Advances and Challenges in Diagnostics of Toxoplasmosis in HIV-Infected Patients

Seroprevalence and risk factors for Toxoplasma gondii infection in solid organ transplant patients: A global systematic review and meta-analysis

This study aimed to assess the global seroprevalence of IgG and IgM antibodies against Toxoplasma gondii (T. gondii) in solid organ transplant (SOT) recipients (kidney, liver, heart) through a literature review of studies published until October 24, 2024. Selected studies reported data on anti-T. gondii IgG and IgM seroprevalence in the post-transplant stage of SOT recipients. A random-effects model estimated pooled seroprevalence rates, and heterogeneity was evaluated using the I2 statistic. Sensitivity analysis examined prevalence changes after excluding studies, while subgroup analysis of IgG seroprevalence accounted for publication years, countries, continents, WHO regions, sample sizes, and types of transplanted organs. Out of 26 articles and 29 datasets analyzed, 21 articles and 24 datasets involving 19,391 transplant recipients and 880 controls were used to assess anti-T. gondii IgG and IgM seroprevalence and odds ratios (ORs). Additionally, 8 articles reported the anti-T. gondii IgG serostatus of donors and recipients. The pooled IgG seropositivity for T. gondii in SOT recipients was 9.8 % (95 % CI, 4.7-19.4 %), showing significant variation by region and organ type. The anti-T. gondii IgM seroprevalence in SOT recipients was 6.4 % (95 % CI, 3.3-12 %). Renal transplant recipients exhibited higher IgG seroprevalence compared to liver and heart transplant recipients. The pooled OR for T. gondii infections in SOT recipients vs. controls was 1.39 (95 % CI, 0.95-2.04, P = 0.08). The highest pooled anti-T. gondii IgG serostatus was 50.7 % in the undetermined group, followed by 38 % in the D-/R- group, 15.4 % in the D-/R+ group, 10.6 % in the D+/R- group, and 9.9 % in the D+/R+ group. Overall, T. gondii active infections and its increased risk trend in SOT recipients should not be overlooked.

Investigating Therapeutic Potential of Beta-Glucan on Experimental Toxoplasmosis in Immunocompetent and Immunocompromised Mice: In Silico and in Vivo Studies

There is a need to find efficient treatment for toxoplasmosis, a global disease with a public health concern, as the used therapeutics have limited effectiveness. Beta-glucan (β-glucan), a natural polysaccharide, has anti-inflammatory, immunomodulatory, and anti-infective activities against bacteria, viruses, and parasites. We aimed to investigate the therapeutic efficacy of β-glucan on toxoplasmosis using an in silico study and an in vivo mice model. The β-glucan drug-likeness characteristics were evaluated by molecular docking simulations, Lipinski's RO5 filter analysis, and the computational quantitative structural-activity relationships/absorption, distribution, metabolism, excretion, and toxicity predictive characteristics compared to spiramycin, an anti-toxoplasmosis drug. Sixty albino mice were divided into two divisions, immunocompetent and immunosuppressed. Each division contained five groups; healthy, diseased, spiramycin-treated, β-glucan-treated, and both β-glucan and spiramycin-treated groups. Parasitological, histopathological examinations, and immunological analysis were detected. β-glucan docked complexes demonstrated H-bonding and hydrophobic interactions towards their promising anti-toxoplasmosis targets compared to the spiramycin. The treated mice revealed a statistically significant reduction (p < 0.001) in the parasite burden. Regarding immunocompetent and immunosuppressed division, the group that was treated with both β-glucan and spiramycin, demonstrated the greatest outcomes, with 71% and 66% efficacy, respectively. It is concluded that β-glucan shows promising potential as an anti-toxoplasmosis candidate by potentiating the spiramycin effect and modulating the immunological response.

Antiparasitic and Antifungal Activities of Cetyl-Maritima, a New N-Cetyl-Modified Maritima Derivative

Background/Objectives: New drugs are urgently needed for the treatment of neglected tropical diseases including leishmaniasis and eumycetoma, as well as globally occurring parasitic diseases such as toxoplasmosis. Fragrances, both natural and synthetic, were shown to be a rich source for the development of new anti-infectives and warrant deeper investigations. Exemplarily, we synthetically optimized the fragrance 4-(4,8-dimethyl-3,7-nonadienyl)-pyridine, a.k.a. Maritima, a pyridine derivative with marine odor. Methods: A new cationic N-cetyl-modified derivative of Maritima (dubbed Cetyl-Maritima), obtained by alkylation of Maritima, was tested for its activity against Madurella mycetomatis (M. mycetomatis) fungi, as well as against Toxoplasma gondii (T. gondii) and Leishmania major (L. major) protozoal parasites. Results: Cetyl-Maritima was found to be more strongly antifungal than the parent Maritima and a known antibiotic cetylpyridinium salt. Cetyl-Maritima also showed a similar activity against T. gondii parasites and, most notably, exhibited sub-micromolar activity against L. major amastigotes. Conclusions: The considerable antileishmanial activity of Cetyl-Maritima might lead to the development of a new potent and cost-effective drug candidate for the therapy of leishmaniasis and other infectious diseases caused by kinetoplastid parasites.

