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Infectious disease
The document discusses the historical and ongoing impact of infectious diseases, with a focus on the West Nile virus outbreak in the U.S. and various factors contributing to the emergence and re-emergence of infectious diseases. It highlights the importance of surveillance, prevention strategies, and the role of public health professionals in managing infectious disease threats. Key challenges include resistance to treatment, climatic changes, and the socio-economic factors affecting disease spread and control.
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Infectious disease
- 1. INFECTIOUS DISEASESINFECTIOUS DISEASES ByMahboob Ali KhanBy Mahboob Ali Khan MHA,CPHQMHA,CPHQ A present day disease scenario.A present day disease scenario.
- 2. IMPACT OF INFECTIOUSIMPACTOF INFECTIOUS DISEASESDISEASES • 14th century - Europe - plague kills 20-45% of the world’s population • 1831 - Cairo - 13% of population succumbs to cholera • 1854-56 - Crimean war – deaths due to dysentery were 10 times higher than deaths due to casualties • 1899-1902 - Boer War – deaths due to dysentery were 5 times higher than deaths due to casualties
- 3. Infectious disease isone of the few genuine adventures left in the world. The dragons are all dead and the lance grows rusty in the chimney corner . . . About the only sporting proposition that remains unimpaired by the relentless domestication of a once free-living human species is the war against those ferocious little fellow creatures, which lurk in the dark corners and stalk us in the bodies of rats, mice and all kinds of domestic animals; which fly and crawl with the insects, and waylay us in our food and drink and even in our love. - (Hans Zinsser,1934 quoted in Murphy 1994)
- 4. • “One canthink of the middle of the 20th century as the end of one of the most important social revolutions in history, the virtual elimination of the infectious diseases as a significant factor in social life” Sir Macfarland Burnet
- 6. LA Times, 14August 2012 Ongoing West Nile Outbreak Being Called The Largest Ever In The US As of August 22, CDC is reporting 1,118 cases of West Nile virus infections in 38 states with 41 deaths. It is the largest West Nile virus outbreak to occur in the US since first reported in 1999. Lyle Petersen, CDC’s vector-borne disease specialist, told the media that the peak usually occurs in mid-August and that he expects many more cases as it takes a couple of weeks for people to develop illness. The cause for the record number of cases this year is unknown but Petersen speculated that unusually warm weather conditions could have made it easier for transmission to humans to occur. Texas has been at the epicenter of the epidemic with approximately half of the cases (586) and half of the deaths (21). To protect themselves, Americans are being urged to “fight the bite” by using mosquito repellent with DEET, dressing in long pants and sleeves, being extra careful at dusk and dawn, and draining any standing water around their premises. Epidemiology News Briefs - August 23, 2012
- 7. LA Times, 13August 2012
- 8. LA Times, Sept2012
- 9. Factors in Promotionof Infectious Disease Agent Host Environment Agent – virus, bacteria, parasite, prion, etc. Host – genetic profile, immune capacity, poverty, nutritional status Environment – biologic and chemical pollution, climate change, deforestation
- 11. THE CHAIN OFINFECTION • Etiologic agent • Reservoir – Humans – Animals – Environment (e.g. soil) • Portal of exit • Mode of transmission – Direct – Indirect – Intermediate host • Portal of entry • Susceptible host
- 12. PORTALS OF ENTRY/EXIT*OF INFECTIOUS AGENTS • Respiratory – influenza, common cold agents, measels • Genitourinary – sexually transmitted agents • Alimentary track (gut) – Campylobacter, cholera, salmonella • Skin – streptococci, – Percutaneous (vector borne diseases e.g. arboviruses) • Eye – C. trachomatis • Transplacental – cytomegalovirus, HIV * Route of entry and exit not necessarily the same for a single agent e.g. HIV, schistosomaisis
- 13. Direct economic impactof selected infectious disease outbreaks, 1990-2003 Heymann DL. Emerging and re-emerging infections. In Oxford Textbook of Public Health, 5th ed, 2009, p1267.
