1. Introduction
Chlamydia abortus (C. abortus) is a non-motile obligate intracellular Gram-negative pathogenic bacterium, belonging to the Chlamydiales family. Sheep and goats, and less frequently cattle, pigs, and horses can be infected by C. abortus; pregnant women can become infected by the microorganism, thus representing a particular concern for human health [1]. C. abortus is known as the causative agent of the enzootic abortion of ewes (EAE) or ovine enzootic abortion (OEA) [2], and along with other infectious agents, such as Campylobacter spp., Salmonella sp., Listeria sp., C. burnetii and Toxoplasma sp., represent the most common causes of ovine and caprine infectious abortion worldwide [3]. The distribution of these abortifacient pathogens may vary among regions and flocks worldwide due to the well-defined risk factors for these diseases, such as management practices, flock size, climatic conditions, vaccination, eradication strategies, or nutritional factors [4,5], although these characteristics do not represent the prevalence of the disease in different regions [6]. Furthermore, the relationship between agents and host to human transmission is influenced by many environmental factors [3]. C. abortus can survive in the environment from a few days to a few months thanks to the elementary body (EB) that can resist dry [7]. This resistance, as for C. burnetii, seems to increase the possibility of coming into contact with many animal species, farmed or wild, and with humans [1,3]. Referring to the literature data on PCR-based methods, co-infections in clinical cases of abortion are relatively frequent in small ruminants [8,9,10]. Taking the results published in an authors’ previous study on the seroprevalence of Q fever [11] structured on a well-defined study design to accurately estimate the prevalence of the infection [12] as a starting point and considering the direct evidence of co-infections based on biomolecular methods [8,9,10], in this study, we propose a retrospective seroprevalence study on sheep and goat serum samples.
Indeed, to the best of our knowledge, the recently published data are all related to C. abortus seroprevalence in small ruminants in non-EU countries [13,14,15,16,17,18]. In Europe, data about the caprine prevalence of OEA is scarce: some reports indicate a low seroprevalence in Slovak Republic (7.7%) [19] and in the Sardinia region, Italy (5.8%) [20], in contrast with a higher prevalence in Canary Islands, Spain (33%) [21]. The observed seroprevalence data are not so similar among studies, showing differences linked to animal breeds, farm management methods, sanitary conditions, and the serological test used. Indeed, the selection in most of the studies to employ an ELISA kit and an accurate estimate of the “true” prevalence adjusted for test sensitivity and specificity instead of the “apparent” prevalence is crucial in the light of harmonized and comparable data over time and between countries [11]. In this study, we use a commercial indirect ELISA kit with low cross-reaction between C. abortus and C. pecorum [22].
For this cross-sectional study, aimed to estimate the C. abortus seroprevalence in small ruminants in North-Western Italy, we selected non-vaccinated flocks along the provinces with higher farm density. Finally, the study also aims to determine the associated risk factors with Chlamydia seropositivity at the herd level.
2. Materials and Methods
2.1. Study Area
The Piedmont region (45°0′ N 08°0′ E, 25,399 km2) is located in the northwest of Italy, bordering Switzerland and France. The territory presents different landscapes with mountains, hills, and plains well-suited for the cultivation of cereal crops such as corn, wheat, and barley. A popular cultivation is rice, especially in the Vercelli province, where traditional rice fields cover a high percentage of the province territory. Piedmont livestock farming is mainly focused on cattle, goat, and sheep, both for meat and dairy production. Piedmontese cattle for meat and typical local cheeses like Toma and Robiola, are typical food products of this region.
Small ruminants farming may be considered representative of prealpine territories. The Italian National Livestock registration database (VetInfo, [23]) recorded, at animal level, 72,505 goats and 108,995 sheep. Among sheep, the Biellese is the typical breed, as well as the most relevant sheep bred in Italy. The prevalent breed among goats is the Alpine goat. At herd level, the farms registered in the region were 8288 (4573 goats, 1647 sheep, and 2078 mixed flocks).
2.2. Study Design
A cross-sectional study was conducted to estimate the seroprevalence of Chlamydia abortus at the farm and animal level in small herds of ruminants (sheep, goats and mixed) in northwestern Italy, between January and December 2012. The survey was planned with a two-stage design at farm level and animal level, setting a constant number of animals to be tested for each farm. Using the formula described by Cannon and Roe [24], the total number of sheep and goat farms to be sampled was selected considering an expected prevalence of 50%, with 7% precision at the 95% confidence level, with a design effect of 1.05. C. abortus vaccination was not applied to the selected target population. A proportional, stratified random sampling design was followed for the 202 flocks. Stratification was carried out by number of flocks per area. We select the number of animals to be sampled within flocks in order to detect at least one seropositive animal, considering an expected seroprevalence of 10% and a confidence level of 95% [25].
Blood samples were collected from small ruminants older than 6 months (i.e., minimum diagnostic age) by government veterinarians from the Local Health Units during annual mandatory brucellosis testing (related to the Brucellosis National Eradication Program). Information on flock management and potential risk factors for Chlamydia were registered using a questionnaire delivered to farmers by vets at the time of sampling.
