Seroprevalence and Risk Factors of Chlamydia abortus Infection in Goats in Hunan Province,Subtropical China

Abstract

Chlamydia abortus is an obligate intracellular Gram-negative bacteria, which can infect animals and human, including goats. However, little information on C. abortus infection is available in goats in Hunan province, subtropical China. To investigate the seroprevalence and risk factors of C. abortus infection in goats in Hunan province, China, a total of 911 goat blood samples were collected randomly from 14 herds having number of goats ranging from 1000 to 3000 from March 2014 to December 2015. Seropositive animals were found in 11 out of 14 (78.57%) goat herds with seroprevalence ranging from 0.00% to 29.94% in individual herds. Overall, the seroprevalence of C. abortus infection was different among regions (southern Hunan: 1.78%; northeast Hunan: 5.47%; and west Hunan: 15.29%), gender (male: 4.58% and female: 9.10%), seasons (spring: 5.97%; summer: 2.61%; autumn: 16.88%; and winter: 10.94%), and ages (year ≤1: 2.39%; 1 < year ≤2: 9.58%; 2 < year ≤3: 9.16%; and year >3: 17.57%). Risk factors for C. abortus infection were associated with region, season, and age in this study. To our knowledge, this is the first document to demonstrate the existence of C. abortus infection in goats, and the seroprevalence was 8.45% out of 911 goats in Hunan province.

Introduction

C hlamydiaceae are obligate intracellular Gram-negative bacteria with broad host spectrum in many countries and can cause various clinical symptoms (Pantchev et al. 2010, Rohde et al. 2010, Schautteet and Vanrompay 2011). Chlamydiaceae have a single genus Chlamydia, but includes 12 species (Longbottom and Coulter 2003, Stephens et al. 2009, Vorimore et al. 2013). Some of them can infect goats, such as Chlamydia pecorum, Chlamydia abortus, Chlamydia psittaci, and Chlamydia suis (Rodolakis and Laroucau 2015). Nevertheless, C. abortus is one of the most important pathogens that could cause abortion in goats being asymptomatic (Szeredi and Bacsadi 2002). Furthermore, C. abortus could be transmitted to pregnant women by an aborted fetus of animal, causing the same outcome for pregnant women (Essig and Longbottom 2015, Opota et al. 2017).

Goat (Capra aegagrus hircus) has a meaningful value and close relationship with human life, which can provide wool, leather, meat, milk, and other products to human beings. An increasing number of people are beginning to raise goats for increasing their revenue. The goat industry is an important pillar industry for agricultural development with 150 million goats in China (Ding and Xiao 2016). However, a variety of diseases, including C. abortus, threaten the development of goat industry (Seth-Smith et al. 2017). Moreover, human health can be threatened by touching infected goats, especially the breeder and veterinarian. So, it is significant and necessary to know the data of C. abortus infection in goats.

Although some serological studies on C. abortus infection are available worldwide (Li et al. 2015, Qin et al. 2015, Sun et al. 2015, Hireche et al. 2016), little information is available about the seroprevalence of C. abortus infections in goats in China. Therefore, this study was conducted to investigate the seroprevalence of C. abortus infection in goats and explore associated risk factors in Hunan province, subtropical China. The results can provide essential reference to prevent and control C. abortus infection in goats in Hunan province, subtropical China.

Materials and Methods

The investigated sites and serum samples

The present investigation was conducted in 14 cities (14 herds) and the number of goats in each herd ranged from 1000 to 3000 in Hunan province. Those cities were divided ordinarily into three regions based on economic and geographical conditions, west Hunan, northeast Hunan, and southern Hunan. A total of 911 goat blood samples were collected randomly from 14 herds from March 2014 to December 2015, that is, 169 samples from southern Hunan, 402 samples from northeast Hunan, and 340 samples from west Hunan. Information of goats was obtained by owners, including region, gender, season, age, and so on. Blood samples of goats were kept at 37°C for 1 h, centrifuged at 1500 g for 10 min, and serum was stored at −20°C until further assay.

