Toxoplasma Infection In Humans Research Articles

Optimal control strategies for toxoplasmosis disease transmission dynamics via harmonic mean-type incident rate

Toxoplasma infection in humans is considered due to direct contact with infected cats. Toxoplasma infection (an endemic disease) has the potential to affect various organs and systems (brain, eyes, heart, lungs, liver, and lymph nodes). Bilinear incidence rate and constant population (birth rate is equal to death rate) are used in the literature to explain the dynamics of Toxoplasmosis disease transmission in humans and cats. The goal of this study is to consider the mathematical model of Toxoplasma disease with harmonic mean type incident rate and also consider that the population of humans and cats is not equal (birth rate and the death rate are not equal). In examining Toxoplasma transmission dynamics in humans and cats, harmonic mean incidence rates are better than bilinear incidence rates. The disease dynamics are first schematically illustrated, and then the law of mass action is applied to obtain nonlinear ordinary differential equations (ODEs). Analysis of the boundedness, positivity, and equilibrium points of the system has been analyzed. The reproduction number is calculated using the next-generation matrix technique. The stability of disease-free and endemic equilibrium are analyzed. Sensitivity analysis is also done for reproduction number. Numerical simulation shows that the infection is spread in the population when the contact rate βh\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta_{h}$$\\end{document} and βc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta_{c}$$\\end{document} increases while the infection is reduced when the recovery rate δh\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\delta_{h}$$\\end{document} increases. This study investigates the impact of various optimal control strategies, such as vaccinations for the control of disease and the awareness of disease awareness, on the management of disease.

Serological and molecular rapid diagnostic tests for Toxoplasma infection in humans and animals.

Infection by Toxoplasma gondii is prevalent worldwide. The parasite can infect a broad spectrum of vertebrate hosts, but infection of fetuses and immunocompromised patients is of particular concern. Easy-to-perform, robust, and highly sensitive and specific methods to detect Toxoplasma infection are important for the treatment and management of patients. Rapid diagnostic methods that do not sacrifice the accuracy of the assay and give reproducible results in a short time are highly desirable. In this context, rapid diagnostic tests (RDTs), especially with point-of-care (POC) features, are promising diagnostic methods in clinical microbiology laboratories, especially in areas with minimal laboratory facilities. More advanced methods using microfluidics and sensor technology will be the future trend. In this review, we discuss serological and molecular-based rapid diagnostic tests for detecting Toxoplasma infection in humans as well as animals.

Impaired social behaviour and molecular mediators of associated neural circuits during chronic Toxoplasma gondii infection in female mice

Toxoplasma gondii (T. gondii) is a neurotropic parasite that is associated with various neuropsychiatric disorders. Rodents infected with T. gondii display a plethora of behavioural alterations, and Toxoplasma infection in humans has been strongly associated with disorders such as schizophrenia, in which impaired social behaviour is an important feature. Elucidating changes at the cellular level relevant to neuropsychiatric conditions can lead to effective therapies. Here, we compare changes in behaviour during an acute and chronic T. gondii infection in female mice. Further, we notice that during chronic phase of infection, mice display impaired sociability when exposed to a novel conspecific. Also, we show that T. gondii infected mice display impaired short-term social recognition memory. However, object recognition memory remains intact. Using c-Fos as a marker of neuronal activity, we show that infection leads to an impairment in neuronal activation in the medial prefrontal cortex, hippocampus as well as the amygdala when mice are exposed to a social environment and a change in functional connectivity between these regions. We found changes in synaptic proteins that play a role in the process of neuronal activation such as synaptophysin, PSD-95 and changes in downstream substrates of cell activity such as cyclic AMP, phospho-CREB and BDNF. Our results point towards an imbalance in neuronal activity that can lead to a wider range of neuropsychiatric problems upon T. gondii infection.

DNA detection of Toxoplasma gondii in sheep milk and blood samples in relation to phase of infection

Toxoplasma gondii is a worldwide parasite that is important both for veterinary medicine (economic losses in the herd) and for public health (immunocompromised patients and pregnant women). An important source of Toxoplasma infection in humans is consumption of contaminated meat and milk (undercooked meat and unpasteurized milk). Small ruminants are important in both milk and meat production throughout the world because of free-range husbandry. The purpose of our study was to detect the presence of T. gondii DNA in ewes’ milk 1 month after the term, and to determine the relationship between the occurrence of this DNA in blood and milk based on the phase of infection. Using enzyme-linked immunosorbent assay (ELISA) the animals were divided into two groups (immunoglobulin M positive (IgM+), IgM−). With real-time polymerase chain reaction (PCR), T. gondii DNA was detected in seven milk samples (28%) and five blood samples (20%) of the IgM+ group (25 samples). In the IgM− group T. gondii DNA was detected in two milk samples (3.6%) out of 55 samples.

