Louping Ill in Man

Abstract

Inasmuch as louping ill,^{1, 2} a natural disease of sheep, can be transmitted to monkeys 3 and mice, 4 and since the disease in these hosts in certain respects resembles poliomyelitis, we procured some of the virus for investigation. After we had been working with the active agent for 5 months, some of it was supplied to another laboratory in the Institute in which after a short time 3 of the workers, one after another, became sick. Two of the individuals developed what seemed to be influenza. In each instance this illness in the patient was followed by apparent health lasting a few days which in turn was followed by a definite encephalitis. The spinal fluids were sterile and showed a mononuclear pleocytosis and an increased amount of globulin. The third patient had what seemed to be influenza without symptoms of involvement of the central nervous system. Inquiry disclosed the fact that an English investigator also had an encephalitis more than a year ago after having worked with louping ill. In this case the spinal fluid also was sterile and showed an increased amount of globulin and a mononuclear pleocytosis. All of the patients made rapid and complete recoveries.

There is no record in the literature of the occurrence of louping ill in man, yet the disease was considered in connection with our cases and attempts to demonstrate the virus in the blood and spinal fluid of 2 of them were made without success. Failure to demonstrate the virus under such conditions, however, was not considered proof that the patients had not had louping ill. Consequently, inasmuch as wre had developed a test 5 for the presence of neutralizing antibodies in the sera of monkeys immune to louping ill, we decided to apply the test to the sera of the 4 individuals who were suspected of having had the disease.