First of all, leukemia is not an infectious disease. Although the exact etiology of human leukemia is still unclear and there are many theories about the pathogenesis of leukemia, there are no cases of leukemia being contracted through close contact with leukemia patients.
Although some studies have found that certain viral infections, such as human T-lymphotropic virus type I, can induce certain T-cell leukemias, mainly due to mutations in the genes of patients caused by the retroviral DNA contained in these viruses, the onset of the disease is caused by infection with these viruses, but mainly due to the presence of intrinsic factors in such patients.
In addition, there have been reports of families in which several family members had the same type of leukemia, but this was not due to mutual transmission, but mainly due to some genetic defect in these families.
In twin identical twins, if one person has acute leukemia, the other person has a significantly higher chance of developing acute leukemia (25%) than the general population (5/100,000). All of the above suggest that certain genetic factors may have an impact on the development of leukemia.