2.3. Serological Test
Blood samples were collected from each animal and centrifuged (10 min, 1600× g). The obtained sera samples were stored at −20 °C ± 5 °C until analysis. A commercial indirect enzyme-linked immunosorbent assay (ELISA) kit was selected for the detection of IgG specific antibodies against C. abortus (ID Screen® Chlamydophila abortus Indirect Multi-species, Innovative Diagnostic, Grabels, France). As declared in the kit instruction for use, the plates are coated with MOMP (Major Outer Membrane Protein) peptide, specific for anti-IgG C. abortus identification. The performances of the kit, as declared by the producer, are 70% (CI95%: 53.5–83.4%) for sensitivity and 100% for specificity (CI95%: 90.5–100%).
To obtain the optical density (OD) of each sample, the colored reaction was read in a microplate spectrophotometer at 450 nm. The percentage of reactivity of each sample was calculated using the suggested formula (ODsample/ODpositive control) × 100, resulting in the sample classification as positive, doubtful, or negative. According to the cut-off established by the assay manufacturers, samples with a reactivity greater than 60% were classified as positive, those with reactivity between 50% and 60% as doubtful, and those with a reactivity lower than 50% as negative.
Serological data on C. burnetii seroprevalence were obtained as described in Rizzo et al., 2016 [11].
2.4. Statistical Analyses
Descriptive statistics were used to calculated the number of seropositive flocks for antibodies against C. abortus. As test specificity was 100% and no vaccination against Chlamydia abortus was used in the farms included in the study, a flock was classified as positive when at least one animal resulted positive to the test. According to Rogan and Gladen [26], the true seroprevalence was calculated using values of diagnostic accuracy given by the kit’s producer. A logistic regression model was used to estimate the association between serological response and potential risk factors for C. abortus to control for confounding. Statistical modelling was initially performed through bivariate analysis in order to select the relevant factors. The significance of factors in the model was tested using Wald’s χ2. As measures of the predictor effect, the estimated OR and 95% Wald’s confidence interval (CI95%) were calculated. Correlations between antibodies against C. abortus and the occurrence of other infections in the flock as C. burnetii were calculated using the Phi index. All of the analyses were conducted using SAS® version 9.4 [27].
3. Results
Sera from 3045 animals (1202 sheep and 1843 goats) belonging to 202 herds (118 goat herds, 72 sheep flocks, and 12 mixed herds) were examined for C. abortus. At the herd level, the true seroprevalence was 56.6% (CI95%: 46.9–66.3%); in detail, in the sheep-farm and goat-farm, the true seroprevalence was 71.4% (CI95%: 54.6–88.3%) and 44.8% (CI95%: 41.3–57.0%), respectively. Mixed herds, made up of both sheep and goats, show the highest true seroprevalence value (83.3%, CI95%: 36.6–100). On the other hand, considering the value of true seroprevalence at the animal level, the overall value is 22.3% (CI95%: 16.9–27.7%). In particular, these data were significantly higher (χ2 = 92.5; p < 0.0001) among sheep (33.4%, CI95%: 24.9–42%) than goats (15.1%, CI95%: 9–21.1%). The spatial distribution of the flocks according to C. abortus seroprevalence is shown in Figure 1. The true and raw seroprevalence at the farm and animal levels are shown in Table 1.
At the animal level, the factors associated with C. abortus seropositivity were species (χ2 = 91.5; p < 0.0001), age (χ2 = 10.2; p < 0.02), sex (χ2 = 7.2; p < 0.007), breed (χ2 = 43.9; p < 0.0001), and seropositivity to C. burnetii (χ2 = 27.9; p < 0.0001), as sheep, female, C. burnetii seropositive, mixed breed, and younger animals were more likely to be seropositive. Table 2 shows the results obtained using multivariate analysis (Wald chi square 103.6; p value < 0.0001). In particular, first kidding animals (1–2 years) (OR 1.6; CI95% 1.2–2.3) showed a nearly two-fold increase in the probability of being seropositive compared with older animals, >4 years (OR 1). However, there was no correlation (phi = 0.09) between C. abortus and C. burnetii seropositivity at the animal level.
The factors associated with C. abortus seropositivity at the herd level are shown in Table 3. The main factors were flock size, introduction of animals, and contacts with cattle, C. burnetii seropositive. A moderate positive correlation (phi = 0.35) resulted between C. abortus and C. burnetii seropositivity at the herd level.
The results of the final logistic regression model (Likelihood Ratio χ2 = 44.6, degrees of freedom = 5, p < 0.001) are shown in Table 4. All of the studied factors were retained as being significantly associated with C. abortus seropositivity: flock size (i.e., farms with >50 heads) increased the probability nearly nineteen fold (OR 18.9; CI95%: 6.1–58.4); if we compare no contact or contact with bovine, the latter increased the probability of being C. abortus positive (OR 2.3; CI95%: 1.1–4.9) two-fold. C. burnetii seropositive flocks were more likely to also be Chlamydia positive, as Coxiella increased the probability of being C. abortus seropositive two-fold (OR 2.7; CI95%: 1.3–5.5). Finally, the introduction of new animals in the flock also doubles the probability of C. abortus seropositivity (OR 2.4; CI95%: 1.1–5.3).
