Seroprevalence of Toxoplasma gondii infection in Tibetan sheep in Tibet, China

In the present investigation, the seroprevalence of Toxoplasma gondii antibodies in 455 Tibetan sheep in Tibet, China, was examined using an indirect hemagglutination test. Of these, 26 (5.7%) Tibetan sheep were seropositive at the cut-off of 1:64 serum dilution. The seroprevalence ranged from 2.2% to 8.9% among Tibetan sheep of <1-yr-old, 1-3-yr-old, and >3-yr-old, but the differences among the age groups were not significant (P > 0.05). The prevalence in male Tibetan sheep (2.8%) was lower than that in female Tibetan sheep (6.6%), but the difference was not statistically significant (P > 0.05). The results of this survey indicated the presence of T. gondii infection in Tibetan sheep, which may cause economic losses to the local livestock industry and which poses a potential threat to human health in this area.     

Prevalence,Associated Risk Factors,and Phylogenetic Analysis of Toxocara vitulorum Infection in Yaks on the Qinghai Tibetan Plateau,China

Toxocara vitulorum has been rarely reported in yaks at high altitudes and remote areas of Sichuan Province of Tibetan Plateau of China. The current study was designed to investigate the prevalence, associated risk factors, and phylogenetic characteristics of T. vitulorum in yak calves on the Qinghai Tibetan plateau. Fecal samples were collected from 891 yak calves and were examined for the presence of T. vitulorum eggs by the McMaster technique. A multivariable logistic regression model was employed to explore variables potentially associated with exposure to T. vitulorum infection. T. vitulorum specimens were collected from the feces of yaks in Hongyuan of Sichuan Province, China. DNA was extracted from ascaris. After PCR amplification, the sequencing of ND1 gene was carried out and phylogenetic analyses was performed by MEGA 6.0 software. The results showed that 64 (20.1%; 95% CI 15.8–24.9%), 75 (17.2; 13.8–21.1), 29 (40.9; 29.3–53.2), and 5 (7.6; 2.5–16.8) yak calves were detected out to excrete T. vitulorum eggs in yak calve feces in Qinghai, Tibet, Sichuan, and Gansu, respectively. The present study revealed that high infection and mortality by T. vitulorum is wildly spread on the Qinghai Tibetan plateau, China by fecal examination. Geographical origin, ages, and fecal consistencies are the risk factors associated with T. vitulorum prevalence by logistic regression analysis. Molecular detection and phylogenetic analysis of ND1 gene of T. vitulorum indicated that T. vitulorum in the yak calves on the Qinghai Tibetan plateau are homologous to preveiously studies reported.     

Seroprevalence of Toxoplasma gondii infection in slaughtered pigs and cattle in Liaoning Province, northeastern China

Toxoplasmosis is an important food-borne parasitic disease. In the present study, the seroprevalence of Toxoplasma gondii infection in slaughtered pigs and cattle was surveyed in Liaoning Province, northeastern China in May and June 2011. In total, 1,164 porcine serum samples and 646 bovine serum samples were collected from 5 counties and examined for T. gondii antibodies by an indirect hemagglutination test. Antibodies to T. gondii were found in 12.0% (140/1,164) of pigs, with some regional differences. The highest prevalence of 14.4% (47/326) was found in Fuxin followed by 12.5% (62/497) in Jinzhou; overall, 6.0% (39/646) was observed in cattle but with no regional difference (P > 0.05). Prevalence of T. gondii infection in pigs was also significantly higher compared to cattle (P < 0.05). The results of the present study indicate that infection with T. gondii in pigs and cattle is widely spread in China including Liaoning Province, northeastern China, and is, therefore, of public health concern.     