Molecular Diagnosis of Toxoplasmosis in Non Immune Pregnant Females

BACKGROUND AND AIM: Infection with the protozoan parasite Toxoplasma gondii has a worldwide distribution. Congenital infection is the most important part of the disease burden due to Toxoplasma infection in humans. Early diagnosis of maternal infection helps to prevent severe complications of toxoplasmosis. In the present study, three PCR assays (conventional, nested & quantitative) were evaluated for diagnosis of recent toxoplasmosis based on detection of Toxoplasma B1 gene.MATERIAL AND METHODS: The present study was carried out on 150 pregnant females who were serologically negative for anti-Toxoplasma IgG and IgM antibodies.RESULTS: The results revealed that out of 12 true positive cases (by 2 out of the 3 PCR protocols), 8 cases were positive by cPCR, 11 cases were positive by nPCR and 12 cases were positive by qPCR. Accurate estimation of genomic Toxoplasma DNA in positive samples was achieved by qPCR. In general, PCR assays offer a sensitive alternative of serological methods for diagnosis of recent maternal toxoplasmosis. In addition, qPCR decreases the risk of contamination of PCR products being a closed tube method and helps in estimation of infection load.CONCLUSIONS: We recommend screening of high-risk pregnant women by qPCR for early diagnosis of toxoplasmosis and proper management.

Molecular Diagnosis of Toxoplasmosis in Non Immune Pregnant Females

BACKGROUND AND AIM: Infection with the protozoan parasite Toxoplasma gondii has a worldwide distribution. Congenital infection is the most important part of the disease burden due to Toxoplasma infection in humans. Early diagnosis of maternal infection helps to prevent severe complications of toxoplasmosis. In the present study, three PCR assays (conventional, nested & quantitative) were evaluated for diagnosis of recent toxoplasmosis based on detection of Toxoplasma B1 gene.MATERIAL AND METHODS: The present study was carried out on 150 pregnant females who were serologically negative for anti-Toxoplasma IgG and IgM antibodies.RESULTS: The results revealed that out of 12 true positive cases (by 2 out of the 3 PCR protocols), 8 cases were positive by cPCR, 11 cases were positive by nPCR and 12 cases were positive by qPCR. Accurate estimation of genomic Toxoplasma DNA in positive samples was achieved by qPCR. In general, PCR assays offer a sensitive alternative of serological methods for diagnosis of recent maternal toxoplasmosis. In addition, qPCR decreases the risk of contamination of PCR products being a closed tube method and helps in estimation of infection load.CONCLUSIONS: We recommend screening of high-risk pregnant women by qPCR for early diagnosis of toxoplasmosis and proper management.

Development of high‐throughput methods to quantify cysts of Toxoplasma gondii

Toxplasma is a protozoan parasite, which forms persistent cysts in tissues of chronically infected animals and humans. Cysts can reactivate leading to severe pathologies. They also contribute to the transmission of Toxoplasma infection in humans by ingestion of undercooked meat. Classically, the quantification of cyst burden in tissues uses microscopy methods, which are laborious and time consuming. Here, we have developed automated protocols to quantify cysts, based on flow cytometry or high-throughput microscopy. Brains of rodents infected with cysts of Prugniaud strain were incubated with the FITC-Dolichos biflorus lectin and analyzed by flow cytometry and high-throughput epifluorescence microscopy. The comparison of cyst counts by manual epifluorescence microscopy to flow cytometry or to high-throughput epifluorescence microscopy revealed a good correlation (r = 0.934, r = 0.993, P < 0.001 respectively). High-throughput epifluorescence microscopy was found to be more specific and sensitive than flow cytometry and easier to use for large series of samples. This reliable and easy protocol allow the specific detection of Toxoplasma cysts in brain, even at low concentrations; it could be a new way to detect them in water and in contaminate food.

