EMERGING AND RE-EMERGING INFECTIOUS DISEASES. Learning Objective To able to define and give example...

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Transcript of EMERGING AND RE-EMERGING INFECTIOUS DISEASES. Learning Objective To able to define and give example...

DISEASE EMERGENCE AND RE-EMERGENCE

EMERGING AND RE-EMERGING INFECTIOUS DISEASESEmerging Infectious DiseasesDetels - 10 Oct 20111Learning ObjectiveTo able to define and give example of emerging and reemerging infectious disease (ERID).Able to discuss what is the factors contributed to ERIDList current pathogens classified as ERIDExplain what steps is used to lower the threat of ERIDHave understanding of Influenza and dengue as ERID casesIMPACT OF INFECTIOUS DISEASES14th century- Europe - plague kills 20-45% of the worlds population1831 - Cairo - 13% of population succumbs to cholera1854-56- Crimean war deaths due to dysentery were 10 times higher than deaths due to casualties1899-1902- Boer War deaths due to dysentery were 5 times higher than deaths due to casualtiesEmerging Infectious DiseasesDetels - 10 Oct 20113Direct economic impact of selected infectious disease outbreaks, 1990-2003Heymann DL. Emerging and re-emerging infections. In Oxford Textbook of Public Health, 5th ed, 2009, p1267.

Emerging Infectious DiseasesDetels - 10 Oct 20114

Forum on Microbial Threats. The impact of globalization on infectious disease emergence and control. Institute of Medicine of the National Academies, Washington DC, 2006, p. 5.Emerging Infectious DiseasesDetels - 10 Oct 20115DefinitionEmerging infectious disease (EID): Infectious disease whose incidence has increased in the past 20 years and threatens to increase in the near futureIncludeNewly recognized agents (SARS, acinetobacter)Mutation of zoonotic agents that cause human disease (e.g., H5N1, H1N1)Resurgence of endemic diseases (malaria, tuberculosis)

Re-emerging infectious disease:re-emergence of microbes that had been successfully controlled.E.g: DengueEnterovirus 71Clostridium difficileMumps virusStreptococcus, Group AStaphylococcus aureusFACTORS CONTRIBUTING TO EMERGENCE OR RE-EMERGENCE OF INFECTIOUS DISEASES (1)Human demographic change Human move to new area 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)Emerging Infectious DiseasesDetels - 10 Oct 20118Multiple 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.FACTORS CONTRIBUTING TO EMERGENCE OR RE-EMERGENCE OF INFECTIOUS DISEASES (2)Economic development and changes in the use of landincluding deforestation, reforestation, and urbanizationGlobal warmingchanges in geographical distribution of agents and vectorsChanging human behavioursincreased use of child-care facilities, sexual and drug use behaviours, and patterns of outdoor recreationSocial inequalityEmerging Infectious DiseasesDetels - 10 Oct 20119FACTORS CONTRIBUTING TO EMERGENCE OR 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 distancesEmerging Infectious DiseasesDetels - 10 Oct 201110FACTORS CONTRIBUTING TO EMERGENCE OR 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.Emerging Infectious DiseasesDetels - 10 Oct 201111FACTORS CONTRIBUTING TO EMERGENCE OR RE-EMERGENCE OF INFECTIOUS DISEASES (5)Resistance of the vectors of vector-borne infectious diseases to pesticides.

Immunosuppression of persons due to medical treatments result in infectious diseases caused by agents not usually pathogenic in healthy hosts.(e.g. leukemia patients)Emerging Infectious DiseasesDetels - 10 Oct 201112FACTORS CONTRIBUTING TO EMERGENCE OR 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 strategiesLack of political will corruption, other priorities

Emerging Infectious DiseasesDetels - 10 Oct 201113Antimicrobial 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 a