Detection of Toxoplasma gondii in Brain Tissues of Pet Birds with Neurological Symptoms Using Loop-Mediated Isothermal Amplification (LAMP) and PCR

BACKGROUND

This study seeks to close this divide by assessing the occurrence of Toxoplasma gondii (T. gondii) in the brain tissues of pet birds displaying neurological symptoms, utilizing Nested Polymerase Chain Reaction (PCR) and Loop-mediated Isothermal Amplification (LAMP) methods. Furthermore, it aims to evaluate and contrast the sensitivity and specificity of different diagnostic procedures. Seventy bird samples, consisting of 50 sick and 20 asymptomatic samples, were assessed using various methods. Brain tissue DNA was isolated and then analyzed using nested PCR and LAMP assays targeting the T. gondii B1 gene and RE gene. Sensitivity and specificity assessments were conducted, and statistical evaluations were made using SPSS software.

RESULTS

Our findings revealed that no T. gondii cysts were detected in the smear preparations. However, T. gondii DNA was found in 6% of the sick birds using nested PCR, and LAMP identified T. gondii DNA in 8% of these individuals. Both techniques demonstrated a high level of specificity, with LAMP showing higher sensitivity and faster processing times than nested PCR. These results significantly contribute to our understanding of toxoplasmosis and highlight the reliability and potential for the widespread use of these diagnostic techniques, providing reassurance and confidence in their effectiveness.

CONCLUSION

The study underscores the importance of molecular diagnostics in promptly identifying and treating toxoplasmosis in birds. This enhances our understanding and control of the disease and underscores the significant impact of this research. The potential for further studies using more extensive and diverse bird populations to enhance surveillance and prevention strategies against T. gondii infections is promising. It should be actively pursued, giving us hope for a better future in avian health.

Disseminated histoplasmosis and presumptive CNS toxoplasmosis-associated immune reconstitution inflammatory syndrome in a patient with HIV/AIDS: a case report

BACKGROUND

Co-infections associated with Immune Reconstitution Inflammatory Syndrome (IRIS) have been described in literature, however they constitute an uncommon finding in the medical community.

CASE PRESENTATION

Here we report a rare case of a 55-year-old woman from Cuba with prior medical history of HIV/AIDS adherent to her antiretroviral therapy (ART) regimen, who was hospitalized in Miami, Florida because of fluid dysphagia, odynophagia and right-sided cervical lymphadenopathy. A prior biopsy of the right cervical lymph node performed in an outside hospital found evidence of non-caseating granulomas with budding yeast, which was later confirmed to be disseminated histoplasmosis by a positive (1-3) -β-glucan assay and histoplasmosis urine antigen in this admission. Furthermore, after multiple imaging testing due to her clinical condition, a brain MRI demonstrated findings concerning for cerebral toxoplasmosis, which was supported by serology findings. Treatment with liposomal amphotericin B and TMP-SMX led to clinical and radiological improvement of this patient's conditions, and she was discharged with an appointment for follow-up in the clinic.

CONCLUSION

This case highlights the complexities and challenges in managing opportunistic infections (OIs) during immune recovery in HIV/AIDS patients on ART, and emphasizes the necessity of continuous, vigilant monitoring and having a broad differential diagnosis in this group of patients.

Antiparasitic Activities of Acyl Hydrazones from Cinnamaldehydes and Structurally Related Fragrances

Background: New drugs for the treatment of protozoal parasite infections such as toxoplasmosis and leishmaniasis are required. Cinnamaldehyde and its derivatives appear to be promising antiparasitic drug candidates. Methods: Acyl hydrazones of cinnamaldehyde, 4-dimethylaminocinnamaldehyde, and of the synthetic fragrances silvialTM and florhydralTM were prepared and tested for activity against Toxoplasma gondii (T. gondii) and Leishmania major (L. major) parasites. Results: Three cinnamaldehyde acyl hydrazones (3-hydroxy-2-naphthoyl 2a and the salicyloyls 2c and 2d) showed good activity against T. gondii, and two compounds derived from cinnamaldehyde and florhydralTM (3-hydroxy-2-naphthoyls 2a and 4a) exhibited moderate activity against L. major promastigotes. Conclusions: In particular, the identified antitoxoplasmal activities are promising and might lead to the development of new potent and cost-effective drug candidates for the therapy of toxoplasmosis.