Serological examination

A commercially available Indirect Hemagglutination Assay (IHA) kit (Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China) was used to test C. abortus antibodies with 100% sensitivity and 95% specificity. The Ministry of Agriculture of the People's Republic of China (NY/T 562-2015) has acknowledged the sensitivity and specificity of the method used in this study (Qin et al. 2015). The detection procedure was carried out according to the manufacturer's instructions as described previously (Zhou et al. 2013, Chen et al. 2014, Qin et al. 2015). In brief, each of the goat sera was diluted from 1:4 to 1:16, using fourfold dilutions in V-bottomed 96-well microtiter plates with positive, negative, and blank control. The antigen was added to each well, shaking gently for 2 min. Then, the sealed V-bottomed 96-well plates were incubated for 12 h at 37°C. The assay was considered positive when the compound of antigen–antibody agglutination layer occurred at 1:16. Sera with dubious results between 1: 4 and 1: 16 were retested.

Statistical analyses

The seroprevalence in different regions, gender, season, and age was analyzed, and the potential relationship and risk factors of C. abortus infection in goats were discussed by statistical analysis. p < 0.05 was considered statistical significant. Each factor was analyzed with odds ratios (ORs) and 95% confidence intervals (CIs) in this study. All statistical analyses were performed by SAS (Statistical Analysis System, Version 9.1) (Zhang et al. 2016, Zheng et al. 2016).

Results and Discussion

In this study, 77 of 911 (8.45%, 95% CI = 6.65–10.26) examined goat sera were positive by IHA at a 1:16 cutoff. And seropositive animals were found in 11 out of 14 (78.57%) goats herds with seroprevalence ranging from 0.00% to 29.94% in individual herds (Table 1). The C. abortus seroprevalence was different among regions (southern Hunan: 1.78%; northeast Hunan: 5.47%; and west Hunan: 15.29%), gender (male: 4.58% and female: 9.10%), seasons (spring: 5.97%; summer: 2.61%; autumn: 16.88%; and winter: 10.94%), and ages (year ≤1: 2.39%; 1 < year ≤2: 9.58%; 2 < year ≤3: 9.16%; and year >3: 17.57%) (Table 2).

Table 1.

The Results of Chlamydia abortus Infection in Goats in 14 Cities (14 Herds) in Hunan Province, Subtropical China

Region	City	No. of goats examined	No. of goats positive	Prevalence %
Southern Hunan	Hengyang	59	0	0.00
	Yongzhou	50	1	2.00
	Chenzhou	60	2	3.33
	Total	169	3	1.78
Northeast Hunan	Changde	78	0	0.00
	Yueyang	58	3	5.17
	Yiyang	48	4	8.33
	Changsha	40	6	15.00
	Loudi	36	0	0.00
	Xiangtan	102	4	3.92
	Zhuzhou	40	5	12.5
	Total	402	22	5.47
West Hunan	Zhangjiajie	79	1	1.27
	Xiangxi	157	47	29.94
	Huaihua	21	3	14.29
	Shaoyang	83	1	1.20
	Total	340	52	15.29
Total		911	77	8.45

Table 2.

Analysis of the Variable Associated with Chlamydia abortus Seroprevalence in Goats in Hunan Province, Subtropical China

Variable	Category	No. of goats examined	No. of goats positive	Prevalence % (95% CI)	p	OR (95% CI)
Region	Southern Hunan	169	3	1.76 (0.00–3.77)	<0.01	Reference
	Northeast Hunan	402	22	5.47 (3.25–7.70)		3.20 (0.95–10.85)
	West Hunan	340	52	15.29 (11.65–19.12)		9.99 (3.07–32.49)
Gender	Male	131	6	4.58 (1.00–8.56)	>0.05	Reference
	Female	780	71	9.10 (7.08–11.12)		2.09 (0.89–4.90)
			10
Season	Spring	67	4	5.97 (0.30–11.64)	<0.01	2.37 (0.74–7.58)
	Summer	460	12	2.61 (1.15–4.07)		Reference
	Autumn	320	54	16.88 (12.77–20.98)		7.58 (3.98–14.43)
	Winter	64	7	10.94 (3.29–11.58)		4.59 (1.73–12.12)
Age	0 < year ≤1	209	5	2.39 (0.32–4.46)	<0.01	Reference
	1 < year ≤2	355	34	9.58 (6.52–13.64)		4.32 (1.66–11.23)
	2 < year ≤3	273	25	9.16 (5.74–12.58)		4.11 (1.55–10.94)
	Year >3	74	13	17.57 (8.90–26.24)		8.70 (2.98–25.36)
Total		911	77	8.45 (6.65–10.56)

CI, confidence intervals; OR, odds-ratios.

