derived from field-collected sera in Africa (humans=1367, cattle=649, goats=806, sheep=493, buffalo=258, camels=156) were categorized according to the results of a virus neutralisation test. In addition, individual sera from 93 laboratory workers immunized with inactivated RVF vaccine, 136 serial bleeds from eight sheep experimentally infected with wild-type of RVFV, and 200 serial bleeds from 10 sheep vaccinated with the live-attenuated strain of the virus, were used to study the kinetics of RVFV antibody production under controlled conditions. At cut-off values selected at 95% accuracy level by the two-graph receiver operating characteristic analysis the ELISA sensitivity ranged from 99.47% (humans) to 100% (sheep, buffalo, camels). The specificity ranged from 99.29% (sheep) to 100% (camels). Compared to virus neutralisation and haemagglutination-inhibition tests, the ELISA was more sensitive in detection of the earliest immunological responses in experimentally infected and vaccinated sheep. Our results demonstrate that the ELISA format reported here can be used as a safe, robust and highly accurate diagnostic tool in disease-surveillance and control programmes, import/export veterinary certification, and for monitoring of the immune response in vaccinees.     

Use of a specific immunogenic region on the Cowdria ruminantium MAP1 protein in a serological assay.

Currently available serological tests for cowdriosis (Cowdria ruminantium infection) in domestic ruminants are hampered by their low specificities because of cross-reactivity with Ehrlichia spp. The use of recombinant major antigenic protein (MAP1) of C. ruminantium for serodiagnosis was investigated. Overlapping fragments of the MAP1 protein were expressed in Escherichia coli and were reacted with sera from sheep infected with either C. ruminantium or Ehrlichia ovina. Two immunogenic regions on the MAP1 protein, designated MAP1-A and MAP1-B, were identified. MAP1-A was reactive with C. ruminantium antisera, E. ovina antisera, and three MAP1-specific monoclonal antibodies, whereas MAP1-B reacted only with C. ruminantium antisera. An indirect enzyme-linked immunosorbent assay (ELISA) based on MAP1-B was further developed and validated with sera from animals experimentally infected with C. ruminantium or several Ehrlichia spp. Antibodies raised in sheep, cattle, and goats against nine isolates of C. ruminantium reacted with MAP1-B. Cross-reactivity with MAP1-B was limited to Ehrlichia canis and Ehrlichia chaffeensis, two rickettsias which do not infect ruminants. Antibodies to Ehrlichia spp. which do infect ruminants (E. bovis, E. ovina, and E. phagocytophila) did not react with MAP1-B. Antibody titers to C. ruminantium in sera from experimentally infected cattle, goats, and sheep were detectable for 50 to 200 days postinfection. Further validation of the recombinant MAP1-B-based ELISA was done with sera obtained from sheep raised in heartwater-free areas in Zimbabwe and from several Caribbean islands. A total of 159 of 169 samples which were considered to be false positive by immunoblotting or indirect ELISA did not react with MAP1-B.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of the Brucella melitensis native hapten to diagnose brucellosis in goats by a rapid, simple, and specific fluorescence polarization assay