Cerebral toxoplasmosis mimicking stroke in a woman living with undiagnosed HIV

Toxoplasma gondii is an opportunistic pathogen that can intrude into the blood-brain barrier and reside in the brain only with low inflammatory reaction. When infected with HIV, the immune system becomes severely compromised and leads to the reactivation of latent toxoplasmosis infection, which can mimic the clinical manifestation of stroke. We report a case of a 65-year-old female patient who presented with sudden right limb weakness, walking difficulty, and numbness without other typical symptoms, raising suspicion of acute ischemic stroke. The HIV serology returned positive, which expedited the diagnostic workup for opportunistic infection. Combining imageological examination and metagenomics next-generation sequencing of cerebrospinal fluid, HIV-associated cerebral toxoplasmosis was confirmed. The patient underwent treatment for toxoplasmosis and HIV. Six months after onset, the patient can walk independently but still exhibits weakness in the right upper limb. In HIV-infected patients, cerebral toxoplasmosis, particularly presenting as isolated stroke-like episodes, poses a more significant challenge, emphasizing the need for more thorough investigations to reduce the potential for misdiagnosis.

Development of a LAMP method with lateral flow DNA chromatography to diagnose toxoplasmosis in immunocompromised patients

BACKGROUND

Rapid and accurate diagnosis of toxoplasmosis is critical, particularly for immunocompromised patients. Several molecular methods could have value for toxoplasmosis diagnosis, but often require sophisticated and expensive equipment, and as such are impractical for use in resource-limited countries. Our study aimed to develop a new rapid diagnostic test for toxoplasmosis that can be used in developed countries as well as low- or middle-income countries.

METHODS

Common primers for conventional loop-mediated isothermal amplification (LAMP) and the new LAMP DNA chromatography method were designed based on a 529-bp repeat present in Toxoplasma gondii genomic DNA. A total of 91 clinical samples from 44 patients suspected of having toxoplasmosis who were treated at several hospitals across Japan were tested using the new LAMP DNA chromatography method, conventional LAMP, and nested PCR and the sensitivity and specificity of the methods was compared.

RESULTS

The LAMP DNA chromatography method showed better sensitivity and specificity (68.2% and 100%, respectively) compared with the nested PCR (45.4% and 100%, respectively) and conventional LAMP (63.6% and 100%, respectively) methods for diagnosis of toxoplasmosis in immunocompromised patients. LAMP DNA chromatography also has better sensitivity and specificity (75% and 100%, respectively) than nested PCR (50.0% and 93.5%, respectively) and conventional LAMP (62.5% and 100%, respectively) to diagnose toxoplasma encephalitis using CSF samples.

CONCLUSION

We developed a LAMP DNA chromatography method to detect T. gondii DNA in clinical samples. This method also successfully detected T. gondii DNA in CSF from patients with toxoplasma encephalitis. This newly developed method can be a valuable rapid diagnostic test for toxoplasmosis in a range of settings, including resource-limited areas like those in low- or middle-income countries.

Seroprevalence of Toxoplasma gondii among HIV Positive Patients under Surveillance in Greek Infectious Disease Units: A Screening Study with Comparative Evaluation of Serological Methods

This study aims to screen for IgG antibodies against Toxoplasma gondii (T. gondii) in the sera of 155 newly diagnosed Human Immunodeficiency Virus (HIV) positive patients under surveillance in Greek Infectious Disease Units. Additionally, risk factors based on patient demographics were examined, and a comparative evaluation of commercially available serological methods was conducted. Three methods were employed to detect IgG antibodies against T. gondii: Enzyme-Linked Immunosorbent Assay (ELISA), Indirect Immunofluorescence Antibody Test (IFAT), and Western Blot (WB), which was used as a reference here. Forty-nine sera samples were true-positive for IgG antibodies against T. gondii, resulting in a 31.61% positivity rate, and the immunoassay test statistical reliability analysis resulted in higher IFAT accuracy (90.97%) compared to ELISA (76.26%). Furthermore, statistical analysis of demographic and immunological data included in the study placed female and foreign/non-Greek individuals at 2.24 (p = 0.0009) and 2.34 (p = 0.0006) times higher risk of positive T. gondii IgG testing compared to their male and Greek counterparts, respectively. Our findings on positivity rates and comparative serology underscore the importance of early and suitable screening measures for newly diagnosed HIV+ patients to mitigate the life-threatening outcomes that may arise from a potential subsequent T. gondii activation.

