The Health bulletin [serial] - University of North Carolina at Chapel Hill

6 The Health Bulletin May, 19511950 there were 1,487 cases of this diseasereported to the North CarolinaState Board of Health. The case fatalityrate Is very low. About 2% of thosewho have the disease die of it.Salmonellosis, a food infection disease,is often transmitted to man fromfood contaminated with infected raturine or feces. The case fatality rateof this disease is about one per cent.Hemorrhagic jaundice, or Weil's disease,is usually acquired by man fromfood or water contaminated by rat excretaor from handling infected rats.In dififerent outbreaks of this diseasemortality has varied from 4 to 48 percent.Rat-bite fever, which has a casefatality rate of about 10% in imtreatedcases, is caused, as its name signifies,by the bite of infected rats. In a studymade in Baltimore of 93 persons bittenby rats seven developed this disease.Trichinosis, a disease acquired by eatingInfected pork, has a mortality rateof about 5%. Normally, the rat playsno part in the transmission of this diseaseas we do not eat rats, but sometimeshogs become infected by eatingrats which have obtained the causativeorganisms by feeding on raw or improperlycooked pork and pass the diseaseon to us when we eat the hogs.Human beings are killed by all ofthese diseases with transmission cyclesInvolving the rat; hence their abilityto spread pathagenic organisms is probablythe most formidable weapon employedby rats in their never-endingstruggle against humanity. Yet, asidefrom their role as disease bearers, thereare other ways In which these rodentsadversely affect mankind, in some casescausing only minor annoyance, but attimes creating major catastrophes.Hordes of rats have been known tobring on starvation and famine by thedestruction of growing as well as storedfood crops. Vast quantities of food arealso rendered unfit for human consumptionupon being polluted by rats.The U. S. Department of Agricultureestimates that the average rat consumesor otherwise destroys $22.00worth of food in a year. If this be true,they cost North Carolina about $88,-000,000 annually. These destructive rodentseat eggs, kill poultry and otherdomestic animals and destroy largequantities of wild life. Structural damageto buildings and auxiliary facilities,such as plumbing and electric wiring.Is often caused by rats. They are alsoresponsible for many fires started bytheir gnawing on or dragging matches.Know the EnemyBefore successfully waging war. It Isnecessary to have knowledge of thehabits and characteristics of the enemy.In rat control, effectiveness is determinedby tiie use which is made ofbasic knowledge of the rat.There are two species of domesticrats In North Carolina, both of whichare known by several names. The Norwayrat, which is also known as thebrown, house, bam, burrowing, sewerand wharf rat, is the larger of the twospecies. The roof rat, which is frequentlyknown as the Alex, grey, black orclimbing rat, as its name implies, Ismost commonly foimd at higher levels.Being a better climber than the Norwayrat, this rodent Is usually the onefoimd In the upper stories and atticsof buildings.The reproduction potential of the ratis enormous. The gestation period Isonly 25 days, and litters range from 6to 14. Mature rats remain fertile regardlessof the season and diiring ayear produce several litters, the numberdepending on such things as food,warmth, and shelter. Studies In Baltimoredisclosed from five to seven littersannually. Heaviest breeding takes placeduring the svmimer months under normalconditions. For this reason, theeffects of poisoning campaigns in thefall last longer than those conductedIn the spring.The behavior of rats is influenced bythe same things which motivate humans,such as hunger, thirst, sex, fear,curiosity and maternal instinct. Hunger,thirst and the requirement for placesto hide from danger are factors mostutilized in rat control.The rat has a highly developed senseof smell. Its taste is somewhat less