ELISA和IHA检测弓形虫抗体的比较试验研究

目的:分析ELISA方法和IHA方法检测弓形虫病的可靠性。方法:本文应用酶联免疫吸附试验(ELISA)和间接血凝试验(IHA)两种方法,平行检测来自龙岩市某个猪场的32份猪血清中的抗弓形虫特异性抗体。结果:ELISA和IHA对猪弓形虫抗体阳性检出率分别为62.5%(20/32)、53.13%(17/32),这两种方法的阳性检出符合率较高,为71.88%(23/32)。其中,ELISA方法的敏感性(93.33%)、检测效率(81.25%)以及Youden指数(63.92%)都在IHA方法之上,但ELISA方法的特异性(12/17,70.59%)略低于I-HA方法(13/17,76.47%)。结论:ELISA和IHA两种方法均可用于猪弓形虫病的诊断和血清学调查,但ELISA方法更适用于猪弓形虫病的血清学调查。     

牛新孢子虫病和弓形虫病的流行病学调查

为了调查我国牛新孢子虫和弓形虫的感染情况，应用新孢子虫酶联免疫吸附试验（ELISA）和弓形虫间接血凝试验（IAT）分别检测了来自国内10个省（市、自治区）的262份乳牛、10份肉牛和40份水牛血清。结果显示，乳牛新孢子虫的抗体阳性率为17．2％，弓形虫的抗体阳性率为2．3％，没有检测到既有新抱子虫抗体又有弓形虫抗体的乳牛血清。各牛场所检乳牛血清的新孢子虫抗体阳性率在0～34．4％之间。在水牛和肉牛血清中未检测到新孢子虫抗体和弓形虫抗体。流产乳牛血清的新孢子虫抗体阳性率为20．2％，未流产乳牛为16．1％，其中血清抗体阳性乳牛主要在妊娠中晚期流产。各个年龄段乳牛血清的抗体阳性率差异不显著（P〉0．05）。不同妊娠胎次的乳牛血清抗体阳性率差异不显著（P〉0．05）。确认新孢子虫病在国内大部分牛场存在。     

Prevalence and genotypes of Toxoplasma gondii in feline faeces (oocysts) and meat from sheep, cattle and pigs in Switzerland

The protozoan parasite Toxoplasma gondii infects almost all warm blooded animal species including humans, and is one of the most prevalent zoonotic parasites worldwide. Post-natal infection in humans is acquired through oral uptake of sporulated T. gondii oocysts or by ingestion of parasite tissue cysts upon consumption of raw or undercooked meat. This study was undertaken to determine the prevalence of oocyst-shedding by cats and to assess the level of infection with T. gondii in meat-producing animals in Switzerland via detection of genomic DNA (gDNA) in muscle samples. In total, 252 cats (44 stray cats, 171 pet cats, 37 cats with gastrointestinal disorders) were analysed coproscopically, and subsequently species-specific identification of T. gondii oocysts was achieved by Polymerase Chain Reaction (PCR). Furthermore, diaphragm samples of 270 domestic pigs (120 adults, 50 finishing, and 100 free-range animals), 150 wild boar, 250 sheep (150 adults and 100 lambs) and 406 cattle (47 calves, 129 heifers, 100 bulls, and 130 adult cows) were investigated by T. gondii-specific real-time PCR. For the first time in Switzerland, PCR-positive samples were subsequently genotyped using nine PCR-restriction fragment length polymorphism (PCR-RFLP) loci (SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico) for analysis. Only one of the cats shed T. gondii oocysts, corresponding to a T. gondii prevalence of 0.4% (95% CI: 0.0-2.2%). In meat-producing animals, gDNA prevalence was lowest in wild boar (0.7%; 95% CI: 0.0-3.7%), followed by sheep (2.0%; 95% CI: 0.1-4.6%) and pigs (2.2%; 95% CI: 0.8-4.8%). The highest prevalence was found in cattle (4.7%; 95% CI: 2.8-7.2%), mainly due to the high prevalence of 29.8% in young calves. With regard to housing conditions, conventional fattening pigs and free-range pigs surprisingly exhibited the same prevalence (2.0%; 95% CI: 0.2-7.0%). Genotyping of oocysts shed by the cat showed T. gondii with clonal Type II alleles and the Apico I allele. T. gondii with clonal Type II alleles were also predominantly observed in sheep, while T. gondii with mixed or atypical allele combinations were very rare in sheep. In pigs and cattle however, genotyping of T. gondii was often incomplete. These findings suggested that cattle in Switzerland might be infected with Toxoplasma of the clonal Types I or III, atypical T. gondii or more than one clonal Type.     