4. Discussion
It is well-known that C. abortus is a zoonotic microorganism that can cause many different symptoms in humans, including subclinical infection and acute flu-like disease [2]. The pathogen can cause serious infections and fetal illnesses in pregnant women due to chlamydial-induced abortions [1,28]. In small ruminants farming, abortion and stillbirth represent important issues because of the financial impact caused by lamb and lactation loss. Many pathogens play a role in small ruminants’ abortion and reproductive failure, including Brucella, Campylobacter spp., Salmonella spp., Listeria spp., C. burnetii, and Toxoplasma sp.: the available word-wide data demonstrate that C. abortus is one of the most commonly diagnosed infectious causes of lamb loss [28]. Recent findings from the UK show that C. abortus was the main infectious agent responsible for reproductive disorders and fetopathy in 2021–2022 and the second one in 2023 [29].
In the Piedmont region, the Brucellosis National Eradication Program, implemented since 1992 (DM 453/1992), has contributed to eradicating the disease, obtaining disease-free status in 2009 (EU Decision 2009/342/CE del 23/04/2009). As for the other above-mentioned pathogens (excluding Brucella), C. abortus has not been the object of a similar national eradication plan; therefore, animals are not periodically tested for those specific pathogens. Reproductive failure or abortion may be investigated by farm vets based on farmers’ requests and/or symptoms and anamnestic outcomes. Consequently, no official epidemiological prevalence data are available. The aim of this retrospective study is to fill this lack of data in order to estimate seroprevalence in small ruminant farms in the Piedmont region (North-Western Italy).
In this study, about 40% of the tested farms resulted positive and the true seroprevalence was found to be even higher considering the specificity and sensibility of the ELISA test used. These data showed a wide spread of C. abortus in small ruminant farms in the Piedmont region; nevertheless, it is difficult to compare these results with other national and/or EU territories. The relevant data are not systematically collected, and often the only available information come from surveys and sporadic case-reports [3]. A previous study conducted between 1999 and 2003 in Sardinia (Italy) showed a low seroprevalence, with a rate of lower than 6% [20]. In neighboring Switzerland, a 19% C. abortus seroprevalence in small ruminant flocks was found, with great geographical variability, reaching a 41% seroprevalence rate in the Graubünden canton [30]. German studies described low seroprevalence in Saxony, as opposed to the 94% seroprevalence in the Thuringia region [31,32]. A Spanish study conducted in the Canary Islands on 325 goats from 11 non-vaccinated herds showed a 33% seroprevalence [21], while serological examination in sheep flocks in Belgium revealed a lower seroprevalence rate of 0.68% [33]. In contrast, Krkalic and colleagues described a 84.2% seroprevalence rate in sheep in Bosnia and Erzegovina territories [34].
A previous study conducted by the authors on small ruminants’ sera in Piedmont [11] revealed a C. burnetii seroprevalence comparable to that estimated for C. abortus, suggesting a possible co-infection for these two pathogens, as confirmed by the moderate positive correlation (phi = 0.35) found between Chlamydia and Coxiella seropositivity. In particular, the analysis of the risk factors associated with Chlamydia seropositivity suggest that, at the flock level, Q fever seropositivity doubled the probability of being C. abortus seropositive farm. This is in line with a study conducted in Spain and Portugal on 1600 small ruminant abortions: C. burnetii and C. abortus are the most common abortifacient agents, with approximately 75% of abortion cases testing positive for both pathogens, followed by Toxoplasma gondii, Campylobacter sp., Salmonella enterica, Border Disease virus, and Neospora caninum [35]. In addition, another Portuguese study described a relevant presence of co-infection of C. abortus and C. burnetii in small flocks of ruminants [10]. This association seems to be the same in large ruminants: a study conducted in Bosnia and Herzegovina in cattle dairy farms found a high correlation (gamma = 0.73, herd level) between C. abortus and C. burnetii co-infections. The authors concluded that the observed overlap between other agents were more random, both at the individual and herd level [36].
In this study, the value of true seroprevalence at the animal level was 22.3%, and the risk factors analysis showed that age (younger), sex (female), and species (sheep) increased the probability of being seropositive: younger animals, especially first kidding ones, tested positive more frequently. Indeed, protective immunity, which also prevents the re-occurrence of abortions, requires time to develop. The contact between ewe and the infected placenta induces a massive antigenic stimulation, followed by the instauration of the stimulated immunity response [3,37,38]. This is why, after their first abortion, ewes became resistant to future reproductive failure caused by C. abortus, even if they may become carriers and persistent shedders of Chlamydiae, especially during the estrus [39]. In addition to abortion, vaccination also confers protective immunity to infection [40].
Also, at the herd level, the seropositivity to Q fever seemed to be associated with the presence of Chlamydia; the other associated factors were flock size, introduction of new animals, and contact with cattle. As for flock size, this factor should be considered as a proxy of herd management and a productive feature: small flocks, with less than 10 subjects, may usually be considered as being not profitable and poorly managed, with a reduced number of the introduction of animals and a low- or no-reproduction rate. In contrast, large flocks are the ones that produce newborns, lactations, milk, and cheese; in these farms, Chlamydia may circulate during reproductive seasons. It should be considered that, in Italy, diagnostic tests for Chlamydia infectious status certification are not mandatory and are not routinely applied by farm vets in cases of the introduction of new subjects in a flock. Therefore, the introduction of animals of unknown health status should be considered a great risk factor, even more for a pathogen like C. abortus with asymptomatic carriers and persistent infected hosts. To reduce the risk of C. abortus introduction in cases of animal replacement, at managing level, may be used closed flocks, negative and/or vaccinated ones [3].
