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FATAL MURINE TYPHUS INFECTION IN THE dba STRAIN OF MICE, WITH OBSERVATIONS ON STRAIN VARIATION IN SUSCEPTIBILITY
1Department of Pathology, St. Louis University School of Medicine, St. Louis.
Abstract:
Injected intracranially in the dba strain of mice, murine typhus rickettsiae caused a serially transmissible meningoencephalitis similar to that produced by psittacosis and certain other viruses. All injected mice of this strain suddenly became ill and approximately half of these animals died on the 5th and 6th days after injection. Swiss mice injected in parallel series showed illness in only a few animals, and no deaths occurred. These experiments were carried out at room temperatures ranging from 60-80 degrees F. After intraperitoneal injection, a uniformly fatal rickettsial peritonitis developed in all dba mice kept at environmental temperatures of 65-73 degrees F. or 70-80 degrees F. Death occurred between the 3rd and 7th days after injection, depending somewhat on the dosage used. Among Swiss, brown agouti, and A albino mice injected in parallel series, the mortality was less than 60 per cent. These experiments indicate that mice of the dba strain are much more susceptible to murine typhus than are mice of the other three strains studied.
Insights
Murine typhus rickettsiae caused meningoencephalitis in dba mice, with high mortality. Other mouse strains showed significantly lower susceptibility to this infectious disease.
Area of Science:
- Microbiology
- Immunology
- Veterinary Medicine
Background:
- Murine typhus, caused by Rickettsia typhi, is a zoonotic disease.
- Previous studies have indicated varying susceptibility of different mouse strains to infectious agents.
Purpose of the Study:
- To investigate the susceptibility of different mouse strains to murine typhus rickettsiae.
- To characterize the pathological effects of murine typhus in susceptible mouse models.
Main Methods:
- Intracranial and intraperitoneal injections of murine typhus rickettsiae into dba mice and other strains (Swiss, brown agouti, A albino).
- Observation of clinical signs, mortality rates, and disease progression at controlled room temperatures.
- Serial transmission studies to assess infectivity.
Main Results:
- dba mice exhibited a serially transmissible meningoencephalitis after intracranial injection, with approximately 50% mortality.
- Intraperitoneal injection in dba mice resulted in uniformly fatal rickettsial peritonitis.
- Swiss, brown agouti, and A albino mice demonstrated significantly lower susceptibility, with less than 60% mortality.
Conclusions:
- The dba mouse strain is highly susceptible to murine typhus rickettsiae, serving as a suitable model for studying the disease.
- Environmental temperature may influence the outcome of rickettsial infections in mice.
- Significant differences in susceptibility among mouse strains highlight the importance of host genetics in infectious disease research.