The performance of the fluorescence polarization assay (FPA) using the recently described Brucella melitensis native hapten and the Brucella abortus O-polysaccharide tracer was evaluated and compared with those of The World Organization for Animal Health tests related to indirect and competitive enzyme-linked immunosorbent assays as classification variables for goat sera obtained from a high-prevalence area where vaccination was performed; test series were also evaluated to increase the final specificity of the tests. Our results showed that the respective relative sensitivity and specificity were 99.7% and 32.5% for the rose Bengal test with a 3% cell concentration (RBT3), 92.8% and 68.8% for the rose Bengal test with 8% cell concentration (RBT8), 98.4% and 84.9% for the Canadian complement fixation test (CFT), 83.7% and 65.5% for the Mexican CFT, 98.4% and 81.0% for the buffered plate agglutination test (BPAT), and 78.1% and 89.3% for the fluorescence polarization assay (FPA). The use of the FPA as the secondary test significantly increased the final specificities of test combinations; the screening tests BPAT, RBT3, and RBT8 plus FPA resulted in 90%, 91.2%, and 91.3% final specificities, respectively, whereas for the combinations RBT3 plus Mexican CFT, RBT8 plus Mexican CFT, and BPAT plus Canadian CFT, the specificities were 65.5%, 63.2%, and 91.7%, respectively. The results suggested that the FPA may be routinely applied as an adaptable screening test for diagnosis of goat brucellosis, since its cutoff can be adjusted to improve its sensitivity or specificity, it is a rapid and simple test, it can be the test of choice when specificity is relevant or when an alternative confirmatory test is not available, and it is not affected by vaccination, thus reducing the number of goats wrongly slaughtered due to misdiagnosis.     

Evaluation and comparison of fluorescence polarization assay with three of the currently used serological tests in diagnosis of human brucellosis

Fluorescence polarization assay (FPA) is a method that has been used for the diagnosis of brucellosis in animals for many years. To test its possible usefulness for the diagnosis of human brucellosis, 230 sera from patients with clinical signs of brucellosis and positive serological tests (Rose Bengal, Standard Agglutination Test, iELISA), and 305 sera from a healthy population with no clinical/epidemiological/serological evidence were examined with FPA. By using ROC analysis, the cut-off value was estimated at 99 mP, with 93.5% sensitivity (95% CI 89.5–96.3) and 96.1% specificity (95% CI 93.2–97.9). The pairwise comparison of ROC curves between FPA and iELISA and between FPA and RBT revealed no significant statistic difference (P < 0.05). On the contrary it revealed a significant statistic difference between FPA and SAT (P > 0.05). SAT also had the lowest sensitivity (81.7%) among the three tests used in case definition while iELISA had a sensitivity of 90.8% and RBT a sensitivity of 88.7%. The Kappa analysis showed that FPA has a very good agreement (0.92) with the “status of the disease” and with iELISA (0.837). According to our results, FPA seems to be a valuable method for the diagnosis of brucellosis in humans. Taking into consideration the advantages of the method such as the speed of results obtaining, the objectivity of results interpretation, as well as the cost, FPA could be considered as a replacement for other established methods. However, further studies are needed to assess the reproducibility of FPA.     

Evaluation of seven tests for diagnosis of human brucellosis in an area where the disease is endemic

The results of seven serologic tests for diagnosis of human brucellosis were evaluated. The titrated Rose Bengal test, microagglutination test, microtiter-adapted Coombs test, and immunocapture-agglutination test (Brucellacapt) were positive for all sera from patients with acute brucellosis. The immunoglobulin G (IgG), IgM, and IgA commercial enzyme immunoassays (ELISAs) failed to show specific antibodies in 3 patients, 10 patients, and 1 patient, respectively. The sensitivity of ELISA is not higher than that of conventional tests.     

Detection of immunoglobulin G to Crimean-Congo hemorrhagic fever virus in sheep sera by recombinant nucleoprotein-based enzyme-linked immunosorbent and immunofluorescence assays

Crimean-Congo hemorrhagic fever virus is a tick-borne virus that causes severe hemorrhagic symptoms with an up to 50% mortality rate in humans. Wild and domestic animals, such as sheep, cattle and goats, are the reservoirs. The recombinant nucleoprotein-based Crimean-Congo hemorrhagic fever virus antibody detection systems for sheep sera were developed by enzyme-linked immunosorbent assay (ELISA) and an indirect immunofluorescence assay techniques. The samples used for evaluation were 80 sera collected from sheep in a Crimean-Congo hemorrhagic fever-endemic area (western part of the Xinjiang Uygur Autonomous Region) and 39 sera collected from sheep in a disease-free region (Shandong province, eastern China). The ELISA and indirect immunofluorescence assay using recombinant nucleoprotein of the virus proved to have high sensitivity and specificity for detecting the immunoglobulin G antibodies to the virus in sheep sera. Within this limited number of samples, the recombinant nucleoprotein-based ELISA and indirect immunofluorescence assay are considered to be useful tools for seroepidemiological study of virus infections in sheep sera.     

