Unraveling the Interplay Between COVID-19 and Toxoplasmosis


The COVID-19 pandemic has brought forth a formidable global public health crisis, prompting a profound examination of the intricate dynamics between the immune system and various pathogens (1). Amid this scrutiny, the presence of co-infections capable of modulating the immune response during SARS-CoV-2 infection, including dengue, malaria, and toxoplasmosis, has garnered significant attention (2, 3).

Toxoplasmosis, caused by the intracellular parasite Toxoplasma gondii, predominantly spreads through oocysts, with zoonotic and congenital transmissions being the most common routes (4). The prevalence of toxoplasmosis exhibits regional disparities, with the highest rates observed in Africa (61.4%), Oceania (38.5%), and South America (31.2%) (5).

Among pregnant women, prevalence stands at an estimated 33.8%, with higher frequencies noted in South America (56%) and low-income regions with low human development indices (6). Consequently, T. gondii emerges as a globally pervasive parasite, manifesting rare clinical symptoms such as fever, myalgia, cervical lymphadenopathy, fatigue, and ocular involvement, particularly in the congenital form (7).

Remarkably, both SARS-CoV-2 and T. gondii engage similar innate immune pathways. Both pathogens activate toll-like receptors (TLRs), including TLR 2, TLR4, and TLR7, through canonical pathways, suggesting potential synergistic effects (8, 9). Furthermore, cytokines produced during toxoplasmosis may exacerbate the severity of COVID-19, underlining the intricate interplay between these infections (8–10).

The nexus between COVID-19 and T. gondii exposure has emerged as a pivotal area of investigation. The objective of this study is to ascertain the prevalence of T. gondii exposure among COVID-19 patients, marking a significant milestone in understanding the interplay between distinct infectious agents.

Conducting a rigorous systematic review and meta-analysis, we meticulously collated and analyzed pertinent data. This meticulous process illuminated the frequency of T. gondii exposure, offering insights into the immune responses of individuals afflicted with both conditions.

This analysis lays a robust foundation for future research endeavors, augmenting the scientific comprehension of clinical management strategies for COVID-19 patients. By probing the potential co-occurrence of infections such as toxoplasmosis, it elucidates noteworthy implications that may influence the diagnosis and treatment paradigms for these individuals.

Understanding Toxoplasmosis: A Comprehensive Analysis

Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii. It is one of the most common parasitic infections worldwide, affecting a broad range of warm-blooded animals, including humans. The prevalence of Toxoplasma gondii infection varies geographically and is influenced by factors such as climate, hygiene practices, and dietary habits.

This parasitic infection has a complex life cycle involving both intermediate and definitive hosts. Domestic cats are the primary hosts in which the parasite can sexually reproduce, shedding oocysts into the environment through feces. Intermediate hosts, including humans, can become infected through ingestion of contaminated food or water, or by handling infected soil or cat litter.

Toxoplasmosis typically presents with mild or asymptomatic symptoms in immunocompetent individuals. However, severe complications can arise in immunocompromised individuals and pregnant women. Congenital toxoplasmosis, resulting from transplacental transmission of the parasite, can lead to miscarriage, stillbirth, or severe neurological and ocular abnormalities in newborns.

The diagnosis of toxoplasmosis often involves serological testing to detect antibodies against Toxoplasma gondii, as well as molecular techniques such as polymerase chain reaction (PCR) to detect the parasite’s DNA in clinical samples. Imaging studies, such as magnetic resonance imaging (MRI) and computed tomography (CT), may be performed to evaluate the extent of organ involvement in severe cases.

Treatment options for toxoplasmosis depend on the severity of the infection and the patient’s immune status. In immunocompetent individuals with mild symptoms, treatment may not be necessary, as the infection often resolves spontaneously. However, antimicrobial therapy with drugs such as pyrimethamine, sulfadiazine, and folinic acid is recommended for severe cases and in immunocompromised patients to prevent disease progression and complications.

