霍乱PPT课件.ppt

霍乱霍乱DEFINITIONn nCholera was defined as Class A communi-cable diseases in the Law of the peoples Republic of China for Prevention and Control of Communicable Disease.n nIts also one of the quarantinable diseases as stipulated by the International Health Regulation(IHRs).DEFINITIONn nCholera is an acute infection of intestinal tract caused by Vibrio cholerae.n nClinical characteristics:a sudden onset of severe watery diarrhea and vomiting,which lead to dehydration even hypovolemic shock.n nAppropriate fluid replacement is the key of treatment and greatly reduces mortality.ETIOLOGY Vibrio choleraeBacillus:curved,facultative anaerobic,curved,facultative anaerobic,gram-gram-negativenegativemotility with a single polar flagellum the erratic movementETIOLOGYn n Culturen nsensitive to low PHn ntolerant in alkaline conditionn nalkaline peptone water:incubated in stool or rectal swab specimen greater sensitivityn nAntigenic typen nflagellar H antigen n nsomatic O antigenETIOLOGYn nClassification V.cholerae O1*n nV.cholerae non-O1 V.cholerae(*agglutination in Oagglutination in O1 1 group specific antiserum)group specific antiserum)n nV.cholerae O1 1 biotype classic biotype EL Torn nO139 strain:agglutinate in O group 139 specific antiserumETIOLOGYn nOnly two serotypes:O1 1 and O139 strain cause epidemic n nVirulence:Cholera toxin(CT)n nResistance sensitive to n ndrynessn n heatn nsunlight n ncommon disinfectantsn nacid,especially gastric acid ETIOLOGYn nWhen conditions in the environment such as temperature,salinity and availability of nutrients are suitable,V.cholerae can survive for years in a free-living cycle without the intervention of humans.EPIDEMIOLOGYn nA disease of antiquityn nthe ancestral home of biotype classic:the Ganges Delta of Indian nsubsequently spread to the world n nseven global pandemics:from 19th century to daten nthe biotype classic:the initial six pandemics EPIDEMIOLOGYn nbiotype EL Tor:recognized first at the EL Tor quarantine station in the Persian Gulf in 1911n nbiotype EL Tor:7th pandemic which began in 1961n nV.cholerae O139139:first designated in India in late 1992 EPIDEMIOLOGYn nSources of infectionn n patients n ncarriers?n nRoutes of transmission large numbers of vibrios sources from the voluminous liquid stools n ncontaminated foodn nflies:as media(contact person to person)EPIDEMIOLOGYn ncontaminated water(river,seawater,wells,etc)n nthe water-borne routeEPIDEMIOLOGYn n Susceptibility of individuals n ngenerally susceptiblen nmore sensitive:n n individuals with low gastric productionn n children under 5 yearsn n persons of blood group OEPIDEMIOLOGYn nnon-sustain immunity from illnessn nnaturally acquired immunity:V.cholerae O1 does not have cross-protect against the O139 strain.EPIDEMIOLOGYn nEpidemiologic featuresn nSeasonalityn nsummer n nautumnn n Endemic n nAreas:along the coast or the riversn nRegions:lack of sanitary water supplies The distribution of cholera in the worldn nRiver overflowed the villages and houses.n nDrinking water was contaminated and no boiling.n nCases occured.Most of cholera cases had relation with contaminated food.peddlersIn China,the nearest outbreak happened in HaiNan province.Cholera in Zimbabwe n nA new large cholera outbreaks have happened in Zimbabwe since August 2008.n nCholera victims lied in the hospital wards in Zimbabwe.n nUntil the end of January 2009 n nexceed 58,000 cases:reported n nover 3,000 people:diedn nThe number of cholera deaths continues to increase each day.n nCholera is closely linked ton ninadequate environmental managementn nlacking of sanitary watern npeople had to drink contaminated watern n Recent interruptions to the water supplies,together with overcrowding.PATHOGENESIS Whether the disease develops or not depends on:n n the hosts non-specific immunity(gastric acidity)n n the amount of the bacteria ingested Ingestion