Seroprevalence of Toxoplasma gondii infection in dogs in Jiangsu Province, eastern China

There is a lack of epidemiological data on Toxoplasma gondii infection in dogs from eastern China. In the present study, serum samples from 288 dogs were collected from Xuzhou, Huaiyin, and Yianchen in Jiangsu Province, eastern China, in August 2010; T. gondii antibodies were assayed by a modified agglutination test (MAT). Antibodies to T. gondii were found in 62 of 288 (21.5%) with MAT titers of 1∶25 in 21 dogs, 1∶50 in 15, 1∶100 in 11, 1∶200 in 6, and 1∶400 and above in 3 dogs. The seroprevalence in ≥3-yr-old dogs was significantly higher (P < 0.05) than that in dogs less than 3-yr-old. The results of the present study indicated that infection with T. gondii in household dogs in Jiangsu Province is a public health concern.     

Seroprevalence of Toxoplasma gondii infection in pigs, in Zhejiang Province, China

Seroprevalence of Toxoplasma gondii infection in pigs in 10 regions of Zhejiang Province, China, was obtained by enzyme-linked immunosorbent assay (ELISA). Anti- T. gondii antibodies were found in 53.4% (434/813) of pigs. Results were analyzed by a chi-square (χ(2)) test. Differences were observed according to farm size, animal age, and sampling regions. Seroprevalences in pigs raised on small farms (71.4%) were significantly higher than that (42.7%) on large farms (P < 0.05), and seroprevalence increased progressively with age. The seroprevalence ranged from 28.1% to 66.0% in different regions, with Jiaxing having the lowest level (28.1%), followed by Hangzhou (36.0%) and Taizhou (42.0%). This is the first study on seroprevalence of T. gondii infection in pigs in Zhejiang Province.     

Seroprevalence of Toxoplasma gondii in pigs, sheep, goats, and cattle from Grenada and Carriacou, West Indies

Prevalence of Toxoplasma gondii infection in pregnant women in Grenada is considered high. Little is known of the epidemiology of T. gondii infection in Caribbean Islands. Serum samples of 750 food animals in Grenada and Carriacou were tested for antibodies to T. gondii by the modified agglutination test (MAT). Antibodies to T. gondii (MAT, 1∶25 or higher) were found in 23.1% of 247 pigs, 44.1% of 204 sheep, 42.8% of 180 goats, and 8.4% of 119 cattle. Seroprevalence increased with age, indicating postnatal acquisition of T. gondii. Antibody titers of 1∶200 or higher were present in 65 of 90 seropositive sheep, 61 of 77 seropositive goats, and 23 of 57 seropositive pigs. However, none of the cattle had a MAT titer of 1∶200, suggesting that bovines are a poor host for T. gondii. Results indicate that pigs, sheep, and goats could be important sources of T. gondii infection if their meat is consumed undercooked.     

Seroprevalence of Toxoplasma gondii infection in dogs in Sichuan Province, southwestern China

There is a lack of information concerning the prevalence of Toxoplasma gondii infection in dogs from southwestern China. In the present study, serum samples from 314 household dogs were collected from Wenchuan, Heishui, and Jiuzhaigou in Sichuan Province, southwestern China, in May and June 201; sera were assayed for T. gondii antibodies using an indirect haemagglutination test (IHA). Antibodies to T. gondii were found in 11 of 314 (3.5%), with IHA titers of 1:64 in 4 dogs, 1:128 in 3, 1:256 in 2, 1:512 in 1, and 1:1024 in 1. No regional difference was observed among the 3 counties (P > 0.05). The results of the present study indicated that infection with T. gondii in dogs is common in China, including household dogs in Sichuan Province, and should be of public health concern.     