Prevention strategies focus on minimizing exposure to Toxoplasma gondii oocysts by practicing good hygiene and food safety measures. Pregnant women are advised to avoid handling cat litter boxes and to cook meat thoroughly to reduce the risk of acquiring the infection. Furthermore, pregnant women with suspected or confirmed toxoplasmosis should receive prompt medical evaluation and treatment to minimize the risk of vertical transmission to the fetus.

Research efforts continue to advance our understanding of Toxoplasma gondii and its interactions with the host immune system. Studies investigating novel drug targets and vaccine development aim to improve treatment outcomes and prevent transmission of the parasite in high-risk populations.


The past three years have witnessed the emergence of COVID-19 as a global crisis, casting a shadow of uncertainty due to co-infections with various viral and parasitic diseases such as chikungunya, zika, dengue, monkeypox, malaria, chagas disease, and toxoplasmosis (24–29). This intricate scenario has magnified the complexities in public health management, underscoring the imperative for integrated strategies and coordinated approaches to tackle the multifaceted dimensions of this pandemic and its interactions with other prevalent diseases (30, 31).

In this systematic review and meta-analysis, a thorough examination revealed that 49% of COVID-19 patients exhibited exposure to T. gondii, as evidenced by IgG detection. Country-specific analysis unveiled variations in exposure frequency, with Iran registering 62% and Egypt reporting 38% among COVID-19 patients. The detection of IgG antibodies implies prior exposure to T. gondii. Previous investigations in Egypt noted a 54% prevalence of toxoplasmosis among COVID-19 patients, with a study by Habib S. et al. indicating a striking 75% prevalence (12, 18).

Similarly, in Iran, Ghaffari et al. found 84% prevalence, contrasting with Geraili et al.’s report of 26.1% in northern Iran (13, 15). In Saudi Arabia, Halawi M. et al. documented a prevalence of 64.3% (14). Conversely, a study in Mexico by Galván-Ramírez MdlL. et al. unveiled a lower prevalence of 21.9% (17). Studies by Gouda MA, et al., and Hasanzadeh M, et al., indicated no active T. gondii infection by IgM detection in COVID-19 patients (20, 22).

Another significant finding was the detection of active T. gondii infection in 2% of COVID-19 patients through IgM detection. Galván-Ramírez MdlL et al. reported a 13.6% prevalence of active infection among 191 COVID-19 patients analyzed (17).

Discrepancies in toxoplasmosis prevalence among COVID-19 patients across studies can be attributed to environmental factors like temperature, humidity, geographical regions, and sociodemographic factors such as age distribution (20, 32). Regions with warm, humid climates exhibit higher infection rates. Additionally, variations in infection rates pre-vaccine era and during COVID-19 pandemic restrictions are noted (33, 34).

These findings elucidate the intricate interactions between pathogens and their implications for public health (35). They underscore the importance of comprehensive epidemiological surveillance tailored to regional peculiarities for a nuanced understanding of associated risks, facilitating tailored management strategies and preventive measures (36).

Authors advocate for bolstering public health programs with a holistic approach encompassing COVID-19 management alongside surveillance of concurrent infections like toxoplasmosis (37–39). Educational campaigns targeting specific preventive measures for both infections are proposed. International collaboration is deemed essential for data dissemination, best practice sharing, research, and public health strategy development (40, 41).

While this study provides valuable insights, it faces limitations. Firstly, scarcity of studies specifically addressing T. gondii exposure frequency in COVID-19 patients. Secondly, potential biases in included studies. Thirdly, access constraints to some studies’ full versions. Fourthly, subgroup analysis limitation due to insufficient data on T. gondii exposure, hindering assessment by sex and age. Lastly, incomplete reporting of clinical manifestations in COVID-19 patients with toxoplasmosis.

Despite limitations, this study stands as the first comprehensive review analyzing T. gondii exposure frequency in COVID-19 patients, employing a rigorous methodological approach following PRISMA guidelines. All study selection procedures were conducted independently by two or more authors.

REFERENCE LINK :https://www.researchsquare.com/article/rs-4009743/v1


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