- 14. MICROBIAL THREATS (1) •Newly recognized agents (SARS, acinetobacter) • Mutation of zoonotic agents that cause human disease (e.g., H5N1, H1N1) • Resurgence of endemic diseases (malaria, tuberculosis) • Persisting diseases (measles, polio)
- 15. MICROBIAL THREATS (2) •Development of drug-resistant agents (tuberculosis, gonorrhea) • Recognition of etiologic role in chronic diseases (Chlamydia causing respiratory and heart disease; HIV and heart disease) • Use of infectious agents for terrorism and warfare (anthrax)
- 16. Forum on MicrobialThreats. The impact of globalization on infectious disease emergence and control. Institute of Medicine of the National Academies, Washington DC, 2006, p. 5.
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- 22. Preventing Emerging InfectiousDiseases: A Strategy for the 21st century. The CDC Plan, p. 26, 1998.
- 23. Enserink M. Olddrugs losing effectiveness against flu; could statins fill gap? Science 309:177, 2005.
- 24. NEWLY IDENTIFIED INFECTIOUS DISEASESAND PATHOGENS (1) Year Disease or Pathogen 1993 Hantavirus pulmonary syndrome (Sin Nombre virus) 1992 Vibrio cholerae O139 1991 Guanarito virus 1989 Hepatitis C 1988 Hepatitis E; human herpesvirus 6 1983 HIV 1982 Escherichia coli O157:H7; Lyme borreliosis; human T-lymphotropic virus type 2 1980 Human T-lymphotropic virus Source: Workshop presentation by David Heymann, World Health Organization, 1999
- 25. NEWLY IDENTIFIED INFECTIOUS DISEASESAND PATHOGENS (2) Year Disease or Pathogen 2012 MERS-CoV 2009 H1N1 2004 Avian influenza (human cases) 2003 SARS 1999 Nipah virus 1997 H5N1 (avian influenza A virus) 1996 New variant Creutzfelt-Jacob disease; Australian bat lyssavirus 1995 Human herpesvirus 8 (Kaposi’s sarcoma virus) 1994 Savia virus; Hendra virus Source: Workshop presentation by David Heymann, World Health Organization, 1999
- 26. DISEASE EMERGENCE AND RE-EMERGENCE:CAUSES • GENETIC/BIOLOGIC FACTORS – Host and agent mutations – Increased survival of susceptibles • HUMAN BEHAVIOR – POLITICAL – SOCIAL – ECONOMIC • PHYSICAL ENVIRONMENTAL FACTORS – crowding • ECOLOGIC FACTORS – Climatic changes – Deforestation – Etc.
- 27. FACTORS CONTRIBUTING TO EMERGENCEOR RE-EMERGENCE OF INFECTIOUS DISEASES (1) • Human demographic change by which persons begin to live in previously uninhabited remote areas of the world and are exposed to new environmental sources of infectious agents, insects and animals • Unsustainable urbanization causes breakdowns of sanitary and other public health measures in overcrowded cities (e.g., slums)
- 28. FACTORS CONTRIBUTING TO EMERGENCEOR RE-EMERGENCE OF INFECTIOUS DISEASES (2) • Economic development and changes in the use of land, including deforestation, reforestation, and urbanization • Global warming - climate changes cause changes in geographical distribution of agents and vectors • Changing human behaviours, such as increased use of child-care facilities, sexual and drug use behaviours, and patterns of outdoor recreation • Social inequality
- 29. FACTORS CONTRIBUTING TO EMERGENCEOR RE-EMERGENCE OF INFECTIOUS DISEASES (3) • International travel and commerce that quickly transport people and goods vast distances • Changes in food processing and handling, including foods prepared from many different individual animals and countries, and transported great distances
- 30. FACTORS CONTRIBUTING TO EMERGENCEOR RE-EMERGENCE OF INFECTIOUS DISEASES (4) • Evolution of pathogenic infectious agents by which they may infect new hosts, produce toxins, or adapt by responding to changes in the host immunity.(e.g. influenza, HIV) • Development of resistance by infectious agents such as Mycobacterium tuberculosis and Neisseria gonorrhoeae to chemoprophylactic or chemotherapeutic medicines.
