The article provides data about the first cases of detection and spread of infectious agalactia in sheep and goats, both in Russia and abroad. It was revealed that these are mainly regions with traditional sheep breeding, which include regions of Europe, Asia, Africa, as well as countries locat-ed along the shores of the Mediterranean Sea. The success of preventing and eradicating this disease depends on the availability of prophylactic vaccines and diagnostic drugs. The basis for their manu-facture is the production and control strains of the pathogen, which are obtained by biological en-terprises of the agro-industrial complex from the state collections of microorganisms. In the collec-tions, strains are studied at the frequency indicated in the passport, and optimal conditions are cre-ated to prevent microorganisms from losing their viability and their biological properties during long-term storage. The present work shows results of studies of strains A-319 and 8899 of the caus-ative agent of infectious agalactia in sheep and goats stored for 20 years, in a lyophilized form. The data obtained for determining the viability and studying the biological properties of the strains showed their compliance with the passport data.