A blood count showing elevated white blood cells and lymphocytes is caused by a viral infection. The white blood cell components are neutrophils, lymphocytes, monocytes, eosinophils, and basophils. High leukocytes represent the presence of acute inflammation, most often due to the presence of foreign toxins or bacteria. Lymphocytosis is mainly seen in infectious diseases and mainly viral infections such as measles, chickenpox, mumps, viral hepatitis, epidemic hemorrhagic fever, but also in whooping cough, tuberculosis, brucellosis, syphilis, etc. Other diseases, such as leukemia, can also cause an increase in leukocytes and lymphocytes, which are relatively malignant and neoplastic changes, commonly lymphocytic tumors, such as lymphocytic leukemia, lymphoma, etc.