Cross-sectional survey on Toxoplasma gondii infection in cattle, sheep and pigs in Serbia: seroprevalence and risk factors

Toxoplasmosis is a globally distributed zoonosis with a clinical impact in the unborn fetus and in the immunosuppressed individual. In Serbia, studies of risk factors for Toxoplasma gondii infection in humans have shown that the relatively high prevalence is associated mainly with consumption of undercooked meat and/or meat products. However, data on T. gondii infection in domestic animals mostly used for human consumption are scarce. We thus conducted a cross-sectional survey on the seroprevalence of T. gondii infection in a representative sample of cattle, sheep and pigs from different regions of Serbia between June 2002 and June 2003, and analyzed the main risk factors associated with the infection. Sera from 611 cattle (yearlings and adults of both sexes), 511 ewes, and 605 pigs (market-weight and sows), were examined for T. gondii antibodies by the modified agglutination test. The seroprevalences determined were 76.3% in cattle, 84.5% in sheep and 28.9% in pigs. The antibody levels ranged from 1:25 to 1:400 in cattle, and up to 1:25,600 in sheep and to 1:12,800 in pigs. Among the seropositive, the proportion of high antibody levels (> or =1:1600), suggestive of acute infection, was 10% in sheep, and 4% in pigs. Possible association of the infection with biologically plausible risk factors including gender, age, herd size/farm type, type of housing, feeding practices and region, was analyzed by univariate analysis, and variables significant at P< or =0.1 were included in multivariate logistic regression models. The results showed that risk factors for cattle were small herd size (odds ratio, OR=2.19, 95% confidence interval, CI=1.28-3.75, P=0.004) and farm location in Western Serbia (OR=2.04, 95% CI=1.10-3.79, P=0.024), while housing in stables with access to outside pens was protective (OR=0.37, 95% CI=0.21-0.67, P=0.001). In sheep, an increased risk of infection was found in ewes from state-owned flocks (OR=4.18, 95% CI=2.18-8.00, P<0.001) vs. private flocks, and, interestingly, also in those from Western Serbia (OR=4.66, 95% CI=1.18-18.32, P=0.028). In pigs, the risk of infection was highly increased in adult animals (OR=3.87, 95% CI=2.6-5.76, P<0.001), as well as in those from finishing type farms (OR=3.96, 95% CI=1.97-7.94, P<0.001). In addition to providing data on the current T. gondii seroprevalence in meat animals in Serbia, the results of this study show the main risk factors associated with infection, thereby pointing to the type of preventive measures to reduce T. gondii infection.     

北京地区犬猫弓形虫病血清学调查

比较了酶联免疫吸附试验（ELISA）和乳胶凝集试验对犬猫进行龚地弓形虫（Toxoplasma gondii）抗体检测的结果.在66只犬猫的血清中,ELISA方法检测的阳性率为24.0%,乳胶凝集试验阳性率为21.0%,二者的检测结果差异不显著（P＞0.05）.后采用ELISA方法对北京地区家养的159只犬和128只猫进行了弓形虫IGg抗体的检测,共有21只犬（13.21%）和18只猫（14.06%）检测结果为阳性.1岁以下犬（3.70%）、猫（4.35%）低于1至3岁犬（11.29%）和猫（6.98%）的感染率.3～6岁犬猫的感染率分别是27.27%和16.22%,6岁以上犬（30.0%）、猫（32.0%）的感染率最高.不同性别之间感染无明显差异（P＞0.05）.     

Seroprevalence of antibodies to Encephalitozoon cuniculi and Toxoplasma gondii in farmed domestic rabbits in Egypt

Rabbit sera from ten commercial farms representing three provinces in Northern Egypt (Behera, Alexandria and Khafr El-Sheikh) were submitted to serological screening for Encephalitozoon cuniculi using an enzyme-linked immunosorbent assay and for Toxoplasma gondii using an indirect hemagglutination test. Antibodies against E. cuniculi were detected in 36/240 (15%) sera examined while antibodies against T. gondii showed a seroprevalence of 22/194 (11.34%). Both infections were detected in all of the examined farms. These results are of epidemiological relevance and public health importance because of the recognized susceptibility of humans to E. cuniculi and T. gondii infections; therefore, routine screening examinations of farm rabbits are advised considering the zoonotic potential of these parasites.     

