Potential contamination of drinking water with Toxoplasma gondii oocysts.

The world's first documented toxoplasmosis outbreak associated with a municipal water supply was recognized in 1995 in Victoria, British Columbia, Canada. It was hypothesized that domestic cat (Felis catus) or cougar (Felis concolor) faeces contaminated a surface water reservoir with Toxoplasma gondii oocysts. An extensive investigation of the Victoria watershed 1 year following the outbreak documented the presence of an endemic T. gondii cycle involving the animals inhabiting the area. Cats and cougars were observed throughout the watershed. Serological evidence of T. gondii infection was demonstrated among domestic cats living in the Victoria area. Cougars were found to shed T. gondii oocysts. Serological evidence of T. gondii infection in deer mice living in the riparian environments of the watershed suggested that T. gondii oocysts were being shed near the water edge. Contamination of Victoria's water supply with T. gondii oocysts potentially occurred during the study period and future waterborne toxoplasmosis outbreaks in this and other communities are possible.     

Immunization with heat-killed Toxoplasma gondii stimulates an early IFN-gamma response and induces protection against virulent murine malaria.

In this study, we describe protection of BALB/c mice by immunization with heat-killed T. gondii tachyzoites against infection with Plasmodium yoelii 17XL which causes cerebral malaria and death in mice by day 7-8 post infection. Immunization resulted significant reduction in parasitemia at the peak period of infection. Protection induced by heat-killed T. gondii was associated with marked increase in NK cell number and IFN-gamma mRNA expression early in the infection. The level of IFN-gamma or TNF-alpha was found to diminish in T. gondii-treated mice as the infection progressed to the late stage. This declined response of IFN-gamma or TNF-alpha was associated with marked increase in the expression of IL-10, a counterregulatory cytokine. Pretreatment of mice with live T. gondii induced poor level of protection as compared with that of heat-killed parasites. Mice that received P. yoelii infection alone, had an elevated IFN-gamma response in the late stage of infection. Development of cerebral malaria in untreated mice was accompanied by an augmented production of TNF-alpha and nitric oxide (NO), the proinflammatory mediators. These findings suggest that nonspecific immunization with T. gondii leads to restoration of an early IFN-gamma response in P. yoelii-infected mice and in the establishment of an immunoregulatory mechanism that effectively antagonizes the disease-promoting effects of proinflammatory cytokines in the late phase of infection.     

Detection of high titres of Toxoplasma gondii antibodies in sera of patients with leprosy in Pakistan.

Untreated and treated leprosy patients and their household contacts were screened for antibody to Toxoplasma gondii using antigen-coated latex particles. A significantly high level of seroprevalence (29.6%) was observed in the untreated leprosy patients compared to endemic controls (P < 0.01) with a mean reciprocal antibody titre of 20,007 +/- 3580 (n = 98) in seropositive patients. In treated patients seroprevalence dropped to 13.5%. Seroprevalence in a group of household contacts of leprosy patients was similar to that of control subjects from an endemic area but not exposed to leprosy (7.8% and 6.1% respectively), indicating that the increased seroprevalence in leprosy patients was not merely due to increased exposure related to socioeconomic factors. Antigenic cross-reactivity between T. gondii and Mycobacterium leprae antigens was ruled out by cross inhibition experiments carried out with soluble antigens from each of the organisms. We believe these antibodies may be induced by an increase in T. gondii load in leprosy due to a transient reactivation of latent T. gondii infections, as the antibodies in these leprosy patients were not associated with any sign of eye or lymphatic pathology related to toxoplasmosis.     

