Toxoplasmosis is a global parasitic illness caused by a specific type of protozoan called Toxoplasma gondii. This protozoan is an obligate intracellular parasite, meaning it can only survive and reproduce inside host cells. (Robert-Gangneux and Dardé, 2012). Approximately one-third of the global population is believed to be infected with this parasite in both industrialised and developing nations (Mizani et al., 2017; Montoya, 1965). Humans can contract the parasite through various means, such as consuming raw or undercooked meat that contains tissue cysts of the parasite, ingesting sporulated oocysts from contaminated water and food, and vertical transmission during pregnancy via the placenta to the foetus (Hill and Dubey, 2002). The parasite T. gondii persists indefinitely in the tissues of the infected host (Wilking et al., 2016). According to Flegr et al. (2014), the majority of persons with a strong immune system who become infected with this parasite do not show any signs or only have mild symptoms. The predominant manifestation of toxoplasmosis in humans is lymphadenopathy, which can be accompanied by fever, sore throat, myalgia, tiredness, and headache (Hill and Dubey, 2002). Severe problems are more likely to occur in patients who are congenitally infected and immunocompromised (Daryani et al., 2014). Rheumatoid arthritis (RA) is a prevalent autoimmune disease that leads to joint inflammation and is the primary cause of disability, affecting around 0.5-1% of the population (Prasad and Vassiliou, 2015; Bullock et al., 2018). Recently, there has been an increasing recognition of the involvement of infectious agents, particularly bacteria and viruses, in the development of autoimmune illnesses. However, the impact of parasitic infections on host immunity and their contribution to autoimmune diseases has not been thoroughly studied. The experimental data suggests that some parasite infections may have a protective effect against the development of autoimmune diseases (Khan et al., 2019). Several geoepidemiological studies have demonstrated that the genetic susceptibility of hosts interacts with various lifestyle and environmental factors, including socioeconomic status, dietary habits, environmental pollutants, and exposure to ultraviolet radiation. Additionally, infections contribute to an increased risk of developing autoimmunity (Shapira et al., 2010). Infectious infections might potentially contribute to the development of autoimmune disorders through mechanisms such as molecular mimicry and epitope dissemination (Fischer et al., 2013).

Collection Samples

All samples of the experiment were taken from cephalic vein in non-heparinized tubes, at the conclusion of each treated and control period, all samples collection from Al-Dewaniyah Hospital, and from clinical private from July-2022 to Feb. 2023.

Experimental design

The experiment was designed and divided into two groups, a group of healthy people and a group of people infected with rheumatoid arthritis with infection with Toxoplasma gondii.

1. Healthy group: 100 samples from peoples without any disease or treatment.
2. Patients group: 100 samples from peoples' patients treated and untreated with rheumatoid arthritis with infection of Toxoplasma gondii.

All samples of the experiment were taken from cephalic vein in non-heparinized tubes, at the conclusion of each treated and control period. After being separated (by centrifugation at 3000 rpm for 5 minutes), blood serum samples were stored at -20 ^o C pending evaluation of the Serological diagnosis of rheumatoid arthritis, Serological screening for specific antibodies to toxoplasmosis in treated and untreated patients, Serological investigation of specific antibodies to toxoplasmosis in the control group.

Ethical approval

This study involves human participants. The Arab Board of Health Specialisations in Iraq (reference 146) and MSc Research Ethics Committee at London School of Hygiene & Tropical Medicine in the UK (reference 27380) provided ethics approval. Participants gave informed consent to participate in the study before taking part

Statistical Analysis:

The results were presented as the average value plus or minus the standard error of the mean (SEM). Comparisons were conducted using one-way analysis of variance (ANOVA1) and Newman-Keuls test to examine the unpaired values of all groups. Significant differences were observed at a significance level of P<0.05. 

Correlation between the anti-Toxoplasma IgG and arthritis

The results of the current study present in Table (1) Through the Odd Ratio (OR) value, it was found that there is a relationship between the incidence of five types of arthritis and the presence of the Toxoplasma gondii infection.

Table (1): Anti-Toxoplasma IgG among arthritis types.

Rheumatoid factor rate (RF) in arthritis with Toxoplasmosis:

The results of the current study showed that there is a significant increase at (P≤0.05) in Rheumatoid factor (60.63±6.69) in a Patients Arthritis Compared with the healthy group (22.72±4.17), whereas the results of the current study also showed that there is an increase in Rheumatoid factor in the patients that was infected with arthritis and those infected with T. gondii together (97.88 ± 7.01), compared to the group that was with arthritis (60.63±6.69), and a group of healthy people (23.18 ± 3.24), (Table 2).

Table (2):  Value of RF (IU/mL) in Arthritis patients with Toxoplasmosis.

