ENTOMOLOGY

DISEASES CARRIED BY FLEAS 351mice, are proven hosts of plague. The following :fleas have been provento be carriers of the organism: Xenopaylla cheopia Rothschild, Ceratophyllu8faaciatus (Bose) Curtis, C. acutus Baker, C. ailantiewi Wagner,Pule:c irritan8 Linnaeus, Ctenocepllalus canis (Curtis) Baker, Leptopayllamusculi Dug~s and PygiopayUa altalae Rothschild.The first successful record of transmission of plague by fleas wasmade Jby Simond in 1898, and corroboration was first obtained by Verjbitskiin 1903 and Liston in 1904.Many other workers have since then proven the role of the :flea incarrying this disease. A synopsis of the evidence is presented by Hermsin his textbook. The flea takes up the organism with the blood of thehost. The stomach of the rat flea, Xenopaylla cheopi8, is capable ofreceiving as many as 5000 germs while imbibing the blood from a plaguerat. Both males and females may carry the infection and they mayremain infective during an epidemic for ~o days. The Indian PlagueCommission found the bacilli only in the stomach and rectum of thefleas and never in the salivary glands or body cavity and rarely in theesophagus. They conclude that the normal course of the bacilli is to bevoided in the feces and to be inoculated by scratching in of the feces.Bacot and Martin, however, have come to the conclusion that plague canbe transmitted during the act of biting when a temporary blocking orobstruction of the proventriculus takes place, causing bacillus-laden bloodto be forced back or regurgitated into the wound, thus producing infcc.:tion.Bacteriwm tularenae McCoy and Chapin, cause of a fatal RODENTPLAGUE which affects the California ground squirrel, Citellua beecheyi,may also be transmitted by fleas. McCoy and Chapin placed fleas(Ceratophyllus acutus Baker and C. faaciatu8 Bosc) with an inoculatedguinea pig and allowed them to remain there until the animal died. Theywere then collected, and crushed and inoculated into healthy guinea pigs.The four animals inoculated with crushed C. fa8ciatu8 immediately afterthe fleas were removed from the dead guinea pig, died of the disease; twoof four inoculated after ~4 hours, died; and one out of four inoculatedafter 48 hours, died. Two out of four animals inoculated with crushedC. acutus immediately after removal from the dead guinea pigs, died, butnone died that were inoculated on subsequent days, although some developedan apparently chronic fonn of the disease. They also succeeded inobtaining one actual case of transmission. About 100 fleas collected froman animal dead of the disease were placed in a clean ca~ with a healthyground squirrel. It died 15 days later and presented the usual lesionsof the plague-like disease, the bubo being in the neck.