健康人群弓形虫感染情况调查

[目的]了解保定市区健康人群弓形虫感染情况。[方法]采用ELISA法,对市区,郊区,乡村不同居住地3 023名普通健康人（无自觉症状,无临床疾病表现者）进行了IgG,IgM,CAg检查。[结果]感染率为2.84%（86/3 023）,和动物弓形虫感染率24.89%（397/1 595,另附文详述）和笔者94年～97年对医院对医院就诊患者进行的弓形虫感染率9.25%（53/573）比较要低。[结论]保定市区健康人群中存在着弓形虫感染,低于全国平均水平5.17%和京,津,石周边区,属低度感染区。应谨防其他地区或动物向人群传播。     

艾滋病合并弓形虫感染研究进展

摘要:弓形虫（Toxoplasma gondii）是一种专性细胞内寄生的机会致病原虫,引起严重的人兽共患弓形虫病。在机体免疫功能正常情况下,弓形虫多为隐性感染,而在免疫缺陷人群如艾滋病患者,弓形虫可对患者的中枢神经系统、呼吸系统、消化系统、内分泌系统、心血管系统等产生不同程度的损害。艾滋病合并弓形虫感染的研究主要集中在流行病学调查和诊断方法、对机体的影响、动物模型研究和治疗药物等方面,本文就艾滋病合并弓形虫感染研究进展进行综述。     

Optimizing admissions to an intensive care unit

This paper presents a model for optimizing admissions to an intensive care unit (ICU) where the objective is to maximize the expected incremental number of lives saved from operating the ICU. The probability distribution of the number of occupied ICU beds is modeled using queueing theory. Three different admissions policies are considered: first come first served (FCFS), first come first served for all referrals whose expected incremental survival benefits gained from ICU admission exceed some hurdle (FCFS-H), and first come first served for all referrals whose expected incremental survival benefits exceed a bed specific hurdle (BSH) that depends upon the number of occupied beds (FCFS-BSH). The model is applied to data describing patients referred to the ICU at Jerusalem's Hebrew University – Hadassah Hospital. After statistically estimating the distribution of expected incremental survival benefits among those referred to the ICU, we show that if only those referrals where ICU admission would improve the probability of survival by at least 19.4 percentage points were admitted, an additional 18 statistical lives would be saved annually compared to the FCFS policy, a relative life saving improvement of 17.9%. Implementing the more complex optimal bed specific hurdle policy would save an additional 1.4 statistical lives annually beyond what can be achieved with FCFS-H, a marginal improvement of only 1.2%.     

Serological screening and toxoplasmosis exposure factors among pregnant women in the Democratic Republic of Sao Tome and Principe

The seroprevalence of Toxoplasma gondii infection among pregnant women in the Democratic Republic of Sao Tome and Principe (DRSTP) from November 2003 to March 2004 was determined by detection of serum anti-T. gondii antibodies. A short questionnaire interview for pregnant women was performed to investigate risk factors associated with T. gondii infection, including consumption of raw meat or unwashed vegetables, drinking unboiled water and keeping pets (cats and dogs). The overall seroprevalence of T. gondii infection was high (75.2%; 375/499). The older age group of > or =35 years had a significantly higher seroprevalence (85.7%; 54/63) than that of the younger age group of 15-25 years (70.4%; 178/253) (odds ratio 2.5, 95% CI 1.2-5.4; P=0.01). No significant difference in the seroprevalence of T. gondii infection was found between the pregnant women with and without exposure to the risk factors studied. However, among pregnant women with high antibody titers of > or =1:1024, it seemed likely that continual contact with pets and consumption of oocyst-contaminated water or raw unwashed vegetables rather than tissue cysts in meat was the primary route of infection. The incidence of congenital toxoplasmosis in unborn babies should be intensively monitored in the DRSTP.     

Use of microbial risk assessment to inform the national estimate of acute gastrointestinal illness attributable to microbes in drinking water

Microbial risk assessment (MRA) evaluates the likelihood of adverse human health effects that occur following exposure to pathogenic microorganisms. This paper focuses on the potential use of MRA to provide insight to the national estimate of acute gastrointestinal illness (AGI) in the United States among persons served by public water systems. This article defines MRA, describes how MRA is implemented, provides an overview of the field of MRA and discusses how MRA may be useful for characterizing the national estimate. Communities served by drinking water systems with relatively contaminated source waters, sub-standard treatment facilities, and/or contamination problems in their distribution systems are subject to higher risks than communities where such issues are less of a concern. Further, the risk of illness attributable to pathogens in drinking water in each community can be thought of as the sum of the risk from the treated drinking water and the risk from the distribution system. Pathogen-specific MRAS could be developed to characterize the risk associated with each of these components; however, these assessments are likely to under-estimate the total risk from all pathogens attributable to drinking water. Potential methods for developing such MRAs are discussed along with their associated limitations.     