青海省可可西里地区几种有蹄类动物的食物重叠初步分析

2005年7月和2006年1月,应用粪便显微组织分析法测定了可可西里地区的藏野驴、藏羚、藏原羚、野牦牛,以及家牦牛和藏羊在冷季(1月)和暖季(7月)的食物构成.用Schoener's Index计算了这些同域分布动物种间的食物重叠度.结果表明,藏野驴分别与藏羚羊、野牦牛、藏原羚在暖季的食物重叠度各为63.0%、48.4%和24.1%,在冷季的重叠度为别为71.6%、42.0%和11.4%;藏羚羊与野牦牛、藏原羚在暖季的食物重叠度分别为52.0%和33.4%,其在冷季的食物重叠度各为50.3%和29.3%;野牦牛与藏原羚在冷暖季的食物重叠度分别为13.1%和15.9%.在可可西里地区吲域分布野牛有蹄类动物种间,藏原羚与其他有蹄类动物食物重叠较少,而藏羚羊、藏野驴、野牦牛之间则存在不同程度的食物重叠,且随季节不同而变化,反映了这些动物之间复杂的竞争和共存关系.此外,家牦牛和藏羊均与这些野生有蹄类动物存在高度的食物重叠.     

Seroprevalence of Toxoplasma gondii infection in domestic sheep in Durango State, Mexico

The seroprevalence of Toxoplasma gondii infection in sheep (Ovis aries) in northern Mexico is largely unknown. Antibodies to T. gondii were determined in serum samples from 511 sheep from 8 farms in Durango State, Mexico, using the modified agglutination test (MAT). Sheep were raised in 3 geographical regions, i.e., mountainous (n = 68), semi-desert (n = 132), and valley (n = 311). Overall, T. gondii antibodies were found in 77 (15.1%) of 511 sheep, with MAT titers of 1∶25 in 27, 1∶50 in 10, 1∶100 in 11, 1∶200 in 11, 1∶400 in 8, 1∶800 in 3, 1∶1,600 in 4, and 1∶3,200 in 3. The seroprevalence of T. gondii infection increased significantly with age, indicating post-natal transmission. In contrast, gender, breed, flock size, and geographic region did not significantly influence the seroprevalence. Seropositive sheep were found in 7 of 8 farms sampled. This is the first report of T. gondii infection in sheep in Durango State, Mexico. Results indicate that infected sheep are probably an important source of T. gondii infection for humans in Durango State.     

青海省冬虫夏草资源适宜性区划分析

冬虫夏草是青藏高原的珍稀物种,具有较高的药用和经济价值,然而其资源的数量特征、空间分布格局及适宜度尚不清晰。本研究以青海省冬虫夏草资源生境条件为依据,以海拔、植被、土壤、气温和降水量作为主要指标,利用地理信息系统(geographic information system,GIS)的空间分析方法对青海省冬虫夏草资源适宜性及空间分布进行分析,并用野外实地采样进行验证。研究表明：玉树州的玉树市、杂多县、称多县、曲麻莱县;果洛州的玛沁县、达日县、甘德县等区域多处在适宜区;海北州的祁连县、刚察县,黄南州的泽库县、河南县、同仁县,玉树州的治多县、囊谦县,海南州的兴海县、同德县、贵南县及其他产冬虫夏草县的部分区域为较适宜区;西宁市的大通县,海东市的互助县和海西州的低海拔地区为不适宜区。整个青藏高原具有冬虫夏草分布面积占当地县域国土面积的76.2%。在青海省具有冬虫夏草分布的地区(市/州)中,玉树州和果洛州冬虫夏草分布的面积占当地县域国土面积的88.3%-99.6%,海北州、海东市、海南州、海西州、黄南州和西宁市冬虫夏草分布面积占当地县域国土面积的30.2%-96.5%。综合区划图能比较真实地反映青海省冬虫夏草资源的空间分布格局,区划结果与实地调查结果相符,表明利用空间分析方法进行冬虫夏草资源的适宜性分布区域的划分是可行的,该研究为合理开发和科学利用冬虫夏草野生资源提供理论依据。     

