448 MOSQUITOES 



its importation to other places has become a rare occurrence. 

 Since Aedes calopus has a much wider range than has yellow fever 

 there is constant danger of the introduction of the disease into 

 places where it has not previously been known and where, due 

 to the non-immune condition of the people, it would become 

 a terrible scourge if once successfully introduced. For this 

 reason the yellow fever mosquito is fought as a public menace 

 in India, Austraha and many of the South Sea Islands, where it 

 is frequently the most abundant mosquito. 



Mosquitoes and Dengue 



The relation of mosquitoes to dengue or breakbone fever was 

 first pointed out by Graham, of Beirut, in 1902, who performed 

 experiments which showed that this disease was not caught by 

 close association with patients in the absence of mosquitoes, 

 whereas isolated men subjected to bites from mosquitoes which 

 had bitten dengue patients readily contracted the disease. 

 • Other workers have adduced evidence in favor of the mosquito 

 transmission of the disease, and Ashburn and Craig in the Philip- 

 pines have shown that laboratory-bred mosquitoes, fed on dengue 

 patients, could transmit the disease three days after the infective 

 meal. The nature of the disease and development of it in mos- 

 quitoes and man is discussed in Chap. X, pp. 186-187. It is a 

 disease which resembles a mild form of yellow fever, is seldom fatal, 

 and occurs in very sweeping and rapidly traveling epidemics. 



Transmitting Species. — So far, only the tropical house mos- 

 quito, Culex quinquefasciatus (fatigans) and Aedes calopus have 

 been shown to be capable of transmitting dengue. Circumstan- 

 tial evidence, such as distribution and epidemiology of the disease, 

 habits of the mosquitoes, etc., all point to C. quinquefasciatus as 

 being the most important species concerned. Aedes calopus 

 has repeatedly been suspected of transmitting the disease, es- 

 pecially in Australia, but conclusive evidence of this has been 

 brought forth only recently (1916) by Cleland, Bradley and 

 McDonald in Australia. 



C. quinquefasciatus is the common house mosquito of the 

 tropics, and very closely resembles the house mosquito of tem- 

 perate climates, C. pipiens, in both appearance and habits. 

 It is brown in color with a broad whitish band on each abdominal 