Detection of antibodies specific for sheeppox and goatpox viruses using recombinant capripoxvirus antigens in an indirect enzyme-linked immunosorbent assay

Viruses in the genus Capripoxvirus, family Poxviridae, cause sheeppox, goatpox and lumpy skin disease, which are the most serious poxvirus diseases of production animals. Despite the considerable threat that these viruses pose to livestock production and global trade in sheep, goats, cattle and their products, convenient and effective serodiagnostic tools are not readily available. To develop a more effective antibody detection capability, selected open reading frames from capripoxvirus DNA were amplified and expressed in Escherichia coli as His-tagged fusion proteins. By screening 42 candidate antigens, two sheeppox virus virion core proteins that were expressed efficiently, purified readily using affinity chromatography and reactive against capripoxvirus immune sera in an indirect enzyme-linked immunosorbent assay (ELISA) were identified. The ELISA performed favourably when sera from sheep and goats infected experimentally with virulent capripoxvirus isolates were tested, with sensitivity and diagnostic specificity ranging between 95 and 97%, but it was unable to detect antibodies reliably in vaccinated sheep or goats. Furthermore, no cross-reactivity with antibodies against orf virus was detected. This assay offers the prospect of a convenient and standardised ELISA-based serodiagnostic test, with no requirement for infectious reagents, that is well suited to high-throughput capripoxvirus surveillance on a flock or herd basis.     

Comparative evaluation of microagglutination test and serum agglutination test as supplementary diagnostic methods for brucellosis.

The diagnosis of brucellosis in cattle and small ruminants requires the use of more than one serological test. The complement fixation test (CFT), the rose bengal test (RBT), and the serum agglutination test (SAT) are among the most useful tests for routine diagnosis. The microagglutination test (MAT) was developed as a simpler and more efficient test than the SAT. The relative efficacy of this test compared with that of the SAT was evaluated by using brucella-free sheep and goats prior to and after vaccination treatment. The specificities of the MAT and the SAT were 100%. Of the ewes and goats with a vaccination history, one ewe, expectedly a negative responder, had reactions in the MAT, the complement fixation test, and the rose bengal test but not in the SAT, suggesting a lower sensitivity of the SAT in this case. The calculated sensitivities of the MAT and the SAT were 93.9%. The agreement between MAT and SAT results from nonresponders was examined by using sera from unvaccinated lambs and kids (95.2% agreement), unvaccinated ewes and goats (84.4%), and ewes and goats with a vaccination history (43.9%). For the latter group higher levels of agglutination units were observed by the MAT than by the SAT in 51.5% of the samples. In testing sera from positive reactors after vaccination neither method was superior (MAT values were greater than SAT values for 23.5% of the samples, and MAT values were less than SAT values for 21.9% of the samples).(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of primary binding assays for presumptive serodiagnosis of swine brucellosis in Argentina

An indirect enzyme-linked immunosorbent assay (IELISA), a competitive ELISA (CELISA), and a fluorescence polarization assay (FPA) for the presumptive serological diagnosis of swine brucellosis were evaluated using two populations of swine sera: sera from brucellosis-free Canadian herds and sera from Argentina selected based on positive reactions in the buffered antigen plate agglutination test (BPAT) and the 2-mercaptoethanol (2-ME) test. In addition, sera from adult swine from which Brucella suis was isolated at least once for each farm of origin were evaluated. The IELISA, CELISA, and FPA specificity values were 99.9, 99.5, and 98. 3%, respectively, and the IELISA, CELISA, and FPA sensitivity values relative to the BPAT and the 2-ME test were 98.9, 96.6, and 93.8%, respectively. Actual sensitivity was assessed by using 37 sera from individual pigs from which B. suis was cultured, and the values obtained were as follows: BPAT, 86.5%; 2-ME test, 81.1%; IELISA, 86.5%; CELISA, 78.5%; and FPA, 80.0%.     