The overall seroprevalence of C. abortus was 8.45% in goats in this study, which was higher than 4.87% in dairy goat farms by ELISA in a hot region in Mexico (Campos-Hernandez et al. 2014). All goats were naturally infected without vaccination in all sampled herds in this study. It cannot be ignored that the seroprevalence could be overestimated, not only in this study that used the commercially available IHA kit but also in previous studies that used the ELISA kit, due to antigenic cross-reactivity with the other organisms that have some similarities to C. abortus (Lme et al. 2010).

No significant difference was observed (p > 0.05), although females (9.10%) had two times (OR = 2.09, 95% CI = 0.89–4.90) higher risk of acquiring C. abortus infection than males (4.58%) in the gender group. However, geographical location is revealed as a risk factor for C. abortus infection in goats (p < 0.01). Among these three regions, goats in west Hunan region (15.29%) had nearly 10 times (OR = 9.99, 95% CI = 3.075–32.49) higher risk of acquiring C. abortus infection than goats in southern Hunan region (1.78%). Compared with goats in southern Hunan region, goats in northeast Hunan region (5.47%) had more than three times (OR = 3.20, 95% CI = 0.95–10.85) higher risk of C. abortus infection. These results indicated that goats had the lowest risk to acquire C. abortus infection in southern Hunan region. Remarkably, although the overall seroprevalence of C. abortus infection was 5.47% in northeast Hunan region, it was still existence uninfected herds in Changde and Loudi city. This result revealed that it was relatively safe for goats in southern Hunan region. Goats had the highest seroprevalence in west Hunan region surrounded by Wuling and Xuefeng mountains and Yunnan Guizhou Plateau. In this study, we only detected the representative herds in which the goat numbers ranged from 1000 to 3000, revealing that 15.29% C. abortus infection in west Hunan region, so we speculated that it could be existence higher seroprevalence of C. abortus infection in this mountainous area where exist a large number of free-range goat.

Furthermore, in the season grou, the seroprevalence of C. abortus infection ranged from 2.61% in to 16.88%, and significant difference of C. abortus infection be observed in season group (p < 0.01). The highest seroprevalence (16.88%) was found in the autumn group that had more than seven times (OR = 7.58, 95% CI = 3.98–14.43) higher risk of C. abortus infection than the summer group (2.61%), which had the lowest seroprevalence. Remarkably, the positive rate of C. abortus infection was gradually decreasing from autumn to next summer, suggesting that the change in the positive rate could be directly related to the season (or climate), which needs further study.

The seroprevalence of C. abortus infection in different age groups was different, ranging from 2.39% in year ≤1 group to 17.57% in year >3 group. Significantly, the seroprevalence of C. abortus infection was nearly gradually increased with increase of age in goats. Compared with goats in year ≤1 group, goats in the year >3 group had more than eight times (OR = 8.70, 95% CI = 2.98–25.36) higher risk of acquiring C. abortus infection, and goats in 2 < year ≤3 group as well as 1 < year ≤2 group had more than four times higher risk of acquiring C. abortus infection, which was consistent with previous studies in other aged animals susceptible to C. abortus (Qin et al. 2014).

In conclusion, this study showed existence of C. abortus antibodies in goats, and the seroprevalence was 8.45% out of 911 goats in Hunan province, which suggested that breeders do not buy goats (males and females), embryos, or semen from other farms without knowing the health status of C. abortus infection or from the areas that lack quarantine. Region, season, and age as risk factors for C. abortus infection were also confirmed in this study. This is the first investigation to detect the prevalence of C. abortus infection in goats, offering basic data for prevention and control of C. abortus infection in goats in Hunan province, subtropical China.

Footnotes

Acknowledgment

Project support was provided, in part, by the Scientific Research Fund of Hunan Provincial Education Department (no. 16A102).

Author Disclosure Statement

No competing financial interests exist. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the funding agencies.

References

Campos-Hernandez

, Vazquez-Chagoyan

, Salem

, Saltijeral-Oaxaca

, et al. Prevalence and molecular identification of Chlamydia abortus in commercial dairy goat farms in a hot region in Mexico. Trop Anim Health Prod, 2014; 46:919–924.

Chen

, Gong

, Zheng

, Cao

, et al. Seroprevalence of Chlamydophila abortus infection in yaks (Bos grunniens) in Qinghai, China. Trop Anim Health Prod, 2014; 46:503–507.

Ding

, Xiao

. Analysis of the current situation and trend of mutton supply and demand in China. Arg Econ Manage, 2016; 37:86–96. (in Chinese)

Essig

, Longbottom

. Chlamydia abortus: New aspects of infectious abortion in sheep and potential risk for pregnant women. Curr Clin icrobiol Rep, 2015; 2:22–34.

