الفهرس 
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Abstract
Toxoplasmosis is a wide-spread parasitic infection that is frequently asymptomatic in immunocompetent patients. However, this obligate intracellular protozoan parasite can evade the immune system and persist predominantly in the brain, retina and muscles. Reactivation of latent cysts may occur when the immune system is suppressed as in HIV patients, patients with malignancies and organ transplant recipients. Cyst reactivation can lead to ocular, cerebral or disseminated toxoplasmosis. Diagnosis is routinely made by serologic detection of specific antibodies. However, definitive diagnosis is obtained by the detection of parasites in blood, cerebrospinal fluid or bronchoalveolar lavage fluid by PCR which is the most sensitive method.
The present study aimed to study the rate of infection with T. gondii in patients with hematological malignancies, using immunological and molecular methods.
Blood samples were collected from 40 patients with hematological malignancies attending the Hematology Department, Medical Research Institute, Alexandria University, Egypt. A control group of 40 age and sex matched healthy individuals was included. The sample collection extended from February 2019 to October 2019. One part of each blood sample was centrifuged to obtain sera. Clear, non-hemolyzed sera of each case was divided into 2 new Eppendorf tubes, labeled and stored at -20o C till used for serological detection of anti-Toxoplasma IgG and IgM. The second part of the blood sample was stored at -20o C till used for DNA extraction and PCR amplification of Toxoplasma 529 RE gene.
The age of patients ranged from 17 to 76 years with a mean of 40 ± 15.9. Among controls the age ranged from 18 to 76 with a mean of 38.6± 15.7 years. Males constituted 47.5% of cases and 40% of the control group. The most common form of malignancy was AML (47.5%) followed by ALL (30%). Less common malignancies were CLL (12.5%), and CML (7.5%). One patient had hairy cell leukemia.
Toxoplasma seropositive rates were 75% and 42.5% in patients and controls respectively with a significant difference. There was no statistically significant association between T. gondii seropositivity and the type of hematological malignancy among the studied patients. Both anti-Toxoplasma IgG and IgM were detected in 7.5% and 2.5% of patients and healthy controls respectively while 67.5% of hematological malignancy patients and 40% of the healthy subjects had IgG antibodies with no detectable IgM. Seropositive patients displayed significantly lower anti-Toxoplasma IgG concentration.
Positive PCR results were more frequent in hematological malignancy patients (32.5%), compared to the healthy control group (2.5%) (P<0.05). In both groups, PCR positive rates were significantly lower than the seropositive rates.
Statistical analysis showed a Kappa index of 0.11, indicating a slight agreement between serology and PCR for the diagnosis of toxoplasmosis in the patient group. The association between conventional PCR results and detection of anti- Toxoplasma IgG and IgM was studied. Positive PCR was found in two out 3 IgG /IgM positive patients (66.7%), and 9
out of 27 IgG positive/IgM negative patients (33.3%). Amplified PCR product was also detected in two seronegative patients.
The association between T. gondii infection and demographic factors, history of contact with cats, consumption of undercooked meat, and clinical data was studied among the study participants. Using ELISA as the diagnostic method, the present study did not report any significant relation between the infection and these factors. Similar findings were observed using PCR as the diagnostic method.