Rough lipopolysaccharide of Brucella abortus RB51 as a common antigen for serological detection of B. ovis, B. canis, and B. abortus RB51 exposure using indirect enzyme immunoassay and fluorescence polarization assay

Rough lipopolysaccharide (RLPS) antigens were prepared from cultures of Brucella abortus RB51, B. ovis, and B. canis. The preparations were standardized by weight and tested with sera from cattle immunized with B. abortus RB51, sheep infected with B. ovis, and dogs infected with B. canis. Populations of unexposed animals of each species were also tested. The tests used were the indirect enzyme immunoassay (IELISA) using RLPS and the fluorescence polarization assay (FPA) using RLPS core fractions, labeled with fluorescein isothiocyanate. The IELISA using B. abortus RB51 RLPS antigen resulted in sensitivity and specificity values of 94.8% and 97.3%, respectively, when testing bovine sera, 98.5% and 97.8% when testing ovine sera, and 95.8% and 100% when testing dog sera. The IELISA using B. ovis RLPS antigen gave sensitivity and specificity values of 80.5% and 91.7%, respectively with bovine sera, 98.9% and 93.8% with sheep sera, and 70.8% and 79.8% with dog sera. The IELISA using B. canis RLPS antigen resulted in sensitivity and specificity values of 97.0% and 97.4%, respectively, with bovine sera, 96.2% and 96.3% with sheep sera, and 95.8% and 98.8% with dog sera. Labeling RLPS core from B. ovis and B. canis with fluorescein was not successful. B. abortus RB51 core labeled with fluorescein resulted in sensitivity and specificity values of 93.5% and 99.8%, respectively, with bovine sera and 78.1% and 99.0% with sheep sera. It was not possible to test the dog sera in the FPA.     

Rapid screening of monoclonal antibodies by spin adherence double immunosorbent test (SADIST)

The spin adherence double immunosorbent test (SADIST) is a simple, rapid immunoassay with sensitivity similar to the enzyme-linked immunosorbent assay (ELISA). A 1-step SADIST has been found suitable for rapid screening of hybridomas for antigen-specific monoclonal antibodies (MAb). In this procedure hybridoma supernatants are added to antigen coated microplates followed by commercially available antiglobulin beads. The microplate is immediately centrifuged. Wells containing antigen-specific MAb produce a mat of beads whilst wells without antigen-specific MAb produce a button of beads. No washing or incubation steps are necessary and results are read within minutes of adding beads to test supernatants. By comparison, ELISA tests require several hours to perform with multiple wash steps and further reagent additions. A 2-step SADIST was also assessed. Supernatants are incubated in the microplate as for an ELISA and a wash step precedes the addition of antiglobulin beads. A panel of 117 hybridoma supernatants was selected to assess the suitability of the SADIST techniques for hybridoma screening. The supernatants were added to antigen-coated microplates and SADIST and ELISA tests performed. The SADIST correctly discriminated most hybridoma supernatants that were clearly positive or negative by ELISA. It was also found possible to perform SADIST followed by ELISA tests on the same microplate well without significantly affecting ELISA values.     

ELISA versus routine tests in the diagnosis of patients with systemic and neurobrucellosis