of V.choleraeResistant to gastric acidColonize small intestineIllness occurs when viable organisms Illness occurs when viable organisms reach the duodenum and jejunum.reach the duodenum and jejunum.PATHOGENESISn n Active motile vibros penetrate mucous layers and attach to the brush border of the intestinal epithelium where they secrete cholera toxin(CT).Cholera toxin Cholera toxin binds to intestinal cellsChloride channels activatedChloride ion-driven secretion,mal-absorption of Chloride ion-driven secretion,mal-absorption of sodium ion and watersodium ion and water Release large quantities of electrolytes&bicarbonatesFluid hyper-secretionDiarrhea and vomitingDehydration(loss of body fluid)PATHOGENESISn n“Watery stool”:n nnon-fecaln nenriched in water,potassium and bicarbonaten nno plasma protein or formed elements of the blood n nReason:no local cellular damage or inflammation PATHOLOGY The most prominent pathological findings:n n dehydration in heart,liver,skin,etcn n mild pathological changes in small intestine CINICAL MANIFESTATIONSn n Incubation:several hours-7 daysn nClinical course of typical cases:three stagesn nStage of diarrhea and vomitingn nStage of dehydrationn nStage of reaction and convalescencen nAll signs and symptoms drive from the fluid losses.CINICAL MANIFESTATIONSn nStage of diarrhea and vomitingn nSudden onset with severe diarrhea and vomiting,several times to more than 10 times per day.CINICAL MANIFESTATIONSn nFluid loss may be extreme,exceeding 1 liter per hour.n nrice-water stools:yellowish and watery or clear with flecks of mucus n nno abdominal pain or tenesmusn n no fever in generalCINICAL MANIFESTATIONSn nStage of dehydrationn nacidosis(loss of sodium bicarbonate)n nmuscle crampsn ncirculatory failure and renal failure(hypovolumia)n ndehydration:hoarse voice;exteme thirstdepletion-sunken eyesscaphoid abdomenpoor skin turgorloss of skin elasticityTable 1 Clinical findings according to degree of Table 1 Clinical findings according to degree of dehydrationdehydrationFindingFindingMildMildDehydrationDehydrationModerateModerateDehydrationDehydrationSevereSevereDehydrationDehydrationLoss of fluidLoss of fluid*5%10%10%MentationMentationAlert Alert RestlessRestlessDrowsy or comatoseDrowsy or comatose Radial pulse rate Radial pulse rateNormalNormalRapidRapidVery rapidVery rapidStystolic blood Stystolic blood pressurepressureNormalNormalLowLowVery lowVery lowSkin elasticitySkin elasticityRetracts Retracts rapidlyrapidlyRetracts Retracts slowlyslowlyRetracts very slowlyRetracts very slowlyEyes Eyes NormalNormalSunkenSunkenVery sunkenVery sunkenUrine Urine prouductionprouductionNormalNormalScant Scant oliguriaoliguriaCINICAL MANIFESTATIONSn nStage of reaction and convalescence:n nrecover from the disease if dehydration corrected promptly.n npyretic reactionCINICAL MANIFESTATIONS In rare instances cholera sicca shock and death occur before diarrhea appears.COMPLICATIONSn nAcute renal failuren nAcute pulmonary edemaDIAGNOSISn nTentative diagnosis:clinical manifestations and epidemiologic datan nPatient develops or dies from severe watery diarrhea and dehydration in an area where cholera is not endemic.n nPatient develops acute watery diarrhea in an area where there is an epidemic or cholera is endemic.n nDefinitive diagnosis:Isolation of V.cholerae in stool,vomit or rectal swabDIFFERENTIAL DIAGNOSISn nBacterial food poisoningsn nGastroenteritis n nenterotoxigenic E.coli n nenteropathogenic E.coli n nshigellosis LABORATORY FINDINGSn n Stool examinationsn n stool routine test:mucus and WBCn n dark-field microscopic examination:darting motility of vibrios in fresh wet preparationsLABORATORY FINDINGSn nstool hanging drop examination and motility inhibition test:The bacteria can be discerned by immobilization with its serotype antiserum.n nculture：alkaline peptone water or thiosulfate-citrate-bile