FAMILY CHAROXACEAE 



1267 



703-717; Ramsey, Am. Jour. Hyg., 13, 

 1931, 129-163; Sawyer, ibid., 25, 1937, 

 221-231; Shannon et al.. Science, 88 

 1938, 110-111; Smith and Theiler, Jour. 

 Exp. Med., 65, 1937, 801-808 ; Smith et al.. 

 Am. Jour. Trop. Med., 18, 1938, 437-468; 

 Soper and De Andrade, Am. Jour. Hyg., 

 18, 1933, 588-617; Soper et al., ibid., 18, 

 1933, 555-587; 19, 1934, 549-566; 27, 1938, 

 351-363; Stefanopoulo and Wassermann, 

 Bull. Soc. Path. Exot., 26, 1933, 557-559; 

 Stokes et al.. Am. Jour. Trop. Med., 8 

 1928, 103-164; Theiler, Ann. Trop. Med. 

 and Parasit., 24, 1930, 249-272; Theiler 

 and Smith, Jour. Exp. Med., 65, 1937, 

 767-786, 787-800; Whitman, ibid., 66, 

 1937, 133-143. 



2. Charon vallis spec. nov. From La- 

 tin vallis, valley. 



Common name : Rift Vallej' fever virus. 



Hosts : HOMINIDAE — Homo sapiens 

 L., man. BOVIDAE — Bos taurus L., 

 cow; Ovis aries L., sheep; Capra hircus 

 L., goat. Experimentally, also Sciiirus 

 carolinensis, grey squirrel; ferret; Crice- 

 tus auratus, golden hamster; Apodemus 

 sylvaticus, wood mouse; Microtus agrestis 

 field vole ; Muscardinus avellanarius , dor- 

 mo "^se ; rat ; mouse ; Macaca midatta ; M. 

 irus; Cebus fatuellus; C. chrysopus; 

 Hapale jacchus; H. penicillata ; Cerco- 

 pithecus callitrichus (symptomless) ; Ery- 

 throcebus patas (symptomless); Cerco- 

 cebus fuliginosus (symptomless); chick 

 embryo in Tyrode's solution ; chorioallan- 

 toic membrane of chick embrj'O. 



Insusceptible species : Horse, pig. 



Geographical distribution : British East 

 Africa. 



Induced disease : In man, benign dis- 

 ease; after 5§ to 6 days, rigors, pains in 

 back, fever for 12 to 36 hours, followed by 

 recovery, with persistence of acquired 

 immune bodies as long as 4 to 5 years 

 after infection. In sheep (lambs), dull- 

 ness, rapid respiration, collapse and death 

 in a few hours or a chronic course ; focal 

 necrosis in liver. In chorioallantoic 

 membrane of chick embryo, experimen- 



tally, areas of hyperplasia and of necrosis ; 

 connective tissue inflamed nearby; liver 

 of embryo mottled with necrotic areas. 



Transmission: Not by contacts. Mos- 

 quito, Taeniorhynchusbrevipalpis {CUL- 

 ICIDAE), suspected as possible vector. 



Serological relationships: Antisera for 

 psittacosis, dengue fever, and sandfly 

 fever viruses fail to protect against infec- 

 tion with Rift Valley fever virus. Spe- 

 cific neutralizing antibody in intraperi- 

 toneally neutral mixture with Rift Valley 

 fever virus may be dissociated so as to 

 free virus by direct dilution in saline 

 solutions, by intranasal inoculation, or by 

 employment of a small dose, all methods 

 probably imph'ing a dilution effect. 



Immunological relationships : No cross 

 immunity with yellow-fever or dengue- 

 fever viruses. If Rift Valley fever virus 

 is inoculated into rhesus monkey simul- 

 taneously with yellow-fever virus, the 

 animal tends to be protected against 

 death from yellow fever (interference 

 effect), but one-day earlier inoculation 

 of Rift Valley fever virus does not 

 protect. 



Thermal inactivation : At 56° C in 40, 

 not 20, minutes. 



Filterability : Passes Berkefeld V, N, 

 and W filters ; passes Chamberland L2, 

 L3, Lo, L7, Lu and occasionally L13 filters ; 

 passes membranes 150 millimicrons in 

 average pore diameter freely, 90 milli- 

 microns with difficulty, 70 millimicrons 

 not at all. 



Other properties : Mable at least 8 

 months at 4° C, more than 4 weeks dry in 

 liver tissues, 6 months in 5 per cent 

 carbolic acid at 4° C. Diameter of in- 

 fective particle estimated from filtration 

 studies to be between 23 and 35 milli- 

 microns. 



Strains: A neurotropic strain im- 

 munizes lambs without producing obvious 

 illness, if given subcutaneoush'. 



Literature: Broom and Findlay, Brit. 

 Jour. Exp. Path., U, 1933, 179-181; 

 Daubney et al.. Jour. Path, and Bact., 

 34, 1931, 545-579; Findlay, Trans. Roy. 



