Seropositive Goats Research Articles

Isolation of caprine herpesvirus type 1 in Spain

Two strains of caprine herpesvirus type 1 (CpHV-1) were isolated after the experimental reactivation of two seropositive goats in Spain. Viral DNA from these isolates was compared with DNA from...

Serological survey of caprine arthritis-encephalitis virus in 83 goat herds of Yucatan, Mexico

A survey was conducted between June and September 2000 in order to detect antibodies against caprine arthritis-encephalitis virus (CAEV) in 83 goat herds in the state of Yucatan, Mexico. A total of 1078 goats older than 4 months of age (mostly of Criollo breed) were sampled in the survey. An agarose gel immunodiffusion (AGID) test showed that three herds (3.6%) were seropositive to CAEV. In those herds a total of four animals sampled were seropositive (0.4%). All of the seropositive goats were imported to the Yucatan either from the neighboring Mexican state of Campeche or the United States of America (USA). These results highlight the need for implementation of control policies in Yucatan and careful monitoring of this goat population in order to ensure a continued low seroprevalence of CAEV. Policies of “rural development” and “genetic improvement” through animal imports, either governmental or private, must take into account the possibility of causing an increase in seroprevalence of CAEV in Yucatan.

Relationships between infection with caprine arthritis encephalitis virus, intramammary bacterial infection and somatic cell counts in dairy goats

Somatic cell counts, the bacteriological condition of the milk and antibodies against caprine arthritis encephalitis virus (cAEv) were measured monthly throughout lactation in 121 lactating goats of the Murcia- Granada...

Risk factors for brucellosis seropositivity of goat herds in the Mexicali Valley of Baja California, Mexico

A case-control study was conducted in the Mexicali Valley to identify risk factors for goat-herd seropositivity for Brucella melitensis. Nineteen case herds (≥2 positive results with the 8% rose bengal plate test (RBT)) and 55 control herds (zero positive results in RBT), matched for herdsize and geographic location, were enrolled. Conditional logistic regression was used to construct a multivariable model of the odds of seropositivity using variables assessed in a questionnaire administered to goat ranchers. The final model for herd seropositivity included increased risk from importation of goats from other Mexican states, the presence of La Mancha breed does, and the presence of does born outside the herd. Increasing herdsize was also highly significant ( p<0.01). In addition, a significant ( p<0.05) positive association was found between the presence of seropositive dogs (as assessed by RBT) and seropositive goats on the same ranch.

Prevalence of antibodies against caprine arthritis–encephalitis virus in goat herds in Norway

Sera from 1326 goats in 51 herds distributed in 11 counties in Norway were examined for antibodies against caprine arthritis–encephalitis virus (CAEV) by an ELISA based on recombinant viral core proteins. Altogether 484 animals (weighted prevalence: 42%) in 44 (86%) herds tested positive, indicating that the CAEV-infected herds are evenly spread throughout the country. The prevalence of positive animals within herds ranged from 0 to 100%, the prevalence rate of seropositive goats increasing with age and northerly location of herd in the country. Seven herds in which no test-positive animal was detected in the first screening, were retested about a year later. On testing all 551 goats above six months of age, at least two animals were found positive in six of the herds. However, when nine of these 27 ELISA-positive sera were examined by Western blotting, only one was found to be positive, indicating that the ELISA employed may give false positive results.

Caprine arthritis-encephalitis in an indigenous Spanish breed of dairy goat

The presence of caprine arthritis and encephalitis (CAE) in Spain has never been officially acknowledged but it is suspected. Goats have been imported from other European countries with a high...