RPA-CRISPR/Cas9-based method for the detection of Toxoplasma gondii: A proof of concept

Toxoplasma gondii is a widespread and specialized intracellular protozoan pathogen that affects one third of the world' s population, posing a great threat to public health. As the definitive host, cats excrete oocysts and play a crucial role in the transmission of toxoplasmosis. The current diagnostic tools usually require bulky equipment and expertize, which hinders the efficient diagnosis and intervention of Toxoplasma infection in cats. In this study, we combined (RPA) with clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technique to establish an easier method for the detection of T. gondii oocysts in cat fecal samples. The sensitivity, specificity, and practicability of the established RPA-CRISPR/Cas9 method were evaluated using a lateral flow strip, with the limitation of detection determined at 10 plasmid copies/μL (corresponding to about one oocyst), cross reactivity to none of Giardia lamblia, Cryptosporidium sp., Microsporidium biberi and Blastocystis hominis that also commonly found in cats, and comparable performance in detecting T. gondii in clinical samples to conventional PCR amplification. This RPA-CRISPR/Cas9 method provides an alternative to conventional molecular tools used in the clinical diagnosis of Toxoplasma infection in cats and other animals.

The diagnosis of central nervous system infections in resource-limited settings and the use of novel and molecular diagnostic platforms to improve diagnosis

INTRODUCTION

Central nervous system infections (CNSI) disproportionately affect individuals in low-resource settings where diagnosis is challenging; large proportions of patients never receive a confirmed microbiological diagnosis resulting in inadequate management and high mortality. The epidemiology of CNSI varies globally and conventional diagnostics deployed in resource-limited settings have significant limitations, with an urgent need for improved diagnostic strategies.

AREAS COVERED

This review describes molecular platforms and other novel diagnostics used in the diagnosis of CNSI that are applicable to resource-limited settings. An extensive literature search of Medline and PubMed was performed. The emphasis is on investigations targeting infections of relevance to resource-limited settings either due to variation in regional CNSI epidemiology or due to increased prevalence in patients with immunosuppression. This includes commercially available multiplex PCR platforms, mycobacterial PCR platforms, and rapid diagnostics tests. To offer a framework for the optimal implementation in clinical settings, existing evidence highlighting the advantages and limitations of available platforms is reviewed.

EXPERT OPINION

The implementation of molecular platforms and other novel diagnostics has the potential to transform CNSI diagnosis in resource-limited settings, with several examples of successful rollout of novel diagnostics such as Xpert MTB/RIF Ultra and cryptococcal antigen testing.

Coinfection with Leishmania infantum and Toxoplasma gondii in Domestic Cats from a Region with a High Prevalence of Feline Immunodeficiency Virus

The aim of this study was to investigate the coinfection of feline retroviruses (feline immunodeficiency virus-FIV, and the feline leukemia virus-FeLV) with Leishmania infantum and Toxoplasma gondii and the factors associated with these pathogens in domestic cats from Mossoró, a city endemic for canine and human leishmaniasis situated in the semiarid region of Northeast Brazil. Blood samples from 120 cats were collected, and an epidemiological questionnaire was applied to investigate the risk factors associated with the infections. Retroviruses, L. infantum, and T. gondii infections were assessed using a point-of-care ELISA and quantitative PCR (qPCR), indirect fluorescent antibody test (IFAT) and qPCR, and IFAT, respectively. The overall seroprevalences observed were 35% (95% CI = 27.0-43.8%) for FIV, 0.8% (95% CI = 0.1-4.5%) for FeLV, 25.8% (95% CI = 18.8-34.3%) for T. gondii, and 4.2% (95% CI = 1.7-9.3%) for L. infantum. Coinfection with FIV and L. infantum was observed in 2.5% (3/120) of the assessed cats, while 12.5% (15/120) were coinfected with FIV and T. gondii. No significant association was found among the investigated agents (p > 0.05). The factors associated with FIV infection in the multivariable analysis were male sex and age above 78 months. The findings of this study demonstrated a high rate of FIV infection in cats from the Brazilian semiarid region and the exposure of these animals to zoonotic and opportunistic agents. Due to the immunosuppressive potential of FIV, cats infected with this retrovirus should be screened for coinfections with L. infantum and T. gondii, and preventative measures should be adopted.

