Carpenter et al.: Mosquitoes of Southern U. S. 5 



or tertian malaria; P. falciparum, which causes malignant tertian, estivo- 

 autumnal or subtertian malaria; P. malariae, which causes quartan malaria; 

 and P. ovale, the cause of ovale malaria. 



The life cycle of the parasite consists of a sexual (sporogony) phase 

 with multiplication in Anopheles mosquitoes and an asexual (schizogony) 

 phase with multiplication in man. 



The primary vectors of human malaria in the United States are Anopheles 

 qiiadrimaculatus in the eastern and southern states, and A. maculipenms 

 freeborni in the western states. 



Bird Malaria. — This disease is caused by an infection with one or more 

 species of blood-inhabiting protozoa belonging to the genus Plasmodium 

 and is transmitted by various species of mosqu'toes. Since the behavior of the 

 parasites causing bird malaria resembles closely that of the plasmodia of 

 human malaria, experimental work with these forms have helped to solve 

 many of the problems of human malaria. Mosquitoes which have been shown 

 to be susceptible to infection with bird malaria parasites are found in the 

 following genera: Aedes, Anopheles, Culex and Cidiseta. Culex pipiens and 

 C. quinquejasciatus are generally considered to be important vectors. 



Yellow fever. — This virus disease often reaches epidemic proportions pro- 

 ducing high mortality among non-immune populations. It occurs in the 

 urban or epidemic form in the presence of the Aedes aegypti mosquito and 

 in the jungle form as an infection of certain animals of tropical forests, trans- 

 mitted from animal to animal, and occasionally to man, by various species of 

 jungle mosquitoes. The two forms of the disease are quite similar in all 

 respects except for variations in the epidemiology. 



The disease is known to occur in certain portions of Central and South 

 America, the Caribbean region and west and central Africa. It has not 

 occurred in the United States during recent years. 



Wild primates, marsupials and rodents have been shown to be susceptible 

 carriers in whose blood the virus circulates for the initial few days of the 

 disease and thus serve as a source of infection to susceptible mosquitoes. 



An impressive list of Culicine mosquitoes belonging to the genera Aedes, 

 Haemagogus, Eretmapodites, Ctdex, Mansonia, Psorophora, Wyeomyia, and 

 Limatus, have either been found naturally infected or have been shown 

 experimentally to be capable of harboring and transmitting the virus. 



Dengue. — Dengue or "breakbone" fever is an acute infectious disease of 

 man caused by a filterable virus and transmitted principally by Aedes aegypti 

 and Aedes albopictus. It is endemic throughout the tropical and subtropical 

 regions of the world and while it may occur sporadically, it usually appears 

 in epidemic form. 



Filariasis. — Filariasis is a disease of man caused by the presence of a 

 parasitic nematode worm, usually Wuchereria bancrofti, the immature forms 

 (microfilaria) of which are transmitted by the bite of certain species of mos- 

 quitoes. The dramatic clinical manifestation of enlarged extremities has given 

 this disease the common name of elephantiasis. Wuchereria bancrofti, the 



