(HAP. XX. INSECTS AND DISEASE. 187 



especially under the toe-nails) and in bad cases causing extensive 

 sores or even permanent crippling, was probably originally ;i native 



>uth America, whence it was carried to West Africa and them e 

 to Easl Africa, and was brought to India in (899 but lias appa- 

 rently not spn-ad beyond Bombay ; however, it is quite likely to be 

 brought in at any time by returned Indian emigrants and to get a 

 footing in sandy plai 



Returning now to the diseases caused directly in man by 

 pathogenic organisms carried by insects we have already seen how 

 malaria is carried by Anopheline mosquitos and may now proceed 



itice brief!) some of the other diseases known to be insect- 

 borne : — 



Relapsing Fever is caused by Spiroschaudimiia carteri, Manson, 

 but it is possible that several distinct forms of disease may be con- 

 fused under the one term. The Head-louse (Pediculus capitis) is 

 probably one carrier, but bed-bugs and mosquitos are not wholly 



1 rom suspicion. 



Indian Kala Asar, caused by Leishmania donovani, is endemic 

 in Madras and is perhaps carried by bed-bugs, possibly by 

 ( 'onorhinus rubrofasciatus. 



Pappataci Fever, Three days' Fever, or Sandfly Fever is an acute 

 fever, lasting three days, whose actual cause is unknown but the 

 infection is carried by sandflies {Phlebotomus spp), the blood of 

 the patient being infective up to the end of the second day of the 

 fever. 



Dengue, an acute fever whose cause is also unknown. is occa- 



illy epidemic and is supposed to be carried by Culex fatigans. 

 Yellow Fever is not as yet known in India hut it is important to 

 note that its carrier (Stegomyia fasciata) occurs commonly in India 

 .\])t\ that the infection can be carried by the eggs of an infected 

 mosquito. 



Plague, caused h> Bacillus pt'stis, is a disease of rats from which 

 it spread- to man In the agency of fleas which desert the dr. id 



and bite man incidentally carrying the infection. In 1N06 it 



id from China to Bombay, whence it has extended almost all over 

 India. It i- common]) spread by Xenopsyllu chcopis, because this is 

 the commonest Ilea found on rats, hut may also he carried by other 

 Ilea- Ceratophyllus fascial us and Pulex irrilans (the Human 



Ilea); it has also been transmitted experimental 1) from man to rat b) 

 the Indian bed-bug (Clinocoris hemipterus) . Plague has unfortu- 

 nate!) made itself too well known in Madras, the Fort St. George 



tte of 20th Ma) [913 giving the numbci ol Plague seizures in 

 Madras onl) from August [898 to 17th M hil> t 



the deaths in tl 



