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<br />The occurrence of malaria outbreaks as a result of improperly <br />prepared reservoirs in the southeastern States is well documented. <br />Malaria has also been associated with irrigation in several States <br />including California, New Mexico, Texas, and in the rice-growing <br />areas of the Mississippi Delta. This disease has been almost eradicated <br />, from the United States; -and at present, there is no significant malaria <br />transmission anywhere in the Nation. The malaria vectors (Anopheles <br />quadrimaculatus in the East and Anopheles freeborni in the West) are <br />still prevalent in some areas where favorable habitats are present. <br />These mosquitoes constitute a potential hazard for the establishment <br />of new foci of malaria transmission, particularly in situations where <br />the disease may be reintroduced from foreign countries. This was well <br />illustrated at Lake Vera in California during the summer of 1952, where <br />35 cases of malaria occurred among Camp Fire Girls. The source of their <br />infections was traced to a soldier who had an attack of malaria while <br />camping at the lake. <br /> <br />Several vicious-biting species including Aedes vexans, Aedes <br />dorsalis, and Aedes nigromaculis may be produced in habitats associated <br />with irrigation and other water resource projects. These mosquitoes <br />often create public health problems aside from the transmission of <br />specific diseases. Such health hazards are illustrated by the results <br />of surveys made by the U.S. Public Health Service in irrigated areas <br />in northern Montana. In three-fourths of the families surveyed, <br />mosquitoes severely annoyed both adults and children and interfered <br />with their normal outdoor activities during the summer months. Mos- <br />quito bites caused some degree of injurious reaction in 8 out of 10 <br />people interviewed; and in one section, 40% of the individuals <br />examined by the physician showed evidence of secondary infection of <br />mosquito bites. Some individuals, particularly children, frequently <br />required medical attention and sometimes even hospitalization for <br />treatment of secondary infections and occasional allergic reactions <br />caused by mosquito bites. <br /> <br />In addition to their public health importance, mosquitoes often <br />create other serious problems in both rural and urban areas. Their <br />vicious biting reduces the efficiency of farm workers and sometimes <br />binders the harvesting of crops. Dense populations of attacking <br />mosquitoes have been reported to kill livestock. The constant <br />attacks of even moderate populations of these insects may reduce <br />the vitality of farm animals and prevent proper feeding, thereby <br />causing reduced weight gains and lower milk and egg production. <br />Mosquitoes are vectors of encephalitis, anaplasmosis, fowl pox, <br />and several other important diseases of animals. These diseases <br />kill large numbers of farm animals each year. Together, mosquito <br />annoyance and mosquito-transmitted diseases undoubtedly result in <br />losses of millions of dollars to farmers every year. <br /> <br />B-2 <br />