Much of the material received by a virus diagnostic laboratory consists of specimens from sporadic cases of central nervous system infection, atypical pneumonia, etc. Adair and his associates1 recently reported the results of virus studies carried out over a period of 11 years of 854 cases of acute aseptic meningitis occurring in military personnel and their dependents in the United States. About 9% of these cases were caused by infection with the virus of lymphocytic choriomeningitis and 12% by the mumps virus. Additional studies of another portion of these patients indicated that the virus of herpes simplex was responsible for about 5% and Leptospira 7%. No specific causative agent was incriminated in about three-fourths of the cases of sporadic aseptic meningitis studied. A similar situation exists in the laboratory diagnosis of atypical pneumonia.
In general, three types of laboratory examinations are used for diagnosis of viral and rickettsial disease: