Toxoplasma gondii seropositivity among patients with sickle cell disease: Prevalence and association with blood transfusion history.

backgroundToxoplasma gondii (T. gondii) is a successful protozoan parasite infecting up to a third of the human population. It has varied transmission routes including ingestion of food and water contaminated by cat feces containing oocysts of the parasite and ingestion of bradyzoites in poorly cooked meat. Blood transfusion is another possible route of transmission especially among people with medical conditions requiring blood transfusion, such as those with sickle cell disease (SCD). This study aimed at finding out the prevalence of T. gondii infection and the association of blood transfusion among patients with SCD.

methodThis study was a cross-sectional study involving SCD patients attending the SCD clinic at the Ho Teaching Hospital in the Volta Region of Ghana. Questionnaire administration was employed to obtain sociodemographic information, cat ownership, consumption of poorly cooked meat, as well as blood transfusion history. A blood sample was collected and anti-T. gondii IgG and IgM were detected using Rapid Diagnostic Test (RDT), while Enzyme-linked Immunosorbent Assay (ELISA) was used as the gold standard and reference. Seropositivity was defined as either positive for IgG, IgM or both. Data was analyzed using SPSS version 23, with frequency distribution done for the sociodemographic variables and the prevalence of RDT and ELISA anti-T. gondii IgG and IgM. Pearson Chi-square analysis was performed to find any significant association between diagnosis of T. gondii infection with sociodemographic variables and blood transfusion. Logistic regression analysis was performed to investigate the odds of seropositivity (ELISA) with sociodemographic variables and blood transfusion.

resultsA total of 156 SCD patients participated in this study of which 124 (79.5%) and 32(20.5%) were HbSS and HbSC respectively. Among the study participants, 105 (67.3%) had a history of blood transfusion. A total of 60 (38.5%) and 83 (53.2%) patients were positive for RDT and ELISA respectively. No significant association was seen between T. gondii diagnosis and cat ownership (RDT,20[37.7%], p = 0.891; ELISA, 27[50.9%], p = 0.673) and consumption of poorly cooked meat (RDT,37[41.6%],p = 0.370;ELISA,53[59.6%], p = 0.211). However there was a significant association between T. gondii diagnosis and age, with seropositive results predominantly seen among older patients (≥20 years) (RDT, 38[52.1%], p = 0.002; ELISA 49 [67.1%, p = 0.002]. Blood transfusion had a significant association with T.gondii diagnosis (RDT, p = 0.003; ELISA, p = 0.001). A total of 66 (62.9%) of SCD patients who had history of blood transfusion tested positive for ELISA and they had 3 times the odds of testing positive for ELISA (adjusted OR 3.14[95% CI 1.50-6.58]; p = 0.002).

conclusionThe prevalence of T. gondii infection was higher by ELISA (53.0%) than by rapid diagnostic testing (RDT) (38.5%), and sickle cell disease patients with a transfusion history had higher odds of seropositivity. These findings highlight the need to strengthen transfusion safety protocols and consider screening strategies for T. gondii among high-risk populations such as patients with sickle cell disease. Also, there is the need for longitudinal research to help elucidate the true contribution of blood transfusion transmission of T. gondii since a cross-sectional study, causality could not be established.