Murine Typhus

MURINE TYPHUS, a disease first described by Loeffler (1892) as an epizootic among white laboratory mice in Greifswald. Loeffler identified the causative agent of this epizootic as a bacterium similar to the bacterium of typhoid fever, which is why he named this causative agent Bact. typhi murium. According to his studies, this bacterium is especially pathogenic for field mice, and therefore he proposed its culture for their extermination. Indeed, the application of cultures of Bact. typhi murium for combating the extremely proliferating field mice in Thessaly gave brilliant results; this served as a pretext for the dissemination of cultures of Bact. typhi murium for the destruction of mice in domestic economy, and according to initial experiments this bacterium was considered harmless to humans and domestic animals. However, this opinion was soon refuted. Bact. typhi murium is capable of killing guinea pigs and rabbits when fed. It is also dangerous for humans. With the widespread application of Bact. typhi murium for the extermination of mice, reports of diseases in humans who came into contact with its cultures began to appear. Thus, in one case 30 people fell ill (3 of them with a fatal outcome) after eating vegetables prepared in wooden vessels in which a culture of Bact. typhi murium had previously been mixed with bait and which was not thereafter disinfected. In another case 34 people fell ill with severe gastroenteritis, and one of them died after consuming horse meat from a horse that had died from accidental infection with Bact. typhi murium. The bacteria of Bact. typhi murium were found in its meat and in the feces of the sick. Such cases led in Germany and Prussia to orders for special precautionary measures when poisoning mice with cultures of Bact. typhi bacteria. Thus losing its economic significance, Bact. typhi murium acquired in recent times fame in science, since it served for extensive experiments of experimental epidemiology in mouse towns of the Rockefeller Institute. At the same time, for practical purposes of exterminating harmful rodents, other bacteria were found and began to be applied. Thus, Merezhkovsky described (1895) the bacterium found by him in ground squirrels, Bact. typhi spermophilorum, Danysz - the bacterium of rat typhus, Isachenko - the bacterium of enteritis of voles, etc. All the listed bacteria were distributed on a large scale by the bacteriological laboratory of the former Ministry of Agriculture (now the Institute of Experimental Agronomy). Of all these bacteria, the most suitable for its harmlessness to other animals and effectiveness for the destruction of mice proved to be Merezhkovsky's bacterium - Bact. typhi spermophilorum. Exclusively it is now applied under the name of Bact. typhi murium. All the bacteria mentioned above - Loeffler's, Danysz's, Isachenko's, and Merezhkovsky's, as well as many other Bact. typhi murium that have no practical significance - are very similar to each other and belong to the family Bact. enteritidis Gartneri. Merezhkovsky, however, pointed out a distinctive sign of his bacterium: the formation of films on weakly alkaline bouillon. For the extermination of mice, daily bouillon cultures of Merezhkovsky's bacterium are used. The classical method of their application consists in preparing dough from them together with rye flour, from which balls are formed, scattered in burrows and generally in places frequented by mice. Rye flour can be replaced by dry bread or rusks moistened with the culture of Bact. typhi murium. Although cultures of Merezhkovsky's bacterium are harmless to humans and domestic animals, when working with it certain precautions should be taken: vessels in which the culture is mixed with bait should not be used for preparing food; hands that have come into contact with the culture must be thoroughly washed; infected balls or rusks must be placed out of the reach of children or domestic animals. In the literature, however, there are no indications of any diseases of humans or domestic animals caused by Merezhkovsky's bacterium.