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1、 Community Health and Community Health and Infectious DiseasesInfectious Diseases社區健康與傳染病社區健康與傳染病K.N. Leung K.N. Leung 梁國南梁國南 Department of Biochemistry, and Food and Nutritional Department of Biochemistry, and Food and Nutritional Sciences Programme ,CUHK Sciences Programme ,CUHK 香港中文大學生化系香港中文大學生化系
2、、食品及營養科學課程食品及營養科學課程 Lecture Outlinev Concepts of Health and Diseasev Human Pathogens and Infections v Prevention of Infectious Diseasesv Microbial Control and Public Health v Emerging and Reemerging Infectious Diseases WHO Definition of Health“Health is a state of complete physical, mental and socia
3、l well-being, and not merely theabsence of disease and infirmity.” Community Health“A healthy community is one that embraces the belief that health is more than merely an absence of disease. A healthy community includes those elements that enable people to maintain a high quality of life and product
4、ivity.” - Department of Health, USA the participation of the community in health care programs.Definition of Disease (1) Dis-ease: opposite of ease, when something is wrong with a bodily function.(2) “An impairment of health due to an interruption, cessation or disorder of body functions.”Louis Past
5、eur (1822-1895)Robert Koch (1843-1910)Founders of Microbiology and Modern MedicineFounders of Microbiology and Modern Medicine Mother is the First Microbiology Instructor!Antonie van Leeuwenhoek (1632-1723) “Father of Microbiology” Infectious vs. Non-infectiousInfectious disease a disease caused by
6、a pathogenic microorganismCommunicable disease an infectious disease that is transmissible from one human to another, either directly or indirectlyContagious disease a communicable disease that is easily transmitted from one person to anotherTypes of DiseaseThe Worlds Most Common Causes of Death The
7、 Worlds Most Common Causes of Death from Infectious Diseasesfrom Infectious Diseases Data from The World Health Report 2002RespiratoryInfections(3.9 million)AIDSDiarrheal diseasesTuberculosisMalariaMeaslesHepatitis BTetanusOthersTypes of Infection Acute vs. ChronicLatent vs. PersistentClinical vs. S
8、ubclinicalHospital-acquired vs. Community-acquiredInfection invasion of the body tissues by living organisms Causes of Infectious DiseaseViruses Bacteria Fungi Protozoa Parasitic worms Most micro-organisms are harmless, only a few are pathogenicPATHOGENS IN OUR ENVIRONMENTTypical Structure of a Viru
9、s20-300 nm in diameter Capsule (mainly polysaccharides)Cell wallCell membranePlasmids (DNA thatcode for toxin production orantibiotic resistance) Flagellum(confers motility)Pili (adhereto host cellsurface)Circular DNAgenomeTypical Structure of a BacteriumDifferent Types of BacteriaStreptococcus that
10、 causes sore throatsLegionella pneumophila that causes Legionnaires diseaseCampylobacter jejuni that causes food poisoning FACTORS AFFECTING THE EXTENT & FACTORS AFFECTING THE EXTENT & SEVERITY OF AN INFECTIONSEVERITY OF AN INFECTIONFactors related to micro-organisms: e.g. Dose, Pathogenicity, Route
11、 of entry Intrinsic host factors: e.g. Age, Sex, Immune competence, Genetic makeup, Previous infections, Nutritional & emotional states Extrinsic factors: e.g.Infections in community, Hygiene & sanitation, Medication used, Environmental pollution ROUTES OF ENTRY ROUTES OF ENTRY OF INFECTIOUS ORGANIS