- 31. FACTORS CONTRIBUTING TO EMERGENCEOR RE-EMERGENCE OF INFECTIOUS DISEASES (5) • Resistance of the vectors of vector-borne infectious diseases to pesticides. • Immunosuppression of persons due to medical treatments or new diseases that result in infectious diseases caused by agents not usually pathogenic in healthy hosts (e.g. leukemia patients)
- 32. FACTORS CONTRIBUTING TO EMERGENCEOR RE-EMERGENCE OF INFECTIOUS DISEASES (6) • Deterioration in surveillance systems for infectious diseases, including laboratory support, to detect new or emerging disease problems at an early stage (e.g. Indonesian resistance to “scientific colonialism”) • Illiteracy limits knowledge and implementation of prevention strategies • Lack of political will – corruption, other priorities
- 33. FACTORS CONTRIBUTING TO EMERGENCEOR RE-EMERGENCE OF INFECTIOUS DISEASES (7) • Biowarfare/bioterrorism: An unfortunate potential source of new or emerging disease threats (e.g. anthrax and letters) • War, civil unrest – creates refugees, food and housing shortages, increased density of living, etc. • Famine causing reduced immune capacity, etc. • Manufacturing strategies; e.g., pooling of plasma, etc.
- 34. STRATEGIES TO REDUCETHREATS (1) • DEVELOP POLITICAL WILL AND FUNDING • IMPROVE GLOBAL EARLY RESPONSE CAPACITY – WHO – National Disease Control Units (e.g. USCDC, CCDC) – Training programs
- 35. STRATEGIES TO REDUCETHREATS (2) • IMPROVE GLOBAL SURVEILLANCE – Improve diagnostic capacity (training, regulations) – Improve communication systems (web, e-mail etc.) and sharing of surveillance data – Rapid data analysis – Develop innovative surveillance and analysis strategies
- 36. STRATEGIES TO REDUCETHREATS (3) • IMPROVE GLOBAL SURVEILLANCE (continued) – Utilize geographical information systems – Utilize global positioning systems – Utilize the Global Atlas of Infectious Diseases (WHO) – Increase and improve laboratory capacity – Coordinate human and animal surveillance
- 38. STRATEGIES TO REDUCETHREATS (4) • USE OF VACCINES – Increase coverage and acceptability (e.g., oral) – New strategies for delivery (e.g., nasal spray administration) – Develop new vaccines – Decrease cost – Decrease dependency on “cold chain” • NEW DRUG DEVELOPMENT
- 39. STRATEGIES TO REDUCETHREATS (5) • DECREASE INAPPROPRIATE DRUG USE – Improve education of clinicians and public – Decrease antimicrobial use in agriculture and food production • IMPROVE VECTOR AND ZOONOTIC CONTROL – Develop new safe insecticides – Develop more non-chemical strategies e.g. organic strategies • BETTER AND MORE WIDESPREAD HEALTH EDUCATION (e.g., west Nile virus; bed nets, mosquito repellent)
- 40. STRATEGIES TO REDUCETHREATS (6) • DEVELOPMENT OF PREDICTIVE MODELS BASED ON: – Epidemiologic data – Climate change surveillance – Human behavior • ESTABLISH PRIORITIES – The risk of disease – The magnitude of disease burden • Morbidity/disability • Mortality • Economic cost – REDUCE POTENTIAL FOR RAPID SPREAD – DEVELOP MORE FEASIBLE CONTROL STRATEGIES
- 41. Ford TE etal. Using satellite images of environmental changes to predict infectious disease outbreaks. Emerging Infect Dis 15(9):1345, 2009.