Infected and aborting ewes excrete Chlamydiae in large amounts in the placenta, uterine discharges, and feces, and those biological products may contaminate pastures, in which elementary bodies may persist and play a role in infecting new subjects, including other ruminants and wild animals. The elementary bodies released into the environment have great resistance to unfavorable conditions: they may remain infectious for a few days during the spring season (mild temperatures), but can resist from weeks to months at lower temperatures during the winter season [3,28]. This prolonged persistence in the environment raises the risk of possible contact with animals and/or humans, especially vets and farm workers; mixed farming in mountain areas during spring and summer may be considered as a risk factor for C. abortus transmission. As suggested by previous studies [41,42], a vaccination program that supports strategies fighting enzootic abortions must be taken into consideration: to date, the efficacy of inactivated and/or attenuated vaccines has been questioned because they can reduce the incidence of abortions and C. abortus shedding at parturition, but they do not prevent it completely. Despite the different approaches in the design of new vaccines against C. abortus (vaccine based on recombinant antigens, DNA vaccine, subcellular vaccine), there is still a lack of safe and efficacious vaccines in terms of shedding and reproductive disorders prevention.
In the present study, no history of stillbirth, preterm deliveries, or reproductive disorders appeared to be associated with Chlamydia seropositivity in the tested farms. However, the percentage of positive herds that had a history of stillbirth (50%) and pre-term deliveries (60%) resulted in a higher percentage of positive herds than those without a history of stillbirth (38.8%) and pre-term deliveries (38.9%). It should be considered that public health authorities be notified of abortions; however, in practice, this does not happen routinely. For this reason, in the Piedmont region, the underestimation of abortions is predictable, especially in small ruminant extensive or semi-extensive managing farming systems.
The study evidenced a high seroprevalence of C. abortus in small ruminant farms in the Piedmont region. Considering its zoonotic potential and the health consequences in humans (mostly pregnant women), communication to healthcare personnel to perform thorough anamnesis in pregnant women in farming areas and to advise them to avoid contact with small ruminants seems to be strategical. of equal importance would be to raise awareness among farmers and farm vets of the importance of applying biosecurity measures on farms due to the direct and indirect forms of human transmission of the pathogen [43]. Moreover, future in-depth analysis in and outside the Piedmont region are necessary to evaluate the C. abortus spread in different territories. These data will be useful for implementing biosafety measures to reduce the impact of the pathogen on small ruminant production systems, as well as to reduce its zoonotic potential. Finally, promising new vaccine strategies may be based on chlamydial outer membrane complexes (COMCs), showing that the conformation of antigens on the chlamydial surface may be important in eliciting the required protective immune response.
5. Conclusions
This is the first investigation on the seroprevalence of C. abortus in sheep and goats in North-Western Italy. The study demonstrates a widespread, high level of antibodies to C. abortus in the small ruminant herds in the Piedmont Region associated with the presence of C. burnetii. These results could be used to raise awareness among farmers about the risk associated with Chlamydia, given its zoonotic potential, as well as to minimize the risk of C. abortus infection in flocks under similar management in other areas. The seroprevalence of C. abortus may be overestimated in terms of the antigenic cross-reactivity between Chlamydia species, which may also operate as co-infections in the same herd or in the same animal. Therefore, planned follow-up studies using molecular tests will presumably improve our knowledge regarding chlamydial infection in these species.
Conceptualization, M.L.M. and N.V.; methodology, M.L.M. and C.N.; software, N.V.; validation, M.L.M., N.V. and C.N.; formal analysis, S.S., M.B. and G.R.; investigation, M.M.; resources, M.L.M.; data curation, N.V. and C.N.; writing—original draft preparation, C.N. and M.M.; writing—review and editing, M.L.M. and N.V. All authors have read and agreed to the published version of the manuscript.
Not applicable.
Not applicable.
The data presented in this study are available on request from the corresponding author.
The authors declare no conflict of interest.
Footnotes
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Enlarge this image.Figure 1. Spatial distribution of tested flocks according to C. abortus seropositivity and provinces. Red dots are positive flocks and blue dots are negative ones. No samplings were performed in the southern parts of VC and NO provinces because these areas are mainly devoted to rice cultures.
Estimates of C. abortus seroprevalence at the flock level and the animal level for each ruminant species. At the flock level, true seroprevalence was adjusted by flock sensitivity and flock specificity, using Rogan-Gladen CL.
| Frequency (n) | Positive (n) | Raw Seroprevalence (CI95%) | True Seroprevalence (CI95%) | |
|---|---|---|---|---|
| Flock level | 202 | 80 | 39.6% (32.8–46.4%) | 56.6% (46.9–66.3%) |
| Goat | 118 | 37 | 31.4% (28.9–39.9%) | 44.8% (41.3–57.0%) |
| Sheep | 72 | 36 | 50.0% (38.2–61.8%) | 71.4% (54.6–88.3%) |
| Mixed | 12 | 7 | 58.3% (25.6–91.1%) | 83.3% (36.6–100%) |
| Animal level | ||||
| Goats | 1860 | 196 | 10.5% (6.3–14.8%) | 15.1% (9–21.1%) |
| Sheep | 1202 | 281 | 23.4% (17.4–29.4%) | 33.4% (24.9–42%) |
| Total animals | 3062 | 477 | 15.6% (11.8–19.4%) | 22.3% (16.9–27.7%) |
Association between animal characteristics and C. abortus serological status with corresponding chi square, p-value, odds ratio (OR), confidence interval (CI95%).