Recognition by the human immune system of candidate vaccine epitopes of Toxoplasma gondii measured by a competitive ELISA

A competitive ELISA for the detection of human antibody to specific candidate vaccine epitopes of Toxoplasma gondii is described. The method is based on competition between antibody in human serum and murine monoclonal antibody to bind to a crude sonicated antigen of T. gondii. A total of 301 normal human sera were tested against a panel of four anti-T. gondii murine monoclonal antibodies. The results obtained with two of the monoclonal antibodies (FMC 22 and FMC 23) gave good agreement with those of an indirect ELISA for human IgG to T. gondii, a measure of previous exposure to the parasite. The epitopes against which these two monoclonal antibodies are directed were recognized by the immune system of all patients previously exposed to the parasite, while greater than 92 and greater than 96% respectively of these patients recognized the epitopes which the other two monoclonal antibodies (FMC 18 and FMC 19) are directed against. An ELISA double antibody binding system was used to ascertain relationships in the epitope binding sites of the four monoclonal antibodies. The data obtained demonstrated that FMC 19 and FMC 22 bound to related epitopes. FMC 18, FMC 22 and FMC 23 also bound to related epitopes, but the binding of FMC 19 was found to be independent of the binding of FMC 18 and FMC 23 to their epitope binding sites.     

Recognition by the human immune system of candidate vaccine epitopes of Toxoplasma gondii measured by a competitive ELISA

A competitive ELISA for the detection of human antibody to specific candidate vaccine epitopes of Toxoplasma gondii is described. The method is based on competition between antibody in human serum and murine monoclonal antibody to bind to a crude sonicated antigen of T. gondii. A total of 301 normal human sera were tested against a panel of four anti-T. gondii murine monoclonal antibodies. The results obtained with two of the monoclonal antibodies (FMC 22 and FMC 23) gave good agreement with those of an indirect ELISA for human IgG to T. gondii, a measure of previous exposure to the parasite. The epitopes against which these two monoclonal antibodies are directed were recognized by the immune system of all patients previously exposed to the parasite, while greater than 92 and greater than 96% respectively of these patients recognized the epitopes which the other two monoclonal antibodies (FMC 18 and FMC 19) are directed against. An ELISA double antibody binding system was used to ascertain relationships in the epitope binding sites of the four monoclonal antibodies. The data obtained demonstrated that FMC 19 and FMC 22 bound to related epitopes. FMC 18, FMC 22 and FMC 23 also bound to related epitopes, but the binding of FMC 19 was found to be independent of the binding of FMC 18 and FMC 23 to their epitope binding sites.     

Toxoplasma gondii and Coxiella burneti antibodies among Brazilian slaughterhouse employees.

Previous studies have indicated toxoplasmosis and Q fever are potential hazards to persons who handle raw meat or who work in slaughterhouses. The prevalence of antibodies to T. gondii and C. burneti was studied among 144 employees of an abattoir in Belo Horizonte, Brazil, to determine what environmental factors may be associated with the occurrence of these agents among persons who handle meat but who have not reported having toxoplasmosis or Q fever. Seventy-two per cent of the 144 employees were serologically positive to T. gondii and 29% were serologically positive for C. burneti. The highest prevalence of antibodies to T. gondii (92%) occurred among meat inspectors, who also had a geometric mean titer (GMT) of 1400. The prevalence levels of antibodies to T. gondii for employees who handled meat in the deboning and sausage departments were 80% and 79% with GMT's of 412 and 340, respectively. These levels exceeded the antibody prevalences of 60% and 65% and GMT's of 168 and 120 for employees who worked with cattle in the corrals or who worked on the killing floor, respectively. Conversely, the prevalence of antibodies to C. burneti was highest (40%) among employees working in the corrals and who were exposed to dust and hides. A similar prevalence of antibodies to C. burneti was found in employees on the killing floor (36% positive) who were exposed to hides and viscera, but employees handling meat in the deboning or sausage section had prevalence levels of 20% and 14% respectively. Serologic testing of zebu cattle processed at the abattoir indicated that 10% of 124 tested had antibodies to T. gondii and 29% of 156 tested had antibodies to C. burneti. These levels in cattle are probably adequate to expose (and infect) persons who process meat daily. Continuous daily exposures to chronically infected cattle may result in sporadic undiagnosed illnesses or seroconversions from subclinical infections.     