Sera from patients in different stages of brucellosis as well as sera and cerebrospinal fluid (CSF) from patients with central nervous system (CNS) brucellosis and controls, were tested by ELISA for Brucella-specific IgG, IgM and IgA. The results were compared with culture findings, micro-agglutination (MA), slide agglutination with Rose Bengal (RB), and Brucella melitensis stained antigens (SA). In sera of patients with acute brucellosis (296), ELISA was positive for IgM (100%), IgG (97%) and IgA (98%), and comparable results were found in sera of patients with subacute brucellosis (44): IgG (100%), IgM (86%) and IgA (100%). However, in patients with chronic brucellosis (40), IgG and IgA were consistently positive (100%) while IgM was only positive in 33% of their sera. The MA and RB showed similar results, being more positive in patients with acute (98%) and subacute (84%) than in chronic (61%) brucellosis. The SA and culture showed significantly lower positive results. In the CSF of patients with CNS brucellosis (45), ELISA was positive in 100%, 20% and 85% for IgG, IgM and IgA, respectively, compared to 13% positive by culture, 25% by MA and 22% by RB. ELISA was negative in the CSF specimens from patients with brucellosis without CNS involvement (66), or meningitis other than Brucella (62), and no meningitis (144). Thus, ELISA with its IgG, IgM and IgA profiles is the test of choice in the diagnosis of patients with brucellosis, especially those with chronic or CNS infection.     

An ELISA detecting antibody to conserved pestivirus epitopes.

A monoclonal antibody based competition-ELISA is described for the detection of pestivirus antibodies directed against conserved epitopes on the p80 viral protein. The ELISA detected increases in serum antibody following experimentally induced infections of pigs, cattle and sheep with a wide range of pestiviruses, although the sensitivity of the test was not uniform for the different viruses studied. The ELISA was compared with virus neutralization tests for the assessment of porcine, bovine and ovine field sera. At a cut-off value of 50% inhibition, the ELISA showed a high specificity relative to virus neutralization tests, but appeared less sensitive for the detection of some weakly positive samples from pigs. Sera from both ruminants and pigs could be assessed without any modification of the test.     

Point seroprevalence survey of Ehrlichia ruminantium infection in small ruminants in The Gambia

Using the MAP1-B enzyme-linked immunosorbent assay, we tested 1,318 serum samples collected from sheep and goats at 28 sites in the five divisions of The Gambia to determine the Ehrlichia ruminantium seroprevalence rates and to assess the risk for heartwater. About half (51.6%) of 639 sheep were positive, with seroprevalence rates per site varying between 6.9% and 100%. The highest seroprevalence was detected in the western part of the country (88.1% in the Western Division and 62.1% in the Lower River Division). Sheep in the two easterly divisions (Central River and Upper River divisions) showed the lowest seroprevalence of 29.3% and 32.4%, respectively, while those in the North Bank Division showed an intermediate prevalence of 40.6%. In goats, less than one-third (30.3%) of 679 animals tested were positive. The highest seroprevalence was detected in goats in the North Bank Division (59%) and Western Division (44.1%). Goats in the Lower River Division showed an intermediate level of 21.9%, whereas the lowest rates were found in the eastern part of the country (4.8% in the Central River Division and 2.3% in the Upper River Division). At nearly all sites, seroprevalence rates were higher in sheep than in goats. The results show a gradient of increasing heartwater risk for susceptible small ruminants from the east to the west of The Gambia. These findings need to be taken into consideration when future livestock-upgrading programs are implemented.     

Bovine respiratory syncytial virus antibodies in non-bovine species

Summary To study the role of non-bovine species in the epidemiology of bovine respiratory syncytial virus (RSV) infections, sera obtained from 9 non-bovine animal species and from humans were examined for bovine RSV specific antibodies. Sera were mainly from animals and humans which had been in contact with cattle. Forty sera of each species were tested in an RSV specific whole virus ELISA as well as in a peptide based ELISA, that was developed to measure antibodies specific for bovine RSV. Antibodies directed against RSV were detected in over 50% of sera obtained from sheep, goat, cattle and human beings, and anti-RSV activity was also found in some roe and dogs and one horse. Antibodies to bovine RSV were found in sera of all tested cattle, 11 (27.5%) goats and in some other individual animals: 3 horses, 2 roe, 1 cat and 1 dog. These results indicate that of the investigated species, besides cattle only goats might play a role in the epidemiology of bovine RSV.