- 42. STRATEGIES TO REDUCE THREATS(7) • Develop new strategies requiring low-cost technology • Social and political mobilization of communities • Greater support for research • Reduce poverty and inequality
- 43. BASIC ELEMENTS IN PREPAREDNESS •International Health Regulations • International -- WHO – Global Outbreak Alert and Response Network (GOARN) • 120 technical institutions participating • 2000-02 -- Responded to 34 events in 26 countries • Coordination of SARS and H5N1 threats – Global Public Health Information Network (GPHIN)
- 44. Daily Flow ofGPHIN Information scanning global news filtering & sorting process 800-1000 articles selected daily 1 2 3 review for relevancy Mon-Fri 7am-5pm EST (Hours are extended during a public health crisis) Ongoing 24/7
- 45. LA Times, 28Aug 2012
- 46. ESSENTIAL FACTORS FOR DISEASEERADICATION • Knowledge of its epidemiology and transmission patterns/mode • Availability of effective tools for diagnosis, treatment and prevention • Knowledge of local cultural and political characteristics • Community acceptance and mobilization • Political will and leadership • Adequate and sustained funding
- 47. ROLE OF THEPUBLIC HEALTH PROFESSIONAL • Establish surveillance for: – Unusual diseases – Drug resistant agents • Assure laboratory capacity to investigate new agents (e.g., high-throughput labs) • Develop plans for handling outbreaks of unknown agents • Inform physicians about responsible antimicrobial use
- 48. VIROLOGY OF INFLUENZA Subtypes: A- Causes outbreak B - Causes outbreaks C - Does not cause outbreaks
- 49. Immunogenic Components ofImmunogenicComponents of the Influenza Virusthe Influenza Virus • Surface glycoproteins, 15 hemagglutinin (H1-H15), nine neurominidases (N1-N9) • H1-H3 and N1N2 established in humans • Influenza characterized by combination of H and N glycoproteins 1917 pandemic - H1N1 2004 avian influenza - H5N1 2009 H1N1 • Antigenic mix determines severity of disease • Human response specific to hemagglutinin and neurominidase glycoproteins
- 50. Figure 1. Natural hostsof influenza viruses Nicholson et al. Influenza. Lancet 362:1734, 2003
- 51. Genetic Changes inInfluenza • Antigenic drift - results of errors in replication and lack of repair mechanism to correct errors • Antigenic shift - reassortment of genetic materials when concurrent infection of different strains occurs in the same host
- 52. Nicholson et al.Influenza. Lancet 362:1735, 2003 Figure 2. Origin of antigenic shift and pandemic influenza. The segmented nature of the influenza A genome, which has eight genes, facilitates reassortment; up to 256 gene combinations are possible during coinfection with human and non-human viruses. Antigenic shift can arise when genes encoding at least the haemagglutinin surface glycoprotein are introduced into people, by direct transmission of an avian virus from birds, as occurred with H5N1 virus, or after genetic reassortment in pigs, which support the growth of both avian and human viruses.
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- 57. CLINICAL OUTCOMES OF INFLUENZAINFECTION • AsymptomaticAsymptomatic • SymptomaticSymptomatic Respiratory syndrome - mild to severe Gastrointestinal symptoms Involvement of major organs - brain, heart, etc. Death
- 58. The figure showspeak influenza activity for the United States by month for the 1976-77 through 2008-09 influenza seasons. The month with the highest percentage of cases (nearly 50%) was February, followed by January with 20% and March and December, with approximately 15% of all cases. Prevention and control of seasonal influenza with vaccines. MMWR 58(RR-8):5, 2009
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- 62. Factors Influencing the Responseto Influenza • Age • Pre-existing immunity (some crossover) • Smoking • Concurrent other health conditions • Immunosuppression • Pregnancy
- 63. Kaplan K. Howthe new virus came to be. LA Times, 14 Sept, 2009; latimes.com/health
- 64. EPIDEMIOLOGY AND BIOLOGY OFH5N1 INFLUENZA
- 65. Characteristics of H5N1 AvianInfluenza 1.Highly infectious and pathogenic for domestic poultry 2.Wild fowl, ducks asymptomatic reservoir 3.Now endemic in poultry in Southeast Asia 4.Proportion of humans with subclinical infection unknown 5.Case fatality in humans is >50%
- 66. Spread of HSpreadof H55NN11 Avian InfluenzaAvian Influenza 12 14 16 18 20 22 24 26 28 30 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 2 December, 2003 January Feb 2005-6 2006-7 2004 SouthKorea Vietnam Japan Thailand Cambodia China& Laos Indonesia Resurgencein Thailand,Vietnam, Cambodiaand Indonesia Europe, Africa
- 67. A New GlobalConcern… Acknowledgment: Mike Perdue
- 68. Intervention StrategiesIntervention Strategies (H5N1)(H5N1) •Culling (killing of infected flocks) • Innovative surveillance strategies - Identification and analysis of human to human clusters - Characterization of strains * Necessity for vaccine development (Science 304:968-9, 5/2004) • Vaccination of bird handlers (vaccine being developed) • Vaccination of commercial bird flocks
- 69. Barriers to H5N1Control • Reservoir in wild birds and ducks • Economic impact of culling of poultry stocks • Popularity of “wet markets” promotes transmission within poultry and to other species (e.g., pigs) • Resistance to antivirals and vaccines • Mistrust of rich nations
- 70. Don’t get theflu vaccine!