Cardiac toxoplasmosis in pathology of acquired immunodeficiency syndrome

Four cases of myocarditis from toxoplasma gondii were observed at autopsy among 18 consecutive cases of acquired immunodeficiency syndrome (AIDS). All cases showed spotty inflammatory myocardial infiltration, consisting mainly of T lymphocytes and, to a lesser extent, of B lymphocytes, histiocytes, mastocytes and eosinophilic granulocytes, with presence of toxoplasma gondii in the cytoplasm of a few myocardial cells. The incidence of toxoplasmic myocarditis in heart involvement in AIDS was 22% in our cases, manifold higher than in preceding reports from the literature. This suggests that cardiac toxoplasmosis is far from rare in patients with AIDS.     

Perinatal mortality and residential proximity to an industrial park

The authors' objective was to determine whether residential proximity to an industrial park (IP) is associated with increased perinatal mortality (PM). This semiecological study included 63,850 delivered births with 840 cases of PM (1995-2000). The authors categorized the study populations by ethnicity (ie, Bedouin and Jewish) and type of locality. Residential distance from the IP served as a surrogate indicator of exposure. Among Bedouin newborns, proximity to the IP was associated with increased PM rates (relative risk = 1.45; 95% confidence interval = 1.22-1.72). The excess in PM was not related to maternal or newborn physical characteristics that the authors observed. The risk of PM and its components in the Jewish localities was not associated with IP proximity. The association between residential proximity to the IP and excess in PM among only Bedouin newborns may be related to vulnerability caused by the nomadic nature of the society.     

Toxoplasma gondii infection in the United States: seroprevalence and risk factors

Infection with Toxoplasma gondii can cause severe illness when the organism is contracted congenitally or when it is reactivated in immune-suppressed persons. To determine the prevalence of T. gondii infection in a representative sample of the US population, the authors tested sera from participants in the Third National Health and Nutrition Examination Survey (1988-1994) for immunoglobulin G antibodies to T. gondii. Of 27,145 persons aged > or =12 years, 17,658 (65%) had sera tested. The overall age-adjusted seroprevalence was 22.5% (95% confidence interval (CI): 21.1, 23.9); among women aged 15-44 years, seroprevalence was 15.0% (95% CI: 13.2, 17.0). Age-adjusted seroprevalence was higher in the Northeast (29.2%) than in the South (22.8%), Midwest (20.5%), or West (17.5%) (p < 0.05). In multivariate analysis, risk for T. gondii infection increased with age and was higher among persons who were foreign-born, persons with a lower educational level, those who lived in crowded conditions, and those who worked in soil-related occupations, although in subset analyses risk categories varied by race/ethnicity. Nearly one quarter of adults and adolescents in the United States have been infected with T. gondii. Most women of childbearing age in the United States are susceptible to acute infection and should be educated about ways to minimize exposure to T. gondii.     