| Factors | Estimate | Adjuste OR | Wald CI95% | chisq | p Value | ||
|---|---|---|---|---|---|---|---|
| SPECIE | sheep | 0.7680 | 2.155 | 1.687 | 2.754 | 113.4917 | <0.0001 |
| age | 0 ≤ 1 | −0.0311 | 0.969 | 0.522 | 1.802 | 37.7271 | <0.0001 |
| age | 1 ≤ 2 | 0.4959 | 1.642 | 1.197 | 2.251 | 0.0097 | 0.9217 |
| age | >2–4 | 0.4100 | 1.507 | 1.126 | 2.016 | 9.4808 | 0.0021 |
| sex | F | 0.9378 | 2.554 | 1.353 | 4.823 | 7.6104 | 0.0058 |
| Breed | Other | 0.7322 | 2.080 | 1.599 | 2.706 | 8.3633 | 0.0038 |
| Coxiella | Positive | 0.5583 | 1.748 | 1.279 | 2.389 | 29.7540 | <0.0001 |
Univariate analysis of farm-based factors associated with C. abortus seropositivity from 202 sampled farms. Significant p-values are given in bold.
| Factors | Category | N° Flocks | Seroprevalence | Chisq | p Value |
|---|---|---|---|---|---|
| Flock location | North | 81 | 43.20% | ||
| South | 58 | 31.00% | 2.3434 | 0.3098 | |
| West | 77 | 41.60% | |||
| Flock composition | Goat | 85 | 30.60% | ||
| Goat and Sheep | 92 | 46.70% | 4.8847 | 0.087 | |
| Sheep | 39 | 41.00% | |||
| Flock size | Large (>50) | 46 | 78.30% | ||
| Medium (10–50) | 95 | 40.00% | 48.3453 | <0.0001 | |
| Small (<10) | 75 | 14.70% | |||
| Production | Meat | 99 | 36.40% | ||
| Others | 99 | 39.40% | 2.3507 | 0.3087 | |
| Milk | 18 | 55.60% | |||
| Cheese production | No | 199 | 38.70% | 0.4592 | 0.498 |
| Yes | 17 | 47.10% | |||
| Summer pasture | No | 86 | 34.90% | 1.1953 | 0.2743 |
| Yes | 130 | 42.30% | |||
| Grazing systems | Sedentary | 211 | 38.40% | 3.5436 | 0.0598 |
| Transhumant | 5 | 80.00% | |||
| Introduction previous year | No | 163 | 34.40% | 6.9476 | 0.0084 |
| Yes | 53 | 54.70% | |||
| Contacts with cattle | No | 158 | 32.90% | 10.2267 | 0.0014 |
| Yes | 58 | 56.90% | |||
| Presence of dog | No | 46 | 28.30% | 3.0125 | 0.0826 |
| Yes | 170 | 42.40% | |||
| Contact with poultry | No | 209 | 39.71% | 0.3523 | 0.5528 |
| Yes | 7 | 28.57% | |||
| Contact with wildbirds | No | 150 | 39.33% | 0.0001 | 0.9933 |
| Yes | 66 | 39.39% | |||
| Contact with others flocks | No | 141 | 34.80% | 3.6005 | 0.0578 |
| Yes | 75 | 48.00% | |||
| Contact with workers | No | 175 | 35.40% | 5.946 | 0.0148 |
| Yes | 41 | 56.10% | |||
| History of stillbirth | No | 206 | 38.80% | 0.4981 | 0.4803 |
| Yes | 10 | 50.00% | |||
| Preterm deliveries | No | 211 | 38.90% | 0.9144 | 0.339 |
| Yes | 5 | 60.00% | |||
| Reproductive disorders | No | 115 | 39.10% | 0.0051 | 0.9433 |
| Yes | 101 | 39.60% | |||
| Coxiella status | Unknown | 17 | 58.80% | ||
| Seronegative | 113 | 23.00% | 23.993 | <0.0001 | |
| Seropositive | 86 | 57.00% |
Final multivariate logistic regression model for the presence of C. abortus antibody in the sera of 202 goats and sheep farms.
| Parameter | Baseline | OR | CI95% | Wald χ2 | p-Value χ2 |
|---|---|---|---|---|---|
| Flock size Large (>50 heads) | small (<10) | 18.9 | 6.1–58.4 | 26 | 0.0001 |
| Flock size Medium (10–50) | 4 | 1.7–9.8 | 9.6 | 0.002 | |
| Coinfection with C. burnetii | Positive | 2.7 | 1.3–5.5 | 7.5 | 0.006 |
| Introduction the previous month | Yes | 2.4 | 1.1–5.3 | 5 | 0.03 |
| Contacts with cattle | Yes | 2.3 | 1.1–4.9 | 4.7 | 0.03 |
References
1. Longbottom, D.; Coulter, L.J. Animal chlamydioses and zoonotic implications. J. Comp. Pathol.; 2003; 128, pp. 217-244. [DOI: https://dx.doi.org/10.1053/jcpa.2002.0629] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/12834606]
2. OIE Terrestrial Manual. Office International des Epizooties. Chapter 3.8.5—Enzootic abortion of ewes (ovine chlamydiosis). Manual of Diagnostic Tests and Vaccines for Terrestrial Animals; World Organisation for Animal Health: Paris, France, 2023; pp. 1456-1465.