salt-sucrose(TCBSTCBS)agarOpaque flat yellow colonies form on TCBS agar in 18 hours at 37.LABORATORY FINDINGSn n Blood examinationsn nincreased RBC,hemoglobin and WBC n nnormal or decreased serum sodium,serum potassium,increased BUNn ndecreased CO2CPn n Urine test:RBC,WBC,albumin,casts.LABORATORY FINDINGSn nSpecific antibody in immobilization test:epidemiological studiesn nSeveral other methods:n nlatex agglutinationn nenzyme immunoassayn npolymerase chain reaction(PCR)PROGNOSISn nWithout treatment,mortality approaches 60 per cent of those affected.n n The mortality is always in greater amongn n the aged and young childrenn n the intemperate and those poorly nourished n n treatment is not vigorous in the early stage of the disease TREATMENTn nIsolation:n n six days after the symptoms disappearn n three negative stools cultures taken once every other dayTREATMENTn nFluid replacementn nthe goal:restore the fluid lossesn nstart as soon as diarrhea beginsn ntwo routes:intravenous fluids,oral fluidsTREATMENTn nIntravenous fluidsn n severe,moderate cases or in shockn n the main principles:early,rapid and enoughn n infuse of salt solution according to the infuse of salt solution according to the reaction to the treatmentreaction to the treatmentn ncorrect of the metabolic acidosis correct of the metabolic acidosis n ngive potassium if patients without oliguriagive potassium if patients without oliguriaTable 2 The volume of intravenous fluids in first 24 hoursVolume of Volume of infusion infusion Mild Mild DehydrationDehydrationModerate Moderate DehydrationDehydrationSevereSevereDehydrationDehydrationadultadult（mlml）30003000400040004000400080008000800080001200012000childchild（ml/ml/kgkg）120120150150150150200200200200250250salt salt solutionsolution（ml/kgml/kg）606080808080100100100100120120(5:4:1 solution:NaCl 5g,NaHCO(5:4:1 solution:NaCl 5g,NaHCO3 3 4g,KCl 1g and 4g,KCl 1g and 50%GS 20 ml 50%GS 20 ml in per liter of water.in per liter of water.)TREATMENTn n Oral fluidsn nmild casesn nsevere cases in which the patients condition has improved after giving intravenous fluids TREATMENTn nOral rehydration solution(ORS):n n NaCl 3.5,NaHCO3 2.5,KCl 1.5 and GS 20 in grams per liter of watern nThe volume in the initial 6 hours:adult 750ml/h;child 1520ml/kg/hn nThe total volume is decided as the degree of dehydration and ongoing fluid loss.TREATMENTn nAntibiotics:n nreduce the duration of diarrhea n ndecrease excretion of the V.choleraen nnorfloxacin,doxycycline,berberinen nTreatment of complicationsn nacute renal failure:corrcet acidosis and electrolytes even hemodialysis n nacute pulmonary edema:sedative,diuretic,cardiaconticPREVENTIONn nControl of sources of infectionn nThe diarrhea clinic need be established.n nCase must be reported to CDC within 6 hours in towns or within 12 hours in villages in China.n nAll patients are strictly isolated in wards.n nsix days after the symptoms disappearsix days after the symptoms disappearn n three negative stools cultures taken once three negative stools cultures taken once every other dayevery other dayPREVENTIONn nclose contactsn nmedical surveillance for 5 days n n take SMZ-TMP or norfloxacin for 2 days n n all carriersn n detection and treatmentPREVENTIONn nInterruption of the routes of transmission n ncorrect the water supply and sewage system as a matter of urgencyPREVENTIONn nprovision of facilities for sanitary disposal of human wasten neducation on good personal hygienen na wide variety of disinfectants:bleaching power,soap n nadhering to proper food safety practices PREVENTIONn nIncrease the immunity of individualsn nVaccination:different V.cholera vaccine strains n nOnce an outbreak has started,WHO does not recommend oral or parenteral vaccine.n nThe vaccines limited efficacy is at least partially due to its failure to induce a local immune response at the intestinal mucosal surface.