786 General and Applied Biology 



A. Human Diseases — Cont'd 



3. Human Diseases 



Caused by Arthropods 

 (a) "Chiggers" 

 (Trombicula 

 irritans) 

 (Fig. 269) 



(b) Human lice 



{Pediculus hu- 

 manis) and other 

 species (Fig. 280) 



B. Diseases of Animals 

 Other Than Human 



1. Protozoan Diseases 



(a) Class Mastigophora 

 (Flagellates) 



( 1 ) Dourine of 

 horses, etc. 

 {Trypanosoma 

 equiperdum) 

 (see Fig. 266) 



(2) Nagana fever 

 {T. brucei) 

 (Fig. 266) 



(3) Surra disease 

 {T. evansi) 



(b) Class Sporozoa 



(4) Silkworm dis- 

 ease or pebrine 

 {Nosema bom- 



' bysis ) 



(5) Texas fever of 

 cattle 

 (Babesia 

 bigejnina) 

 (Fig. 267) 



Diseases of Animals 

 Caused by Worms 

 (a) Flatworms (Platy- 

 helminthes) 

 ( 1 ) Liver rot of 



sheep {Fasciola 

 hepatica) (Figs. 



The immature stages of this mite (class Arach- 

 noidea) have 3 pairs of legs, while the adult has 

 4 pairs; mites are transmitted from the soil and 

 vegetation to human skin where their claws 

 cause irritation; they are reddish in color ("red- 

 bugs"), just visible to the naked eye, and suck 

 blood with piercing-sucking mouth parts; adults 

 do not attack man but attack insects 



Transmitted from person to person and by flies, 

 bedding, clothing, etc.; there are sev-eral vari- 

 eties of human lice each with its particular point 

 of attack and structure; sucking blood and 

 scratching by claws cause irritations; may trans- 

 mit other diseases 



Transferred directly from host to host; usually a 

 chronic disease of horses, dogs, rabbits, etc., of 

 the United States, Canada, and parts of Europe 

 in which paralysis results in death in a few 

 months 



Transferred by tsetse fly (Glossina) ; causes fever 

 in various African domestic mammals 



Probably transmitted by tabanid flies; disease of 

 horses, mules, cattle, and camels of India 



Transmitted by spores in the various stages of the 

 life cycle of the silkworm; within the silkworm 

 (Bombyx mori) the spores develop and invade 

 all body tissues, eventually killing the host; this 

 disease must not be confused with a bacterial 

 disease of the silkworm 



Transmitted by cattle tick (Boophilus) ; present in 

 southern United States, parts of Europe, and 

 Africa; characterized by destruction of red blood 

 corpuscles, enlarged spleen, and aff"ected liver; 

 in acute stage the parasites usually appear as 

 pairs of pear-shaped bodies in the blood cor- 

 puscles 



180, 181, 374) 



(2) Tapeworm of 

 dogs, etc. 



Transmitted by the snail (Lymnaea) ; not as com- 

 mon in this country as in Europe; very compli- 

 cated life cycle which is described elsewhere in 

 other chapters; also present in cattle, pigs, and 

 occasionally in man 



Transmitted from dogs and other carnivorous ani- 

 mals to pigs, sheep, and man; the larvae, known 