Mean ± SE significant difference at (P≤0.05). * Significant

The results demonstrated that the proportion of T. gondii IgG antibodies was higher in ailing females than healthy females (Salman & Mohammed, 2015). Toxoplasmosis seroprevalence was higher among patients receiving therapy and follow-up examinations than those who had just been diagnosed. The rate of increase decreases after age 50, except during the reproductive years (Mose et al., 2020). Clinical significance is at issue when choosing a serological method for diagnosing toxoplasmosis. In certain clinical situations, additional tests may be necessary, and it is essential to grasp the advantages and disadvantages of a particular assay. The choice of an assay may also be influenced by other factors, such as robustness, the need for a rapid result, or the availability of qualified personnel; these variables may differ based on the screened population, the laboratory's location and resources, and the country's health care policy (Kalantari et al., 2015; Siyadatpanah et al., 2013). Even though only one study was conducted, the performance characteristics of the two newly developed RDTs were comparable. The combined sensitivity of the three rapid tests was 100%; however, false-positive results are possible. They can detect both isotypes, which is beneficial for determining the recentness of an infection (İnal & Taş, 2019; Zarean et al., 2022). Reliable IgG detection has significant clinical implications, such as the possibility of diagnosing Toxoplasma reactivation in an immunocompromised patient and the ability to identify seropositive organ donors who could transmit the infection to seronegative transplant recipients if performed at the beginning of pregnancy. In the first case, the positive predictive value (PPV) and specificity are crucial, whereas, in the second, the negative predictive value (NPV) is required to rule out a diagnosis (Salman & Mohammed, 2015). Consequently, PPV and NPV are extremely significant markers, although their relative significance varies substantially between populations. Ideal in this situation would be an immunochromatographic test capable of identifying both isotypes, allowing for the detection of both newly acquired and reactivated infections (Salman & Mohammed, 2015). Immunochromatographic tests and hemagglutination procedures are suitable for screening expectant women at prenatal care centres to determine their serologic status at the onset of pregnancy and offer hygiene recommendations to seronegative patients (Sarfraz-ur-Rahman et al., 2021; Tian et al., 2017).

Pregnant women and organ transplant recipients/donors are the primary patient populations for whom serological diagnostics are administered in high-income nations (Khattab et al., 2019; Saheb et al., 2020). For a pregnant woman to be considered immune and safe, it is necessary to have a technique that produces positive results with the utmost degree of certainty. Chemoprophylaxis can be directed based on the serostatus of the transplant recipient and the organ donor. Integrated into multiparameter automated systems with a high cadence oriented towards crises, EIAs with a high PPV are the most suitable approaches in these circumstances (Salman & Mohammed, 2015). According to the results of this study, T. gondii may initiate a pathological process in humans, rendering them more susceptible to toxoplasmosis or increasing their risk of developing rheumatoid arthritis. According to some evidence, this parasite can serve as a ligand for toll-like receptors (TLRs), allowing it to trigger an inflammatory response (Orevaoghene et al., 2020). Furthermore, individuals with toxoplasmosis have been seen to exhibit heightened levels of interleukin 17 (IL-17) expressions. This cytokine significantly contributes to the pathogenesis of certain autoimmune illnesses, such as rheumatoid arthritis. There is a clear connection between toxoplasmosis and rheumatoid arthritis (Taylor et al., 2018). The incidence of anti-T. gondii antibodies was greater in 33 out of 100 arthritis patients compared to 7 out of 100 healthy individuals. The increased levels of T. gondii IgG indicate a significant contamination of the environment in Iraq due to factors such as persistent hostilities, economic sanctions, and the inflow of individuals from the provinces (Andrade et al., 2023). A strong link exists between the presence of anti-T. gondii antibodies and overall health. Measurement of IgG and RF antibodies against T. gondii in the city of Diwaniyah, Iraq. Patients with rheumatoid arthritis were shown to have a higher vulnerability to opportunistic T. gondii infection (Andrade et al., 2023). The weakened adaptive cellular immunity caused by rheumatoid arthritis increases the likelihood of getting T. gondii infection, as this intracellular virus requires a strong immune response to be kept in check. Rheumatoid arthritis is linked to changes in T. gondii, reduced reproduction of naïve T. gondii in response to an unidentified substance, and decreased movement of naive T. gondii from the thymus (Marufatuzzahan et al., 2017).

The current study revealed a correlation between Toxoplasma gondii infection and an elevated susceptibility to five distinct forms of arthritis. The research found that patients with arthritis exhibited markedly elevated levels of the rheumatoid factor in comparison to the healthy group. In addition, people with both arthritis and T. gondii infection showed a higher level of rheumatoid factor compared to those with either arthritis or only T. gondii infection. This study offers initial indications of a correlation between the two diseases; nevertheless, further research is necessary to establish conclusive findings.

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