Plasma Cholinesterase Activity in Patients With Rheumatoid Arthritis and Toxoplasmosis

Background and objective Rheumatoid arthritis (RA) is a chronic autoimmune disease causing synovium inflammation and functional impairment. Toxoplasmosis is an intracellular zoonotic parasitic infection and a risk factor in immunosuppressed diseases including RA. The involvement of the cholinergic mechanism is not clear when both diseases exist in combination. This study aimed to examine plasma cholinesterase (ChE) activity in patients suffering from RA with concomitant toxoplasmosis, taking into account the enzyme susceptibility to in vitro inhibitory challenge with the organophosphate dichlorvos in RA patients. Methods This was a case-control study involving 88 RA patients and 61 healthy controls of both genders. The RA patients were allocated into three groups. The first group received no therapy (n=14), the second group received conventional anti-arthritis therapy (n=49), and the third group received conventional + biologic therapy (n=25). Plasma ChE activity was determined by an electrometric method. Plasma samples were screened for Toxoplasma gondii (T. gondii) infection, using ELISA T. gondii antibodies IgG and IgM. In vitro inhibition of plasma ChE activity was assessed by incubating the samples with dichlorvos at 0.25 and 0.5 μM. The time-dependent dichlorvos (0.25 μM)-induced plasma ChE inhibition and its kinetics were determined. Results The RA patients comprised 76 (86.4%) females and 12 males (13.6%), whereas healthy controls included 22 (36.1%) females and 39 (63.9%) males. The rates of toxoplasmosis IgG positivity in controls and RA patients were 26.2% and 39.8%, respectively. Plasma ChE activity in patients with RA was significantly higher than that in the control group, by 16%. Plasma ChE values of RA patients with conventional therapy and conventional + biologic therapy were higher than that of the control group, by 18% and 27%, respectively. Odds and risk ratios of elevated plasma ChE activity (20%) in RA patients with therapy indicated that high plasma ChE activity among RA patients with therapy is a risk factor. The plasma ChE activity of T. gondii IgG-positive RA patients was not significantly different from that of the IgG-negative ones. Dichlorvos at 0.25 and 0.5 μM significantly inhibited in vitro plasma ChE activity in controls and RA patients. The rates of plasma ChE inhibition by dichlorvos were lower in the RA groups with conventional therapy in comparison with those in the control group (77% vs. 91%). Examining the dichlorvos time-dependent ChE inhibition kinetics, RA groups showed increases in the half-life of inhibition by 23.6% to 32.7% and the total inhibition time by 23.5% to 32.5%, together with decreases in the inhibition rate constant by 19% to 24.5%, an indication of reduced inhibition rate of plasma ChE activity compared to that of the control group. Conclusions The autoimmune nature of RA and its chronicity might have contributed to the increase in plasma ChE activity among the patients. This increase in enzyme activity could be a risk factor in RA patients undergoing conventional therapy alone or in combination with biologic therapy; however, the clinical significance of such a condition remains obscure at present. The in vitro inhibition of plasma ChE activity in RA patients suggests reduced susceptibility of the enzyme to ChE inhibition by dichlorvos. Toxoplasmosis was not a risk factor when plasma ChE activity was taken into account among RA patients.

The Medical Relevance of Toxoplasma Infections in Terms of the Safety of Blood Recipients under Immunosuppression-A Meta-Analysis

Laboratory diagnosis of Toxoplasma gondii infection plays a crucial role in ensuring the safety of blood recipients, especially in the case of immunosuppressed people, such as organ transplant patients. Toxoplasmosis, caused by the parasite Toxoplasma gondii, is a potential threat to people with weakened immune systems, and blood transfusions from infected donors can lead to severe complications. In this publication, we analyze the medical relevance of Toxoplasma infection in the context of the safety of blood recipients, focusing on the immunosuppressed patient population. We present various diagnostic methods, such as serological, molecular, and microscopic tests, which can detect the presence of Toxoplasma gondii in donors' blood. We also discuss the importance of adequately interpreting diagnostic results, considering risk factors, and detectability of the infection. We pay special attention to high-sensitivity and -specificity diagnostic techniques, which allow us to minimize the risk of Toxoplasma gondii transmission to blood recipients. Our findings have important implications for clinical practice and organ transplantation guidelines, emphasizing the need to diagnose and monitor Toxoplasma infections in blood donors and recipients.