Xiao-Xuan Zhang

Toxocara Seroprevalence among Clinically Healthy Individuals, Pregnant Women and Psychiatric Patients and Associated Risk Factors in Shandong Province, Eastern China

Background Toxocarosis is a widespread zoonosis caused by the ascarid nematodes Toxocara canis and Toxocara cati, which primarily infect dogs and cats, respectively. Most human infections with Toxocara are asymptomatic; however, some infected individuals may develop a serious illness and even death. Nevertheless, epidemiological knowledge regarding the prevalence and risks associated with Toxocara infection is limited in China. Therefore, we performed a cross-sectional pilot study and estimated the seroprevalence of Toxocara infection in humans in Shandong Province, eastern China for the first time, from June 2011 to July 2013, involving clinically healthy individuals, pregnant women and psychiatric patients, aiming to attract public attention to Toxocara infection. Methodology/Principle Findings Seroprevalence of Toxocara was determined using an enzyme-linked immunosorbent assay based on a cross-sectional study conducted in Qingdao and Weihai, Shandong Province, eastern China. Factors potentially associated with Toxocara infection were identified by logistic regression analysis. The overall Toxocara seroprevalence among the study population (n = 2866) was 12.25%, and a significantly higher seroprevalence in psychiatric patients (16.40%, 73/445) than that in clinically healthy individuals (13.07%, 187/1431) and pregnant women (9.19%, 91/990) was revealed. Univariate analyses suggested that keeping dogs at home (OR = 0.06, 95% CI 0.05–0.08, P<0.001), contact with cats and dogs (OR = 0.42, 95% CI 0.33–0.53, P<0.001) and exposure with soil (OR = 0.37, 95% CI 0.28–0.49, P<0.001) were risk factors associated with Toxocara infection. Conclusions/Significance The present study revealed, for the first time, that human infection with Toxocara is common in eastern China, posing a significant public health concern. Increasing human and dog populations, population movements and climate change all will serve to increase the importance of this zoonosis. Further studies under controlled conditions are necessary to define potential morbidity associated with Toxocara infection.

Prevalence, Risk Factors and Multilocus Genotyping of Giardia intestinalis in Dairy Cattle, Northwest China

Giardia intestinalis is a cosmopolitan protozoan parasite that can infect a range of animals, including dairy cattle. As information regarding the prevalence and genotyping of G. intestinalis infection in dairy cattle in northwestern China is limited, 2,945 feces samples from 1,224 dairy cattle in Gansu Province and from 1,614 in Ningxia Hui Autonomous Region (NXHAR) were examined between December 2012 and March 2014. The overall prevalence of G. intestinalis was 3.63% (107/2,945), with 2.63% and 4.38% in Gansu and NXHAR, respectively. Logistic regression analysis showed region, age and season to be significant risk factors for G. intestinalis infection. Assemblage analysis identified 106 assemblage E and one assemblage A at the triose phosphate isomerase (tpi) locus in this study. Intravariations were also detected at tpi, glutamate dehydrogenase (gdh) and beta giardin (bg) loci within assemblage E, showing seven, three, and five new subtypes, respectively. Moreover, 13 new multilocus genotypes (E20‐E32) were observed in assemblage E. Effective strategies and measures should be taken to prevent and control giardiasis in Gansu and NXHAR.

First Report of Hepatitis E Virus Infection in Sika Deer in China

Hepatitis E virus (HEV), a single stranded RNA, nonenveloped virus, belongs to the genus Hepevirus, in the family of Hepeviridae. In this study, 46 (5.43%) out of the 847 serum samples from sika deer (Cervus nippon) were detected as seropositive with hepatitis E virus (HEV) by enzyme linked immunosorbent assay (ELISA). These samples were collected from Inner Mongolia and Jilin and Heilongjiang provinces in China, between October 2012 and October 2013. Seroprevalence of HEV infection in male and female deer was 4.82% and 6.52%, respectively. HEV seroprevalence in sika deer from different geographical locations varied from 3.13% to 6.73%. There was no significant difference in HEV seroprevalence between sika deer collected in autumn (5.65%) and winter (4.85%). This is the first report of HEV seroprevalence in sika deer in China, which will provide foundation information for estimating the effectiveness of future measures to control HEV infection in sika deer in China and assessing the potential risk of humans infected with HEV after consumption of undercooked or raw meat from infected sika deer.

Prevalence and Genotyping of Cryptosporidium Infection in Pet Parrots in North China

Cryptosporidiosis is a worldwide zoonosis caused by Cryptosporidium spp., sometimes leading to severe diarrhea in humans and animals. In the present study, 311 parrots, belonging to four species, namely, Budgerigars (Melopsittacus undulatus), Lovebirds (Agapornis sp.), Alexandrine parakeets (Psittacula eupatria), and Cockatiel (Nymphicus hollandicus), from Beijing and Weifang cities, were examined for Cryptosporidium spp. infection. Blood samples of each bird were examined using enzyme linked immunosorbent assay (ELISA) and fecal samples were examined by Sheathers sugar flotation technique. Prevalence of Cryptosporidium infection were 3.22% (10/311) and 0.64% (2/311) by ELISA and Sheathers sugar flotation technique, respectively. Seroprevalence of Cryptosporidium infection in different breeds varied from 0 to 15.39%. Sequencing analysis showed that both positive samples from fecal samples belonged to Cryptosporidium avian genotype V. This is the first report of Cryptosporidium avian genotype V in Budgerigars. The results of the present study provided foundation-data for prevention and control of cryptosporidiosis in pet birds in China.