12、MSOF INFECTIOUS ORGANISMS Through the skin or mucus membrane 1) by direct close contact: e.g. Venereal disease (花柳病花柳病); AIDS (愛滋病愛滋病) 2) by contamination of abrasions and wounds: e.g. Rabies (狂犬病狂犬病); Tetanus (破傷風破傷風) 3) by inoculation: insect bite Malaria (瘧疾瘧疾); syringe serum hepatitis (血清性肝炎血清性肝
13、炎) ROUTES OF ENTRY ROUTES OF ENTRY OF INFECTIOUS ORGANISMSOF INFECTIOUS ORGANISMSBy ingestion of contaminated food and water: e.g. Cholera (霍亂霍亂); Infective hepatitis (傳染性肝炎傳染性肝炎) By inhalation of dust and aerosols-borne pathogens: e.g. Influenza (流行性感冒流行性感冒); Tuberculosis (肺結核肺結核) SARS ( (嚴重急性呼吸道症候
14、群嚴重急性呼吸道症候群) ) The Human Immune System 人體的免疫系統病毒病毒細菌細菌真菌真菌寄生蟲寄生蟲癌細胞癌細胞花粉花粉骨髓骨髓幹細胞幹細胞 Lymphocytes 淋巴細胞淋巴細胞 B cells: 10-15% of blood lymphocytes T cells: 70-80% of blood lymphocytesInclude Macrophages & GranulocytesPhagocytes 吞噬細胞吞噬細胞Immune MechanismsInnate (Non-specific) Immunity Acquired (Specific)
15、Immunity Resistance not improved by repeated antigen exposureWithout memoryFast response Resistance improved by repeated antigen exposureWith memorySlow response Physical barriers: Skin, Mucus membraneBiochemical factors: Complement, Acute phase proteins, LysozymeChemical barriers: Acid in stomach,
16、Mucus in saliva Cellular factors: Phagocytes, NK cells, Eosinophils Humoral Immunity: (B cells + Antibodies)Cell-mediated Immunity: (T cells + Accessory cells + Cytokines)Normal Resistance to Microbial InfectionNormal Resistance to Microbial Infection Infectious Disease: Dynamic Interaction and Bala
17、nce of Various FactorsHOSTPATHOGENENVIRONMENTChain of Infection (Infectious Disease Cycle)Chain of Infection (Infectious Disease Cycle)The pathogenReservoir(Source of pathogen)Mode of transmissionSusceptibility ofthe hostExit from hostPrevention of Infectious Diseases breaking the chain of infection
18、v Isolation and Quarantine - remove the source of infectionv Modify environment - improve sanitation, eradication of vectorsv Increase host resistance - vaccination and immunopotentiationIsolation and Quarantine Separation of ill infected patients in hospitals (Isolation) or infected suspects in the
19、ir homes, or in community-based facilities (Quarantine) Voluntary basis or mandatory to protect publics health Edward Jenner: “Father of Immunology”Discovery of smallpox vaccine From Variolation to Vaccination (1796) Vaccination against smallpox in 1796Vaccination against smallpox in 1796 Eradicatio
20、n of smallpox in 1979 Eradication of smallpox in 1979Invention of VaccinationVariolation in Ancient ChinaVariolation introduced to Europe (1721) by Lady Mary MontaguPrinciple of VaccinationPrimaryAntibody ResponseSecondaryAntibody ResponseAntibody titerMemory cellformationVaccinationToxoid1st Exposu
21、reNaturalinfectionToxin2nd ExposureTimeSTRATEGIES FOR VACCINATIONSTRATEGIES FOR VACCINATIONSynthetic Synthetic PeptidesPeptidesNatural Natural Infectious InfectiousAgentAgentLive Live AttenuatedAttenuated Organism OrganismKilledKilledOrganismOrganismDNA forDNA forProtectiveProtectiveAntigensAntigens
22、 Protective Protective AntigensAntigensProtein subunitsProtein subunitsRecombinantRecombinantproteinsproteins VACCINES CURRENTLY VACCINES CURRENTLY AVAILABLE FOR HUMANS AVAILABLE FOR HUMANS Live attenuated Polio (小兒痲痺)Measles (痲疹), Mumps (痄腮)& Rubella (德國痲疹) (MMR) BCG (TB肺癆)SubunitHepatitis B (乙型肝炎)