Hireche

, Ababneh

, Bouaziz

, Boussena

. Seroprevalence and molecular characterization of Chlamydia abortus in frozen fetal and placental tissues of aborting ewes in northeastern Algeria. Trop Anim Health Prod, 2016; 48:255–262.

, Cao

, Fu

, Chao

, et al. Identification and characterization of Chlamydia abortus isolates from yaks in Qinghai, China. Biomed Res Int, 2015; 2015:658519.

Lme

, Lancaster

, Butler

, Cgv

. Serological analysis of Chlamydophila abortus in Australian sheep and implications for the rejection of breeder sheep for export. Aust Vet J, 2010; 88:32–38.

Longbottom

, Coulter

. Animal chlamydioses and zoonotic implications. J Comp Pathol, 2003; 128:217–244.

Opota

, Brouillet

, Greub

, Jaton

. Methods for real-time PCR-based diagnosis of Chlamydia pneumoniae, Chlamydia psittaci, and Chlamydia abortus Infections in an opened molecular diagnostic platform. Methods Mol Biol, 2017; 1616:171–181.

10.

Pantchev

, Sting

, Bauerfeind

, Tyczka

, et al. Detection of all Chlamydophila and Chlamydia spp. of veterinary interest using species-specific real-time PCR assays. Comp Immunol Microbiol Infect Dis, 2010; 33:473–484.

11.

Qin

, Huang

, Yin

, Tan

, et al. Seroprevalence and risk factors of Chlamydia abortus infection in free-ranging white yaks in China. BMC Vet Res, 2015; 11:8.

12.

Qin

, Yin

, Cong

, Zhou

, et al. Seroprevalence and risk factors of Chlamydia abortus infection in Tibetan sheep in Gansu province, northwest China. Sci World J, 2014; 2014:193464.

13.

Rodolakis

, Laroucau

. Chlamydiaceae and chlamydial infections in sheep or goats. Vet Microbiol, 2015; 181:107–118.

14.

Rohde

, Straube

, Essig

, Reinhold

, et al. Chlamydial zoonoses. Dtsch Arztebl Int, 2010; 107:174–180.

15.

Schautteet

, Vanrompay

. Chlamydiaceae infections in pig. Vet Res, 2011; 42:29.

16.

Seth-Smith

HMB

, Buso

, Livingstone

, Sait

, et al. European Chlamydia abortus livestock isolate genomes reveal unusual stability and limited diversity, reflected in geographical signatures. BMC Genomics, 2017; 18:344.

17.

Stephens

, Myers

, Eppinger

, Bavoil

. Divergence without difference: Phylogenetics and taxonomy of Chlamydia resolved. FEMS Immunol Med Microbiol, 2009; 55:115–119.

18.

Sun

, Meng

, Cong

, Shan

, et al. Herd-level prevalence and associated risk factors for Toxoplasma gondii, Neospora caninum, Chlamydia abortus and bovine viral diarrhoea virus in commercial dairy and beef cattle in eastern, northern and northeastern China. Parasitol Res, 2015; 114:4211–4218.

19.

Szeredi

, Bacsadi

. Detection of Chlamydophila (Chlamydia) abortus and Toxoplasma gondii in smears from cases of ovine and caprine abortion by the streptavidin-biotin method. J Comp Pathol, 2002; 127:257.

20.

Vorimore

, Hsia

, Huot-Creasy

, Bastian

, et al. Isolation of a New Chlamydia species from the feral sacred ibis (Threskiornis aethiopicus): Chlamydia ibidis . PLoS One, 2013; 8:e74823.

21.

Zhang

, Zheng

, Ma

, Yao

, et al. Occurrence and multilocus genotyping of Giardia intestinalis assemblage C and D in farmed raccoon dogs, Nyctereutes procyonoides, in China. Parasit Vectors, 2016; 9:471.

22.

Zheng

, Cong

, Meng

, Ma

, et al. Seroprevalence and risk factors of Toxoplasma gondii infection in farmed minks (Neovison vison) in northeastern and eastern China. Vector Borne Zoonotic Dis, 2016; 16:485–488.

23.

Zhou

, Zhao

, Xia

, Xu

, et al. Seroprevalence of chlamydial infection in dairy cattle in Guangzhou, southern China. Ir Vet J, 2013; 66:2.