Toxoplasma gondii virulence prediction using hierarchical cluster analysis based on coding sequences (CDS) of sag1, gra7 and rop18

Toxoplasma gondii consists of three genotypes, namely genotype I, II and III. Based on its virulence, T. gondii can be divided into virulent and avirulent strains. This study intends to evaluate an alternative method for predicting T. gondii virulence using hierarchical cluster analysis based on complete coding sequences (CDS) of sag1, gra7 and rop18 genes. Dendrogram was constructed using UPGMA with a Kimura 80 nucleotide distance measurement. The results showed that the prediction errors of T. gondii virulence using sag1, gra7 and rop18 were 7.41%, 6.89% and 9.1%, respectively. Analysis based on CDS of gra7 and rop18 was able to differentiate avirulent strains into genotypes II and III, whereas sag1 failed to differentiate.     

Seroprevalence of Toxoplasma gondii infection in sheep and alpacas (Llama pacos) in Chile.

Serum samples from 408 sheep from different regions of Chile and 447 alpacas (Llama pacos) from the north of the country were tested for Toxoplasma gondii antibodies. The indirect haemagglutination test (IHAT) was used in both species and the indirect immunofluorescence test (IIFT) was also used on the sheep samples in order to compare the performance of the tests in that species. In both tests, titers ≥1:16 were considered diagnostically significant. Sera from 49 sheep (12%) were positive to T. gondii antibodies by the IHAT. When using the IIFT, 114 sheep sera (28%) were positive. The different results obtained in sheep sera between the tests were significant (p<0.0001). No differences were observed between geographical locations or sex of the sampled sheep regarding serological detection of T. gondii antibodies in sheep. As expected, adult sheep showed higher T. gondii reactivity than young sheep (p=0.0008). The corrected prevalence of toxoplasmosis in alpaca was 16.3% (32 positive out of 447). The rather low prevalence in alpacas may be associated with their extensive management as well as the extreme climatic conditions of The Andes which apparently would not be favorable for the transmission of the parasite.     

Extracts of wild Egyptian plants from the desert inhibit the growth of Toxoplasma gondii and Neospora caninum in vitro

Wild medicinal plants have been traditionally used as antimicrobial agents. Here, we evaluated the in vitro activity of extracts from wild Egyptian desert plants against Toxoplasma gondii and Neospora caninum. From 12 plant extracts tested, the methanolic extracts from Artemisia judaica, Cleome droserifolia, Trichodesma africanum, and Vachellia tortilis demonstrated potent activity against the growth of T. gondii, with half-maximal inhibitory concentrations (IC₅₀s) of 2.1, 12.5, 21.8, and 24.5 µg/ml, respectively. C. droserifolia, an ethanolic extract of P. undulata, T. africanum, A. judaica, and V. tortilis demonstrated potent efficacy against N. caninum, with mean IC₅₀s of 1.0, 3.0, 3.1, 8.6, and 17.2 µg/ml, respectively. Our data suggest these extracts could provide an alternative treatment for T. gondii and N. caninum infections.     

Seroprevalence of Toxoplasma gondii in mainland and sub-Antarctic New Zealand sea lion (Phocarctos hookeri) populations

AIMS: To investigate the seroprevalence of antibodies to Toxoplasma gondii in New Zealand sea lions (Phocarctos hookeri), as a potential contributor to reproductive failure.

METHODS: Archived sera were sourced from New Zealand sea lions from two recolonising mainland populations in the Otago Peninsula (n=15) and Stewart Island (n=12), as well as a declining population at Enderby Island (n=28) in the New Zealand sub-Antarctic. Sera were tested for antibodies to T. gondii using a commercially available ELISA (with samples considered positive if the sample to positive ratio was?>30%), and latex agglutination test (LAT; with titres ≥1:32 considered positive). Western blot analysis was used to validate the results of a subset of 14 samples.

RESULTS: Five samples from sea lions in mainland locations were confirmed positive for antibodies to T. gondii. Two adult females exhibited high LAT antibody titres (min 1:2048, max 1:4096) on both occasions when sampled 1 and 2 years apart, respectively. No animals from Enderby Island were seropositive.