3. Turin, L.; Surini, S.; Wheelhouse, N.; Rocchi, M.S. Recent advances and public health implications for environmental exposure to Chlamydia abortus: From enzootic to zoonotic disease. Vet. Res.; 2022; 53, 37. [DOI: https://dx.doi.org/10.1186/s13567-022-01052-x] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/35642008]
4. Nayeri, T.; Sarvi, S.; Moosazadeh, M.; Daryani, A. Global prevalence of Toxoplasma gondii infection in the aborted fetuses and ruminants that had an abortion: A systematic review and meta-analysis. Vet. Parasitol.; 2021; 290, 109370. [DOI: https://dx.doi.org/10.1016/j.vetpar.2021.109370] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/33550003]
5. Zendoia, I.I.; Barandika, J.F.; Hurtado, A.; López, C.M.; Alonso, E.; Beraza, X.; Ocabo, B.; García-Pérez, A.L. Analysis of environmental dust in goat and sheep farms to assess Coxiella burnetii infection in a Q fever endemic area: Geographical distribution, relationship with human cases and genotypes. Zoonoses Public Health; 2021; 68, pp. 666-676. [DOI: https://dx.doi.org/10.1111/zph.12871]
6. Arteaga-Troncoso, G.; Luna-Alvarez, M.; Hernández-Andrade, L.; Jiménez-Estrada, J.M.; Sánchez-Cordero, V.; Botello, F.; Montes de Oca-Jiménez, R.; López-Hurtado, M.; Guerra-Infante, F.M. Modelling the unidentified abortion burden from four infectious pathogenic microorganisms (Leptospira interrogans, Brucella abortus, Brucella ovis, and Chlamydia abortus) in ewes based on artificial neural networks approach: The epidemiological basis for a control policy. Animals; 2023; 13, 2955. [DOI: https://dx.doi.org/10.3390/ani13182955]
7. Ravichandran, K.; Anbazhagan, S.; Karthik, K.; Angappan, M.; Dhayananth, B. A comprehensive review on avian chlamydiosis: A neglected zoonotic disease. Trop. Anim. Health Prod.; 2021; 53, 414. [DOI: https://dx.doi.org/10.1007/s11250-021-02859-0] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/34312716]
8. Alzuguren, O.; Domínguez, L.; Chacón, G.; Benito, A.A.; Mencía-Ares, O. Infectious abortions in small domestic ruminants in the Iberian Peninsula: Optimization of sampling procedures for molecular diagnostics. Front. Vet. Sci.; 2023; 10, 1152289. [DOI: https://dx.doi.org/10.3389/fvets.2023.1152289] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/36968459]
9. Thomas, K.M.; Kibona, T.; Claxton, J.R.; de Glanville, W.A.; Lankester, F.; Amani, N.; Buza, J.J.; Carter, R.W.; Chapman, G.E.; Crump, J.A. et al. Prospective cohort study reveals unexpected aetiologies of livestock abortion in northern Tanzania. Sci. Rep.; 2022; 12, 11669. [DOI: https://dx.doi.org/10.1038/s41598-022-15517-8] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/35803982]
10. Santos, S.; Azenha, D.; Oliveira, C.; Almeida, A. Coxiella burnetii and Chlamydia spp. coinfection in small ruminant abortion in Portugal. Small Rumin. Res.; 2022; 207, 106616. [DOI: https://dx.doi.org/10.1016/j.smallrumres.2022.106616]
11. Rizzo, F.; Vitale, N.; Ballardini, M.; Borromeo, V.; Luzzago, C.; Chiavacci, L.; Mandola, M.L. Q fever seroprevalence and risk factors in sheep and goats in northwest Italy. Prev. Vet. Med.; 2016; 130, pp. 10-17. [DOI: https://dx.doi.org/10.1016/j.prevetmed.2016.05.014] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/27435642]
12. Guatteo, R.; Seegers, H.; Taurel, A.F.; Joly, A.; Beaudeau, F. Prevalence of Coxiella burnetii infection in domestic ruminants: A critical review. Vet. Microbiol.; 2011; 149, pp. 1-16. [DOI: https://dx.doi.org/10.1016/j.vetmic.2010.10.007] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/21115308]
13. Ali, H.H.M.; Al-Bayati, L.H. Serological and Histopathological Investigation of Chlamydia abortus in Aborted Ewes in Wasit, Iraq. Arch. Razi Inst.; 2022; 77, pp. 1105-1111. [DOI: https://dx.doi.org/10.22092/ARI.2022.357270.2009] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/36618285]
14. Li, C.X.; Gao, J.; Shi, S.R.; Gao, W.W.; Zhu, X.Q.; Lei, Y.P.; Zhang, Y.; Zheng, W.B. The Seroprevalence of Chlamydia Infection in Sheep in Shanxi Province, China. Vet. Sci.; 2022; 9, 656. [DOI: https://dx.doi.org/10.3390/vetsci9120656]
