Further studies on the transmission of the agent of infectious hepatitis to patas monkeys.

Studies on the leucocytes of healthy patas monkeys have shown that there is a diurnal increase in the numbers of neutrophils and a nocturnal increase in the numbers of mononuclear cells. Neutropenia occurred 4 days after feeding human infectious hepatitis liver suspension. There was no evidence of disease of myeloid cells in the bone marrow or of neutrophils in the blood. During the first 4 days after infection the diurnal rise in neutrophils was progressively decreased because fewer immature cells were liberated from the bone marrow. Necrosis was detected in the spleen 3-4 days after infection and persisted for 6-8 weeks. The red pulp was affected more than the white. Lesions were also found in the mesenteric and, to a lesser extent, in other lymph nodes. Abnormal mononuclear cells appeared in the blood 4 days after feeding. The sera of infected monkeys was found to be infectious for healthy monkeys between 4-70 days but not at 1 year. It is considered that infectious hepatitis in monkeys is predominantly a disease of lymphoid tissue and that degeneration in the spleen and lymph nodes is responsible for depression of bone marrow function and the presence of abnormal cells in the blood.