1266 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



fifth or sixth day; relapses may occur 

 until 2 or 3 weeks after onset ; case mor- 

 tality varies from 10 to 90 per cent in 

 different epidemics. A transitory im- 

 munity due to transfer of serum anti- 

 bodies through the placenta protects 

 offspring of immune mothers for a short 

 time. 



Transmission: By mosquitoes, Aedes 

 aegypti L., Aedes leucocelaemxs (D. 

 and S.), Haemogogvs capricorni Lutz 

 (CULICIDAE). The mosquito Aedes 

 aegypti becomes infective, after feeding 

 on a suitable virus source, in 4 days at 

 37° C, 5 days at 36° C, 6 days at 31° C, 8 

 days at 25.1° C, 9 to 11 days at 23.4° C, 

 18 days at 21° C, and 36, not 30, days at 

 18° C; virus in head, thorax, and ab- 

 domen before bites are infective ; no 

 evidence of transmission of virus through 

 eggs to offspring or to larvae eating in- 

 fected adults. Experimentally, also by 

 Aedes scapidaris (Rondani), A.fluviatilis 

 (Lutz), A. Ivteocephalus , A. apico-an- 

 nulatus {CULICIDAE). Experimen- 

 tally, by feeding, to Macacn mulatta and 

 Cercopithecus aethiops; by rubbing in- 

 fected blood into intact and unshaved 

 skin of monkeys. 



Serological relationships : Complement - 

 fixation and precipitating antibodies arc 

 specific. 



Immunological relationships : A specific 

 immunity develops after an attack of the 

 disease or after vaccination with virus 

 grown in media containing tissues of chick 

 embryo minus head and spinal cord. 



Thermal inactivation : At 55 to 60° C, 

 not at 50° C, in 10 minutes. 



Filterability : Passes membranes of 55, 

 and to some extent membranes of 50. 

 millimicron average j)ore diameter. 

 Passes Berkefeld V and N, as well as 

 Chamberland F, filters. 



Other properties : Particle estimated 

 from filtration data to have a diameter of 

 17 to 28 millimicrons ; by ultracentrifuga- 

 tion data, 19 millimicrons. Inactivated 

 or inhibited by 30-minute exposure to 

 1:15 formalin, 1:6 ethyl alcohol; 1 :3(X) 



yellowish eosin, 1 : 50 sodium oleate, 1 :200 

 liquor cresolis compositus; viable after 

 30-minute exposure at 30° C to 1:7500 

 mercuric chloride, 1:150 phenol, 1:1500 

 hexylresorcinol, 1:150 sodium oleate. 

 Sedimentation constant between 18 and 

 30 X 10~" cm per sec. per dyne. Viable 

 in 50 per cent glycerine at 2 to 4° C for 58, 

 not for 100, days ; in mouse brain at — 8° C 

 for 160 days. Viability may be lost on 

 simple drying but retained if drying is 

 carried on in vacuo over a desiccating 

 agent. 



Strains : Distinctive strains have been 

 isolated. One, to which much study has 

 been given, differs from the typical vis- 

 cerotropic strain by possessing marked 

 neurotropic or pantropic characteristics. 



Literature : Bauer and Hughes, Am. 

 Jour. Hyg., 21, 1935, 101-110; Bauer and 

 Mahaffy, ibid., 12, 1930, 155-174; 175- 

 195; Bugher and Gast-Galvis, ihid., 39, 

 1944, 58-66; Bugher et al., ibid., 39, 1944, 

 16-51; Davis, ibid., 16, 1932, 163-176; 

 Davis and Shannon, ibid., 11, 1930, 335- 

 344; Davis et al., Jour. Exp. Med., 58, 

 1933, 211-226; Findlay, Jour. Path, and 

 Bact., 38, 1934, 1-6; Lancet, 227, 1934 

 (2), 983-985; Findlay and Clarke, Jour. 

 Path, and Bact., 40, 1935, 55-64 ; Findlay 

 and MacCallum, Brit. Jour. Exp. Path., 

 19, 1938, 384-388; Jour. Path, and Bact., 

 49, 1939, 53-61; Findlay and Mackenzie, 

 ibid., 43, 1936, 205-208; Findlay and 

 Stern, ibid., 40, 1935, 311-318; Fox and 

 Cabral, Am. Jour. Hyg., 37, 1943, 93-120; 

 Frobisher, Am. Jour. Hyg., 11, 1930, 300- 

 320; 13, 1931, 585-613; 14, 1931, 147-148; 

 18, 1933, 354-374; Goodpasture, Am. 

 Jour. Path., 8, 1932, 137-150; Haagen, 

 Deutsch. med. Wochnschr., 60, 1934, 

 983-988; Hudson, Am. Jour. Path., 4, 

 1928, 395-430; Klotz and Simpson, ibid., 

 3, 1927, 483-488; Laemmert and Mous- 

 satche. Jour. Inf. Dis., 72, 1943, 228-231 ; 

 Lloyd et al., Am. Jour. Hyg., 18, 1933, 

 323-344 ; Trans. Roy. Soc. Trop. Med. and 

 Hyg., 29, 1936, 481-529; Mahaffy et al., 

 Am. Jour. Hyg., 18, 1933, 618-628; Pickels 

 and Bauer, Jour. Exp. Med., 71, 1940, 



