The endemic diseases of the southern states . Fig- SS-—ilany breeding places are left upon the lowlands after the overflowhas receded. Mississippi, and of other large streams. Levees, dykes, andother engineering means of large dimensions are the onlyremedies; these being expensive are rarely employed merelyfor sanitary purposes. Marshes and swamps when too extensive to be filled maybe effectively drained. The drains should be narrow, ofsufficient depth and fall to drain effectively, and may beparallel, crowfoot fashion or otherwise, as best suited to localconditions. If concreted they require
The endemic diseases of the southern states . Fig- SS-—ilany breeding places are left upon the lowlands after the overflowhas receded. Mississippi, and of other large streams. Levees, dykes, andother engineering means of large dimensions are the onlyremedies; these being expensive are rarely employed merelyfor sanitary purposes. Marshes and swamps when too extensive to be filled maybe effectively drained. The drains should be narrow, ofsufficient depth and fall to drain effectively, and may beparallel, crowfoot fashion or otherwise, as best suited to localconditions. If concreted they require less after-treatment. Fig. 56.—A stranded skiff containing a little water and many anopheles wrigglers. and may be cheaper in the end. If not concreted they shouldbe frequently inspected to prevent caving, deposit, or fillingwith vegetation. The tile drains are usually very efficient. Large swamps in the vicinity of streams have been renderedunfit as breeding places by directing the course of the streamthrough them. The water is thus given a current, and if thestream contains much mud in suspension the bed of the marshis gradually filled. Fresh-water ponds close to the sea have been successfullytreated by filling with salt water. Water strong in salt is l82 ENDEMIC DISEASES OF THE SOUTHERN STATES not attractive for breeding purposes, though brackish watermay harbor numerous larvae. The rendering innocuous of borrow pits along railroad linesis difl&cult. It is much easier to prevent the stagnation ofwater during the construction of the road than it is to remedythe defect after completion. Filling and
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Keywords: ., boo, bookcentury1900, bookdecade1910, booksubjectdiseaseoutbreaks