CONCLUSIONS: Toxoplasma gondii infection is unlikely to be a major contributor to poor reproductive success in New Zealand sea lions. However, continued surveillance is pertinent to assess subclinical and clinical impacts of the parasite on these threatened populations. The commercial tests evaluated here, with further species-specific threshold refinement could provide a fast, inexpensive and reliable indicator of T. gondii exposure in New Zealand sea lions.     

Toxoplasma gondii Infections in Chickens (Gallus domesticus): Prevalence,Clinical Disease,Diagnosis and Public Health Significance

Chickens are considered one of the most important hosts in the epidemiology of Toxoplasma gondii infection because they are an efficient source of infection for cats that excrete the environmentally resistant oocysts and because humans may become infected with this parasite after eating undercooked infected chicken meat. The objective of this study is to review worldwide prevalence of T. gondii infection in chickens and to assess the role of infected chickens in the epidemiology of toxoplasmosis in humans. A very high prevalence of the parasite was found in chickens raised in backyards (up to 100%) and free‐range organic (30–50%) establishments.     

Seroprevalence of Toxoplasma gondii in wild boar and deer in Brandenburg,Germany

Consumption of game in Germany has increased during the past 10 years. Wild boar (Sus scrofa), roe deer (Capreolus capreolus) and red deer (Cervus elaphus) are the most frequently hunted and consumed game animals in Germany, yet information on the occurrence of zoonotic pathogens in these animal species is scarce. To better estimate the public health risk emanating from handling and consumption of game, this study investigated seroprevalences of Toxoplasma gondii in game hunted in the German federal state of Brandenburg during two hunting seasons from 2017 to 2019. Toxoplasma gondii‐specific antibodies were detected in 24.4% (44/180, 95% CI: 18.4%–31.4%) of wild boar, 12.8% (16/125, 95% CI: 7.5%–20%) of roe deer and 6.4% (3/47, 95% CI: 1.3%–17.5%) of red deer using a commercial ELISA kit. Seroprevalences were similar in the two hunting seasons. Correlation between sex and seropositivity could not be observed. A rise in seroprevalence was seen with increasing age in all studied game species. Observed seroprevalences suggest that T. gondii is endemic in the sylvatic environment in the German federal state of Brandenburg and imply that game could represent a relevant source for human T. gondii infection.     

Seroprevalence of Toxoplasma gondii in cattle, sheep and goats slaughtered for food in Mazandaran province, Iran, during 2005

Serum samples from 290 cattle, 400 goats and 588 sheep slaughtered for food in various areas of the Mazandaran province, Iran were tested for antibodies to Toxoplasma gondii by the indirect immunofluorescence antibody test (IFAT), from December 2004 to April 2005. Antibodies to T. gondii were found in 30% (120/400) goats and 35% (206/588) sheep and 0% (0/290) cattle, at a dilution of 1:16 or more for goats and sheep and 1:128 or more for cattle. The highest titres observed in cattle, goats and sheep were 1:64 (0.7%), 1:128 (1%), 1:64 (2%), respectively. These results indicate that T. gondii antibodies are widespread in the animal populations and suggest that toxoplasmosis is a widely spread zoonotic infection in northern Iran.     

桦褐孔菌多糖对感染弓形虫小鼠治疗作用及其对血清中细胞因子含量的影响

建立小鼠弓形虫病模型后,将小鼠随机分成6组,统计小鼠存活率及时间,再应用ELISA检测血清中IFN-γ、IL-2等细胞因子水平,以检测桦褐孔菌多糖对感染弓形虫小鼠的治疗效果及对小鼠血清中IFN-γ、IL-2细胞因子水平的影响。结果表明,桦褐孔菌多糖中剂量组小鼠存活率最高;桦褐孔菌多糖的高、中剂量组IFN-γ水平极显著高于其他各组(P<0.01),高剂量组IL-2水平与其他各组比较差异极显著(P<0.01);除感染组外,其余各组IFN-γ、IL-2均在第6天出现峰值。说明桦褐孔菌多糖中剂量治疗弓形虫感染小鼠效果最好,并且中剂量可使小鼠血清中IFN-γ、IL-2值升高到适当水平,有效改善弓形虫感染对小鼠的伤害。     

Toxoplasma gondii sexual cross in a single naturally infected feline host: Generation of highly mouse-virulent and avirulent clones, genotypically different from clonal types I, II and III