First report of Babesia bigemina infection in white yaks in China

White yaks, a unique yak breed and the pearl of the plateau, only live in Tianzhu Tibetan Autonomous County (TTAC), Gansu Province, northwest China, contributing significantly to local economy. However, there was no information on the prevalence of Babesia bigemina in white yaks. In this study, a total of 974 serum samples collected from white yaks in TTAC were examined for specific antibodies against B. bigemina using a commercially available ELISA kit. The overall seroprevalence of B. bigemina in white yaks was 17.76% (173/974). A multivariate logistic regression analysis was performed to determine the risk factors associated with B. bigemina seroprevalence, and the results indicated that age, gender and the numbers of pregnancies of white yaks were not the significant risk factors. However, the white yaks in spring (OR=3.523, 95% CI=1.899-6.538, P<0.001) and summer (OR=3.439, 95% CI=1.909-6.193, P<0.001) encountered higher risk of being exposed to B. bigemina than that in winter. Thus, season was considered as a risk factor associated with B. bigemina infection. This is the first survey of B. bigemina seroprevalence in white yaks in China, which extends the host range for B. bigemina and provides useful information for controlling B. bigemina infection in white yaks.

Seroprevalence and risk factors of Toxoplasma gondii infection in domestic sika deer (Cervus nippon) in northeastern China

Toxoplasmosis is a worldwide zoonosis caused by Toxoplasma gondii, which can infect warm-blooded animals and humans. A serological survey was undertaken to examine the seroprevalence and risk factors associated with T. gondii infection in sika deer in northeastern China. 114 (13.46%, 95% CI 11.16-15.76) out of 847 serum samples were positive to T. gondii by modified agglutination test (MAT) at a 1:25 cut-off, with titers of 1:25 in 44, 1:50 in 32, 1:100 in 17, 1:500 in 11, 1:1500 or higher in 10. These samples were collected between November 2012 and October 2013 from Inner Mongolia, Jilin and Heilongjiang provinces in China. However, statistically significant differences were not observed between T. gondii seroprevalence and genders or regions of sika deer in the logistic regression analysis (P>0.05) and left out of the final model. Seroprevalence of T. gondii infection in male sika deer was 14.07% (95% CI 11.14-17.01), slightly higher than that in the female (12.38%) (95% CI 8.69-16.06) and seroprevalence of T. gondii infection in Harbin, Changchun city, Jilin city and Chifeng city were 12.02% (95% CI 7.60-16.44), 15.51% (95% CI 11.52-19.50), 12.27% (95% CI 7.23-17.31) and 12.50% (95% CI 7.38-17.63), respectively. Seasons of sampling were considered as main risk factors associated with T. gondii infection, autumn (15.32%) were more than two times (OR=1.98, 95% CI=1.18-3.33, P=0.01) at risk of acquiring T. gondii infection compared to winter (8.37%). Our results indicated a widespread exposure to T. gondii among sika deer in China. To our knowledge, this is the first report of T. gondii seroprevalence in sika deer in China.

Occurrence of Enterocytozoon bieneusi in Donkeys (Equus asinus) in China: A Public Health Concern

Enterocytozoon bieneusi is an important zoonotic parasite. It can infect virtually all animal species and has a global distribution. However, the prevalence of E. bieneusi in donkeys (Equus asinus) has only been reported in Algeria and Spain, and no information is available concerning genotypes of E. bieneusi in donkeys worldwide. In the present study, a total of 301 donkey fecal samples (48 from Jilin Province, 224 from Shandong Province and 29 from Liaoning Province) were collected and examined by PCR amplification of the internal transcribed spacer (ITS) region. The overall E. bieneusi prevalence was 5.3% (16/301), with 6.3% (3/48) in Jilin Province, 4.9% (11/224) in Shandong Province, and 6.9% (2/29) in Liaoning Province. Prevalence in different age groups ranged from 4.2 to 5.5%. E. bieneusi prevalence in donkeys sampled in different seasons varied from 4.2 to 6.5%. Altogether, four E. bieneusi genotypes were identified in this study, with two known genotypes (J and D) and two novel genotypes (NCD-1and NCD-2). Phylogenetic analysis revealed that genotypes D, NCD-1 and NCD-2 belonged to group 1, while the remaining genotype J was clustered into group 2. These findings revealed the occurrence of E. bieneusi in donkeys in China for the first time. Moreover, the present study also firstly genotyped the E. bieneusi in donkeys worldwide. These findings extend the distribution of E. bieneusi genotypes and provide baseline data for controlling E. bieneusi infection in donkeys, other animals and humans.

