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Seroprevalence of Neospora caninum Infection in Dairy Cattle of Southern ChinaAuthor(s): Hui-Yan Xia, Dong-Hui Zhou, Kun Jia, Xian-Bin Zeng, Dun-Wei Zhang, Li-Xuan She, Rui-Qing Lin, Zi-Guo Yuan, Shou-Jun Li, and Xing-Quan ZhuSource: Journal of Parasitology, 97(1):172-173. 2011.Published By: American Society of ParasitologistsDOI: http://dx.doi.org/10.1645/GE-2643.1URL: http://www.bioone.org/doi/full/10.1645/GE-2643.1

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Seroprevalence of Neospora caninum Infection in Dairy Cattle of Southern China

Hui-Yan Xia*�, Dong-Hui Zhou*�, Kun Jia*, Xian-Bin Zeng*, Dun-Wei Zhang*, Li-Xuan She*, Rui-Qing Lin*, Zi-Guo Yuan*, Shou-Jun Li*I,and Xing-Quan Zhu`§I, *College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province 510642, China;�These authors contributed equally to this work; `College of Animal Science and Technology, Yunnan Agricultural University, Kunming, YunnanProvince 65021, China; §State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province,Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu Province 730046, China; ITo whom correspondence should be addressed. e-mail:xingquanzhu1@hotmail.com; shoujunli@scau.edu.cn

ABSTRACT: A seroepidemiological survey of Neospora caninum infectionin dairy cattle was carried out in China’s southern Guangdong Provincebetween July 2009 and March 2010. A total of 370 serum samples of dairycattle was collected from 5 farms and examined for antibodies to N.caninum by enzyme-linked immunosorbent assay. The overall seropreva-lence of N. caninum in dairy cattle was 18.9% (70/370). The seroprevalenceof N. caninum in aborting cows (22.7%) was higher than that innonaborting cows (16.3%), but the difference was not statisticallysignificant (P . 0.05). Five-yr-old dairy cattle had the highestseroprevalence (27.8%), followed by those that were 6-yr-old (20.4%).Dairy cattle with 4 pregnancies had the highest seroprevalence (29.2%).There was no apparent association of N. caninum seropositivity with ageor number of pregnancies (P . 0.05). The results of the present surveyindicated that the infection with N. caninum is prevalent in dairy cattle ofall ages in southern China, which may be one of the causes of bovineabortion. This is the first report of seroprevalence of N. caninum in dairycattle in southern China.

Abortions and neonatal mortality are major problems in livestockproductions, and neosporosis caused by Neospora caninum is a majorcause of abortions in cattle (Dubey et al., 2007). Infection with N. caninumhas been associated with a 3–4% decrease in milk production and ashortened production life (Thurmond and Hietala, 1997; Hernandez et al.,2001). A number of serological techniques have been developed to detectspecific antibodies to N. caninum; these include indirect fluorescentantibody tests, a variety of enzyme-linked immunosorbent assays(ELISAs), and a N. caninum–agglutination test (Wapenaar et al., 2007;Zhai et al., 2007).

A number of surveys of N. caninum infection in dairy cattle have beencarried out in many countries and regions (Dubey, 2003; Dubey et al.,2007) of the world. One such survey has been conducted in northeasternChina (Wang et al., 2010), revealing a prevalence of 13.3%. However,there has been no comprehensive survey of N. caninum infection in dairycattle in southern China, except a pilot survey in which only 18 dairy cattlewere examined (Yu et al., 2007). Southern China is very different fromnortheastern China in terms of climate, ecology, and animal productionpractice. The objective of the present study was to determine theseroprevalence of N. caninum infection in dairy cattle in China’s southernGuangdong Province.

Blood samples were collected from 370 dairy cattle on 5 farms (Table I)in Guangdong Province between July 2009 and March 2010. The dairycattle populations represented a local breed (Chinese Holstein), as well asintroduced breeds (American/Australian Holstein-Friesian and BritishJersey). The animals of each herd were randomly selected, and 1 bloodsample was collected from each animal. All the blood samples wereimmediately transported to the laboratory at South China AgriculturalUniversity (Guangzhou, Guangdong Province). Blood samples werecentrifuged at 1,000 g for 10 min, and serum was obtained, frozen, andstored at 220 C until analysis. The breed, age, and pregnancy andabortion history of dairy cattle were obtained through a questionnaire atthe time of blood collection.

Antibodies to N. caninum in dairy cattle serum samples were detected byELISA using the N. caninum antibody test kit (IDEXX Laboratories,Westbrook, Maine) according to the manufacturer’s recommendations.