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- 72. STRATEGIES TO PREVENTFLU (1) • COVER MOUTH AND NOSE WHEN SNEEZING • WASH HANDS FREQUENTLY WITH SOAP AND WATER OR ALCOHOL • AVOID TOUCHING EYES, NOSE AND MOUTH • AVOID CONTACT WITH SICK PEOPLE • AVOID CROWDED CONGESTED ENVIRONMENTS
- 73. STRATEGIES TO PREVENTFLU (2) • IF SICK STAY HOME, DON’T EXPOSE OTHERS • FOLLOW PUBLIC HEALTH ADVICE; e.g. school closures etc. • GET FLU SHOT(S) • TAKE ANTIVIRAL DRUGS IF PHYSICIAN RECOMMENDS
- 74. WHAT’S AHEAD? Microbes andvectors swim in the evolutionary stream, and they swim faster than we do. Bacteria reproduce every 30 minutes. For them, a millennium is compressed into a fortnight. They are fleet afoot, and the pace of our research must keep up with them, or they will overtake us. Microbes were here on earth 2 billion years before humans arrived, learning every trick for survival, and it is likely that they will be here 2 billion years after we depart (Krause 1998).
Editor's Notes
- #28 Multiple factors contribute to the emergence of new or re-emergence of previously known diseases (Lederberg et al. 1992; Centers for Disease Control and Prevention 1994; Murphy 1994), including the following: -Human demographic change by which persons begin to live in previously uninhabited remote areas of the world and are exposed to new environmental sources of infectious agents, insects and animals. -Breakdowns of sanitary and other public health measures in overcrowded cities and in situations of civil unrest and war. -Economic development and changes in the use of land, including deforestation, reforestation, and urbanization. -Other human behaviors, such as increased use of child-care facilities, sexual and drug use behaviors, and patterns of outdoor recreation. -International travel and commerce that quickly transport people and goods vast distances. -Changes in food processing and handling, including foods prepared from many different individual animals and transported great distances. -Evolution of pathogenic infectious agents by which they may infect new hosts, produce toxins, or adapt by responding to changes in the host immunity. -Development of resistance of infectious agents such as Mycobacterium tuberculosis and Neisseria gonorrhoeae to chemoprophylactic or chemotherapeutic medicines. Resistance of the vectors of vector-borne infectious diseases to pesticides. -Immunosuppression of persons due to medical treatments or new diseases that result in infectious diseases caused by agents not usually pathogenic in healthy hosts. -Deterioration in surveillance systems for infectious diseases, including laboratory support, to detect new or emerging disease problems at an early stage. Examples of emerging infectious disease threats include the following: -Toxic shock syndrome, due to the infectious toxin-producing strains of Staphylococcus aureus, illustrates how a new technology yielding a new product, super-absorbent tampons, can create the circumstances favoring the emergence of a new infectious disease threat. -Lyme disease, due to the infectious spirochete Borrelia burgdorferi, illustrates how changes in the ecology, including reforestation, increasing deer populations, and suburban migration of the population, can result in the emergence of a new microbial threat that has now become the most prevalent vector-borne disease in the United States. -Shigellosis, giardiasis, and hepatitis A are examples of emerging diseases that have become threats to staff and children in child-care centers as the use of such centers has increased due to changes in the work patterns of societies. -Opportunistic infections, such as pneumocystis pneumonia caused by Pneumocystis carinii, chronic cryptosporidiosis caused by Cryptosporidium species, and disseminated cytomegalovirus infections, illustrate emerging disease threats to the increasing number of persons who are immunosuppressed because of cancer chemotherapy, organ transplantation, or HIV infection. -Foodborne infections such as diarrhea caused by the enterohemorrhagic strain 0157:H7 of Escherichia coli and waterborne infections such as gastrointestinal disease due to Cryptosporidium species are examples of emerging disease threats that have arisen due to such factors as changes in diet, food processing, globalization of the food supply and contamination of municipal water supplies. Hantavirus pulmonary syndrome first detected in the USA in 1993 and caused by a previously unrecognized hantavirus illustrates how exposure to certain kinds of infected rodents can result in an emerging infectious disease. Nipah virus disease first detected in Malaysia in 1999 and caused by a previously unrecognised Hendra-like virus demonstrates how close contact with pigs can result in an emerging infectious disease. Emergence of the new toxigenic Vibrio cholerae O139 strain of cholera in Asia is an example of a new strain of an infectious agent for which there is no protection from prior infection with other strains or with current vaccines and for which standard diagnostic tests are ineffective.
