— 19 — 



The recent outbreak of pneumonic plague in Manchuria showed another 

 "phase of infection. This disease is not dependent on fleas for its transmission, 

 but it could be traced to an outbreak of plague in the tarabagans or marmots, a 

 kind of squirrel. Dr. Cantlie says that Plague may develop or appear in the 

 following stages: (i) as a disease in animals; (2) Pestis minor conveyed by 

 infected insects; (3) bubonic plague, sporadic cases, carried from animals to man 

 by insects; (4) epidemic bubonic plague carried from man to man by insects; 

 (5) pneumonic plague passing from man to man directly, or conveyed by insects. 

 Dr. Kitasato is quoted as saying that the (Manchurian) pulmonary plague can- 

 not spread through the air, the digestive tract is plague-proof, and that direct 

 contact is necessary. 



Rocky Mouutaiu Spotted Fever Tick (Dermacentor Venustus) 1. An^ngorged female ; 

 2. same male. (Year Book, U.S. Dept. Agr. 1910. 



Lice and Certain Diseases. — Typhus fever is transmitted from man to man 

 by the Body Louse (Pediculus vestimenti), and Beriberi probably by the Head 

 Louse (Pediculus capitis). 



Ticks and Certain Fevers. — Although ticks are not true insects yet they 

 have been considered as coming under the field of the entomologist. Li certain 

 western states, viz., Montana, Idaho, Wyoming, Utah and Nevada, the Rocky 

 Mountain Spotted Fever occurs and is produced by the bites of ticks (Derma- 

 centor venustus, et al.) The African tick-fever is caused and carried by another 

 tick (Ornithodoros moubata), the African Relapsing fever possibly by a tick, 

 and the African East Coast fever of cattle by ticks (Rhipicephalus appendicula- 

 tus). The Texan fever of cattle is caused by a tick (Margaropus annulatus). 



Other Diseases. 



The terrible "hookworm" disease of the South is probably carried by the 

 common house-fly. The causal organism (Anchylostoma duodenale) may also 

 enter the skin from infected soil. Pellagra is transmitted, according to many 

 authorities, by the bites of species of black-fly (Simulium) and by the ingestion 

 of mouldy corn. 



