[Detection of Chlamydia abortus in bovine reproductive losses in the province of La Pampa, Argentina]

Bovine infectious abortion: a systematic review and meta-analysis

The aim of the present systematic review and meta-analysis was to identify the main infectious agents related to bovine abortion worldwide in the period between 2000 and 2022. First, we investigated the global prevalence of infectious agents related to bovine abortion. For this analysis, only 27 articles detected of a wide panel of agents were included. The random effects model revealed that the estimated prevalence of the abortifacient agents in bovine abortion was 45.7%. The heterogeneity among studies was high, but Egger's test showed that there was no publication bias, even though the total number of samples analyzed in these articles was variable. There was no significant effect of the year of the study publication on the estimated prevalence, although an increasing trend was observed over time, possibly due to the implementation of new diagnostic techniques. Then, we analyzed the prevalence of the main transmissible agents in bovine abortion. For this analysis, 76 studies that analyzed 19,070 cases were included. Some infectious agent was detected in 7,319 specimens, and a final diagnosis was reached in 3,977 of these, when both the infectious agent and compatible histopathological changes were detected. We found that Neospora caninum was the most detected agent (22.2%), followed by opportunistic bacteria (21.4%), Chlamydiaceae family (10.9%) and Coxiella burnetii (9.5%). Regarding viral agents, bovine herpes virus type 1 and bovine viral diarrhea displayed similar prevalence rates (approximately 5%). After considering the description of specific histopathological changes, our analyzes showed that N. caninum was a confirmed cause of abortion in 16.7% of the analyzed cases, followed by opportunistic bacteria (12.6%) and Chlamydia spp. (6.8%); however, C. burnetii was only confirmed as a cause of abortion in 1.1% of the cases. For all agents, the heterogeneity among studies was high, and the subgroup analyzes discarded the diagnostic method as the cause of such heterogeneity. This study provides knowledge about the global prevalence of the different infectious agents related to bovine abortion, the most coming of which is N. caninum. In addition, this review reveals the existing deficiencies in the diagnosis of bovine abortion that must be addressed in the future.

Presence of Chlamydia abortus in colostrum, milk and vaginal discharge samples of sheep

Background: The main transmission route of Chlamydia abortus is by ingesting the microorganism that has been eliminated in vaginal secretions, placental membranes or abortions that contaminate the environment and, possibly, through milk and colostrum. Elimination through vaginal secretions is well documented. However, there are no reports about isolation and identification of C. abortus in the colostrum or milk of infected sheep, so it is important to determine whether or not C. abortus may be present in these secretions, which are the only food of lambs. Objective: To detect C. abortus in colostrum, milk, and vaginal secretions of sheep with a history of reproductive disorders. Methods: Colostrum, milk, and vaginal exudates were collected from 66 sheep. The samples were inoculated in mouse fibroblast cell cultures and the presence of C. abortus determined by direct immunofluorescence. Results: 19 out of 66 colostrum samples (28.7%), 14 out of 66 milk samples (21.2%) and 17 out of 66 vaginal swabs (25.7%) were positive for C. abortus. The 50 samples positive for isolation and detected by immunofluorescence, together with 42 negative samples were subjected to qPCR to amplify a fragment of the ompA gene from C. abortus. Thirty-eight of the 92 samples processed by this technique were positive for C. abortus. Conclusion: The results demonstrated the presence of C. abortus in a high proportion in colostrum, milk and vaginal secretions of infected sheep. To the best of our knowledge, this is the first field study confirming the presence of C. abortus in colostrum, which shows that excretion of Chlamydia by lactogenesis could occur in the first hours after birth.

Seroprevalence of antibodies to Chlamydia abortus and risk factors in cattle from Villavicencio, Colombia

Chlamydia abortus is a Gram-negative obligate intracellular bacterium, responsible for abortions and reproductive problems. The disease has a high zoonotic potential and causes great economic losses in ruminant farmers. A cross-sectional study was carried out with 514 cattle from 24 farms of Villavicencio, Colombia. The blood samples were collected from each individual animal and analyzed by Indirect Elisa for immunoglobulin G (IgG) in blood serum (Idexx Chlamydiosis total Ab test). A serum was considered positive when the optical density (OD) of the sample was ≥30% of that of the positive control serum. Data on potential risk factors associated with the disease were collected through a questionnaire in each farm and analyzed. The individual and herd prevalence was estimated. A risk factors analysis was performed through univariate and multivariable using the software SPSS version 20. The animal level seroprevalence was found to be 47.1% and the herd 91.6%. The prevalence in cattle aged 0-1, 1-3 and >4 years was 23.8%; 31.4% and 51.4% respectively. The risk factors associated with the prevalence of disease were female sex (OR = 2.102 CI: 1.066-4.144), age older than 4 years (OR = 2.707 CI: 1.667-4.394), presence of canines on the farm (OR = 2.556 CI: 1.560-4.189) and retention of placenta (OR = 2.678 CI: 1.670-4.295). A high prevalence was identified, suggesting natural infection where the pathogen could be transmitted to humans at the animal-human interface.

First report of caprine abortions due to Chlamydia abortus in Argentina

Infectious abortions of goats in Argentina are mainly associated with brucellosis and toxoplasmosis. In this paper, we describe an abortion outbreak in goats caused by Chlamydia abortus. Seventy out of 400 goats aborted. Placental smears stained with modified Ziehl‐Neelsen stain showed many chlamydia‐like bodies within trophoblasts. One stillborn fetus was necropsied and the placenta was examined. No gross lesions were seen in the fetus, but the inter‐cotyledonary areas of the placenta were thickened and covered by fibrino‐suppurative exudate. The most consistent microscopic finding was found in the placenta and consisted of fibrinoid necrotic vasculitis, with mixed inflammatory infiltration in the tunica media. Immunohistochemistry of the placenta was positive for Chlamydia spp. The results of polymerase chain reaction targeting 23S rRNA gene performed on placenta were positive for Chlamydia spp. An analysis of 417 amplified nucleotide sequences revealed 99% identity to those of C. abortus pm225 (GenBank AJ005617) and pm112 (GenBank AJ005613) isolates. To the best of our knowledge, this is the first report of abortion associated with C. abortus in Argentina.