Outbreak of foot-and-mouth disease in Northern Benin during the 1990-1991 dry season

An outbreak of foot-and-mouth disease damaged the North-Benin during the 1990-1991 dry season (November to May). Coming from outside the Benin, it spread out very quickly in the country essentially because of trans-humant herds. No measures have been taken to limit this sickness which is endemic and which regularly exhibits outbreaks in Benin. Antibodies to types A, O and SAT2 of the foot-and-mouth disease virus were detected in the sera during this outbreak.     

Mycobacterium paratuberculosis in dairy herds in Alberta

Fifty dairy herds in Alberta were tested for the presence of Mycobacterium paratuberculosis by fecal culture and serum enzyme linked immunosorbent assay (ELISA). Individual sera (1500) were tested for antibodies to M. paratuberculosis by ELISA. Fecal samples were combined in pools of 3 (10 pools/herd) for a total of 500 pools that were cultured for M. paratuberculosis. Thirty cultures, including all 10 pools from 1 herd, were not readable due to fungal contamination. The remaining 470 cultures, representing 49 herds, yielded 16 positive pools (3.4% +/- 2.1%) from 10 herds (20.4% +/- 11.3%). The ELISA of each of the 1500 sera detected 105 (7.0% +/- 2.4%) positive sera and 20 (40.0% +/- 13.6%) positive herds, based on 2 or more individual positive sera in the herd. The true herd-level prevalence, as determined by ELISA, was 26.8% +/- 9.6%. The true herd-level prevalence, as determined by M. paratuberculosis fecal culture, ranged from 27.6% +/- 6.5% to 57.1% +/- 8.3%, depending on whether 1, 2, or all 3 individual fecal samples in the positive fecal pool were culture positive.     

Serological survey of Brucella abortus antibody prevalence in the one-humped camel (Camelus dromedarius) from eastern Sudan

A five year investigation of Brucella antibody prevalence in camel sera was conducted in 1502 one-humped camels of both sexes and different ages. The average (mean +/- SD) incidence rate of positive results was 6.95 +/- 1.55%. Among adult one-humped camels, the rate was 4.94 +/- 2.51% in males and 13.76 +/- 4.41% in females. Juvenile one-humped camel calves showed a 0% incidence rate in males and a 1.82 +/- 3.64% in females. Antibodies against Brucella abortus were prevalent in one-humped camel sera throughout the five years of the survey with incidence rates of 6.54, 5.79, 9.32, 5.03 and 8.06%, respectively from 1985 to 1989.     

Rabies surveillance in the United States during 1991.

In 1991, 49 states, the District of Columbia, and Puerto Rico reported 6,972 cases of rabies in nonhuman animals and 3 cases in human beings to the Centers for Disease Control. Ninety-one percent (6,354 cases) were wild animals, whereas 8.9% (618 cases) were domestic species. The total number of reported cases of rabies increased 42.9% over that of 1990 (4,881 cases), with most of the increase resulting from continued spread of the epizootic of rabies in raccoons in the mid-Atlantic and northeastern states. Large increases in cases of rabies in animals were reported from Connecticut (200 cases in 1991, compared with 3 in 1990, an increase of 6,567%), Delaware (197 cases in 1991, compared with 44 in 1990, an increase of 348%), New York (1,303 cases in 1991, compared with 242 in 1990, an increase of 326%), and New Jersey (994 cases in 1991, compared with 469 in 1990, an increase of 112%). Other noteworthy increases were reported by Wyoming (96.4%), Texas (69.7%), California (41.3%), Oklahoma (33.1%), Minnesota (31.4%), Georgia (26.7%), and Maryland (23.7%). Hawaii reported 1 imported case of rabies in a bat. Only 16 states reported decreases in rabies in animals in 1991, compared with 30 in 1990. Pennsylvania and Iowa reported decreases of 40.6% and 27.4%, respectively. Rhode Island was the only state that did not report a case of rabies in 1991.     

