Pedro Cármenes

Role of enteric pathogens in the aetiology of neonatal diarrhoea in lambs and goat kids in Spain

Faeces samples from diarrhoeic and non-diarrhoeic lambs and goat kids aged 1-45 days were examined for enteric pathogens. Cryptosporidium parvum was detected in both diarrhoeic lambs (45%) and goat kids (42%) but not in non-diarrhoeic animals. F5+ (K99+) and/or F41+ Escherichia coli strains were isolated from 26% and 22% of the diarrhoeic lambs and goat kids, respectively, although these strains, which did not produce enterotoxins ST I or LT I, were found with similar frequencies in non-diarrhoeic animals. A F5-F41-ST I+ E. coli strain was isolated from a diarrhoeic lamb (0.6%). Verotoxigenic E. coli was isolated from both diarrhoeic and non-diarrhoeic lambs (4.1% and 8.2%, respectively) and there was no association between infection and diarrhoea. The prevalence of group A rotavirus infection in diarrhoeic lambs was very low (2.1%). Groups A and B rotaviruses were detected in three (8.1%) and five (13.5%) diarrhoeic goat kids from two single outbreaks. Group C rotaviruses were detected in four non-diarrhoeic goat kids. An association of diarrhoea and infection was demonstrated only for group B rotavirus. Clostridium perfringens was isolated from 10.8% of the diarrhoeic goat kids but not from non-diarrhoeic goat kids or lambs. Salmonella arizonae was isolated from a diarrhoeic goat kid (2.7%) and the clinical characteristics of the outbreaks where these two latter enteropathogens were found different from the rest. Picobirnaviruses were detected in a diarrhoeic lamb. No coronaviruses were detected using a bovine coronavirus ELISA. No evidence was found of synergistic effect between the agents studied. Enteric pathogens were not found in four (8.7%) and three (20%) outbreaks of diarrhoea in lambs and goat kids, respectively.

Evaluation of the California mastitis test as a discriminant method to detect subclinical mastitis in ewes

Abstract The reliability of the California mastitis test (CMT) has been compared in a field study with another indirect method, somatic cell count (SCO, and with direct bacteriological cultures. A total of 1366 half-udder samples from ewes in mid-lactation were tested, using animals of three different breeds. Admitting a threshold value of 300000 cells ml −1 to detect subclinical mastitis, prevalence of subclinical mastitis was 43%, and 39.2% had bacterial infection. Accuracy of CMT was higher when compared with SCC, with a correlation of 0.82, 87% of correctly classified samples, 4% false-positives and a predictive value of positive results of 89.6%. According to bacteriological analysis, correctly classified samples were 78.4%, 10% false-positives, and 75.5% the predictive value of positive results. Periodical sampling was carried out in an experimental flock throughout the milking period; the number of false-positives classified with CMT increased towards the end of lactation.

Seroprevalence of canine ehrlichiosis in Castilla-León (north-west Spain)

A study was undertaken of antibodies to Ehrlichia canis in dogs in the Comunidad Autonoma de Castilla-Leon (north-west Spain). A total of 308 serum samples, collected between January 1993 and May 1994, were analysed. The seroprevalence was 19.2 ± 2.24% (2 SE). The distribution of seropositive animals was not homogeneous in the different provinces; Salamanca had the highest seroprevalence (53.3 ± 25.2%). In relation to age, sex and evidence of tick infestation, no significant differences were noted. Dogs from rural areas (25.4 ± 8.1) presented higher prevalence than those from urban areas (17.3 ± 5.9) and dogs from kennels (9.5 ± 8.8). As far as the different functions of sampled dogs were concerned, guard and shepherd dogs had higher seroprevalence (28.5 ± 7.8%) than hunting (15.3 ± 7.6%) and companion (10.3 ± 6.1%) dogs.

Seroepidemiological survey for Borrelia burgdorferi (Lyme disease) in dogs from northwestern of Spain

A random epidemiological study was undertaken to estimate the prevalence of canine borreliosis (Lyme disease) in Castilla y León, the largest region in Spain. The presence of antibodies was determined by indirect immunofluorescence assay (IFA), using theBorrelia burgdorferi B31 strain as antigen. Sera from 308 dogs from 7 provinces in the region were tested. Of all the animals sampled, 37 (21%) were seropositive (titres of 1/64 or above). Almost all the provinces had seroprevalence of 20% or below, except for an important focus of borreliosis in the Zamora province (42.8%). Potential risk factors (age, sex, use, habitat, season, and presence of ticks on the animals) relating to the presence of antibodies were evaluated. Those dogs which had at some time had ticks were more often seropositive, at 24.2%, than those which had never had them, at only 6.2% (p<10−n). No significant differences were discovered for the remaining factors studied. This work indicates that dogs in Castilla y Leon, even if in most cases they do not develop the disease, are exposed to the Lyme disease agent.

Serpulina hyodysenteriae challenge of fattening pigs vaccinated with an adjuvanted bivalent bacterin against swine dysentery

An experimental fattening period was performed with 36 pigs in order to evaluate the safety and efficacy of a bivalent adjuvanted Serpulina hyodysenteriae bacterin. The pigs originated from three different farms and were split into six groups. Eighteen pigs were vaccinated twice, two weeks apart and the rest served as controls. One unvaccinated pig in each group was inoculated intragastrically with 4 x 10(8) active S. hyodysenteriae spirochaetes, B 78 strain. Weight evolution, clinical symptoms, shedding of S. hyodysenteriae and serum antibody titres were monitored for 12 weeks in all pigs. The severity of clinical symptoms and shedding of spirochaetes in faeces were significantly reduced in vaccinated pigs as compared to controls. Statistically significant differences in weight gain between vaccinates and controls were detected coinciding with the maximum shedding of S. hyodysenteriae in faeces. All vaccinated pigs seroconverted, as measured by indirect ELISA, and had a good anamnestic response after the second vaccine dose. The bacterin proved to be useful for both the reduction of clinical symptoms and the number of infected animals in a fattening unit. Adverse post-vaccinal reactions were not observed in any pig.

