Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Human cytomegalovirus wikipedia , lookup
Hepatitis C wikipedia , lookup
Orthohantavirus wikipedia , lookup
Canine distemper wikipedia , lookup
Henipavirus wikipedia , lookup
Canine parvovirus wikipedia , lookup
Marburg virus disease wikipedia , lookup
Hepatitis B wikipedia , lookup
Swine influenza wikipedia , lookup
INFECTIOUS DISEASES IN HONG KONG and ITS PREVENTION Dr Margaret IP Dept of Microbiology 17th Jan 05 Definition of Infectious Disease: “An illness due to a specific infectious agent or its toxic products that arises through transmission of that agent or its products from an infected person, animal, or reservoir to a susceptible host, either directly or indirectly through an intermediate plant or animal host, vector, or the inamimate environment” John M. Last Dictionary The “chain of infection” The infectious agent The means of transmission The host Route of Transmission Vertical – Mother to foetus Horizontal – direct Contact Inhalational Ingestion – indirect via bugs eg mosquitoes, fleas Infectious Diseases : A Dynamic Interaction HOST ORGANISM ENVIRONMENT Causes of Infectious Disease Bacteria – Staphylococcus aureus Viruses – Influenza virus, Hepatitis virus Fungi - Candida spp., Aspergillus spp. Mycobacteria - M.tuberculosis, Protozoa – Entamoeba histolytica Worms – Pork and beef tapeworms Robert Koch, 1843-1910 • Doctor and Founder of Medical Microbiology • Experiments on ‘Germ theory of disease’ • Koch’s postulates • Bacterial culture plate technique • Microscopy of Bacteria •Discovery of tubercle bacillus • Isolation of bacteria causing cholera 大腸桿菌 幽門螺旋菌 乙型肝炎病毒 Source: Department of Microbiology, The Chinese University of Hong Kong Source: Department of Microbiology, The Chinese University of Hong Kong 曲黴菌 阿米巴變形 蟲 蛔虫 (成年) Source: Department of Microbiology, The Chinese University of Hong Kong 控制傳染病的健康機構 國際性組織 香港本地組織 疾病預防及 控制部 世界衛生組織 (WHO) 美國疾病控制中心 疾病預防及 控制部 (CDC) (CHP) 醫院管理局 (HA) 食物環保 衛生署 (FEHD) Infectious Diseases of New Concern Additions to the Notifiable Diseases List, Hong Kong: Severe Acute Respiratory Syndrome, 27 Mar 03 Avian Influenza A, H5, 30 Jan 04 Japanese Encephalitis, 16 Jul 04 Avian Influenza A (H7) and (H9), 30 Dec 04 Electron Microscopy of Influenza virus 1918 2001 Avian Influenza http://www.cdc.gov/flu/ Influenza Pandemics 1889 H2N2 1900 H3N8 1918 H1N1 1957 H2N2 1968 H3N2 1977 H1N1 Current H3N2 & H1N1 H1N1 H3N2 H1N1 H2N2 H3N? Droplet Transmission • Droplets generated during coughing, sneezing, and talking, • Deposited on host’s conjunctivae, nasal mucosa, or mouth Influenza A, Prince of Wales Hospital 1996-2001 ( Epidemics due to antigenic drift ) 200 H3N2 Sydney 180 160 120 H3N2 Wuhan 100 80 60 40 20 Oct Jul Apr 2001-Jan Oct Jul Apr 2000-Jan Oct Jul Apr 1999-Jan Oct Jul Apr 1998-Jan Oct Jul Apr 1997-Jan Oct Jul Apr 0 1996-Jan No. of Cases 140 Typing and Sub-typing of Influenza Virus MAN PIG Haemagglutinin (H) RNA (8 segments) Nucleoprotein (A,B & C types) Envelope Neuraminidase (N) H types H1 √ H2 √ H3 √ H4 H5 √ H6 H7 √ H8 H9 √ H10-H15 N types N1 √ N2 √ N3 N4 N6 N7 N8 HORSE BIRD √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ N5 √ √ √ √ N9 √ Reassortment of Influenza Virus Genes Avian Progeny reassortants 256 different combinations Cell cytoplasm H5N1 H5N2 Infection of both viruses into the same cell H5N1 Genomic exchange H3N1 H3N2 Human H3N2 Reassortment / Cross-species Transmission Outbreak of Avian H5N1 & H9N2 Influenza in Hong Kong 06/04/97 3 chicken farms with H5N1 infection, 4500 chicken died 21/05/97 3 years old boy infected with influenza A, died 18/08/97 confirmed to be H5N1 - Dept. of Health, 2 universities, CDC formed expert committee 24/11/97 29/11/97 06/12/97 09/12/97 2 years old boy H5N1 infected, lived 54 years old man died of H5N1 pneumonia 13 years old girl infected with H5N1, multi-organ failure, died 20 years old Filipino woman H5N1 infected, critical 27/12/97 confirmed 18 infected with H5N1, 3 suspected 6 patients died 29/12/97 killing of all 1.4 million chickens in Hong Kong UNTIL NOW no new cases of H5N1 Aug, 97 to Jan 98 Surveillance of avian flu in poultry showed 20% H5N1 5% H9N2 28/02/99 4 years old girl with H9N2 04/03/99 1 year old girl with H9N2 H5N1 Avian Influenza Cases YEAR LOCATION CASES 1997 Hong Kong 18 DEATHS (%) 6 (33%) 2003 China 2 1 (50%) 2003 - 4 Vietnam 27 20 (74%) 2003 - 4 Thailand 17 12 (71%) 74 39 (53%) TOTAL (Accessed www.medscape.com/viewarticle/493090, 11Nov04) Control Measures for Influenza Inactivated Influenza Vaccine Made by inactivating purified vaccine strain viruses grown in eggs New vaccine strains are made as reassortants with high growth virus carrying the necessary H & N Ag Constituent viruses in vaccine determined by circulating strains as suggested by WHO (Feb for north, Sep for south) Global prevalence data and new strains originate from WHO influenza surveillance network Influenza Vaccination 2004-5 