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第一類法定傳染病. 衛福部 疾病管制署 中區傳染病防治醫療網 王任賢 指揮官. 第一類法定傳染病. 中華民國行政院衛生署疾病管制局在2009年6月19日修正公布 第一類:天花、鼠疫、嚴重急性呼吸道症候群(SARS)、霍亂、狂犬病、H5N1流感 處理原則 : 24小時內報告,應於指定隔離治療機構施行隔離治療. 天花. Microbiology. Variola virus 2 strains Major and minor Variola major Classic smallpox Predominant form in Asia
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第一類法定傳染病 衛福部 疾病管制署 中區傳染病防治醫療網 王任賢 指揮官
第一類法定傳染病 • 中華民國行政院衛生署疾病管制局在2009年6月19日修正公布 • 第一類:天花、鼠疫、嚴重急性呼吸道症候群(SARS)、霍亂、狂犬病、H5N1流感 • 處理原則:24小時內報告,應於指定隔離治療機構施行隔離治療
Microbiology • Variola virus • 2 strains • Major and minor • Variola major • Classic smallpox • Predominant form in Asia • Highest mortality (>30%) • Form most likely to be seen
Microbiology • Variola minor • Milder disease • Less morbidity/mortality (< 1%) • Less severe prodrome and rash • Predominant form in N. America
Diagnosis • Base on signs and symptoms • Notify Local Health Department • Suspicious cases
Clinical Features • Incubation period: 12-14 days • Three stages of disease • Incubation • Prodromal (pre-eruptive) • Eruptive Photo courtesy of CDC PHIL
Classic Centrifugal Rash of Smallpox Involving Face and Extremities. Photo courtesy of National Archives
Progression of Smallpox Lesions in Semiconfluent Case Patient Who Survived. Demonstrates Vesicles, Pustules, Scabs Then Scars.
Smallpox VS Chickenpox Photo courtesy of CDC Photo courtesy of CDC PHIL
Infection Control • Highly infectious • Droplet, aerosol or clothing • Transmission slower and less likely than with measles or chickenpox • Attack rate 25-40% • 3-4 secondary cases/primary case • 10–20 not uncommon Photo courtesy of National Library of Medicine and WHO
Infection Control • Airborne and Contact Precautions • Negative pressure or HEPA-filtered room • N-95 mask • Gown and gloves • D/C when all scabs separate • Monitor contacts 17 days • Isolate febrile contacts • Home isolation Photo courtesy of National Library of Medicine
Infection Control • Disposal of linens/laundry • Dispose in biohazard containers • Autoclave before laundering • Launder in hot water & bleach • Cremation recommended for casualties
Vaccination • Vaccinia virus vaccine • No longer produced • 6 -12 million doses still exist • 1972: routine childhood vaccination stopped • Half of US citizens have never been vaccinated Photo courtesy of National Archives
Vaccination • Immunity lasts 3-5 years: • Partial immunity • Booster • Prior infection = lifelong immunity
Post Exposure Prophylaxis • Exposure • Inhalation during initial release, household or face to face contact, or direct contact with contaminated linens or lab specimens from known case • Vaccination • Within 3-5 days of exposure • All household or close contacts, hospital employees, hospitalized patients (at the same time as the infected patient), lab employees and mortuary employees
Decontamination • Virus inactivated within 2 days • Buildings • Not needed • Standard hospital disinfectants • Bleach also effective, but should only be used if you run out of standard disinfectants Photo courtesy of National Archives
Epidemiology • Three forms of plague • Bubonic • Most common form in naturally occurring cases • Mortality: 13% • Bioterrorism: release of infected fleas • Septicemic • Systemic infection; Mortality: 22% • Pneumonic • Least common, most severe form • Mortality: 57% • Form most likely to be encountered in BT attack
Plague • Early diagnosis essential • Without treatment, death within 2-3 days • Presumptive diagnosis • Symptoms; obtain culture specimens and send to reference lab • Definitive diagnosis • Positive blood, sputum or bubo aspirate culture
Clinical Features • Incubation period: 2-4 days • Early symptoms • Flu-like symptoms • Fever • Chills • Body aches • Weakness • WBC’s • Headache
Clinical Features • Bubonic • Buboes • Enlarged tender lymph nodes • Usually unilateral • Usually inguinal/femoral in adults • Cervical/submaxillary more common in age < 10
Clinical Features • Pnuemonic • Primary • Inhalation • Secondary (bubonic) • Spread to lungs • Interstitial pattern initially • Presents like typical pneumonia • CXR: usually patchy bilateral infiltrates, consolidation • Hemoptysis • Mortality nearly 100%