Effects of Infection by Caprine Arthritis-Encephalitis Virus on Milk Production of Goats

The effects of caprine arthritis-encephalitis virus on lactational performance of goats were examined. The results of an ELISA for antibodies against caprine arthritis-encephalitis virus were compared with milk production records. Mean production of milk, protein, fat, and lactose and somatic cell counts were compared for seropositive and seronegative goats of similar ages. The results from 1799 lactating goats from 66 herds suggested that milk production was similar for 1-yr-old goats that tested seropositive and those that tested seronegative. For 900 of those goats for which data permitted comparison, milk fat and protein were also similar. A comparison of 331 goats showed that lactose contents did not differ between 1- and 2-yr-old goats, but somatic cell counts were higher in 2-yr-old seropositive goats.

Immunohistochemical identification of caprine arthritis-encephalitis virus in paraffin-embedded specimens from naturally infected goats.

The expression of caprine arthritis-encephalitis virus capsid protein was studied in seropositive naturally infected asymptomatic goals (10< seropositive naturally infected encephalitic kids (12) and goats (4), and noninfected control goats (3). Rabbit antiserum to recombinant viral capsid and matrix proteins were used in a biotin-streptavidin-alkaline phosphatase complex immunohistochemical method on sections of formalin- and ethanol-fixed tissue specimens. Macrophages in inflamed areas of the lung (8/12), in the brain (5/16), and in the spinal cord (4/16) from encephalitic animals harbored viral antigens, as revealed by immunohistochemistry and use of a capsid protein-specific antiserum. Altogether 12/16 encephalitic animals tested positive for viral antigen. Viral antigens were found in 5/10 seropositive asymptomatic goals in macrophages located in the lung (3), the udder (1), and the medulla of lymph nodes (4). None of the control animals tested positive for viral antigen. Ethanol fixation showed highest sensitivity, and the lowest antigen concentration that revealed a positive signal discernible from background was twofold higher in ethanol-fixed specimens than in formalin-fixed specimens. The evaluation was performed on artificial antigen substrates embedded with defined concentrations of recombinant viral capsid protein. Immunohistochemistry is a valuable supplement to the methods presently available for diagnosis in cases suspicious of caprine arthritis-encephalitis.

Risk Factors for Transmission and Methods for Control of Caprine Arthritis-Encephalitis Virus Infection

The major route of transmission of caprine-encephalitis virus (CAEV) is through the ingestion of CAEV-infected colostrum or milk. Less efficient routes of transmission are associated with prolonged contact with infected goats and are reviewed in this article. Prevention of CAEV is based on the removal of kids from their dam at birth, and feeding the kids heat-treated colostrum and pasteurized milk until weaning. Serologic testing and segregation or culling of seropositive goats is necessary to minimize horizontal transmission of CAEV.

A Long Term Study of Goats Naturally Infected with Caprine Arthritis-Encephalitis Virus

The caprine arthritis-encephalitis virus (CAEV) is a big problem in dairy goat industry. Little is known about its characteristics in naturally infected goat herds. The aims of this study were: 1) to study how antibody expression, measured by agar gel immunodiffusion test (AGIDT), varied over time in naturally infected, seropositive goats, 2) to observe clinical signs in seropositive adult goats and 3) to follow seroconversion and gamma globulin concentration in goat kids artificially reared on cow milk replacement product only, compared to kids reared on untreated goat milk. The antibody expression pattern to the viral proteins gp135 and p28 varied in the individual goat and intermittent negative reactions were seen in 19 adult animals followed for 30-91 weeks. Four seropositive goats developed clinical symptoms with difficulties to move. However, no correlation between clinical signs and antibody expression pattern was seen. During the first 27 weeks of age no kid in the milk replacement reared group (N = 4) seroconverted, but 5 of the 7 kids fed goat milk occasionally showed a positive antibody reaction. The gamma globulin concentration was significantly higher in the goat milk fed group until the kids had become more than 19 weeks old. The results show that a great variation of the antibody pattern in individual goats occurs, and therefore the AGIDT is only reliable as a herd screening test. Frequent sampling is necessary to get reliable information about spreading of the CAEV in a naturally infected goat herd. Removing kids from their dams immediately after birth combined with segregation and artificial rearing protected them from CAEV infection. However their gamma globulin concentration was initially low.