弓形虫先天感染与妊娠结局及脐带血T淋巴细胞亚群构成的关系

目的 探讨弓形虫先天感染与脐带血T淋巴细胞亚群构成及妊娠结局的关系.方法 2009年3月至2010年5月于合肥市某医院采集784份新生儿脐带血标本,并收集所有新生儿的妊娠结局资料.应用ELISA检测血清弓形虫IgM抗体,对抗体阳性者和10名健康新生儿采用流式细胞术检测脐带血中的T淋巴细胞亚群构成.结果 根据弓形虫IgM抗体检测结果,将784名新生儿中分为感染组(21例)和对照组(763名).感染组体重及1 min Apgar评分分别为(3116.4±352.6)g、(8.21±1.26)分,低于对照组的(3220.1±242.3)g、(8.77±1.61)分,差异有统计学意义(P值均＜0.01).感染组中不良妊娠结局占19.0％(4/21),高于对照组的4.8％(37/763),差异有统计学意义(P=0.004).感染组中伴或不伴不良妊娠结局的新生儿,其脐带血CD3+T淋巴细胞比例分别为(64.51±5.27)％、(64.32±4.56)％,低于健康新生儿的(69.92±4.32)％(P值均＜0.01);其脐带血CD;/CD8+分别为1.39±0.24、1.64±0.28,低于健康新生儿的2.34±0.46(P值均＜0.01).结论 弓形虫感染可导致新生儿不良妊娠结局和细胞免疫功能紊乱,妊娠结局与T淋巴细胞亚群构成有关.     

某医学院学生弓形虫感染血清流行病学研究

目的 了解某医学院在校大学生弓形虫感染情况及影响因素。方法 运用ELISA 法检测入校新生和三年级以上学生血清弓形虫IgG抗体,并进行相关问卷调查。结果 弓形虫感染总阳性率为5.58%,新生(8.14%)感染率高于老生(3.56%),差异有统计学意义。职业家庭学生感染率(10.21%)高于非职业家庭学生(3.84%),差异有统计学意义。接触动物、禽类等的程度不同,弓形虫感染率有差异。结论 医学生中存在弓形虫感染,卫生、饮食和家庭职业环境对弓形虫感染有影响。需要加强医学生弓形虫病的流行和预防知识教育。     

Haptoglobin polymorphism in patients with inflammatory bowel diseases

BACKGROUND: Since functional differences were found among three major haptoglobin phenotypes, haptoglobin polymorphism was reported to be associated with the risk and clinical course of different inflammatory diseases. The aim of the study was to investigate the Hp polymorphism distribution in Hungarian Crohn's disease patients. METHODS: 511 Hungarian IBD patients were investigated (Crohn's disease patients: 468, m/f ratio: 233/235, duration 8.2 +/- 6.7 ys, and ulcerative colitis patients: 43, m/f: 22/21, duration: 9.5 +/- 10.6 ys) and 384 healthy subjects served as controls. Hp phenotypes were determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis of sera followed by immunoblotting. Clinical data were come by the questionnaires prepared by the physicians. RESULTS: The frequency of haptoglobin-1 allele was significantly higher in Crohn's disease (0.395) compared to the controls (0.345; OR: 1.24, 95%CI: 1.02-1.52, p = 0.03), but the phenotype distribution showed no such differences. Haptoglobin phenotype was associated to disease behavior in Crohn's disease (B1 and B2, in haptoglobin 1-1 and 2-2: 36.6%-34.3% and 32.4%-32.5% vs. in 2-1: 44.9% and 20.3%; ORB1Hp2-1 vs. others: 2.06, 95%CI: 1.29-3.28). Furthermore, an increased frequency of primary sclerosing cholangitis was observed in haptoglobin 2-2, compared to the 1-1 (6.5% vs. 0.0%, p = 0.039). No associations were found in ulcerative colitis. CONCLUSIONS: haptoglobin-1 allele was associated with Crohn's disease, whereas the phenotypes with the disease behavior and frequency of primary sclerosing cholangitis, exhibiting a disease-modifying effect.     