23、Haemophilus B (流感杆菌性腦膜炎) InactivatedInfluenza (流感), Rabies (狂犬病)Hepatitis A (甲型肝炎)Cholera (霍亂)Pertussis (百日咳)ToxoidTetanus (破傷風)Diphtheria (白喉)Newly Developed VaccinesNewly Developed VaccinesConjugate vaccine forHaemophilus influenzae type b (Hib)Oral vaccine for RotavirusBacterial MeningitisViral G
24、astroenteritisMicrobial Control MethodsPhysical Agents:Dry heat (incineration) and moist heat (autoclaving and Pasteurization)Radiation (gamma irradiation and UV irradiation)Chemical Agents:Gases (ethylene oxide, beta-propiolactone)Disinfectants and antiseptics (alcohols, chlorine compounds)Mechanic
25、al Removal Methods:Filtration and sanitizationDisinfectants Commonly Used in Hospitals 60 - 90% Alcohols (Ethanol, Isopropanol) Chlorine compounds (Halazone, Hypochlorite) Glutaraldehyde Iodine and iodophors Phenolic compounds (Lysol, Cresol) Quaternary Ammonium Compounds Action of Antibiotics Inhib
26、it cell wall synthesis:Penicillins CephalosporinsInhibit protein synthesis:TetracyclineErythromycinChloramphenicolInhibit nucleicacid synthesis:Nalidixic acid RifampicinChange cell membrane permeability: PolymyxinInhibit synthesis of essential metabolites:SulfonamideAntibiotic Resistance Mechanisms
27、Altered receptor sites do not allowantibiotics to fitAntibiotics are broken downby enzymesAntibiotics areremoved fromcell via pumpsDecreased cell membranepermeability does not allow antibiotics to enterAntibiotic Personal Protection Against Personal Protection Against Infectious Diseases Infectious
28、Diseasesv Wash hands frequentlyv Wear cap, gloves and gownsv Wear face masks (N95/Surgical)v Cook and store foods properly v Observe healthy lifestylesv Stay up-to-date on immunizations Strategies to Improve Public Health Strategies to Improve Public Health Better cooperation between the public and
29、private health sectors Maintain and improve vector control programs Increase monitoring and surveillance programs Promote education of the public for community health matters Increase research in public health and infectious diseasesMajor Public Health AgenciesMajor Public Health AgenciesInternation
30、alLocal (HKSAR)World Health Organization世界衛生組織Centres for Disease Control and Prevention, USA美國疾病控制及預防中心HospitalAuthority醫管局Department of Health衛生署Food and Environmental Hygiene Department食物及環境衛生署Centre for Health Protection衛生防護中心Surveillance & Epidemiology Branch監察及流行病學處部 “New viruses and drug-resi
31、stant bacteria are reversing human victories over infectious diseases” Time Sept. 12, 1994 Dengue Fever (登革熱)An acute viral disease caused by infection with dengue virus which is transmitted through mosquito bites Sept. 2002 : First local cases detected in Hong Kong The Human Immunodeficiency Virus
32、(HIV) 人體免疫缺陷病毒人體免疫缺陷病毒 HIV-1 major cause of AIDSHIV-2 less harmfulWhat is AIDS ? AIDS is a transmissible disease caused by infection with HIV which impairs or destroys the bodys immune system. Death may result from wasting syndromes, opportunistic infections and cancers Transmitted by (1) sexual con
33、tact (2) blood-borne and (3) maternal route Global Summary of HIV/AIDS EpidemicGlobal Summary of HIV/AIDS Epidemic No. of cases People living with HIV/AIDS 39.4 millionNew HIV infection in 2004 4.9 millionDeaths due to HIV/AIDS in 2004 3.1 millionCumulative AIDS deaths since 1980s 34 millionFrom the
