Typhoid fever is basically a septicaemia / bacteriemia and in cases of generalized septicaemia we get leucopenia due to suppression of bone marrow due to toxin produced
Relative lymphocytosis occurs when there is a higher proportion (greater than 40%) of lymphocytes among the white blood cells, while the absolute lymphocyte count (ALC) is normal (less than 4000 per microliter). Relative lymphocytosis is normal in children under age 2.
Yes, relative lymphocytosis and leucopenia are often seen in typhiod fever. Normalisation of WBC total count and neutropenia are associated with reduction in toxemia and fever.