15. Haif, A.; Khelifi-Ouchene, N.A.; Khelifi, M.; Ouchetati, I.; Zeroual, F.; Ouchene, N. Abortive diseases and their various associated risk factors in small ruminants in Algeria: A systematic review. Trop. Anim. Health Prod.; 2021; 53, 520. [DOI: https://dx.doi.org/10.1007/s11250-021-02926-6] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/34669051]
16. Nankam, R.C.; Kouamo, J.; Kouengoua, A.P.K.; Tchinze, G.J.T.; Dzousse, M.F.; Gapgueu, S.V.; Guefack Noumedem, R.N.; Ngoula, F. Seroprevalence and Risk Factors Associated with Toxoplasma gondii and Chlamydophila abortus Infection in Domestic Small Ruminants in Cameroon. Parasitologia; 2022; 2, pp. 198-205. [DOI: https://dx.doi.org/10.3390/parasitologia2030017]
17. Fayez, M.; Elmoslemany, A.; Alorabi, M.; Alkafafy, M.; Qasim, I.; Al-Marri, T.; Elsohaby, I. Seroprevalence and Risk Factors Associated with Chlamydia abortus Infection in Sheep and Goats in Eastern Saudi Arabia. Pathogens; 2021; 10, 489. [DOI: https://dx.doi.org/10.3390/pathogens10040489] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/33920727]
18. Benkirane, A.; Essamkaoui, S.; El Idrissi, A.; Lucchese, L.; Natale, A. A sero-survey of major infectious causes of abortion in small ruminants in Morocco. Vet. Ital.; 2015; 51, pp. 25-30. [DOI: https://dx.doi.org/10.12834/VetIt.389.1814.1]
19. Cisláková, L.; Halánová, M.; Kovácová, D.; Stefancíková, A. Occurrence of antibodies against Chlamydophila abortus in sheep and goats in the Slovak Republic. Ann. Agric. Environ. Med.; 2007; 14, pp. 243-245.
20. Masala, G.; Porcu, R.; Daga, C.; Denti, S.; Canu, G.; Patta, C.; Tola, S. Detection of pathogens in ovine and caprine abortion samples from Sardinia, Italy, by PCR. J. Vet. Diagn. Investig.; 2007; 19, pp. 96-98. [DOI: https://dx.doi.org/10.1177/104063870701900116] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/17459840]
21. Tejedor-Junco, M.T.; González-Martín, M.; Corbera, J.A.; Santana, Á.; Hernández, C.N.; Gutiérrez, C. Preliminary evidence of the seroprevalence and risk factors associated with Chlamydia abortus infection in goats on the Canary Islands, Spain. Trop. Anim. Health Prod.; 2019; 51, pp. 257-260. [DOI: https://dx.doi.org/10.1007/s11250-018-1654-z]
22. Selim, A. Chlamydophila abortus Infection in Small Ruminants: A Review. Asian J. Anim. Vet. Adv.; 2016; 11, pp. 587-593. [DOI: https://dx.doi.org/10.3923/ajava.2016.587.593]
23. VetInfo. Available online: https://www.vetinfo.it/j6_statistiche/#/report-list/20 (accessed on 24 October 2023).
24. Cannon, R.M.; Roe, R.T. Livestock Disease Surveys: A Field Manual for Veterinarians; Australian Government Publishing Service: Canberra, Australia, 1982; 35.
25. Martin, S.W.; Meek, A.H.; Willeberg, P. Veterinary Epidemiology; Iowa State University Press: Ames, IA, USA, 1987; pp. 48-78.
26. Rogan, W.J.; Gladen, B. Estimating prevalence from the results of a screening test. Am. J. Epidemiol.; 1978; 107, pp. 71-76. [DOI: https://dx.doi.org/10.1093/oxfordjournals.aje.a112510]
27. SAS Institute Inc. Base SAS® 9.4 Procedures Guide: Statistical Procedures; 2nd ed. SAS Institute Inc.: Cary, NC, USA, 2013.
28. Essig, A.; Longbottom, D. Chlamydia abortus: New Aspects of Infectious Abortion in Sheep and Potential Risk for Pregnant Women. Curr. Clin. Microbiol. Rep.; 2015; 2, pp. 22-34. [DOI: https://dx.doi.org/10.1007/s40588-015-0014-2]
29. Great Britain Disease Surveillance and Emerging Threats Reports; Available online: https://www.gov.uk/government/publications/small-ruminant-gb-disease-surveillance-and-emerging-threats-reports (accessed on 18 November 2023).
30. Borel, N.; Doherr, M.G.; Vretou, E.; Psarrou, E.; Thoma, R.; Pospischil, A. Ovine enzootic abortion: Seroprevalence in Switzerland using a competitive enzyme-linked immunosorbent assay (cELISA). Schweiz. Arch. Fur Tierheilkd.; 2002; 144, pp. 474-482. [DOI: https://dx.doi.org/10.1024/0036-7281.144.9.474]
31. Runge, M.; Binder, A.; Schotte, U.; Ganter, M. Investigations concerning the prevalence of Coxiella burnetii and Chlamydia abortus in sheep in correlation with management systems and abortion rate in Lower Saxony in 2004. Berl. Und Munch. Tierarztl. Wochenschr.; 2012; 125, pp. 138-143.