Classical and alternate complement pathway activities in paired dairy cow-newborn calf sera

Hemolytic assays were used to compare alternate and classical C pathway activities in sera obtained from clinically normal newborn dairy calves and their mothers at the time of delivery. Mean alternate and classical CH50 concentrations in sera from newborn calves were both significantly lower than in their dams (P less than 0.001). The titer of alternate C pathway activity, expressed as CH50 units/ml, in sera from 17 calves was 12.9 +/- 5.5, whereas for the cows it was 25.8 +/- 6.2. The ratio of cow: calf serum alternate CH50 titers averaged 2.25 +/- 0.80 and ranged from 0.88 to 4.14. Classical CH50 titers were 78.0 +/- 42.7 units/ml in calf sera and 246.0 +/- 44.5 in cow sera. The ratio of cow: calf serum classical CH50 titers averaged 3.71 +/- 1.49 and ranged from 1.19 to 6.87. The wide range of values, noted for both the alternate and classical C pathways, within maternal and neonatal groups was assumed to reflect the biologic variability of complement levels in bovine serum. The possible relationships between deficient levels of alternate and classical CH50 activity in newborn calves and their susceptibility to infections is discussed.     

Prevalence of serum antibodies to canine adenovirus and canine herpesvirus in the European red fox (Vulpes vulpes) in Australia

OBJECTIVES: To determine the seroprevalence and aspects of the epidemiology of canine adenovirus (CAdV) and canine herpesvirus (CaHV-1) in European red foxes (Vulpes vulpes) in Australia. DESIGN: Serum samples were collected opportunistically from foxes in 1991-1994 in Western Australia (WA) and South Australia (SA) and in 1980-1984 and 1990-1994 in New South Wales (NSW) and the Australian Capital Territory (ACT). The sera were examined for antibody to CAdV and CaHV-1 using ELISAs. Seroprevalence in the different regions was determined for both viruses and the CAdV data were analysed for interactions between decade of collection, age, season, region and gender using logistic regression. RESULTS: The overall prevalence of antibody to CAdV was 23.2% (308/1326) but was significantly higher in sera collected in the eastern states of Australia (47%: 233/498) than in WA (9%: 75/828). Overall, in NSW and the ACT, there was a significantly lower prevalence in juveniles than in adults and the prevalence in juveniles in the 1990s was significantly lower than in the 1980s. The prevalence was also significantly lower in the autumn than in the winter for juveniles but the reverse held for adults. The NSW and ACT data were subdivided into eastern (including the ACT) and western regions. This revealed a significantly higher prevalence in the winter than in the autumn for the west and the reverse in the east. In WA, the northern rangeland regions of WA had lower prevalence (1.9%) than the southern agriculture regions (10.7%). Seasonally, there was a peak prevalence in the spring dropping through the summer and autumn and rising again in the winter. This seasonal pattern was also found in the combined data for all sites in the 1990s. There was no gender difference in prevalence of CAdV either overall or in different regions. The overall prevalence of antibody to CaHV-1 was 2.2% (28/1300). The small number of positives allowed only limited statistical analysis that did not reveal any differences in decade of collection, age, season or region. CONCLUSIONS: CAdV infection is common in the Australian fox population whereas CaHV-1 infection is rare. For CAdV, the age and seasonal patterns of seroprevalence were generally consistent with the recruitment of young susceptible foxes into the population in the spring and the accumulation of infections with age. The differences in regional prevalences correlated with fox density. The low prevalence of antibody to CaHV-1 suggests that CaHV-1 may be a more suitable vector than CAdV for bait delivery of immunocontraceptive antigens to foxes in Australia.     

Seroprevalence of Trichinella infection in domestic swine based on the National Animal Health Monitoring System's 1990 and 1995 swine surveys

Swine sera collected by the US Department of Agriculture's Center for Animal Health Monitoring during 1990 and 1995 was tested for antibodies to Trichinella spiralis using an enzyme immunoassay. From a total of 3048 sera collected from lactating sows in 1990, five sera tested positive for a prevalence of 0.16%. From a total of 7987 sera collected from both finishing pigs and gestating sows in 1995, one serum was positive for a prevalence of 0.013%. Responses to questionnaires administered at the time of serum collection showed that seropositive farms had management variables consistent with known risk factors for exposure to trichinae.     

