Haematological disorders represent a major global health concern due to their diverse causes, high morbidity, and significant mortality, and they include conditions such as anaemia, leukemia, lymphoma, myelodysplastic syndromes, and myeloma that disrupt vital functions like oxygen transport, immune defence, coagulation, and nutrient delivery (1).

Anaemia is the most common haematological disorder worldwide, affecting about 1.8 billion people, with the greatest burden occurring in low- and middle-income countries (2). In the Mediterranean region, childhood anaemia prevalence is estimated at approximately 34.25%, although considerable regional variation exists (3). In Egypt, anaemia affects about 38.7% of adults, with significantly higher rates among females (53.8%) compared with males (23.3%) (4). Additionally, paediatric studies indicate that nearly two out of five young Egyptian children suffer from some degree of anaemia (5). Anaemia also contributes substantially to disability-adjusted life years (DALYs) through its negative effects on childhood development, maternal health, and economic productivity (6).

Haematological malignancies represent another important global oncological challenge, with non-Hodgkin lymphoma ranking among the most common cancers in Egypt and leukemias affecting both adults and children (7). Treatment for these malignancies commonly involves intensive immunosuppressive therapies such as chemotherapy and stem cell transplantation, which increase susceptibility to opportunistic infections (8).

Parasitic infections contribute to haematological disorders through several mechanisms, including chronic inflammation, disruption of haematopoiesis, and increased hepcidin expression that can lead to anemia of chronic disease (9). Intestinal helminths such as hookworms may also cause anaemia through chronic blood loss and impaired absorption of nutrients such as iron and vitamin B12 (10).

Patients with haematological malignancies are particularly vulnerable to parasitic infections, including intestinal protozoa such as Cryptosporidium spp., Giardia intestinalis, Cystoisospora belli, and Blastocystis spp., which can act as opportunistic pathogens (11,12). In addition, Toxoplasma gondii infection is widespread globally and may contribute to anaemia and pose a higher risk for reactivation or severe infection in immunocompromised patients with haematological malignancies (13,14) The connection of high parasitic prevalence and direct haematopathological conditions highlights the necessity of integrative parasitic screening and targeted interventions in at-risk clinical populations.

Inclusion Criteria:

• a) Aged ≥2 years. b) Provision of written informed consent (assent for minors). c) Group A: Meets WHO criteria for anaemia (15). d) Group B: Histologically/cytologically confirmed haematological malignancy. e) Group C: No clinical evidence of anaemia, haematological malignancy, or active systemic infection.

Exclusion Criteria:

• a) Received antiparasitic medication within 4 weeks prior to enrollment. b) Received blood transfusion within 4 weeks prior to enrollment. c) Unable or unwilling to provide stool sample or blood specimen. d) Known HIV infection (due to fundamentally different immune pathophysiology).

Group A: Meets WHO criteria for anaemia (15). d) Group B: Histologically/cytologically confirmed haematological malignancy. e) Group C: No clinical evidence of anaemia, haematological malignancy, or active systemic infection.