- #33 Antimicrobial drug resistance as a major factor in the emergence and re-emergence of infectious diseases deserves special attention. Although significant reductions in infectious disease mortality have occurred since the introduction antimicrobials for general use in the 1940s, antimicrobial drug resistance has emerged because of their widespread use in humans. Drugs that once seemed invincible are losing their effectiveness for a wide range of community-acquired infections, including tuberculosis, gonorrhea, pneumococcal infections (a leading cause of otitis media, pneumonia, and meningitis), and for hospital-acquired enterococcal and staphylococcal infections. Resistance to antiviral (e.g. amantadine-resistant influenza virus and acyclovir-resistant herpes simplex), anti-fungal (e.g. azole-resistant Candida species), and anti-protozoal (e.g., metronidazole-resistant Trichomonas vaginalis) drugs is also emerging. Drug-resistant malaria has spread to nearly all areas of the world where malaria occurs. Concern has also arisen over strains of HIV resistant to antiviral drugs. Increased microbial resistance has resulted in prolonged hospitalizations and higher death rates from infections; has required much more expensive, and often more toxic, drugs or drug combinations (even for common infections); and has resulted in higher health care costs (Centers for Disease Control and Prevention 1994). Antimicrobial drug resistance has also emerged because of the use of antimicrobials in domesticated animals. For example, the use of fluoroquinolones in poultry has created a reservoir of quinolone-resistant Campylobacter jejuni that has now been isolated in humans. An aggressive public health response to these new, emerging and re-emerging infectious disease threats must be made to characterize them better and to mount an effective response for their control. For example, the 1999 outbreak of West Nile fever in New York City and surrounding areas demonstrates how a viral encephalitis, initially classified as St. Louis encephalitis and later confirmed to be due to West Nile-like virus, can reach far beyond its normal setting. The WHO (WHO 1995a) has outlined the following high priority areas: (a) strengthen global surveillance of infectious diseases; (b) establish national and international infrastructures to recognize, report and respond to new disease threats; (c) further develop applied research on diagnosis, epidemiology, and control of emerging infectious diseases; and (d) strengthen the international capacity for infectious disease prevention and control. Another unfortunate source of a new or emerging disease threat is the spectre of biological warfare or bioterrorism, especially in an age where terrorist acts are frequent events (Christopher et al, 1997). Several countries are developing rapid response capability to deal with such contingencies.
- #45 Now, I will give an overview of how GPHIN works on a daily basis. Information is gathered from a multitude of media sources, e.g.internet, news sources (Reuters) Approximately, 500-600 news articles are selected using Health Canada’s established search criteria. These selected articles are disseminated immediately to the GPHIN system where further filtering of duplications and irrelevants and the categorization of articles into GPHIN’s seven subject areas. This automated process only takes a couple of seconds. At this time, the filtered articles can be viewed by users. Both steps 1 and 2 is on-going on a 24/7 basis. Human review is still needed to ensure the relevancy of information and the quality of GPHIN’s content. GPHIN analysts therefore, review all filtered articles for subject relevancy resulting in approximately 400-500 articles posted on the GPHIN system daily.
- #68 On the heels of SARS was H5N1 and the fear of the next Influenza pandemic – we all know it is long overdue. I may not be H5N1 strain, it is not a question of I F, but of WHEN .