Infection Control • Bubonic or Septicemic: • Standard precautions • Contact precautions • If bubo is draining • Pneumonic plague: • Droplet isolation (D/C 48 hours) • Do not discontinue isolation until patient is clinically improving • Antibiotic resistant strain is possible
Infection Control • All forms of plague: • Avoid surgery or other aerosol-generating procedures (including autopsies) • Wear N-95 masks and perform procedure in negative pressure room
Treatment • Mortality for untreated cases: • Bubonic 50% • Systemic and Pneumonic: 100% • Tx immediately • Streptomycin 30 mg/kg/day IM in 2 divided doses or • Gentamicin 2 mg/kg then 1 – 1.5 mg/kg q 8 hrs or • Doxycycline 200 mg IV then 100 mg IV q 12 hrs
Prophylaxis • Doxycycline (drug of choice) • Close contacts (within 2 meters) of pneumonic plague patients • Monitor close contacts refusing prophylaxis • Alternative therapy: • Tetracycline or Chloramphenicol • Provide prophylaxis for 7 days
Decontamination • Viable for only 1 hr as an aerosol • Sunlight, heat or lack of host kills bacteria • Environmental decontamination unnecessary • Standard hospital-approved disinfectants
V. cholerae • Grows in salt and fresh water • Can survive and multiply in brackish water by infecting copepods • Has over 150 identified serotypes based on O-antigen • Only O1 and O139 are toxigenic and cause Cholera disease • 2 categories of O1 serotypes – Classical and El Tor
V. cholerae • Transmitted by fecal-oral route • Endemic in areas of poor sanitation (India and Bangladesh ) • May persist in shellfish or plankton • 7 pandemics since 1817 – first 6 from Classical strains, 7th from El Tor • 1993: Cholera in Bengal caused by O139 – may be cause of 8th pandemic
Strains Causing Epidemics • 2 main serogroups carry set of virulence genes necessary for pathogenesis • O1 • Classical: 1 case per 30-100 infections • El Tor: 1 case per 2-4 infections • O139 • Contained in India, Bangladesh
Transmission • Contaminated food or water • Inadequate sewage treatment • Lack of water treatment • Improperly cooked shellfish • Transmission by casual contact unlikely
Period of Communicability • During acute stage • A few days after recovery • By end of week, 70% of patients non-infectious • By end of third week, 98% non-infectious
Infectious Dose • 106-1011 colony-forming units • Why such a high dosage? • Series of changes as moves from aquatic environment to intestine • Temperature, acidity • Acidic environment of stomach • Intestinal environment • Bile salts, organic acids, complement inhibit bacteria growth • Must penetrate mucous lining of intestinal epithelial cells
Symptoms • Occur 2-3 days after consumption of contaminated food/water • Usually mild, or no symptoms at all • 75% asymptomatic • 20% mild disease • 2-5% severe • Vomiting • Cramps • Watery diarrhea (1L/hour) • Without treatment, death in 18 hours-several days
Cholera Gravis • More severe symptoms • Rapid loss of body fluids • 6 liters/hour • 107 vibrios/mL • Rapidly lose more than 10% of bodyweight • Dehydration and shock • Death within 12 hours or less • Death can occur within 2-3 hours
Consequences of Severe Dehydration • Intravascular volume depletion • Severe metabolic acidosis • Hypokalemia • Cardiac and renal failure • Sunken eyes, decreased skin turgor • Almost no urine production
Mortality Rate • Causes 120,000 deaths/year worldwide • With prompt rehydration: <1% • Without treatment: 50%-60%
第五類法定傳染病 衛福部 疾病管制署 中區傳染病防治醫療網 王任賢 指揮官
第五類法定傳染病 • 中華民國行政院衛生署疾病管制局在2009年6月19日修正公布 • 第五類:裂谷熱(里夫谷熱)、馬堡病毒出血熱、黃熱病、伊波拉病毒出血熱、拉薩熱 • 處理原則:依中央主管機關公告之期限及規定方式為之
病毒性出血熱(VHF) • Acute infection: fever, myalgia, malaise; progression to prostration • Small vessel involvement: increased permeability, cellular damage • Multisystem compromise (varies with pathogen) • Hemorrhage may be small in volume (indicates small vessel involvement, thrombocytopenia) • Poor prognosis associated with: shock, encephalopathy, extensive hemorrhage
Viral Hemorrhagic Fever: viruses • Filoviruses Ebola Hemorrhagic fever (EHF) Marburg virus • Arenaviruses Lassa fever “New World Arenaviruses” • Bunyaviruses Rift Valley fever (RVF) Crimean Congo Hemorrhagic fever (CCHF)
Ebolavirus • 1-2 week incubation • Abrupt onset fever, headache, myalgia • GI symptoms, chest pain, delerium • 53-88% case-fatality • ~ 45% hemorrhage • Person-to-person transmission • African rainforest • Unknown reservoir