Seroprevalence and Risk Factors forToxoplasma gondiiInfection on Finishing Swine Reared in the Umbria Region, Central Italy

Toxoplasma gondii is a worldwide zoonotic protozoan parasite and pork is considered the major meat source of Toxoplasma infection in humans. To determine the prevalence of infection of Toxoplasma gondii in pigs reared in the Umbria Region (central Italy), blood samples of 960 pigs from 10 different farms (96 for each farm) were randomly collected and tested for antibodies (IgG) against T. gondii using an IFA assay. Sera were screened at 1/16 titrr and the endpoint titre was determined. Farm management questionnaires were completed and used to develop descriptive statistics on the tested farms as well as to determine measures of association for risk factors for the presence of T. gondii-seropositive pigs. A total of 155 seropositive pigs (16.14%) were identified; within herds prevalence ranged from 8.33 to 25%. The statistical analysis identified all-in-all-out housing and cleaning method as risk factors for Toxoplasma infection.

Serotyping of Toxoplasma gondii: striking homogeneous pattern between symptomatic and asymptomatic infections within Europe and South America

Field isolates of Toxoplasma gondii in Europe and North America have been grouped into three clonal lineages that display different virulence in mice. Whether the genetic structure of the parasite is related to clinical expression in humans has not yet been demonstrated. We developed an enzyme-linked immunosorbent assay which uses lineage-specific, polymorphic polypeptides derived from the dense granule antigens, GRA5 and GRA6. Our goal was to compare serotypical patterns observed in asymptomatic versus symptomatic (ocular disease and severe infection in human immunodeficiency virus (HIV)-positive patients) infections among patients from Europe and South America. Independent of the clinical presentation of the disease, serotypes differed according to geographical origin, with a homogeneous distribution of serotype II in Europe and of serotypes I and III in South America. We conclude that GRA5–GRA6 serotyping is an interesting tool to study serotype prevalence in populations but it is not an accurate marker of pathogenicity of Toxoplasma infection in humans.

The Differential Agglutination Test as a Diagnostic Aid in Cases of Toxoplasmic Lymphadenitis

Lymphadenopathy (LN) is the most common clinical manifestation of acute acquired toxoplasma infection in humans. The diagnosis of toxoplasmic lymphadenitis (TL) is established by serological methods and/or lymph node biopsy. In the United States, the differential agglutination (of acetone [AC]-fixed versus that of formalin [HS]-fixed tachyzoites) test (AC/HS test) has primarily been used in assessments of pregnant women as a component of the toxoplasma serological profile to distinguish between recently acquired infections and infections acquired in the distant past. We studied the AC/HS test in patients with TL to define its usefulness in diagnosing individuals presenting with LN and to determine its kinetics after the onset of LN. One hundred nine consecutive patients (158 serum samples) diagnosed serologically and by lymph node biopsy as having TL were studied. Specific patterns in the AC/HS test were noted to be dependent on the time from the clinical onset of LN (COLN). Acute AC/HS patterns were observed for more than 75% of patients who according to their histories had developed their TL within 6 months after COLN. Acute patterns were not observed beyond the 12th month except for a single patient for whom an acute pattern (400/800) persisted to the 13th month after COLN. Equivocal patterns were observed up to 36 months after COLN. Nonacute patterns were observed only for serum samples drawn at least 13 months after COLN. A nonacute pattern in an individual at less than 12 months after COLN should suggest an etiology other than TL. In such cases, investigation for alternative causes, including malignancy, should be instigated.

Antigen(s) responsible for immunoglobulin G responses specific for the acute stage of Toxoplasma infection in humans.

An agglutination test for immunoglobulin G (IgG) Toxoplasma antibodies with acetone-fixed tachyzoites (AC antigens; AC agglutination test) was positive only with sera from patients during the acute stage of their infection. In contrast, when the test was performed with Formalin-fixed tachyzoites (HS antigens; HS agglutination test), positive results were obtained during both the acute and chronic (latent) stages of the infection. Studies were performed to define the antigen(s) of T. gondii which are detected by IgG antibodies present only during the acute stage of the infection. Sera of mice immunized with AC antigens recognized predominantly 10 antigens of tachyzoites by immunoblot analysis. Sera from individuals with the acute but not chronic infection reacted strongly with these same 10 antigens in immunoblots. Sera of mice immunized with HS antigens recognized more Toxoplasma antigens on immunoblots than did mouse AC antibodies. Absorption of the latter with HS antigens removed detectable reactivity of AC antibodies in immunoblots and in the AC and HS agglutination tests, suggesting that AC antigens are a selected portion of HS antigens. AC antigens were specific for tachyzoites in that AC antibodies reacted with the cell membranes of both forms of the organism in an indirect fluorescent-antibody test. Tachyzoite-specific antigen(s) appear to be useful in differentiating between the acute and chronic stages of Toxoplasma infection through their detection by IgG antibodies.