Toxoplasmosis is one of the most common zoonotic diseases caused by the obligate intracellular parasite, T. gondii. It affects up to one-third of the world's population Horizontal transmission is mostly caused by ingestion of tissue cysts in infected meat, or through consumption of food or drink contaminated with sporulated oocysts, while vertical transmission occurs due to primary acquired maternal infection throughout pregnancy.In immunocompetent hosts, acquired infection is asymptomatic in more than 80% of cases, or is associated with fever,cervical lymphadenopathy, or myalgia.

In immunocompromised patients,toxoplasmosis is always life-threatening where toxoplasmic encephalitis is the most important presentation. Among those patients, the disease may be caused by a newly acquired infection, reactivation following cyst rupture, donation of a cyst-containing organ from a seropositive donor to a seronegative recipient, or reactivation of dormant infection in the recipient Patients with hematological malignancy (HM), including those with acute myelogenous leukemia, and those who have undergone hematopoietic stem cell transplantation or treated with aggressive immunosuppressive regimens are at high risk of opportunistic infections The association between toxoplasmosis and cancers remains dual. Most cancer patients are in a state of impaired cellular and humoral immune systems either from the primary disease, or from chemotherapy and/or radiotherapy administration. Chemotherapeutic drugs work by killing both fast growing cancer cells, and healthy white blood cells causing neutropenia. So, patients receiving chemotherapy are more susceptible to Toxoplasma infections.

Many studies have reported that the rate of reactivation of a latent T. gondii infection was higher in different types of cancers particularly those of the eye, brain, blood and breast. On the other side, T. gondii was also implicated as possible oncogenic pathogen with suggested role in induction and progression of malignant diseases. This was explained by many theories such as preventing apoptosis, enhancing the motility of dendritic cells and macrophages.

Inclusion Criteria:

• This study will be conducted on a group of patients who are diagnosed as have hematological malignancies

Exclusion Criteria:

• Patients with other non hematological malignancies.