Canine seroprevalence ofRickettsia conorii infection (Mediterranean spotted fever) in Castilla y León (northwest Spain)

A seroepidemiological study was conducted in 308 dogs to determine the presence of antibodies toRickettsia conorii, using an indirect immunofluorescence assay (IFA). Seven of the provinces of the Castilla y León region (Burgos, León, Palencia, Salamanca, Soria, Valladolid, and Zamora) were covered by the study. Of the 308 dogs analysed, 72 (23.4%) showed significant titers by IFA (1/40 or higher). Seroprevalences were significantly differents between provinces of origin of the animals. These were below 30% in almost all the provinces studied, except for Salamanca province, where the percentage of seropositive dogs was much greater (93.3%). Potential risk factors (presence of ticks on the animals, age, sex, use, habitat, and season) relating to the presence of Mediterranean spotted fever, or Boutonneuse fever, were evaluated. Animals used for guard or pastor activities and those living in rural areas (these factors are closely linked), together with those suffering from tick infestation, had significantly higher seroprevalence than the remainder. The frequency of seropositive dogs increased during the summer months, and these coincide with the period of greatest activity by the vector. Sex and age variables were not identified as risk factors.

An outbreak of diarrhoea associated with atypical rotaviruses in goat kids.

The presence of rotaviruses was investigated in the faeces of 31 goat kids in a dairy herd that experienced an outbreak of severe diarrhoea which caused dehydration, anorexia and prostration in seven (22.6 per cent) of them. All the affected animals were two to three days old. A group A-specific ELISA failed to detect rotaviruses in any of the samples but the characteristics electropherotype of group B rotaviruses was observed by electrophoresis in polyacrylamide gels in six of the animals. A highly significant statistical association between the shedding of rotavirus and the occurrence of diarrhoea was demonstrated. All the rotaviruses were detected in animals three to four days old. Cryptosporidium parvum, Clostridium perfringens and enterotoxigenic Escherichia coli were not detected in the seven diarrhoeic animals.

Immune response following a vaccination campaign against rabies in dogs from northwestern Spain

A cross-sectional study was carried out to determine the seroprevalence of antibodies to the rabies virus in 156 vaccinated dogs from two provinces in the Castilla y León Autonomous Community (northwest Spain). An obligatory anti-rabies programme is currently in place in this region. Seroprevalence was established by an indirect enzyme-linked immunosorbent assay. Of the 156 animals tested, 91 (58.3%) were positive (titres of 0.5 IU ml-1 or above). However, Soria province showed a significantly higher seroprevalence (77.1%) than León province (50%). Age, sex, habitat and use were evaluated with regard to the response obtained after vaccination: no significant differences were discovered for any of these factors. However, guard and herding dogs in León province tended to have lower seroprevalence than dogs not used in these ways. In general, there is a limited response to the vaccination programme in dogs from Castilla y León-especially in León province.

Seroprevalence of porcine epidemic diarrhea virus infection among different types of breeding swine farms in Spain

Abstract A cross-sectional study for determining the seroprevalence of porcine epidemic diarrhea virus (PEDV) infection among swine breeding farms in the Castilla y León region (Spain) was carried out. Breeding farms were stratified according to size and type of production (intensive or extensive). The number of farms to be sampled in each stratum was calculated from the latest census data available and the prevalence of seropositive farms obtained in other countries. Within each herd, the number of sows needed to detect the presence of the disease were sampled, according to within-herd seroprevalence data obtained by us in previous studies. A total of 5098 sow serum samples from 794 different farms were collected during 1992–1993 and tested for the presence of PEDV-specific antibodies, using a blocking ELISA with monoclonal antibodies; 55.9% of herds had at least one positive animal; 29.6% of sera were positive. Seropositive farms were detected throughout the sampled region, indicating that the infection was widespread. Higher farm-level prevalence rates were found in farms with more than 20 sows compared with small ones (≤ 20 sows) and in intensive than in extensive herds. On the other hand, within-farm seroprevalence and mean blocking percentage of positive sera decreased with increasing size of the farm.

Evaluation of an enzyme-linked immunosorbent assay for the detection of sheep infected and vaccinated with Brucella melitensis

An indirect enzyme-linked immunosorbent assay (ELISA), using the lipopolysaccharide of the cell wall as an antigen, was used to detect Brucella melitensis antibodies in ovine serum. The test was carried out on 703 samples of field serums, which were also analyzed by the complement fixation (CF) test and the rose Bengal (RB) test. The ELISA results were more similar to those of the CF test (kappa = 0.89) than to the results of the RB test (kappa = 0.73). The ELISA also had high sensitivity (94.7%) and a somewhat lower specificity (90.4%). One group of 139 young brucellosis-free animals 3-6 months of age were vaccinated with B. melitensis rev. 1 at a dose of 1.2 × 109 live organisms. The ELISA detected a significantly lower number of reactors than the CF and RB tests (P < 0.001). The ELISA values remained below the cutoff level during the 9 months following vaccination.