32. Lenzko, H.; Moog, U.; Henning, K.; Lederbach, R.; Diller, R.; Menge, C.; Sachse, K.; Sprague, L.D. High frequency of chlamydial co-infections in clinically healthy sheep flocks. BMC Vet. Res.; 2011; 7, 29. [DOI: https://dx.doi.org/10.1186/1746-6148-7-29] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/21679409]
33. Yin, L.; Schautteet, K.; Kalmar, I.D.; Bertels, G.; Van Driessche, E.; Czaplicki, G.; Borel, N.; Longbottom, D.D.; Frétin, D.; Dispas, M. et al. Prevalence of Chlamydia abortus in Belgian ruminants. Vlaams Diergeneeskd. Tijdschr.; 2014; 83, pp. 164-170. [DOI: https://dx.doi.org/10.21825/vdt.v83i4.16642]
34. Krkalić, L.; Šatrović, E.; Varatanović, N.; Džaja, P.; Krešimir Severin, K. Seroprevalence of Chlamydia Abortus in Sheep in Bosnia and Herzegovina. Vet. Arhiv.; 2016; 86, pp. 373-381.
35. Ramo, M.L.; Alfredo, A.; Joaquín Quílez, B.; Monteagudo, L.V.; Baselga, C.; Tejedor, M.T. Coxiella burnetii and Co-Infections with Other Major Pathogens Causing Abortion in Small Ruminant Flocks in the Iberian Peninsula. Animals; 2012; 12, 3454. [DOI: https://dx.doi.org/10.3390/ani12243454]
36. Softic, A.; Asmare, K.; Granquist, E.G.; Godfroid, J.; Fejzic, N.; Skjerve, E. The serostatus of Brucella spp., Chlamydia abortus, Coxiella burnetii and Neospora caninum in cattle in three cantons in Bosnia and Herzegovina. BMC Vet. Res.; 2018; 14, 40. [DOI: https://dx.doi.org/10.1186/s12917-018-1361-z]
37. Hagemann, J.B.; Simnache, U.; Longbottom, D.; Livingstone, M.; Maile, J.; Soutschek, E.; Walder, G.; Boden, K.; Sachse, K.; Essig, A. Analysis of Humoral Immune Responses to Surface and Virulence-Associated Chlamydia abortus Proteins in Ovine and Human Abortions by Use of a Newly Developed Line Immunoassay. J. Clin. Microbiol.; 2016; 54, pp. 1883-1890. [DOI: https://dx.doi.org/10.1128/JCM.00351-16] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/27194684]
38. Brown, J.; Entrican, G. Interferon-Gamma Mediates Long-Term Persistent Chlamydia Psittaci Infection in Vitro. J. Comp. Pathol.; 1996; 115, pp. 373-383. [DOI: https://dx.doi.org/10.1016/S0021-9975(96)80072-7] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/9004079]
39. Nietfeld, J.C. Chlamydial Infections in Small Ruminants, The Veterinary Clinics of North America. Food Anim. Pract.; 2001; 17, pp. 301-314. [DOI: https://dx.doi.org/10.1016/S0749-0720(15)30030-X] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/11515403]
40. García-Seco, T.; Pérez-Sancho, M.; Salinas, J.; Navarro, A.; Díez-Guerrier, A.; García, N.; Pozo, P.; Goyache, J.; Domínguez, L.; Álvarez, J. Effect of Preventive Chlamydia abortus Vaccination in Offspring Development in Sheep Challenged Experimentally. Front. Vet. Sci.; 2016; 3, 67. [DOI: https://dx.doi.org/10.3389/fvets.2016.00067]
41. Montbrau, C.; Fontseca, M.; March, R.; Sitja, M.; Benavides, J.; Ortega, N.; Caro, M.R.; Salinas, J. Evaluation of the Efficacy of a New Commercially Available Inactivated Vaccine Against Ovine Enzootic Abortion. Front. Vet. Sci.; 2020; 7, 2020. [DOI: https://dx.doi.org/10.3389/fvets.2020.00593]
42. Livingstone, M.; Wattegedera, S.R.; Palarea-Albaladejo, J.; Aitchison, K.; Corbett, C.; Sait, M.; Wilson, K.; Chianini, F.; Rocchi, M.S.; Wheelhouse, N. et al. Efficacy of Two Chlamydia abortus Subcellular Vaccines in a Pregnant Ewe Challenge Model for Ovine Enzootic Abortion. Vaccines; 2021; 9, 898. [DOI: https://dx.doi.org/10.3390/vaccines9080898]
43. Pichon, N.; Guindre, L.; Laroucau, K.; Cantaloube, M.; Nallatamby, A.; Parreau, S. Chlamydia abortus in Pregnant Woman with Acute Respiratory Distress Syndrome. Emerg. Infect. Dis.; 2020; 26, pp. 628-629. [DOI: https://dx.doi.org/10.3201/eid2603.191417]
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; Mandola, Maria Lucia 1 1 Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta, S.S. Diagnostica Virologica Specialistica, Via Bologna 148, 10154 Torino, Italy;
2 Servizio Veterinario ASL TO5, S.C. Sanità Animale, 10023 Chieri, Italy;
3 Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta, S.S. Osservatorio delle Regioni, Via Bologna 148, 10154 Torino, Italy;