CLIMATOLOGY 



1255 



Climatology. — It is found in all the countries bordering on the 

 Mediterranean and Adriatic Seas, and it is known in India, Egypt, 

 South America, and in South Africa (Cairs). It is possible that it 

 may be found to be cosmopolitan in its distribution. 



In temperate climates it only occurs in the summer months, and, 

 when studied epidemiologically, it is found to be correlated with the 

 distribution of Phlebotomus papatasii. How the infection is main- 

 tained during the winter months is not understood, as the imagines 

 do not live through the winter, and as a relapse after a long period is 

 unknown. Doerr believes that the female flies transmit the infec- 

 tion to their progeny, which in turn restart the disease during the 

 succeeding summer. It is, however, by no means certain that the 

 infective agent disappears from the blood when it ceases to be infec- 

 tive on inoculation. 



105° 

 102° 

 10 1'" 

 lOO" 



93° 



m 



Figs. 634 and 635. — Temperature Charts of Pappataci Fever. 



etiology. — ^The causation of the fever is quite unknown, but the 

 researches of Doerr, fully confirmed by Birt and others, have proved 

 that a virus exists in the blood of patients suffering from the disease; 

 that this virus is infective during the first day, and up to the end of 

 the second day of the fever, but not later ; that it is filterable through 

 a Pasteur-Chamberland candle F; that PMehotomus papatasii 

 Scopoli, 1786, is the carrier of the disease, but does not become 

 infective at once after feeding, but, on the contrary, is not infective 

 under a week, after which it can convey the infection. This proves 

 that the organism undergoes development in the fly. How long the 

 fly remains infective is not known with certainty, as it usually dies 

 after ten days' captivity, but it is probable that the disease is trans- 

 missible to young broods of flies. The incubation period of the 

 experimental cases varied from three days sixteen hours to seven 

 days, and a few of these cases showed only the gastro-intestinal 

 symptoms, without any sign of fever. Animals have so far not 

 been infected with fever except one small monkey by Tedeschi and 

 Napolitani. Chalmers and O'Farr ell have also infected a monkey by 

 intravenous inoculation of human infected blood. It may be noted 

 that phlebotomus can bite in the daytime and not merely at night. 



Pathology. — ^Antibodies appear to be generated during an attack, 

 as Doerr has shown that the serum from convalescents may neutral- 