The prevalence of bovine viral diarrhea virus infection in a population of feedlot calves in western Canada.

The prevalence of bovine viral diarrhea virus (BVDV) infection was examined in a population of 5129 recently weaned steer calves entering a large feedlot in central Saskatchewan from September to December 1991. Serum samples were collected within 24 h of arrival at the feedlot from every fifth calf processed and again 96 d postarrival. A microtiter virus isolation test was used to determine the prevalence of calves viremic with BVDV on entry to the feedlot. An enzyme-linked immunosorbent assay (ELISA) which detects antibody against glycoprotein 53 of the BVDV was used on paired sera to determine the seroconversion risk during the first 96 d in the feedlot. A virus neutralization (VN) test for BVDV was conducted on a sub-sample of paired sera to measure agreement in determination of seroconversion risk with the ELISA. A polymerase chain reaction (PCR) test which detects BVDV was used to determine if cattle were acutely viremic when treated for disease. The estimated prevalence of persistently infected calves in this population was < 0.1%. The seroconversion risk for BVDV was 27% (236/864) according to the ELISA and it varied from 0 to 63% among the 20 pens sampled. According to the VN test, the seroconversion risk for BVDV was 40% (132/327) and it varied from 0 to 100% among the 11 pens tested. The agreement between the ELISA and VN tests in seroconversion risk to BVDV was very poor (kappa = 0.15 +/- 0.039 SE). The prevalence of acute viremia in calves treated at the feedlot hospital was low at 4% (6/149).(ABSTRACT TRUNCATED AT 250 WORDS)     

An outbreak of ovine granular keratoconjunctivitis of chlamydial origin, in Ivory Coast]

During the dry season 1990-1991, an outbreak of ovine granular keratoconjunctivitis occurred in C?te-d'Ivoire. The chlamydial etiology was demonstrated. All flocks were affected, with a morbidity rate of 30 to 70%. Lesions of keratitis were observed in 5 to 15% of the sick animals. The treatment with Auréomycine (ND-Specia, ophthalmic ointment) was constantly efficient.     

A longitudinal study of disease incidence and case-fatality risks on small-holder dairy farms in coastal Kenya

A longitudinal study was carried out in the coastal lowlands coconut-cassava agro-ecological zone of Kaloleni Division, Coast Province, Kenya between June 1990 and December 1991 to estimate disease incidence and cause-specific case-fatality risk in an average of 120 cattle in 26 small-holder dairy herds kept in two grazing-management systems. East Coast fever (ECF) was the predominant disease diagnosed; the mean monthly incidence rate was 2.5 and 6.9% in animals < or = 18 months of age under stall-fed and herded-grazing systems, respectively. In cattle > 18 months of age, the monthly incidence rate was < 1%. The 6-month ECF incidence rate was 20+/-8% (S.E.) in the stall-feeding system compared with 39+/-7% in the herded-grazing systems. There was a gradual increase in antibody prevalence with age to over 90% in cattle over 18 months of age in herded-grazing systems, whilst less than a third of cattle in the stall-feeding systems were sero-positive at any age. Overall accumulated mortality to 18 months of age was estimated to be 56%. Annual mortality in cattle > 18 months averaged 9%. Cattle managed in the herded-grazing system had a 60% higher mortality, although not significantly so, than those fed in stalls. Deaths due to ECF accounted for over two-thirds of the deaths. ECF was then the major disease constraint to small-holder dairy production in the coconut zone of coastal Kenya. Clinical cases occur the whole year round (especially in young stock)--despite apparent tick control, and in both herded-grazing and stall-feeding system.     