基于地形因子的藏狐生境评价及其空间容纳量的估算

依据藏狐的“出现点”数据,基于藏狐对家域内地形因子的利用,作者对青海省都兰县沟里乡野生藏狐的生境质量进行初步评价,并在基于个体藏狐最小空间需求的基础上,估算了研究地区的空间环境容纳量。 选择海拔、坡度、坡位和地形起伏度等4个主要的地形因子,应用Bonferroni置信区间比较藏狐对各因子的利用及其可获得性来建立单个因子评价准则,并依据各因子的分布特征进行综合生境评价。研究结果：藏狐最适宜的海拔高度为4 050～4 300 m,坡度为5～20°,坡位为上坡位和下坡位;藏狐对地形起伏度因子没有明显的选择性。根据藏狐对不同生境因子的利用,及不同藏狐个体生境利用的一致性,建立的综合评价准则为：X i=（X²_海拔×X²_坡位×X_坡度×X_{地形起伏度}）^1/6。研究地区内适宜性区域面积约为17.4 km²,占总研究地区面积的38.8%,其中最适宜生境仅0.4 km²。藏狐家域面积从2.53 ～4.99 km²不等,不同个体间家域重叠指数（OI）从0.16～0.66不等。藏狐的最小空间需求为2.09～3.55 km²,研究地区藏狐的空间容纳量为7～12只。根据生境资源现状及监测结果表明,研究地区的藏狐种群数量保持稳定。     

Seroprevalence and isolation of Toxoplasma gondii from sheep from São Paulo state, Brazil

Sheep are important in the epidemiology of Toxoplasma gondii infection but little is known of ovine toxoplasmosis in Brazil. Antibodies to T. gondii were assayed in sera of 495 sheep from 36 counties of S?o Paulo State, Brazil, using the modified agglutination test (MAT titer > or =1:25) and found in 120 (24.2%). Samples of brain, heart, and diaphragm of 82 seropositive sheep were pooled, digested in pepsin, and bioassayed in mice. Toxoplasma gondii was isolated from tissue homogenates of 16 sheep and the isolates were designated TgShBr1-16. Six of the 16 T. gondii isolates killed 100% of infected mice. Results indicate that asymptomatic sheep can harbor mouse-virulent T. gondii, and hence they can serve as a source of infection for humans.     

Toxoplasmic encephalitis in a free-ranging Rocky Mountain bighorn sheep from Washington

A 4-mo-old free-ranging Rocky Mountain bighorn sheep (Ovis canadensis canadensis) from the Hells Canyon area (Washington, USA) was diagnosed with encephalitis associated with Toxoplasma gondii infection. The sheep had concurrent pneumonic pasteurellosis and resided in a geographic area with endemic Pasteurella-associated pneumonia and mortality in bighorn sheep. The brain had multifocal necrotizing and nonsuppurative encephalitis with intralesional protozoa. The protozoa were identified as T. gondii by immunohistochemistry. To our knowledge, this is the first report of T. gondii infection in a Rocky Mountain bighorn sheep.     

Infection survey and morphological characteristics of Sarcocystis spp. in naturally infected Tibetan sheep from Qinghai in northwestern China

Sarcocystosis is a parasitic disease caused by intracellular coccidian protozoans that belong to the genus Sarcocystis. These parasites can cause diseases of the nervous system, abortion and economically significant losses in host animals. Previous studies have reported that Sarcocystis is found in mammals, birds and reptiles, while molecular and morphological studies of infected Tibetan sheep have not been performed in the Qinghai region. The aim of this study was to determine the prevalence of Sarcocystis spp. in Tibetan sheep in Qinghai, northwestern China. The results showed that in 1155 samples, sarcocysts from unspecified species were found in 50% (577/1155) of the sheep tissues by microscopy detection. The positive rates of sarcocysts in the diaphragmatic, esophageal and cardiac muscles were 78.4% (175/223), 29.1% (207/711), and 88.2% (195/221), respectively. Ultrastructural features were exclusively observed in Sarcocystis gigantea in the esophageal tissues. The specific architecture was characterized as a space between the two layers of the original capsule wall, which was filled with fiber bundles and tissue fluid. Cauliflower-like protrusions of the original capsule wall were observed toward the outer surface of the capsule. Prominent protrusions contained fibers and matrix. In addition, the Sarcocystis 18S rRNA genes from 6 esophageal tissue samples were cloned, sequenced, and aligned to related sequences from GenBank. All 5 S. gigantea sequences examined in this study were grouped into the same cluster and belonged to the same genotype. The other 5 Sarcocystis tenella sequences were obtained from cardiac muscle and diaphragm muscle and belonged to the same clade. Overall, this study revealed a high infection rate of Sarcocystis in Tibetan sheep in the region. The results of this study may provide a reference for further research investigating the sarcocystosis epidemic in Qinghai, China.     