Immunization with Toxoplasma gondii GRA17 Deletion Mutant Induces Partial Protection and Survival in Challenged Mice

Toxoplasmosis remains a world-threatening disease largely because of the lack of a fully effective vaccine. Here, we created a ΔGRA17 mutant by disrupting the virulence factor GRA17 using CRISPR-Cas9 method. Then, we tested whether ΔGRA17 tachyzoites can be used as a live-attenuated vaccine against acute, chronic, and congenital Toxoplasma gondii infection in mice. Immune response evoked by ΔGRA17 immunization suggested a sequential Th1 and Th2 T cell response, indicated by high levels of Th1 and a mixed Th1/Th2 cytokines at 28 and 70 days after immunization, respectively. ΔGRA17-mediated immunity fully protected mice against lethal infection with wild-type (wt) RH strain, heterologous challenge with PYS, and TgC7 strains of the Chinese ToxoDB#9 genotype, and T. gondii Pru strain. Although parasite cysts were detected in 8 out of 10 immunized mice, cyst burden in the brain was significantly reduced (P < 0.05) in immunized mice (53 ± 15 cysts/brain) compared to non-immunized mice (4,296 ± 687 cysts/brain). In respect to congenital infection, the litter size, survival rate, and body weight (BW) of pups born to ΔGRA17-immunized dams were not different compared to pups born to naïve control dams (P = 0.24). However, a marked reduction in the litter size (P < 0.001), survival rate, and BW (P < 0.01) of pups born to non-immunized and infected dams was detected. Also, immunized dams infected with type II Pru strain had significantly (P < 0.001) less cyst burden in the brain compared with non-immunized and infected dams. These findings show that immunization with ΔGRA17 strain evokes cell-mediated and neutralizing antibody responses and confers some degree of protection against challenge with homologous and heterologous virulent T. gondii strains.

Prevalence and genotypes of Enterocytozoon bieneusi in sika deer in Jilin province, Northeastern China.

Enterocytozoon bieneusi is one of the most important zoonotic pathogen that can infect almost all animals, including humans. However, little information is available regarding prevalence and genotypes of E. bieneusi in sika deer. In the present study, the prevalence of E. bieneusi infection in sika deer in Jilin province, Northeastern China was examined using PCR amplification of the internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) gene. 23 (7.06%) of 326 samples were tested E. bieneusi-positive, and the risk factor significantly associated with E. bieneusi prevalence was the age of sika deer. Sequence analysis of the ITS rRNA gene suggested that 8 genotypes of E. bieneusi were found in this study, with five known genotypes, namely J (n = 11), BEB6 (n = 4), EbpC (n = 1), CHN-DC1 (n = 1), KIN-1 (n = 1) and three novel genotypes, namely JLD-1 (n = 2), JLD-2 (n = 2) and JLD-3 (n = 1). Phylogenetic analysis indicated that genotypes CHN-DC-1, KIN-1, EbpC, JLD-2 and JLD-3 fell into group 1, while other three genotypes (genotypes J, BEB6 and JLD-1) were clustered into group 2 (so-called bovine-specific groups). These findings indicated the presence of zoonotic E. bieneusi in Jilin province, Northeastern China. Effective strategies should be performed to control E. bieneusi infection in sika deer, other animals and humans.

Seroprevalence and Risk Factors of Bluetongue Virus Infection in Tibetan Sheep and Yaks in Tibetan Plateau, China

Bluetongue (BT), caused by bluetongue virus (BTV), is an arthropod-borne viral disease in ruminants. However, information about BTV infection in yaks in China is limited. Moreover, no such data concerning BTV in Tibetan sheep is available. Therefore, 3771 serum samples were collected from 2187 Tibetan sheep and 1584 yaks between April 2013 and March 2014 from Tibetan Plateau, western China, and tested for BTV antibodies using a commercially available ELISA kit. The overall seroprevalence of BTV was 17.34% (654/3771), with 20.3% (443/2187) in Tibetan sheep and 13.3% (211/1584) in yaks. In the Tibetan sheep group, the seroprevalence of BTV in Luqu, Maqu, Tianzhu, and Nyingchi Prefecture was 20.3%, 20.8%, 20.5%, and 19.1%, respectively. The seroprevalence of BTV in different season groups varied from 16.5% to 23.4%. In the yak group, BTV seroprevalence was 12.6%, 15.5%, and 11.0% in Tianzhu, Maqu, and Luqu counties, respectively. The seroprevalence in different seasons was 12.6%, 15.5%, 15.4%, and 9.0% in spring, summer, autumn, and winter, respectively. The season was the major risk factor concerning BTV infection in yaks (P < 0.05). The date of the BTV seroprevalence in Tibetan sheep and yaks provides baseline information for controlling BT in ruminants in western China.