Evaluation of the test for detecting trypanosoma circulating antigens using monoclonal antibodies. Experimental and natural infections]

An antigen detection ELISA for the diagnosis of trypanosomes was recently proposed by Nantulya and Lindqvist (1989). Based on species-specific monoclonal antibodies, this test could be used to diagnose a current infection and to identify the causing trypanosomes. The test was evaluated at CRTA during experimental infections in small ruminants and with sera from naturally infected cattle, thanks to reagents supplied by the International Laboratory for Research on Animal Diseases (ILRAD). Sera from cattle sampled in France were also tested. Cattle sera from France gave optical densities (OD) from 0.007 to 0.009 with three monoclonal antibodies against T. congolense, T. vivax and T. brucei. These OD values were well below 0.050, which is considered as a positive threshold OD reading. In the small ruminant experimental infections, the sensitivity of the test was 63.2% for T. congolense-infected animals and 9.9% for T. vivax-infected animals. The sensitivity of parasitological tests was 55.1 and 48.6%, respectively. The combination of the antigen- and parasite-detection tests increased the sensitivity to 82.4 and 52.8%, respectively. Means of OD values, with the naturally infected cattle sera, were 0.116 +/- 0.030 for T. congolense, and 0.011 +/- 0.028 for T. vivax-infected animals. Sixteen out of 20 T. congolense-infected sera (sensitivity of 80%) and one out of 20 T. vivax-infected sera (sensitivity of 5%) gave an OD value exceeding 0.050. The determination of a threshold OD reading lower than 0.050 would greatly improve the sensitivity of the test. This determination could either be done by studying the preinfection sera or a local population of animals living in an area free from trypanosomosis.(ABSTRACT TRUNCATED AT 250 WORDS)     

A comparison of four serological tests for the diagnosis of caseous lymphadenitis in sheep and goats

A double antibody sandwich ELISA (ELISA A) developed for the detection of Corynebacterium pseudotuberculosis infection in sheep and goats was modified to improve its sensitivity. To establish the sensitivity and specificity of this modified ELISA (ELISA B), sera from 183 sheep and 186 goats were tested using ELISAs A and B. Comparison was also made with two further ELISAs (C and D) developed in Australia that, respectively, detect antibodies to cell wall antigens or toxin.ELISA B had the best performance of the four tests. Its specificity was 98+/-1% for goats and 99+/-1% sheep. Its sensitivity was 94+/-3% for goats and 79+/-5% for sheep. ELISA B will now be tested for use in caseous lymphadenitis eradication and control programmes in The Netherlands. It will also be used in experimental studies of CL in Scotland.     

Serum level of cartilage oligomeric matrix protein (COMP) in equine osteoarthritis

This study was designed to assay and compare cartilage oligomeric matrix protein (COMP) in horse sera, in samples from normal and joint diseased horses, and to investigate the relationships between COMP in sera and synovial fluids (SF) with keratan sulphate (KS) data. Sera from 38 horses free of any joint pathology (controls) and from horses with aseptic joint disease (AJD horses, n = 40) were assayed for COMP and KS concentrations. Of the 78 horses in the study, 53 were also assayed for COMP and KS concentrations in SF. COMP and KS were measured by inhibition ELISA, using monoclonal antibodies 12C4 and 5D4, respectively. The COMP concentration in sera from AJD horses (mean +/- s.d. 10.7 +/- 7.4 microg/ml) was significantly (P<0.02) lower than in control sera (14.8 +/- 7.8 microg/ml). The joint disease sera also had significantly lower (P<0.01) KS levels (180.5 +/- 61.8 ng/ml) than controls (237.1 +/- 116.1 ng/ml). A significant correlation (r = 0.52, n = 53, P<0.001) was seen between serum and SF in COMP levels; no such relationship was seen in KS levels. It is possible that serum COMP concentration could be a more specific marker of equine joint disease than any other described to date.     

Determination of Canine Factor VIII-related Antigen Using Commercial Antihuman F VIII Serum

Factor VIII-related antigen (F VIII:AGN) in 21 canine plasma samples was assayed by immunoelectrophoresis using a rabbit anticanine F VIII serum prepared from a canine F VIII concentrate and a commercial rabbit antihuman F VIII serum. A good correlation existed (r value 0.916) between the antigen levels obtained using the two sera. In normal dogs the plasma F VIII:AGN level was 95 +/- 39% (Mean +/- SD) compared to 175 +/- 40% in dogs with severe hemophilia A and 17 +/- 15% in dogs with von Willebrand's disease. It was concluded that there was sufficient cross reactivity between canine F VIII and commercial rabbit antihuman F VIII serum to make the latter useful in the differential diagnosis of F VIII deficiencies in the dog.     

