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

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.

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.