46 SPIROCHETES 



is in inverse proportion to the prevalence of the use of soap and 

 water. Relapsing fever, in countries where it is transmitted by 

 lice, always spreads most rapidly in cold weather when people 

 are huddled together in stuff}-, filthy houses, thus giving the lice 

 ideal opportunities for doing their evil work. 



In Mexico and Central America it is believed that certain ticks, 

 Ornithodorus talaje and 0. turicata, which in form and habits 

 closely resemble the African relapsing fever tick, transmit the 

 disease, but this has not been proved. 0. turicata is said to be 

 the transmitter in Colombia, but the bedbug and other ticks are 

 also suspected. 



Relapsing fever is not a contagious disease as was formerly 

 supposed. A typical case in the Bellevue Hospital in New York 

 failed to spread the infection to anyone else during the 89 da^^s' 

 stay of the patient, although no special precautions were taken 

 to prevent it from spreading. 



The Disease. — In the human body the spirochaetes appear to 

 live exclusively in the blood, where they become fairl}'^ common, 

 though never abundant, at regular intervals. In the meantime 

 they apparently disappear though they are undoubtedly present 

 either in the granular form, or else in such limited numbers as 

 to be practicall}^ impossible to find. The repeated increase and 

 decrease of the spirochaetes in the blood goes hand in hand with a 

 recurring fever broken by periods of apparently almost normal 

 health. The time of incubation of the disease varies from two 

 days to two weeks, but in most cases the initial attack comes on 

 the third or fourth day. It usually begins with severe chilly 

 sensations, headache and shooting pains in the limbs. The 

 ensuing fever lasts intermittently for several daj^s, being accom- 

 panied by such symptoms as rapid pulse, enlarged spleen, con- 

 stipation, nausea and mental disturl)ances. After several days 

 the temperature suddenly drops below normal and remains so 

 for a period of seven or eight days, during which time the patient 

 recovers rapidly, feels perfectly well and thinks it unnecessary to 

 remain at home or in the hospital any longer. Then comes the 

 first relapse, repeating all the symptoms of the first attack, some- 

 times in somewhat milder form. Following this there is a second 

 period of apparently normal health, usually followed by a second 

 relapse, this time nmch milder. The number of relapses varies: 

 in the European and allied types the second relapse is mild, and 