Evaluation of an enzyme-linked immunosorbent assay for the detection of Mycoplasma hyopneumoniae antibody in porcine serum

An enzyme-linked immunosorbent assay (ELISA) for detecting antibody to Mycoplasma hyopneumoniae in porcine serum is described. The results are presented as an ELISA ratio, calculated by dividing the absorbance of the test sample by the mean absorbance of control negative sera. In known infected pigs, the ELISA ratio was highest when the serum concentration applied to the ELISA plate was diluted 1 in 20 in PBS - Tween. Mean ELISA ratios ranged from 1.2 +/- 0.3 for pigs without porcine enzootic pneumonia (PEP) lesions to 5.5 +/- 1.5 for pigs observed with a PEP lesion reacting positively with immunofluorescent histopathology. Pigs observed with typical PEP lesions at slaughter, but not confirmed by immunofluorescent histopathology had a mean ELISA ratio of 4.9 +/- 1.7. The ELISA was highly sensitive (95.6%) and specific (98.8%) when pig sera from commercial piggeries of known M hyopneumoniae infection status were assessed. No cross-reactivity with serum from a pig hyperimmunised with killed M flocculare was detected, and reactivity with serum from another pig hyperimmunised with killed M hyorhinis showed only weak cross-reactivity, which failed to reach the ELISA positive threshold (ELISA ratio 3) for M hyopneumoniae.     

Changes in serum immunoglobulin values in kittens after ingestion of colostrum.

Immunoglobulin values were determined in fetal and kitten sera. In the fetal and precolostral kitten sera, only IgG was detected, except in 1 case in which IgM was detected. The IgG, IgA, and IgM were transferred to the kittens through colostrum ingestion with some selectivity. Concentration of the transferred IgG, IgA, and IgM decreased significantly with half-lives of 4.15 +/- 1.29 days, 2.03 +/- 0.33 days, and 2.2 +/- 1.2 days, respectively. As a result of this decrease and increase of de novo immunoglobulin synthesis, IgG, IgA, and IgM were at their lowest values when kittens were 20 to 25 days, 14 to 20 days, and 8 to 10 days old, respectively. After their nadir was reached, IgG values increased gradually, IgA slowly, and IgM rapidly, as a result of de novo immunoglobulin synthesis. When the kittens were 90 days old, their immunoglobulin values were 80% (IgG), 7% (IgA), and 100% (IgM), compared with those of adult cats. These findings suggest that kittens that receive inadequate colostrum from their mothers will be particularly susceptible to infection after they are 5 weeks old.     

Clinical assessment of selenium status of livestock.

Assessment of the selenium status of livestock is an important aspect of production medicine, but variations in reported values between laboratories and between methods may be > 30%. Reliable interpretations require considerable experience with an assay and an extensive database from field and research case samples of a variety of species. The Michigan State University Animal Health Diagnostic Laboratory (MSU-ADHL) has offered Se analyses by acid-digestion and fluorometric detection since 1982. This laboratory expects serum Se values (nanograms per milliliter) of livestock to increase gradually with age from starting ranges for neonates of 50 to 80 for calves and sheep and 70 to 90 for foals and pigs. Expected or "normal" values for the adults are in the ranges of 70 to 100 for cattle, 120 to 150 for sheep, 130 to 160 for horses, and 180 to 220 for swine. Normal liver Se concentrations are considered to range between 1.2 and 2.0 micrograms/g on a dry weight basis, regardless of the species or age. Based on samples submitted to MSU-AHDL between September 1990 and August 1991, contemporary feeding practices in the Michigan area resulted in mean serum Se values (nanograms per milliliter) of 75 +/- 19 for adult Holsteins, 170 +/- 27 for adult swine (mixed breeds), and 137 +/- 30 for adult race horses. Within that period of time, two field cases of Se toxicity were diagnosed. One involved feeder pigs with a recorded high serum Se value of 1,525 ng/mL due to a commercial premix manufacturing error.(ABSTRACT TRUNCATED AT 250 WORDS)     

Development of a monoclonal antibody-based competitive enzyme-linked immunosorbent assay for the detection of Leptospira borgpetersenii serovar hardjo type hardjobovis antibodies in bovine sera.