Seroprevalence of toxoplasmosis in HIV(+)/AIDS patients in Iran

Toxoplasma gondii has arisen as an important opportunistic agent especially in the central nervous system and in advanced HIV disease can cause significant morbidity and mortality. This study was carried out to determine the seroprevalence of toxoplasmosis among HIV-positive patients in Iran. Blood samples were collected from 201 HIV-positive patients and anti-toxoplasma antibodies were detected by using conventional ELISA. An antibody titer of >3 IU/ml was considered positive. The majority of studied patients were male (male to female ratio: 5 to 1) with the mean age of 36 ± 1 yrs. The seroprevalence of toxoplasmosis in HIV-positive patients was 49.75%. The mean CD4 count in HIV patients with positive toxoplasma serology was 332.5 ± 22.4 cells/μl. Only 1% of the patients had IgM anti-toxoplasma antibodies and 10% of the patients had clinical toxoplasma encephalitis. The mean CD4 count in this group was 66.4 ± 15.5 cells/μl and there was a significant association between CD4 count and rate of toxoplasma encephalitis (P<0.001). Previous reports suggested that toxoplasma encephalitis could be prevented by appropriate chemoprophylaxis. In view of the relatively high prevalence of toxoplasma infection found among the HIV-infected patients in our study, we suggest that routine screening for toxoplasma should be undertaken for all HIV-infected patients in Iran.     

Predictors of anticipated breastfeeding in an urban, low-income setting

BACKGROUND: Although the proportion of women who breastfeed is known to vary by demographic group, breastfeeding practices have not been sufficiently studied among urban, lower income African American populations seen in family medicine centers. METHODS: A cross-sectional design was used to examine demographic, clinical, and attitudinal factors that affect anticipated infant feeding practices reported by postpartum women from a low-income, urban family practice setting. Data was analyzed using chi-square, odds ratios (OR), and multiple logistic regression techniques. RESULTS: Among 66 respondents, only 3 subjects (4.5%) indicated that they planned to breastfeed exclusively, while an additional 11 subjects (16.7%) reported plans to use a combination of bottle-feeding and breastfeeding. Based on univariate analyses, women with less than 12 years of education were less likely to report anticipated breastfeeding. Otherwise, breastfeeding plans were not associated with subject demographic features or with reproductive characteristics. Respondents planning to bottle-feed noted that breastfeeding was too complicated. Logistic regression demonstrated an inverse relationship between level of maternal education and anticipated breastfeeding (OR=0.13, 95% confidence interval [CI], 0.05-0.35), and a direct association for encouragement from the baby's father or the woman's mother to breastfeed and anticipated breastfeeding (OR=12.4; 95% CI, 4.92-31.4). CONCLUSIONS: This study reports unique data regarding anticipated infant feeding practices among patients from an urban, low-income community served by a family medicine center. Findings from this study will be used to develop a family-centered educational intervention involving the mothers, grandmothers, and partners of pregnant patients to promote the benefits of breastfeeding in this community.     

辽西地区高危人群弓形虫感染情况调查分析

[目的]了解辽西地区(锦州市、朝阳市)高危人群弓形虫感染情况,为预防控制弓形虫病提供科学依据。[方法]选择重点人群,采用ELISA进行弓形虫抗体IgM、IgG检测。[结果]共调查1216人,人群弓形虫抗体阳性率10.03%,其中IgM阳性率5.43%,IgG阳性率4.60%。男性阳性率10.00%,女性阳性率10.06%,两者间差异无统计学意义。婚前妇女、孕妇、妇科病人阳性率10.74%;屠宰员和动物饲养员阳性率14.17%;招工体检人员阳性率7.22%;医护人员阳性率4.17%。养狗、猫等宠物的人群阳性率13.89%,不养者阳性率6.60%,两者间差异有统计学意义。[结论]辽西地区(锦州市、朝阳市)重点人群弓形虫感染的阳性率高于全国平均阳性率水平。以屠宰员和动物饲养员阳性率最高,养狗、猫等宠物的人群次之,婚前妇女、孕妇和妇科病人再次之。养狗、猫等宠物的人群阳性率明显高于不养者。应加强弓形虫病防治知识的宣传,不食未煮熟的猪、牛、羊、兔、鸡肉,并引起有关部门的重视。