Northern Hemisphere (WHO Recommendation on Vaccine Composition) An A/Fujian/411/2002 (H3N2)-like virus An A/New Caledonia/20/99(H1N1)-like virus A B/Shanghai/361/2002-like virus (or B/Jiangsu/10/2003) Control Measures for Influenza Vaccine Application WHO Recommendations: • Residents of institutions for elderly & disabled • Any age with chronic illness • Age > 65yr • HCWs contact with high-risk persons • Household contacts of high-risk persons Influenza Vaccination Efficacy and Side Effects Efficacy varies from 70-90% protection in young adults to 60-70% in the elderly vaccine reduces 70% hospitalization & 85% of death in the elderly in nursing homes, vaccine can reduce hospitalization by 50%, pneumonia 60% & death by 75-80% very little side effect, <1/3 with soreness, 5-10% experience mild side effects e.g. headache or low grade fever Control Measures for Avian Influenza Human disease surveillance Control at source…poultry Hygiene improvement in farms and markets Education and publicity Import Control Contingency & pandemic planning Development of diagnostic tests & vaccine Segregation policy for poultry processing Prevention of Infectious Diseases Breaking the chain of infection • Isolation & Quarantine • Remove source of infection • • Modifying host eg. vaccination Modifying environment • Eg. Improve sanitation, eradication of vectors eg mosquitoes Hospital Isolation •Handwashing / alcohol handrub •Cap •Eye protection •Masks (N95/surgical) •Gloves •Gowns •Uniforms Prevention of Infectious Diseases Breaking the chain of infection • Isolation & Quarantine • Remove source of infection • • Modifying host eg. vaccination Modifying environment • Eg. Improve sanitation, eradication of vectors eg mosquitoes Control Measures Control of Source - chicken culling Continuous H5N1 virus isolation from wholesale market and chicken farms No effective antiviral treatment & vaccine Influenza season coming in Feb - March 1.5 millions birds killed from 29 - 31 Dec 97 Control Measures Market and Farm Hygiene Issue guidelines to all operators of food premises, fresh provision shops and market stalls for handling poultry Clean farms and wholesale & retail outlets System to ensure H5N1-free chicken: – – – – – quarantine certification blood tests at border labeling hold-and-sale Influenza A H5N1 in Hong Kong Lessons Learned International collaboration is essential Institution of effective measures especially in livestock control Continuous surveillance of influenza activity in both human and animals Environmental Control and Education http://www.fehd.gov.hk/events/mos/anti_mos_2004.html Signs and Symptoms in 57 Hospitalized Cases of DHF, Puerto Rico, 1990 - 1991 SIGNS AND SYMPTOMS FREQUENCY* % Fever Rash Hepatomegaly Effusions Frank shock Coma Any hemorrhage** 57 27 6 3 3 2 57 100 % 47.4% 10.5% 5.3% 5.3% 3.5% 100 % * Minimum estimate, search was not uniform for all patients ** Only 2 (3.5%) cases had severe hemorrhagic manifestations Warning Signs for Dengue Shock Four Criteria for DHF: • Fever • Hemorrhagic manifestations • Excessive capillary permeability • 100,000/mm3 platelets Initial Warning Signals: • Disappearance of fever • Drop in platelets • Increase in hematocrit Alarm Signals: • Severe abdominal pain • Prolonged vomiting • Abrupt change from fever to hypothermia • Change in level of consciousness (irritability or somnolence) When Patients Develop DSS: • 3 to 6 days after onset of symptoms Mean Annual Number of DHF Cases Reported Cases (Thousands) Thailand, Indonesia and Vietnam, by Decade 200 180 160 140 120 100 80 60 40 20 0 1950s 1960s * Provisional data through 1998 1970s 1980s 1990s* Reasons for Dengue Expansion in the World Extensive vector infestation, with declining vector control Unreliable water supply systems Increasing non-biodegradable containers and poor solid waste disposal Increased air travel Increasing population density in urban areas The Challenge Achieve active community involvement Solicit input from the earliest program planning stages Encourage community ownership Programs that emphasize telling communities what to do, without involving them or taking their views into account, are not effective True community participation is key Prevention of Infectious Diseases Breaking the chain of infection • Isolation & Quarantine • Remove source of infection • • Modifying host eg. vaccination Modifying environment • Eg. Improve sanitation, eradication of vectors eg mosquitoes http://www.sc.edu/library/spcoll/nathist/jenner.html Hong Kong Immunization Programme Age Newborn 1 month 2-4 months Immunization recommended BCG, Polio 1, Hepatitis B vaccine Hepatitis B vaccine DPT (Diphtheria, pertussis, tetanus) Polio trivalent 3-5 months DPT 4-6 months DPT, Polio trivalent 6 months Hepatitis B vaccine 1 year MMR (Measles, mumps, rubella) 1 ½ yr DPT, Polio trivalent Primary 1 DT, Polio trivalent, MMR Primary 6 DT, Polio trivalent Thank you for Listening!