Causative Agent Of Abortion Research Articles

An Outbreak of Salmonella Abortusovis Abortions in Sheep in South Croatia

The aim of the study was to give an account of the epidemic of abortions in sheep caused by Salmonella enterica ssp. enterica serovar Abortusovis, which occurred in Dalmatia, south Croatia, in winter 2003-2004. Five sheep flocks with rate of abortion ranging from 22% to 38% during the last-third of gestation were examined. Salmonella Abortusovis was isolated from 13 vaginal smears and two fetuses. Direct inoculation was found to be superior to pre-enrichment and enrichment in selective broth for Salmonella Abortusovis isolation. The isolates were biochemically identified, and characterized by serotyping and polymerase chain reaction based on the amplification of the IS200 sequence specific for Salmonella Abortusovis. A fragment of 900 bp was detected in all Salmonella Abortusovis isolates. The sensitivity testing of the isolates, carried out by the disk diffusion method and the determination of the minimal inhibitory concentrations, resulted in a high sensitivity to almost all antimicrobials used. Only two isolates were moderately sensitive to oxytetracycline, whereas one isolate showed resistance to streptomycin. Campylobacter fetus ssp. fetus and Listeria monocytogenes were excluded as causative agents of abortion in sheep by culture testing, and brucellosis, leptospirosis, Q fever and chlamydiosis by serological testing.

A polymerase chain reaction for detection of equine herpesvirus-1 in routine diagnostic submissions of tissues from aborted foetuses.

Equine herpesvirus 1 (EHV-1) is the causative agent of abortion, perinatal foal mortality, neurological and acute respiratory diseases in horses. Conventional laboratory diagnosis involving viral isolation from aborted foetuses is laborious and lengthy and requires processing of samples within 24 h of collection, which is problematic for samples that come from long distances. The aim of this study was to develop a polymerase chain reaction (PCR) assay useful in Argentina to detect DNA sequences of EHV-1 in different tissues from aborted equine foetuses with variable quality of preservation and without the use of conventional DNA fenolic extraction. Several DNA extraction protocols and primers were evaluated. The amplification method was standardized and its specificity was analysed using 38 foetal samples of variable quality of preservation. Of the 38 different foetal tissues, nine livers, six spleens and two lungs in good preservation and eight livers, one spleen and four lungs in a poor state of preservation were positive for PCR. EHV-1 was recovered only from the nine livers, five spleens and two lungs in good preservation. No virus was isolated from the samples that were poorly preserved. Viral isolation was confirmed by cytopathic effect and indirect immunofluorescence. The specificity of the PCR results was confirmed by the restriction endonuclease digestion of PCR products and hybridization.

Serological investigation of an outbreak of Neospora caninum-associated abortion in a dairy herd in southeastern United States

An outbreak of Neospora caninum-associated abortion occurred in a South Carolina dairy wherein greater than 10% of the herd aborted over a 4-month period. Of the total number of cows at mid-late gestation, nearly 40% (28/71) aborted while the remaining 60% (43/71) gave birth to normal calves. Immunohistochemical examination of brain tissue from a subset of aborted fetuses confirmed N. caninum as the causative agent of abortion in these animals. A variety of serological assays, including indirect fluorescence antibody test (IFAT), recombinant enzyme-linked immunosorbent assay (rELISA), ISCOM-ELISA, avidity ELISA, and Neospora agglutination test (NAT), were used to evaluate sera collected during the outbreak from 240 cows for antibodies to N. caninum. IFAT and ISCOM-ELISA testing showed that nearly 80% of the dairy cows had antibodies to N. caninum. NAT and rELISA had similar levels of seropositivity relative to IFAT and ISCOM-ELISA, but the percentage of positive sera was dependent on the cut-off value chosen. As indicated by κ coefficient statistical analysis, ISCOM-ELISA and IFAT exhibited the highest level of agreement in identifying N. caninum-positive and -negative cows. A decrease in the percentage of seropositive cows as determined by ISCOM-ELISA and IFAT with increasing cow age was noted. However, no significant difference was observed between cow age and abortion status. In addition to these tests, an avidity ELISA was performed on all sera with high (≥0.4) ISCOM-ELISA readings. Avidity index (AI) increased with time post-abortion suggesting that most abortions were due to recent N. caninum infection. Of the cows at risk for abortion, the mean serological AI of aborting cows was significantly lower ( P<0.05) than mean serological AI of non-aborting cows.

Histology of Reproduction and the Estrus Cycle in the Female Fur Seal, Callorhinus ursinus

Gross and histological analyses of the reproductive tracts from 72 multiparous females, 12 nulliparous females, and 28 non-pregnant females, taken pelagically in the eastern Pacific and on the Pribilof Islands between 1959 and 1961, have been used to determine the histology and physiology of the estrus cycle, the age of sexual maturity, and certain causes of prenatal mortality.The ovaries alternate in function, one ovary ovulating in one breeding season, the opposite ovary ovulating in the next. An undetermined factor suppresses follicular development in the ovary containing a corpus luteum of pregnancy; suppression maintains for 6 months after parturition. Graafian follicular development is greatest in June, with an average of 15 follicles in the ovary destined to ovulate. About four of these will enlarge abruptly in July; one will reach ovulation size (10 mm or greater in diameter) and rupture; the rest will become atretic.Ovulation occurs spontaneously 3–5 days after parturition in mid July. If fertilization is accomplished, the resulting blastocyst remains free in the uterus until early or mid November, when it implants in the mucosa.The newly formed corpus luteum is actively secretory for a month after ovulation. During this time, follicular development is suppressed in both ovaries, and the uterine mucosa prepares for implantation. From the middle of August, the corpus luteum regresses; the luteal cells are vacuolated, and secretion is minimal. This is reflected in a recrudescence of follicular activity in the ovary containing the corpus luteum, and regression of the associated uterine mucosa. Immediately prior to implantation the corpus luteum resumes secretion, and the mucosa is prepared for implantation. Placentation is established during December. Luteal degeneration begins in January and is progressive until parturition, when the corpus luteum appears to be non-secretory. Luteal degeneration has no effect on the pregnant uterine horn; it is assumed that the placenta secretes hormones sufficient to replace the luteal hormones.A nulliparous female ovulates for the first time in late August or September, [Formula: see text] months later than subsequent ovulations. On the basis of gross reproductive examination, approximately 70% of females ovulate for the first time at 4 years of age. Since the pregnancy rate of 5-year-olds is consistently about 50%, probably a number of 4-year-olds do not mate, either because ovulation occurs after the breeding season, or because breeding males are not available.Prenatal mortalities take 3 forms: "missed" pregnancies, abortions, and resorptions. On the basis of histological examinations, "missed" pregnancies are ultimately due to failure of implantation. Three conditions are responsible: failure of fertilization, failure of implantation, or malfunction of the reproductive tract which precludes pregnancy. Abortion results in the expulsion of a conceptus from the uterus before term; resorption is a gradual process of dissolution of the conceptus within the uterus. On the basis of histological evidence, three causative agents of abortion and resorption are apparent: degeneration of the corpus luteum after implantation, malfunction of the uterine mucosa, and inter-uterine mortality of the conceptus.