Toxoplasmosis in Sheep

The presence of Toxoplasma gondii in the diaphragm was correlated with the dye test titres in 174 sheep. In 94 of these the presence of the parasite was also correlated with the haemoglobin (Hb) type. T. gondii was recovered from 3 % of the sheep with titres < 1/16, compared with 30 % of those with titres 1/16 and 70 % of those with titres ≥ 1/32. The results indicate that the distinction between serologically positive and negative individuals at a final serum dilution of 1/16 is justified. Some evidence was found that the parasite is easier to recover from dye test positive mature sheep than from dye test positive lambs. Of the 174 sheep, 143 were examined at random among 186 sheep culled or cast for age during a 4-year period from 1 flock in which the prevalence of Toxoplasma antibodies was representative for flocks in the southern Norway, and T. gondii was recovered from 53 (37 %) of these. It was concluded that 10—15 % of the lamb carcases and 25—37 % of the carcases from mature sheep in this country have T. gondii in their muscles detectable by the peptic digestion technique. A possible genetical influence on the infection was indicated by the higher frequency of recoveries of T. gondii from sheep with Hb type B than from sheep with the Hb types A or AB, but the number of individuals with Hb type B was too small to demonstrate statistically significant differences. The epidemiological importance of infected sheep carcases is discussed.     

Genetic characterization of Toxoplasma gondii isolates from pigs in southwestern China

The genetic diversity of Toxoplasma gondii varies in different geographical regions. Isolates of T. gondii in South America, for example, are genetically and biologically divergent from those in North America and Europe, where the population structure is highly clonal and composed mainly of 3 distinct lineages, i.e., Types I, II, and III. However, little is known of the T. gondii genotypes in the People's Republic of China. Toxoplasma gondii infection in pigs causes significant economic loss and presents a risk for human infection. We conducted a survey to determine the genetic diversity of this parasite in slaughtered pigs from Yunnan Province, southwestern China. In total, 412 DNA samples were extracted from hilar lymph nodes and livers of pigs from slaughterhouses in Yunnan Province in southwest China, 56 of which were found to be positive for the T. gondii SAG3 gene. These positive DNA samples were typed at 10 genetic markers, including 9 nuclear loci, i.e., SAG1, SAG2, SAG3, BTUB, GRA6, L358, PK1, c22-8, c29-2, and an apicoplast locus Apico. Of these, 5 isolates were genotyped with complete data for all loci. Only 1 genotype (ToxoDB 9) was identified, previously reported as a widespread lineage from pigs, cats, and human patients in China. The results indicate that this genotype may be the major T. gondii lineage in China and possibly all of eastern Asia. This is the first report of genetic typing of T. gondii isolates from pigs in China's southwestern Yunnan Province, the results of which have implications for the prevention and control of T. gondii infections in humans and other animals.     