The prevalence data were statistically analyzed using SPSS software(SPSS, version 13.0, Chicago, Illinois). Chi-square analysis was used to

compare the seroprevalence of aborting cows with that of nonabortingcows and to analyze the difference in seroprevalence of dairy cattle fromdifferent farms, between different age groups and pregnancy groups. Thedifferences were considered statistically significant if P , 0.05.

Neospora caninum antibodies were detected in 70 (18.9%) of 370 dairycattle (Table I). The overall seroprevalence was higher than that reportedin other countries (Garcia-Vazquez et al., 2009; Yildiz et al., 2009), andHeilongjiang (Wang et al., 2010) and Qinghai (Liu et al., 2008) Provinces,China, similar to that reported in West Africa (Kamga-Waladjo et al.,2010), but lower than that reported in northwest Spain (Panadero et al.,2010).

All of the 370 dairy cows had a pregnancy history record for the analysisof the association of abortion and N. caninum infection. The seroprev-alence of N. caninum in aborting dairy cattle (22.7%) was higher than thatin nonaborting dairy cattle (16.3%), but the difference was not statisticallysignificant (P . 0.05). Our study found that abortions in N. caninum–positive cows occurred mostly in the second and third trimesters,consistent with the finding by Weston et al. (2005), who reported thatabortions occurred predominantly between days 120 and 152 of gestationamong N. caninum–seropositive dairy cows.

As shown in Table II, the seroprevalence varied in different age groups,ranging from 12.0% to 27.8%, with the highest prevalence of 27.8% in 5-yr-old dairy cattle, followed by 6-yr-old dairy cattle (20.4%). However,there were no statistically significant differences in the prevalence amongdifferent age groups (P . 0.05). An early study in the Netherlands showedsimilar seroprevalence across all age groups, suggesting that the infectionhad most likely been perpetuated by vertical transmission (Wouda et al.,1999). However, a Danish study showed that seropositivity increased with

DOI: 10.1645/GE-2643.1

TABLE I. Seroprevalence of Neospora caninum infection in dairy cattle byELISA in China’s southern Guangdong Province.

Codes of farm No. examined No. positive Prevalence (%)

A 74 9 12.2

B 75 14 18.7

C 60 12 20.0

D 60 8 13.3

E 101 27 26.7

Total 370 70 18.9

TABLE II. Seroprevalence of Neospora caninum infection in dairy cattle ofdifferent ages by ELISA in China’s southern Guangdong Province.

Age (yr) No. examined No. positive Prevalence (%)

1 25 4 16.0

2 50 7 14.0

3 52 8 15.4

4 25 3 12.0

5 90 25 27.8

6 49 10 20.4

7 50 8 16.0

$8 29 5 17.2

J. Parasitol., 97(1), 2011, pp. 172–173

F American Society of Parasitologists 2011

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age (Jensen et al., 1999). Neither of these findings was observed in ourstudy. The varied seroprevalence in different age groups suggested thepossibility of horizontal transmission in the investigated herds.

The association between seroprevalence and numbers of pregnancieswas also analyzed in our study (Table III). The seroprevalence in dairycattle that had given 4 births was the highest (29.2%), followed by dairycattle with 5 pregnancies, but the difference in seroprevalence betweendairy cattle with different numbers of pregnancy was not statisticallysignificant (P . 0.05). Jensen et al. (1999) found that seropositivity rosewith increasing numbers of pregnancy, but a positive relationship was notobserved in our study.

In conclusion, the results of the present survey indicated that theinfection with N. caninum is prevalent in dairy cattle of all ages in southernChina, which may be one of the causes of bovine abortion. These resultsprovided base-line data for the implementation of improved strategies andmeasures for the control of infection with N. caninum in dairy cattle insouthern China.

This work was supported, in part, by grants from the National SpecialResearch Program for Non-Profit Trades (Agriculture) (GrantNo. 200803017), the Yunnan Provincial Program for Introducing High-level Scientists (Grant No. 2009CI125), the State Key Laboratory ofVeterinary Etiological Biology, Lanzhou Veterinary Research Institute,Chinese Academy of Agricultural Sciences, the Program for ChangjiangScholars and Innovative Research Team in University (GrantNo. IRT0723), the Guangdong Scientific and Technological Programs(Grant No. 2008A020100012), and the Scientific and TechnologicalPrograms of Guangzhou City (Grant No. 2009Z1-E731).

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TABLE III. Seroprevalence by ELISA for Neospora caninum infection indairy cattle in China’s southern Guangdong Province, according to thenumber of pregnancies.

No. pregnancies No. examined No. positive Prevalence (%)

0 48 8 16.7

1 72 14 19.4

2 56 9 16.1

3 40 6 15.0

4 65 19 29.2

5 34 7 20.6

6 38 5 13.2

$7 17 2 11.8

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