Additional Highly Virulent Strains of Rocky Mountain Spotted Fever Virus Isolated in Georgia

1942 ◽  
Vol 57 (36) ◽  
pp. 1342 ◽  
Author(s):  
George D. Brigham ◽  
James Watt
Pathogens ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 744
Author(s):  
Eliane Esteves ◽  
Chanida Fongsaran ◽  
Ingeborg M. Langohr ◽  
Sean P. Riley ◽  
Marcelo B. Labruna ◽  
...  

Rocky Mountain spotted fever (RMSF) is a life-threatening tick-borne disease caused by Rickettsia rickettsii, which is widely distributed throughout the Americas. Over 4000 cases of RMSF are recorded annually in the United States, while only around 100 cases are reported in Brazil. Conversely, while case fatality rates in the United States oscillate around 5%, in Brazil they can surpass 70%, suggesting that differences in tick vectoring capacity, population sensitivity, and/or variability in virulence of the rickettsial strains may exist. In this study, we compared the susceptibility of C3H/HeN mice to two highly virulent strains of R. rickettsii, one from the United States (Sheila Smith) and the other from Brazil (Taiaçu). Animals inoculated with the Taiaçu strain succumbed to infection earlier and exhibited severe histological lesions in both liver and spleen sooner than mice infected with the Sheila Smith strain. These differences in survival and signs of the disease are not related to a greater proliferation of the Taiaçu strain, as there were no significant differences in the rickettsial load in mice tissues inoculated with either strain. The present study is the first step to experimentally assess differences in fatality rates of RMSF in two different regions of the American continent.


1956 ◽  
Vol 34 (5) ◽  
pp. 417-423 ◽  
Author(s):  
A. W. F. Banfield

A collection of 245 ticks (Dermacentor andersoni, Stiles, and Dermacentor albipictus, Packard) was made in the spring of 1953, from 17 localities in Banff National Park, Alberta. Laboratory tests indicated the presence of Colorado tick fever virus in three of 17 lots examined. One complement-fixation test was significantly positive for the Rocky Mountain spotted fever Rickettsia out of 19 tests. There was no indication of tularemia. One determination of the Q-fever virus was probably caused by laboratory contamination. The unfed adult ticks (D. andersoni) were found to be locally active from April 20 to June 22, 1953. The bighorn sheep (Ovis canadensis) was found to be the common local host of the adult tick. The Columbian ground squirrel (Citellus columbianus) was found to be the common host of the nymphs.


Praxis ◽  
2005 ◽  
Vol 94 (47) ◽  
pp. 1869-1870
Author(s):  
Balestra ◽  
Nüesch

Eine 37-jährige Patientin stellt sich nach der Rückkehr von einer Rundreise durch Nordamerika mit einem Status febrilis seit zehn Tagen und einem makulösem extremitätenbetontem Exanthem seit einem Tag vor. Bei suggestiver Klinik und Besuch der Rocky Mountains wird ein Rocky Mountain spotted fever diagnostiziert. Die Serologie für Rickettsia conorii, die mit Rickettsia rickettsii kreuzreagiert, war positiv und bestätigte die klinische Diagnose. Allerdings konnte der beweisende vierfache Titeranstieg, möglicherweise wegen spät abgenommener ersten Serologie, nicht nachgewiesen werden. Nach zweiwöchiger antibiotischer Therapie mit Doxycycline waren Status febrilis und Exanthem regredient.


2019 ◽  
Vol 19 (3) ◽  
pp. 238-257
Author(s):  
Suresh Antony

Background:In the United States, tick-borne illnesses account for a significant number of patients that have been seen and treated by health care facilities. This in turn, has resulted in a significant morbidity and mortality and economic costs to the country.Methods:The distribution of these illnesses is geographically variable and is related to the climate as well. Many of these illnesses can be diagnosed and treated successfully, if recognized and started on appropriate antimicrobial therapy early in the disease process. Patient with illnesses such as Lyme disease, Wet Nile illness can result in chronic debilitating diseases if not recognized early and treated.Conclusion:This paper covers illnesses such as Lyme disease, West Nile illness, Rocky Mountain Spotted fever, Ehrlichia, Tularemia, typhus, mosquito borne illnesses such as enteroviruses, arboviruses as well as arthropod and rodent borne virus infections as well. It covers the epidemiology, clinical features and diagnostic tools needed to make the diagnosis and treat these patients as well.


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