STUDIES ON PROTECTION AND CONTROL OF EPIDEMIC HEMORRHAGIC FEVER (EHF) IN LABORATORY ANIAML EXPERIMENTATION

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Two cases of laboratory type HFRS (EHF) were recorded in 1984 in Japan. Thereafter, we have no new patient reported. Every year, we have written annual report of our group-research and the guide-lines for protection and diagnosis of laboratory type infection of HFRS issued by the Ministry of Education, Science and Culture, Japan. We delivered them to all biomedical institutions in Japan. These measures increased the level of understanding of HFRS by biomedical researchers and people working in the animal facilities. As the results, the number of HFRS patients decreased. Most of the cases of the HFRS reported in Japan were caused by viral infection from contaminated laboratory rats. Newborn mice and newborn rats were experimentally infected with viral strains isolated from rats and stripe field mouse. Comparison of the mortality among the infected animals and the recovery of the infective viruses from various organs of them indicates that the animals are more susceptible to the virus st … More rains derived from the animals lelonging to the same genus than those from the animals belonging to the different genus. HFRS viruses are classified as a Bunya virus and devided into four subtypes according to animal species from which they were isolated. Immunological difference of these subtypes was found by using the specific monoclonal antibodies prepared against each viral strain. Electronmicroscopy demonstrated that the HFRS viral particle had a lattice-like surface structure, and some viral particles of certain strains derived from rats had a tail-like structure. Virus strains derived from rats could infect adult rats, resulting in persistnce in several organs. Persistence of the virus in the brain of the infected rats was observed for more than eight months. On the basis of the pathological observation that the virus sometimes caused inflamation of blood vessels, the HFRS might be classified as a "Blood Vessel Disease." Clinical and serological examinations of a HFRS patient was carried out during the hospitalization period. These examinations provided valuable informations for clinical diagnosis. Studies on the low-titre seropositive aniamls and the modes of transmission among experimental animals are to be carried out. Less