A murine monoclonal antibody (designated M553) that binds to an epitope on whole cell antigens prepared from Leptospira borgpetersenii serovar hardjo type hardjobovis and Leptospira interrogans serovar hardjo type hardjoprajitno, was produced and incorporated into a competitive enzyme-linked immunosorbent assay for the detection of bovine antibodies to serovar hardjo. The epitope recognized by M553 was susceptible to periodate oxidation. The M553 antibody was characterized by western blot with hardjobovis whole cell antigen. This antibody does not cross-react with whole cell antigens prepared from 11 other pathogenic Leptospira serovars, or, Leptospira biflexa serovar patoc. The sensitivity estimate of the competitive ELISA was 100% with field sera (n = 165) with serovar hardjo microscopic agglutination test (MAT) titres of > or = 100. The specificity estimate was 100% with sera (n = 128) obtained from a specific pathogen free herd of cattle that were negative in the MAT at a dilution of 1:100 for serovars hardjo, pomona, sejroe, copenhageni, canicola, and grippotyphosa. The specificity estimate with field sera (n = 301) with serovar hardjo MAT titres of < 100, was 98% (95% confidence interval = +/- 1.58%). There was no cross-reactivity with field sera (n = 306) with serovar pomona titres > or = 100 and serovar hardjo titres < 100. The specificity estimate with the combined populations of sera with serovar hardjo MAT titres of < 100 (n = 735) was 99.18% (95% confidence interval = +/- 0.65%). There was a high level of agreement (kappa = 0.977) between the results of the competitive ELISA and those of the MAT.     

Laboratory diagnosis and disease occurrence in the current African swine fever eradication program in Spain, 1989–1991

The purpose of this study was to determine the rate of decline and geographical distribution by municipality of clinical and subclinical African swine fever (ASF) in the affected areas of Spain. A second aim was to evaluate the performance of diagnostic tests in the Spanish ASF eradication program. Clinical outbreaks were confirmed using both the direct and indirect immunofluorescence test (and if both were negative, by the hemabsorption test). The serological status of swine was determined by an enzyme-linked immunosorbent assay (ELISA) and suspect serum samples were confirmed by the immunoblot assay.

The number of clinical outbreaks (herds) of ASF for 1989, 1990 and 1991 was 170, 347 and 207, respectively. The numbers of municipalities within each affected province experiencing acute outbreaks for the same time periods were 49, 69 and 48, respectively. Serologically diagnosed animals positive for ASF were 1.1% of animals tested in 1989, 0.5% in 1990 and 0.8% in 1991. The corresponding positive predictive values of the standard ELISA test used were 99.0, 97.9 and 98.8, respectively. Similarly, the number of municipalities within each affected province experiencing serologically positive subclinically infected animals was 269, 178 and 147 for each of the years 1989, 1990 and 1991, respectively.     

Seroprevalence of anti-Toxoplasma IgG in Canadian swine.

In 1990, 1443 sera randomly selected by computer generated random numbers from a bank of greater than 15,000 sera collected earlier from sows at slaughter in various geographic regions of Canada were tested for anti-Toxoplasma immunoglobin G (IgG) by the modified direct agglutination test. One hundred and thirty-six (9.4%) samples were positive for anti-Toxoplasma IgG while 36 (2.5%) of the sera gave borderline reactions. The highest prevalence of anti-Toxoplasma IgG was in swine originating in the Atlantic provinces and Ontario while the lowest was in swine from Manitoba and Saskatchewan.