Detection of caprine arthritis-encephalitis virus by polymerase chain reaction.

Detection of caprine arthritis-encephalitis virus (CAEV) infection in goats is currently limited to serologic testing or cell culture. We developed a polymerase chain reaction (PCR) assay to detect CAEV sequences in peripheral blood mononuclear cells (PBMC), synovial fluid cells (SFC), and milk cells (MC) obtained from infected goats. Results were positive for 18 of 20 PBMC, 8 of 8 MC, and 5 of 5 SFC samples from seropositive goats, whereas 3 of 33 PBMC samples and none of 8 MC or 5 SFC samples from seronegative goats were positive. Two of the PCR-positive and seronegative goats seroconverted upon follow-up testing 2 months later. This PCR assay provides a useful method for detecting CAEV infection in goats.

Delayed seroconversion following naturally acquired caprine arthritis-encephalitis virus infection in goats

Summary One hundred eight milking goats from a dairy that had been using a modified caprine arthritis-encephalitis virus (caev) eradication program were tested for caev antibodies by serologic methods and for proviral caev dna by use of polymerase chain reaction (pcr) technology. All goats were free of clinical symptoms of caev infection. Twenty-seven of the 108 goats were considered seropositive, on the basis of elisa results. Proviral caev dna was detected, using pcr techniques, in mononuclear leukocytes in blood samples obtained from 25 of the these 27 seropositive goats. Twenty of the 81 seronegative goats also had positive pcr test results. Ten of these goats seroconverted by 8 months later, and virus was readily isolated from mononuclear leukocytes in venous blood samples after the goats had seroconverted. Virus was also isolated from mononuclear leukocytes in blood samples collected from 4 of 11 goats that were seronegative, but had positive pcr test results. These results indicated that seroconversion can be delayed for many months following natural infection with caev. Delayed seroconversion appears to be a feature of caev infection, which may have direct implications for caev eradication programs and epidemiologic studies that rely on serologic methods to detect infected goats.

Seroprevalence of Toxoplasma gondii infection in cattle, swine and goats in four Mexican states

A serological survey for antibody activity against Toxoplasma gondii in cattle, swine and goats was carried out in four Mexican states. A total of 1203 pig sera from Cuernavaca, Morelos abattoir, 490 cattle sera on 12 ranches from four municipalities and 707 goat sera from nine farms were tested by the enzyme-linked immunosorbent assay (ELISA) test. Sera from 107 of the 1207 pigs (8.9%) were positive, and there was no significant difference ( P>0.05) due to the state of origin of the positive sera. Five of the nine goat farms had T. gondii seropositive goats and the average seroprevalence was 3.2%. Antibody activity to T. gondii was found in 47 of 397 cattle (11.9%) tested. Food animals in Morelos, faced two problems, the reproductive losses from toxoplasmosis and the public health implications associated with infected meat and milk.

A cluster of Coxiella burnetii infections associated with exposure to vaccinated goats and their unpasteurized dairy products.

An outbreak of Q fever occurred among patients and staff of a psychiatric institution in southern France. Some of the patients and staff left the institution daily to work on a farm where goats were raised for raw milk and cheese production. The goats had all been vaccinated annually with a commercial vaccine containing phase II Coxiella burnetii antigen. A serologic survey revealed that 40 (66%) of the 61 patients and staff had elevated titers to C. burnetii. Seropositive persons were more likely to report an acute illness (P = 0.001), fever (P = 0.04), weakness (P = 0.04), arthralgia (P = 0.04), and headaches (P = 0.06) in the preceding year than were seronegative persons. Seropositivity rates were significantly higher among persons who worked on the farm and consumed unpasteurized milk products (69% [22 of 32]; P = 0.007), those who only had worked on the farm (75% [9 of 12]; P = 0.009), and those who only had consumed unpasteurized milk products (75% [9 of 12]; P = 0.009), compared with those who had not worked with the goats or consumed unpasteurized milk products (0 of 5). Despite vaccination against Q fever, no antibodies to C. burnetii were detectable in 17 (59%) of 29 goats. All 12 seropositive goats had antibodies to both phase I and phase II antigens, indicating that they were naturally infected, and two of three goats examined were shedding C. burnetii in their milk. Vaccination of this herd did not prevent the outbreak and might have increased shedding of C. burnetii in the dairy products.