34、 Joint United Nations Programme on HIV/AIDS (UNAIDS) - Figures in December 2004 Structure of HIV gp41gp120 Reverse transcriptasess RNAProteaseWhat Causes The Immune System to Collapse in AIDS? Direct killing of HIV-infected CD4+ T cells or indirect lysis of uninfected CD4+ T cells Life-threatening i
35、mmune suppressionWhat is Avian Influenza (Bird Flu) (What is Avian Influenza (Bird Flu) (禽流感禽流感禽流感禽流感)?)? An infectious disease of birds caused by certain type A flu virus Infected birds shed virus in saliva, nasal secretions and feces Mainly infect birds but occasionally affect humans Can cause hig
36、h fever, chest infection, respiratory and multi-organ failure and death in humansThe Influenza Viruses (A, B, C) Types A and B viruses cause widespread outbreaks in humans Type C viruses cause only mild upper respiratory tract infection in humans Type A viruses can infect several animal species, inc
37、luding birds, pigs, horses, seals and whales Type B and C viruses do not affect domestic animalsInfluenza A Virus (甲型流感病毒) 病毒基因 Segmented RNA 膜蛋白 Matrix protein(N1 N9)神經氨酸酵素神經氨酸酵素Neuraminidase (H1 H15) 血凝素血凝素Hemagglutinin Human Infection with Flu and Avian Flu VirusesHuman Infection with Flu and Avi
38、an Flu Viruses Virus strain Year Location EffectsHuman FluH1N1 1918 Spain? 40 - 50 million deathsH2N2 1957 Asia 1 million deathsH3N2 1968 Hong Kong Virus still circulating H1N1 1977 Russian Virus still circulatingAvian FluH5N1 1997 Hong Kong Highly pathogenic for birds & humansH9N2 1999 Hong Kong Mi
39、ld infection in humans Not highly pathogenic in birdsH7N7 2003 Netherlands Highly pathogenic for birdEmergence of “new” influenza viruses Emergence of “new” influenza viruses by genetic recombination?by genetic recombination? Human flu virus(XX)Avian flu virus(YY) XYPig (Blender)Human New flu virus
40、(XY)Severe Acute Respiratory Syndrome (SARS) 嚴重急性呼吸道症候群嚴重急性呼吸道症候群Worldwide Cases 8,098 probable cases& 774 deaths(By Dec. 2004 Source: CDC) What is SARS? A highly contagious and sometimes fatal respiratory infection First appeared in China in Nov. 2002, then spread to 30 countries Causative agent (S
41、ARS-CoV) was identified in late March 2003 Transmitted mainly by close person-to-person contact via respiratory droplets or via air-borne route (?) Incubation period ranged from 2 to 11 days Symptoms include high fever (38.0C 24 h), chills, body aches, dry cough, breathing difficulties; Diarrhea is
42、seen in 10 - 20% patients; Most patients develop pneumonia 刺蛋白刺蛋白Spike Protein 膜蛋白膜蛋白Membrane protein病毒基因病毒基因 RNA SARS-CoV Virus (沙士冠狀病毒)Treatment and Prevention of SARS v No specific treatment for SARSv Anti-viral drugs: (a) inhibit virus entry to target cells (b) block virus-induced cell fusion (c
43、) inhibit virus replicationv Immunosuppressants (e.g. corticosteroids) v Development of SARS vaccines Know More About Communicable Diseaseswww.info.gov.hk/dh/diseases/CD/CD_index.htmlwww.who.int/vaccines-diseases/ THE ENDThank you for your attention!1、字体安装与、字体安装与设设置置如果您对PPT模板中的字体风格不满意，可进行批量替换，一次性更改各页面字体。1.在“开始”选项卡中，点击“替换”按钮右侧箭头，选择“替换字体”。（如下图）2.在图“替换”下拉列表中选择要更改字体。（如下图）3.在“替换为”下拉列表中选择替换字体。4.点击“替换”按钮，完成。552、替、替换换模板中的模板中的图图片片模板中的图片展示页面，您可以根据需要替换这些图片，下面介绍两种替换方法。方法一：更改图片方法一：更改图片1.选中模版中的图片（有些图片与其他对象进行了组合，选择时一定要选中图片本身，而不是组合）。2.单击鼠标右键，选择“更改图片”，选择要替换的图片。（如下图）注意：注意：为防止替换图片发生变形，请使用与原图长宽比例相同的图片。55赠送精美图标
