Seroprevalence of Toxoplasma gondii infection in dairy goats in Shaanxi Province, Northwestern China
- Guang-Hui Zhao†1, 2,
- Miao-Tao Zhang†1,
- Li-Hui Lei3,
- Chuan-Chuan Shang1,
- Duo-Yao Cao1,
- Ting-Ting Tian1,
- Jie Li1,
- Jun-Yan Xu1,
- Yun-liang Yao1,
- De-Kun Chen1Email author and
- Xing-Quan Zhu2, 4, 5Email author
© Zhao et al; licensee BioMed Central Ltd. 2011
Received: 30 January 2011
Accepted: 1 April 2011
Published: 1 April 2011
Toxoplasma gondii is an important zoonotic pathogen causing significant human and animal health problems. Infection in dairy goats not only results in significant reproductive losses, but also represents an important source of human infection due to consumption of infected meat and milk. In the present study we report for the first time seroprevalence of T. gondii infection in Guanzhong and Saanen dairy goats in Shaanxi province, Northwestern China.
Sera from 751 dairy goats from 9 farms in 6 counties were examined for T. gondii antibodies with an indirect haemagglutination (IHA) test. Antibodies to T. gondii were detected in 106 (14.1%) serum samples, with antibody titres ranging from 1:64 to 1:1024. Seropositive goats were found in all 9 farms and seroprevalences in Guanzhong (16.3%, 75/461) and Saanen (10.7%, 31/290) dairy goats were not statistically significantly different. All the factors (sex, age and location) reported in the present study affected prevalence of infection, and seroprevalence increased with age, suggesting postnatal acquisition of T. gondii infection.
The results of the present survey indicate that infection by T. gondii is widely prevalent in dairy goats in Shaanxi province, Northwestern China, and this has implications for prevention and control of toxoplasmosis in this province.
Toxoplasma gondii can infect nearly all the warm-blooded animals, including mammals and birds throughout the world [1–4]. Infection in dairy goats not only results in significant reproductive losses, but also represents an important source of human infection due to consumption of infected meat and milk constituting zoonotic transmission [3, 5–8]. The seroprevalence of T. gondii in goats has been surveyed in many countries, and these worldwide reports were recently summarized . Viable T. gondii was isolated from goats killed for human consumption [9, 10].
Prevalence of Toxoplasma gondii infection in goats in People's Republic of China (PRC)
Factors associated with seroprevalence of Toxoplasma gondii infection in dairy goats in Shaanxi Province, Northwestern China
No. positive (%)
Exp (95% CI)
Saanen dairy goat
Guanzhong dairy goat
2.233 (0.406, 12.269)
0.259 (0.080, 0.833)
0.363 (0.189, 0.696)
0.612 (0.227, 1.646)
Zhuangli town, Fuping county
Wangliao town, Fuping county
13.031 (4.830, 35.158)
Dongshangguan, Fuping county
3.105 (1.108, 8.698)
Mizi town, Fuping county
1.474 (0.499, 4.349)
5.479 (0.938, 31.997)
1.584 (0.195, 12.834)
9.030 (1.093, 74.597)
2.823 (0.265, 30.105)
5.213 (0.638, 42.576)
Blood sampling and serological examination
Approximately 3 ml of blood were obtained via a jugular vein, centrifuged at 2000 g for 5 min and stored at -20°C. Antibodies to T. gondii were determined in sera using an indirect hemagglutination antibody (IHA) test with a commercially available kit (Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, China) according to the manufacturer's instructions. In brief, sera were added to 96 well V bottomed polystyrene plates, and diluted in a four-fold series from 1:4 to 1:2048. The plates were shaken for 2 min and then incubated at 37°C for 2 h without shaking. The test was considered positive when a layer of agglutinated erythrocytes was formed in wells at dilutions of 1:64 or higher, and positive and negative controls were included in each test.
Differences in seroprevalence of infected goats between the two breeds and among associated factors were analyzed using the binary logistic regression in SPSS for Windows (Release 17.0 standard version, SPSS Inc., Chicago, IL, USA), 95% confidence intervals (CI) are given. The Differences between levels within factors and interactions were considered to be statistically significant and highly significant when P < 0.05 and P < 0.01, respectively.
Results and discussion
Antibodies to T. gondii were found in 106 (14.1%) of 751 goats with titres of 1:64 in 79 dairy goats, 1:256 in 16 dairy goats and 1:1024 in 11 dairy goats. Both Saanen and Guanzhong dairy goats were positive for T. gondii antibody, with higher prevalence in Guanzhong dairy goats than in Saanen dairy goats. The binary logistic regression showed that all the factors (sex, age and location) reported in the present study affected prevalence of infection. The seroprevalence in male goats (15.7%) was higher than that in females (14.0%), and the difference was statistically significant (Exp = 0.259, CI = 0.080-0.833, P = 0.023) (Table 2). Seroprevalence in goats increased progressively with age, and prevalence in older goats (>2-year-old) was higher than that in animals below 2-year-old. Seroprevalence at the individual farms ranged from 5.1% to 36.8% and seropositive goats were found in all 9 farms (Table 2).
In the present study, the overall seroprevalence was 14.1%, which was far less than other reports from the PRC (Table 1). The difference could be associated with ecological conditions, life styles of inhabitants, climates, husbandry practice and the numbers of cats and rodents present. The present study showed that the breeding dairy goats had the lowest prevalence (Table 2), possibly because breeding goats have better welfare and relatively less chance to come into contact with cats and rodents that play a significant role in the transmission of T. gondii. The Guanzhong dairy goat is a unique goat breed in Shaanxi province. The prevalence in Guanzhong dairy goats was different among individual farms, ranging from 5.6% to 36.8%, which is slightly higher than that in Saanen dairy goats. The differences may be attributed to breed differences in susceptibility to T. gondii. The present study showed that older dairy goats (>2-year-old) were more likely to be seropositive than goats under 2-year-old, which provided further evidence for the increased risk of T. gondii infection with acquisition of age through ingestion of infective oocysts from the environment.
The results of the present survey indicated that infection of dairy goats with T. gondii is widespread in Shaanxi Province, China, which is of public health concern and has implications for prevention and control of toxoplamosis in this province. Therefore, integrated control strategies and measures are recommended to prevent and control T. gondii infection in dairy goats.
1College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi Province 712100, PR China. 2State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu Province 730046, PR China. 3Department of Animal Husbandry and Veterinary Medicine, Beijing Vocational College of Agriculture, Beijing 102442, PR China. 4College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang Province 163319, PR China. 5College of Animal Science and Technology, Yunnan Agricultural University, Kunming, Yunnan Province 650201, PR China.
Project support was provided in part by grants from the Special Fund for Agro-scientific Research in the Public Interest (Grant No. 201103038) to JL; the State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, the Program for Changjiang Scholars and Innovative Research Team in University (Grant No. IRT0723) and the Special Fund for Agro-scientific Research in the Public Interest (Grant No. 200803017) to XQZ; and the Special Funds for Talents in Northwest A & F University to GHZ.
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