Neutralization-resistant antigenic variants of caprine arthritis-encephalitis lentivirus associated with progressive arthritis.

Fifteen newborn Saanen goats were orally infected with a biologically cloned isolate of caprine arthritis-encephalitis virus (CAEV-63). At 33.5 months after infection, 8 of 12 seropositive goats had CAEV-63-specific neutralizing antibody. Five neutralization-positive goats developed clinically apparent arthritis of carpal joints, three of which had periarticular swelling indicating severe synovitis. Arthritis was not evident in age-matched controls or infected goats without neutralizing antibody. Multiple viral isolates were obtained from synovial fluid or synovial fluid cells of arthritic joints between 36.4 and 44.9 months after infection, and successive isolates from individual joints were defined as antigenic variants expressing type-specific neutralization epitopes. Thus, the evolution of neutralizing antibody does not arrest viral replication or development of progressive inflammatory lesions. Rather, some antigenic variants produced in the presence of neutralizing antibody are clonally expanded within carpal joints, and severe joint inflammation is specifically associated with these variants.

Enzyme-linked immunosorbent assay for detection of antibodies against Mycobacterium paratuberculosis in goats

SUMMARY Using a heat and sonicated Mycobacterium paratuberculosis Cordoba antigen (coa1) and the commercial protoplasmic-antigen (ppa-3) as antigens, an elisa for detecting goat antibodies was standardized. When 2 reference populations, 1 positive (17 goats) and the other negative (63 goats) to disease, were used, this test showed 87.5% sensitivity and 93.6% specificity for coa1, and 88.2 and 95.2%, respectively for ppa-3. Absorption with M phlei was performed; no significant differences were found for coa1 but a lower sensitivity was found with ppa-3. This test was not especially affected by cross-reactivity with other mycobacterial disease because when 9 goats with M bovis infection were included in the M paratuberculosis control group, the specificity was only slightly different for absorbed (94.4%) and nonabsorbed sera (91.7%) for coa1 and (93.1 and 94.4%, respectively) for ppa-3. This test was used to study the percentage of seropositive goats for M paratuberculosis in 3 herds with different prevalences. Among 251 goats in southern Spain (Huelva), 40% were found positive for coa1 and 41% for ppa-3. Among 242 goats studied in southern Spain (Córdoba), 10.0% were positive for coa1 and 13.0% for ppa-3. In the Canary Island population of 176 goats, 3% were positive for coa1 and 0.5% for ppa-3. According to the accuracies of both positive and negative predictions, our test could be applied to populations with high prevalence to prevent additions to the herd and to cull infected animals (with 40% prevalence, the positive and negative predictive values are 90%), and to prevent adding infected animals to populations with moderate or low prevalence.

A serological survey of rinderpest antibody in wildlife and sheep and goats in Northern Tanzania

An extensive serological survey for rinderpest antibody in wildlife, principally buffalo (Syncerus caffer), and sheep and goats has been undertaken in the previously endemic region of Northern Tanzania to determine whether or not the virus has continued to cycle in susceptible species since the last occurrence of overt disease in 1982. The results show that infection but not disease has occurred at least until 1987 in buffalo in parts of the Serengeti National Park but not in the other game areas of Tanzania where samples were taken. Sero-positive sheep and goats were widely distributed and have been found in 10 of the 14 districts sampled but there have been no reports of disease. These findings bring into question the possibility of eradicating the disease from Africa and continuous annual monitoring of this and other similar ecological zones will be required.

