Toxoplasmosis: an overlooked infection in cancer patients

Background
Toxoplasmosis is a widespread disease caused by the Apicomplexan, coccidian protozoan Toxoplasma gondii (T. gondii). Human prevalence rates for toxoplasmosis vary greatly in different parts of the world ranging from 0% in North Alaska and Canada to 94% in Costa Rica and Guatemala. Once the host acquires the infection by ingestion, T. gondii crosses the intestinal epithelium, disseminates into the deep tissues and traverses biological barriers to reach sites where it causes severe pathology. Normally, the immune response efficiently prevents the dissemination of the parasite. In immunocompromised hosts, however, such reactivation may be more frequent, leading to a massive and potentially fatal recrudescence. Studies of prevalence of Toxoplasmosis in patients with neoplasms are scarce. This report represents the first prevalence study of Toxoplasmosis in cancer patients in Egypt.
Methods
Blood samples were collected from 150 immunocompromised patients having different types of malignancies as well as 50 immunocompetent individuals as a control group, to assess the seroprevalence of anti-T.gondii antibodies. The “CTK biotech Onsite Toxo IgG/IgM Rapid Test Cassettes” was used according to the manufacturer's enclosed manual for the detection of infection.
Results
In our study, 34 cases of toxoplasmosis were detected. Toxoplasmosis was higher in patients' group than in control group. Among cancer patients, prevalence of T.gondii was significantly higher (20% & 4% for IgG and IgM respectively) compared with control (8% and 2%) (p = 0.003). Toxoplasmosis was higher in patients having solid organ tumors (24%) than in patients with haematological malignancies (12%) (p = 0.06). On the other hand, the type of treatment doesn't seem to affect the prevalence of T.gondii. The prevalence in patients treated with chemotherapy was equal to the prevalence in those treated with irradiation (20% both).
Conclusions:T. gondii is an opportunistic parasite that remains a serious cause of morbidity and mortality in immunocompromised patients. However, screening for this parasite is usually omitted in non-HIV immunocompromised persons such as patients having malignancy. Proper diagnosis and treatment of these patients before starting treatment is mandatory as it can save their lives.