Over the past three years, COVID-19 has triggered a global crisis, creating uncertainty due to co-infections with other viral diseases, such as chikungunya (24), zika (24), dengue (2), and monkeypox (25, 26), as well as parasitic diseases such as malaria (27), chagas disease (28, 29), and toxoplasmosis (3). This complex and multifaceted scenario has accentuated the challenges in public health management, underscoring the need for integrated strategies and coordinated approaches to address the various dimensions of this pandemic and its interactions with other prevalent diseases (30, 31).
In this systematic review and meta-analysis, 49% of COVID-19 patients were exposed to T. gondii, according to IgG detection. When analyzing the data in detail by country, it was found that the frequency of exposure in patients with COVID-19 in Iran reached 62%, compared to 38% in Egypt. The detection of IgG in these patients with COVID-19 is interpreted as evidence of previous exposure to T. gondii. In previous investigations, a 54% prevalence of toxoplasmosis was observed among COVID-19 patients registered in Egypt (12). Another study conducted by Habib S. et al. in the same country noted that 75% of patients with COVID-19 had toxoplasmosis (18). In Iran, Ghaffari et al. found that 84% of patients with COVID-19 had anti-Toxoplasma gondii antibodies (IgG) (13). In contrast, Geraili et al. reported a prevalence rate of 26.1% in northern Iran (15). In Saudi Arabia, Halawi M. et al. reported that 64.3% of patients with COVID-19 had toxoplasmosis (14). On the other hand, a similar study proposed by Galván-Ramírez MdlL. et al. in Mexico revealed that 21.9% of patients with COVID-19 showed the presence of T. gondii (17). Studies by Gouda MA, et al., (20) and Hasanzadeh M, et al. (22) indicated the absence of active T. gondii infection in patients with COVID-19 by IgM detection.
Another important result was that 2% of patients diagnosed with COVID-19 showed evidence of active T. gondii infection, which was assessed by IgM detection. In their study, Galván-Ramírez MdlL et al. reported that, when analyzing 191 patients with COVID-19 by IgM detection, 13.6% were found to have an active T. gondii infection (17).
Disparities in the prevalence of toxoplasmosis in patients with COVID-19 in various studies can be attributed to environmental factors such as temperature, humidity, geographic regions, and also sociodemographic factors such as the age distribution of the population examined (20, 32). A greater propensity for infection has been noted in areas with humid and warm climates. In addition, reference is made to the variability of infection prior to the introduction of the toxoplasmosis vaccine, linking it to the restrictive measures implemented by different countries during the coronavirus pandemic (33, 34).
The results of this research highlight our understanding of how the various pathogens interact and their impact on public health (35). It is also worth highlighting the importance of carrying out comprehensive epidemiological surveillance adapted to the particularities of each geographical region, which allows a more complete knowledge of the associated risks and thus facilitates the implementation of management strategies and the adoption of preventive measures according to the specific circumstances of each country (36).
Some authors suggest strengthening public health programs through a comprehensive approach that includes not only the management of the COVID-19 pandemic but also the surveillance of another concurrent infection, such as toxoplasmosis (37–39). Also, it is proposed to carry out educational campaigns aimed at the public with the exclusive objective of promoting specific preventive measures to reduce the transmission of both infections. International collaboration, in this case, is considered crucial to disseminate data and best practices, as well as to coordinate efforts in research and the development of public health strategies (40, 41).
This study has some important limitations. First, there is a shortage of studies specifically addressing the frequency of T. gondii exposure in patients with COVID-19. Secondly, it is crucial to recognize the possibility of biases present in the studies included. Thirdly, despite the authors' requests, we were unable to access some potential studies in their full version. Fourthly, the analysis was limited to subgroups by country due to the lack of specific data on T. gondii exposure in patients with COVID-19, which prevented assessment by sex and age in the included articles. Fifthly, studies do not fully report the clinical manifestations of patients with COVID-19 and toxoplasmosis.
With regard to its positive aspects, this study is positioned as the first systematic review that analyzes in a comprehensive manner the frequency of exposure of T. gondii in patients with COVID-19, using a rigorous methodological approach following the guidelines proposed by the PRISMA guides. In addition, all the procedures used for the selection of studies were carried out independently by two or more authors.