Molecular and serological diagnosis of toxoplasmosis: a systematic review and meta-analysis

Comparative evaluation of funduscopy, PCR and serology in the diagnosis of ocular toxoplasmosis at ECWA Eye Hospital, Kano

OBJECTIVE

Ocular toxoplasmosis, caused by Toxoplasma gondii, is a significant cause of posterior uveitis and vision impairment globally. Accurate diagnosis is essential to prevent retinal damage and optimise treatment. This study aimed to compare three diagnostic methods funduscopy, serology (ELISA), and PCR in detecting ocular toxoplasmosis in patients at ECWA Eye Hospital, Kano, Nigeria.

METHODS AND ANALYSIS

A total of 264 patients suspected of having ocular toxoplasmosis were enrolled. Funduscopy was performed to identify retinal lesions typical of T. gondii. Serological analysis was conducted using ELISA to detect anti-Toxoplasma IgG antibodies. Additionally, PCR was used to confirm the presence of T. gondii DNA in blood samples. The results from these methods were compared with assess their sensitivity, specificity and diagnostic value.

RESULTS

Funduscopy detected T. gondii in 25.4% (67/264) of the patients, while ELISA showed a higher detection rate of 36.7% (97/264). PCR, the most specific method, confirmed infection in only 3.8% (10/264) of cases, with 60% (6/10) of these being male and 40% (4/10) female. T. gondii detected had 196 base pairs. The study found that ELISA had the highest sensitivity (90.0%) but lower specificity (64.9%), whereas funduscopy showed high specificity (74.4%) but low sensitivity (20.0%). PCR had the highest specificity but a low detection rate, emphasising its role in confirming diagnosis.

CONCLUSION

Although ELISA and funduscopy detected more positive cases, PCR remains the gold standard for confirming T. gondii infection due to its high specificity. In resource-limited settings like ECWA Eye Hospital, combining serology and PCR offers a practical approach for improving diagnostic accuracy and ensuring timely treatment of ocular toxoplasmosis.

A customizable multiplex protein microarray for antibody testing and its application for tick-borne and other infectious diseases

Tick-borne infections are the most common vector-borne diseases in the USA. Ticks harbor and transmit several infections with Lyme disease being the most common tickborne infection in the US and Europe. Lack of awareness about tick populations, specific diagnostic tests, and overlapping signs and symptoms of tick-borne infections can often lead to misdiagnosis affecting treatment and the prevalence data reported especially for non-Lyme tick-borne infections. The diagnostic tests currently available for tick-borne diseases are severely limited in their ability to provide accurate results and cannot detect multiple pathogens in a single run. The multiplex protein microarray developed at Vibrant was designed to detect multiple serological antibodies thereby detecting exposure to multiple pathogens simultaneously. Our microarray in its present form can accommodate 400 antigens (molecules that can bind to specific antibodies) and can multiplex across antigen types, whole cell lysates, recombinant proteins, and peptides. A designed array containing multiple antigens of several microbes including Borrelia burgdorferi, the Lyme disease spirochete, was manufactured and evaluated. The immunoglobulin M (IgM) and G (IgG) responses against several tick-borne microbes and other infectious agents were analyzed for analytical and clinical performance. The microarray improved IgM and IgG sensitivities and specificities of individual microbes when compared with the respective gold standards. The testing was also performed in a single run in comparison to multiple runs needed for comparable testing standards. In summary, our study presents a flexible multiplex microarray platform that can provide quick results with high sensitivity and specificity for evaluating exposure to varied infectious agents especially tick-borne pathogens.

Toxoplasmal meningoencephalitis in a 14 week-old shelter cat with presumed feline infectious peritonitis

Toxoplasmal meningoencephalitis is a sporadic condition that is often misdiagnosed antemortem, frequently resulting in euthanasia especially in resource-limited settings. Here we report a case of a 7-week-old female domestic shorthair cat from an animal shelter who presented in a compromised condition and continued to display clinical signs consistent with a "failure to thrive" kitten. Weight loss and decreased activity were observed, and later on, neurological dysfunction became apparent. Based on clinical signs, non-effusive feline infectious peritonitis (FIP) was strongly suspected. Other possible conditions, such as a portosystemic shunt or toxoplasmosis, were also considered. Due to a poor prognosis, euthanasia was elected. Molecular testing at necropsy revealed no evidence for feline coronavirus infection; however, histopathological examination of the brain tissue revealed disseminated necrotizing meningoencephalitis with the presence of Toxoplasma gondii bradyzoites and tachyzoites, which was further confirmed by PCR and sequence analysis. In hindsight, it became clear that the kitten's failure to thrive was due to severe neurological compromise caused by overwhelming toxoplasmosis infection. This report underscores the diagnostic challenges associated with feline neurological disorders.

Serosurvey of Toxoplasma gondii and Toxocara spp. co-infection in pregnant women in low-income areas of Brazil

Introduction

Despite human toxoplasmosis and toxocariasis having been listed among the top six most neglected parasitic zoonoses worldwide, presenting similar associated risk factors and transmission routes, few studies have been conducted in pregnant women and the consequences of concurrent infection remain to be fully established. Accordingly, the present study has serologically assessed the co-infection and associated risk factors for Toxoplasma gondii and Toxocara spp. in pregnant women, assisted by the public Unified National Health System (SUS) in southeastern Brazil.

Materials and Methods

Blood samples were collected and tested for IgG antibodies against Toxoplasma gondii by chemiluminescence immunoassay and against Toxocara spp. by enzyme-linked immunosorbent assay (ELISA). An epidemiological questionnaire was applied to gather socioeconomic information to assess the risk factors associated with seropositivity to toxocariasis/toxoplasmosis by univariate analysis followed by logistic regression.

Results

Overall, seropositivity was 69/280 (24.6, 95% CI: 19.96-30.01) for T. gondii and 56/280 (20.0, 95% CI: 15.73-25.08) for Toxocara spp. Co-infection was observed in 25/280 (8.9, 95% CI: 6.12-12.85) pregnant women, with increased odds (OR: 3.3, CI 95%: 1.77-6.14, p = 0.0002). Logistic regression revealed that a higher educational level (high school or college) significantly reduced the likelihood of co-infection seropositivity, owning cats increased the odds of toxocariasis, and older pregnant women presented significantly higher T. gondii seropositivity.

Conclusion

Co-infection herein highlights the importance of educational programs in the prevention of toxocariasis and toxoplasmosis in pregnant women and other high-risk populations.