386 Microbes and You 



ago as 400 B.C., if writings left by ancient historians and physicians 

 are being properly interpreted. 



Typhus fever is endemic in Russia and in sections of Poland, 

 and it has been epidemic during times of war, as is shown by the 

 100,000 cases reported in Russia alone during the first year of 

 World War I. Between 1917 and 1921 it is estimated that at least 

 twenty-five million people suffered from this disease in territories 

 controlled by Russia, with a mortality rate of about 10%. Over 

 300,000 deaths were reported in Serbia during World War I. 



There are two principal forms of typhus fever; epidemic and 

 ENDEMIC. The former is louse-borne and is caused by Rickettsia 

 prowazekii, while the endemic form is borne by the rat flea Xeno- 

 psijlla cheopis which carries the etiological organism Rickettsia 

 typhi. Since rats carry the fleas, endemic typhus is commonly 

 referred to as murine or rat typhus, which goes under the name of 

 tabardillo in Mexico. 



Severe headache, chills, and fever mark the onset of the disease, 

 and about four days following the first symptoms, a macular 

 ( spotty ) eruption appears on the skin and lasts as long as the fever. 

 The acute symptoms disappear on about the twelfth day with a 

 subsequent slow recovery. In parts of the United States where 

 typhus is endemic, it is sometimes called Brill's disease. 



The human body louse, Pediculus var. corporis carries the 

 rickettsiae in its gut, and this louse is primarily responsible for 

 epidemic typhus. The microorganisms gain entrance to the human 

 body through apparently intact skin or through injured skin after 

 being deposited there in the excreta of lice. 



TSUTSUGAMUSHI DISEASE (SCRUB TYPHUS) 

 A mite-transmitted disease that is widespread in Japan, Malaya, 

 and other parts of the southwest Pacific is caused bv Rickettsia 

 tsutsugamushi (meaning "of a dangerous mite"). Field mice are 

 infested with these mites whose larvae bite animals and man. 

 The adult mite does not transmit scrub typhus to man but does 

 pass the organisms on to her eggs. These mites are members of 

 the 2;enus Throjnbicida. 