Enzootic toxoplasmosis in sheep in north-central United States

Of 1,564 serum samples from adult ewes from 33 farms in Iowa, Minnesota, South Dakota, Kansas, and Nebraska where toxoplasmosis-induced ovine abortions had been diagnosed, 65.5% were found positive for Toxoplasma gondii antibodies using the modified agglutination test. Toxoplasma gondii antibody titers of ewes were: less than 64 (34.5%), 64 (14.9%), 256 (22.0%), 1,024 (14.5%), and greater than 4,096 (13.8%). Thus, 28.3% of sheep had high titers (greater than 1,024) indicating recently acquired T. gondii infection. On certain farms, up to 95% of ewes were seropositive. Prevalence of T. gondii antibodies increased with age of the ewe. Of 665 ewes, 53.6% of 1-yr-old ewes were seropositive (titers greater than 64) versus 75% of 5-yr-old ewes. Results indicate that T. gondii infection in sheep in the United States is widespread.     

Prevalence of Toxoplasma gondii antibodies and DNA in dogs in Shanghai, China

The aim of this study was to estimate the prevalence of Toxoplasma gondii infection in dogs in Shanghai, China. A total of 1,736 sera (1,178 from the city center and 558 from the outskirts) was collected from healthy dogs and tested for T. gondii infection by indirect hemagglutination; 56 sera (3.2%) were considered positive, with titers > 1∶64. The seroprevalence in dogs from the outskirts of the city (town dogs, 6.0%; countryside dogs, 9.8%) was significantly higher (P > 0.05) than that in city center dogs (1.3%). The age of the dog has an apparent association with T. gondii infection; that is, the seroprevalence ranged from 1.9% (in dogs ≤ 1 year old) to 3.6% (in dogs > 5 years old). There was no significant difference in gender (P ≥ 0.05), that is, 1.4% versus 1.1% for male and female dogs in the city center, 6.2% versus 5.9% in town dogs, and 8.4% versus 11.5% in country dogs, respectively. These results suggest that T. gondii infections are common in dogs from the city center and outskirts of Shanghai, but the T. gondii seroprevalence in dogs is considerably lower than in other regions in PR China. The presence of T. gondii DNA was investigated by nested PCR on 110 blood samples from city center dogs, but no positive samples were found, which may suggest that there were no acute infections of T. gondii in the city center samples. Our results indicate that the control and treatment of toxoplasmosis in Shanghai has been effective. However, it is still essential to further implement integrated strategies to prevent and control T. gondii infection in dogs in both the city center and the outskirts.     

Seroprevalence of Toxoplasma gondii in rats in southern China

Toxoplasma gondii is widely distributed in humans and other animals, including wild rats throughout the world, but little is known of the prevalence of T. gondii in rats in China. The seroprevalence of T. gondii in rats ( Rattus norvegicus and Rattus flavipectus ) was investigated in Guangzhou, southern China, between November 2009 and January 2010. In total, 217 rat serum samples were collected; antibodies to T. gondii were detected by the modified agglutination test (MAT), and 7 (3.2%) were found positive (titers ≥ 1:40). The seroprevalence was higher (3.4%) in R. norvegicus than in R. flavipectus (3.0%), but the difference was not statistically significant (P > 0.05). All 7 positive rats were female; no T. gondii antibodies were detected in males. This is the first extensive survey of T. gondii infection in rats in southern China, and the results have public health implications in this region.     

Long-Term Study of Toxoplasma gondii Infection in a Swedish Sheep Flock

The infection rate of Toxoplasma gondii was studied during 6 years in a sheep flock in central Sweden. The flock consisted of 165-249 breeding ewes of which 20-35% were lambs less than 1 year old. Most ewes were slaughtered when 5 years old. The sheep were kept indoors from end of September to early May. Lambing took place in March and April. Individual serum samples were collected twice a year, once just before turning the sheep out to pasture in the spring, and again after housing in the autumn. Sera were analysed by ELISA for antibodies to T. gondii. The seroprevalence varied between 10% and 45% during the 6 years of observation. Seroconversion was detected predominantly at the autumn sampling, indicating that in most cases infection was acquired at pasture. Subclinical effects of T. gondii infection on lamb weight, litter size, total litter weight and ewe weight were also studied. Lambs born to chronically infected ewes were lighter at birth than those of uninfected ewes, but this disparity was no longer evident at weaning.