ABSTRACT: Tachyzoite clones obtained from a single Toxoplasma gondii oocyst field sample were genotyped and characterized regarding mouse virulence. PCR-RFLP genotyping of tachyzoites initially isolated from interferon-γ-knockout (GKO) mice, BALB/c mice and VERO cell culture using the nine independent, unlinked genetic markers nSAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico revealed mixed T. gondii infections showing combinations of type II and type III alleles at different loci. Forty-five individual clones were obtained from all mixed T. gondii tachyzoite cell cultures by limiting dilution. Sixteen T. gondii clones showed type III alleles at all loci and 29 clones displayed a combination of type II and type III alleles at different loci. Five clone groups were identified in total, four of which include T. gondii clones that showed a non-canonical allele pattern and have never been described in natural infections before. All tested clones, except two, were highly virulent in BALB/c mice. The isolation of different non-canonical T. gondii clones originating from an oocyst sample of a single naturally infected cat demonstrate that sexual recombination as well as re-assortment of chromosomes via a sexual cross of T. gondii occur under natural conditions and result in the emergence of clones with increased virulence in mice.     

Seroepidemiology of infection with Toxoplasma gondii in waste pickers and waste workers in Durango, Mexico

Municipal waste is a potential source of infection for Toxoplasma gondii as it may contain contaminated meat with parasite tissue cysts and cat excrement with parasite oocysts. Therefore, we sought to determine the prevalence of T. gondii infection and associated characteristics in two populations exposed to municipal solid waste in Durango, Mexico. Ninety waste pickers and 83 waste workers of Durango City, Mexico were examined for T. gondii infection. They were tested for anti-T. gondii IgG and IgM antibodies using enzyme-linked immunoassays. In addition, socio-demographic and behavioural characteristics from each participant were obtained. Nineteen (21.1%) of the 90 waste pickers and seven (8.4%) of the 83 waste workers were positive for anti-T. gondii IgG antibodies. The difference in prevalence among the groups was statistically significant (P =0.03). Waste pickers aged 31-50 years showed a significantly higher prevalence (40.9%) than waste workers of the same age group (2.9%, P < 0.001). Anti-T. gondii IgM antibodies were found in two (2.2%) of the waste pickers but in none of the waste workers. The seroprevalence of T. gondii was significantly higher in workers of the waste transfer station (25.0%) than in drivers or helpers of waste vehicles (2.5%) (P =0.03). Multivariate analysis showed that T. gondii infection was associated with consuming food found in the garbage [adjusted odds ratio (OR) = 4.4; 95% confidence interval (CI) 1.6-11.8] and with lack of education (adjusted OR = 3.2; 95% CI 1.1-8.8). From this study, we conclude: (i) waste pickers may represent a risk group for T. gondii infection; (ii) lack of education might be a contributing factor for T. gondii infection; (iii) the higher the exposure to garbage, the higher the seroprevalence of T. gondii infection; (iv) Eating food products from the garbage may represent an important route for T. gondii infection.     

Prevention of shedding and re-shedding of Toxoplasma gondii oocysts in experimentally infected cats treated with oral Clindamycin: a preliminary study

This work aimed to evaluate the effects of preventive oral Clindamycin in cats infected with Toxoplasma gondii. Twelve short hair cats were divided into two groups (group 1 and group 2). No titres of T. gondii antibodies were detected in these cats before the experiment. The animals from group 1 were infected with tissue cysts of T. gondii and group 2 were infected and treated with Clindamycin (20 mg/kg/day). The infection was done with almost 40-50 tissue cysts for each cat on day 0. The cats from group 2 were treated with Clindamycin by oral rout for 24 days (from day -3 to day 21). At day 45, the groups 1 and 2 were divided into two subgroups with three animals each. Subgroups 1A and 2A were immunosuppressed with dexamethasone (1 mg/kg/day) for30 days and subgroups 1B and 2B were not immunosuppressed. Faecal exam looking for oocyst shedding was made by 30 days after T. gondii infection, and for 30 days after immunosuppression. All kittens from group 1 shedding oocysts after infection, while animals from group 2 did not shed. After immunosuppression period, all animals from group 1A re-shed oocysts and animals from group 2A remained without shed. However, 2 (66.6%) of the kittens from subgroup 2B shed oocysts 19-20 days after re-challenge. Based on this preliminary study, Clindamycin had a complete inhibitory effect on shedding of oocysts by cats, even under severe immunosuppression, which is a new finding not reported elsewhere.