Epidemiology of Potomac horse fever: an investigation into the possible role of non-equine mammals.

A serological study of antibodies to Ehrlichia risticii was carried out on 10 species of wild and domestic mammals found on or near 21 horse farms in an area of the USA in which Potomac horse fever is endemic. No antibodies were found in 133 peridomestic rodents (Norway rats and house mice), nor in 108 wild rodents (white-footed mice and meadow voles) captured on farms. Three of the six domestic animal species examined, cats, pigs and a goat, showed serological evidence of exposure to E risticii. Seropositive animals were detected on three of the 21 premises. The eight seropositive cats (of 48 cats tested) were on two farms, and the three seropositive pigs (of 14 tested) were all on one farm which lay some 3 km from where the one seropositive goat (of three tested) was found. None of the 79 dogs, 75 cattle and seven sheep tested had antibodies to E risticii. The significance of these findings is discussed in the light of current understanding of the transmission of Potomac horse fever and of the epidemiology of other related ehrlichial diseases.

Analysis of caprine IgG1 and IgG2 subclass responses to Chlamydia psittaci infection and vaccination

Enzyme-linked immunosorbent assays (ELISAs) specific for caprine IgG (H+L), IgG1 and IgG2 were developed and evaluated for serodiagnosis of Chlamydia psittaci infections in a Tunisian goat flock with currently occurring chlamydial abortions and a clinically inapparent goat flock of an animal research facility. Additionally, ELISAs were applied to record the IgG1 and IgG2 dynamics of four goats vaccinated with inactivated Chlamydia psittaci and Coxiella burnetii. For screening purposes, the IgG (H+L) ELISA proved to be superior to the complement fixation test because it detected a larger number of chlamydial abortions and was easier to perform and to interpret. Analysis of Chlamydia psittaci-specific IgG1 and IgG2 responses to naturally occurring infections by ELISA revealed high IgG1 levels associated with IgG2 in goats with current abortions, whereas clinically inapparent, but seropositive goats were characterized by significantly lower IgG1 levels only ( P<0.001). Similarly, the four vaccinated goats responded initially with Chlamydia psittaci-specific IgG1, whereas second and third vaccinations induced (as in goats with chlamydial abortions) predominantly IgG1, but also IgG2. The results indicated that clinically inapparent chlamydial infection may be distinguished from overt disease by analysing specific IgG1 and IgG2 responses. Applying Coxiella burnetii- specific ELISAs on field samples, IgG1 alone could be detected in eight, IgG2 alone in one and IgG1 combined with IgG2 in nine goats. The coxiella-specific antibody response of the four vaccinated goats was — in contrast to the chlamydia-specific response — characterized by IgG2 dominance.

Antibodies to Corynebacterium Pseudotuberculosis in Adult Goats from a Naturally Infected Herd

Serum samples taken in 3 successive years (1977, 1978 and 1979) from adult dairy goats (Norwegian breed) originating from 1 herd were examined for antibodies to Gorynebacterium pseudotuberculosis. Both bacterial agglutination test (BAT) and hemolysis inhibition test (HIT) were used. The proportion of seropositive goats increased 10–12 % during the investigation period. In 1979 all animals were seropositive to BAT and about 95 % had antihemolysins in their sera. Twenty-two of the 23 one-year old goats recruited to the herd in 1978 were seropositive. The average age-specific titres increased up to the age of 3 years, and subsequently decreased for goats aged 4–7 years. Caseous lymphadenitis is thus regarded as a chronic infection. The effect of age on the titre values was significant at the 5 % level in 1977 and 1978 when HIT was used and in 1978 when BAT was used. During the investigation period the same 36 and 40 goats were examined every year by BAT and HIT, respectively. Intermediate to high correlations between titre values for the same goats from year to year were found. Both BAT and HIT are suitable for sero-epidemiological investigations concerning infection with G. pseudotuberculosis in goats.