Prevention of infectious hepatitis remains an important problem. The fact that the infectious agent has not yet been isolated complicates prevention. Thus, there are no specific methods available for the detection of the infectious agent in clinical cases or carriers, even if the Au-test may help us to sort out some of the serum hepatitis cases. Neither is there a vaccine against infectious hepatitis, and there will probably not be one for many years. The preventive measures against the disease, therefore, have to be based to a large extent on epidemiological experience and knowledge about the modes of transmission of the disease. Much of this information derives from the investigations carried out in human volunteers, by MacCallum, Neefe, and Havens and by Ward, Krugman, and Giles at Willowbrook State School, New York.
These investigations demonstrate the importance of the fecal-oral transmission route in type A infections. The infectious agent is