876 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



way than by the bite of a particular mosquito, Aedes (Stegomyia) 

 calopus (Meigen). These mosquitoes were allowed to bite patients 

 suffering from yellow fever at different stages of the disease. Sub- 

 sequently these same mosquitoes were allowed to bite healthy men 

 at different periods of time following their application to the infected 

 individual. It was proved that the mosquito, in order to be capable of 

 conveying the disease, must bite an infected individual during the first 

 three days of the fever and at least twelve days must elapse thereafter 

 before the mosquito is capable of transmitting the disease to a sus- 

 ceptible individual. 



Quite recently Noguchi* has isolated from cases of yellow fever a 

 spiral microorganism which he calls Leptospira icteroides. He has 

 grown this microorganism in pure cultures which proved pathogenic 

 for guinea-pigs. Infected guinea-pigs develop symptoms and lesions 

 resembling those of yellow fever in man. Leptospira icteroides is cap- 

 able of passing through Berkefeld niters. The present indications are 

 that it is the cause of yellow fever. 



DISEASES CAUSED BY PROTOZOA^ 



RHIZOPODA (von Seibold) 



The amoebae are the most important of the parasites belonging to the rhizopods. 

 Various species of amoebae are parasitic in the intestines of cattle, horses, mice, frogs 

 and fish as well as human beings and most of them, like Entamoeba coli of man, are 

 harmless. One species, Entamosba histolytica, produces a very severe dis- 

 ease of man. Entamosba meleagridis is the cause of a fatal disease of turkeys 

 (page 879). Entamceba gingivalis (buccalis) is a parasite which is frequently found 

 in a diseased condition of the gums characterized by peridental abscesses but is 

 also frequent in apparently healthy mouths. Amoebae have also been found in 

 purulent and serous fluids from the chest and abdomen as well as in urine. The 

 parasitic species lack the contractile vacuole which is a feature of the free living 

 species that are commonly encountered so that it is not difficult to distinguish the 

 two types. 



AMCEBIC DYSENTERY 



Entamceba histolytica Schaudinn, 1903 



Syn.: Entamoeba tetragena Viereck, 1907 



Distribution. Amoebic dysentery occurs most frequently in tropical, 

 or sub-tropical, countries, but cases of it occasionally occur in Great 

 Britain, in Central Europe, and in the United States. 



* Noguchi, H., Etiology of Yello\y Fever, .jour. E.xp. Med., Vol. XXIX, No. 6, e( seq., 1919. 

 t Diseases arranged generically. 

 | Prepared by J. L. Todd. 



