15 October 2003 Emerging Infectious Diseases 1 Public Health 150 Contemporary Issues in Public Health Emerging Infectious Diseases Robert Kim-Farley, MD, MPH

15 October 2003Emerging Infectious Diseases2 Infectious disease is one 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)

15 October 2003Emerging Infectious Diseases3 CONTROL AND PREVENTION PROGRAMS Public heath planning for the control of infectious diseases must consider a number of factors to design optimal, rationally based control and prevention programs, including: Public heath planning for the control of infectious diseases must consider a number of factors to design optimal, rationally based control and prevention programs, including: the risk of disease; the risk of disease; the magnitude of disease burden (as measured by mortality, degree of disability, morbidity, and economic costs); the magnitude of disease burden (as measured by mortality, degree of disability, morbidity, and economic costs); the feasibility of control strategies; the feasibility of control strategies;

15 October 2003Emerging Infectious Diseases4 CONTROL AND PREVENTION PROGRAMS (continued) the cost of control measures; the cost of control measures; the effectiveness of such measures (on current levels of disease and impact on future cases or outbreaks); the effectiveness of such measures (on current levels of disease and impact on future cases or outbreaks); the adverse effects or complications of the control measures; and the adverse effects or complications of the control measures; and the availability of resources. the availability of resources.

15 October 2003Emerging Infectious Diseases5 Risk and Magnitude of Diseases The tools of disease surveillance for recognition and evaluation of the patterns of disease can provide the information on the risk and magnitude of disease burden to individuals, persons in institutions, subgroups of populations, and the community at large. The tools of disease surveillance for recognition and evaluation of the patterns of disease can provide the information on the risk and magnitude of disease burden to individuals, persons in institutions, subgroups of populations, and the community at large. Establishment and maintenance of the infrastructure for surveillance, including a system for the reporting of notifiable infectious diseases and unusual events, must be a high priority. Unusual events, like with SARS, may portend new and emerging diseases. Establishment and maintenance of the infrastructure for surveillance, including a system for the reporting of notifiable infectious diseases and unusual events, must be a high priority. Unusual events, like with SARS, may portend new and emerging diseases.

15 October 2003Emerging Infectious Diseases6 Feasibility of Control Feasibility of possible control and prevention strategies must be assessed through operational research, pilot projects or from field experience. Feasibility of possible control and prevention strategies must be assessed through operational research, pilot projects or from field experience. The fact that a particular measure can help control a disease does not mean it can be applied on a sufficient scale to have the desired impact. The fact that a particular measure can help control a disease does not mean it can be applied on a sufficient scale to have the desired impact.

15 October 2003Emerging Infectious Diseases7 Cost of Control The cost of control activities (in both manpower and materiel) can be assessed through costing studies. The cost of control activities (in both manpower and materiel) can be assessed through costing studies. A costly measure, even if it provides a high degree of control for an infectious disease, may not be affordable to the society or reasonable to apply in the light of other less expensive alternative strategies. A costly measure, even if it provides a high degree of control for an infectious disease, may not be affordable to the society or reasonable to apply in the light of other less expensive alternative strategies.

15 October 2003Emerging Infectious Diseases8 Effectiveness of Control Measures Effectiveness of control measures may be assessed through epidemiologic studies to find out their impact on reduction in the incidence or prevalence of disease. Effectiveness of control measures may be assessed through epidemiologic studies to find out their impact on reduction in the incidence or prevalence of disease.

15 October 2003Emerging Infectious Diseases9 Availability of Resources The availability of resources for preventive and control programs forces public health planners to set priorities by taking into account all these factors and then designing programs that have maximum impact within available resources. The availability of resources for preventive and control programs forces public health planners to set priorities by taking into account all these factors and then designing programs that have maximum impact within available resources. Planners have a responsibility to mobilize additional necessary resources by raising public awareness and generating political will. Planners have a responsibility to mobilize additional necessary resources by raising public awareness and generating political will.

15 October 2003Emerging Infectious Diseases10 Availability of Resources (continued) Effective communication of disease burden and the results achievable through well- managed and effective control programs can be a powerful tool for advocacy. Effective communication of disease burden and the results achievable through well- managed and effective control programs can be a powerful tool for advocacy. Ideally, communities should actively participate in the planning, execution, and evaluation of public health programs. Ideally, communities should actively participate in the planning, execution, and evaluation of public health programs.

15 October 2003Emerging Infectious Diseases11 International Migration The situation of international migration of many persons in the world today presents an additional complexity to the design of programs for the control of infectious diseases, especially emerging infectious diseases. The situation of international migration of many persons in the world today presents an additional complexity to the design of programs for the control of infectious diseases, especially emerging infectious diseases. Pertinent issues include: Pertinent issues include: refugee camps, refugee camps, legal status of migrants in recipient countries, and legal status of migrants in recipient countries, and temporary return migration. temporary return migration.

15 October 2003Emerging Infectious Diseases12 International Commerce and Transportation International commerce and transportation are specific areas of concern for public health infectious disease control programs and emerging diseases, especially as the speed of travel has increased. International commerce and transportation are specific areas of concern for public health infectious disease control programs and emerging diseases, especially as the speed of travel has increased.

15 October 2003Emerging Infectious Diseases13 International Commerce and Transportation (continued) The tools of control include such measures as: The tools of control include such measures as: spraying insecticides effective against mosquito vectors of malaria in aircraft before departure, in transit, or on arrival; and spraying insecticides effective against mosquito vectors of malaria in aircraft before departure, in transit, or on arrival; and rat-proofing or periodic fumigation to control rats on ships, docks, and warehouses to prevent plague. rat-proofing or periodic fumigation to control rats on ships, docks, and warehouses to prevent plague.

15 October 2003Emerging Infectious Diseases14 International Commerce and Transportation (continued) Specific international control measures relating to aircraft, ships, and land transportation for infectious diseases have been specified in the WHO International health regulations. Specific international control measures relating to aircraft, ships, and land transportation for infectious diseases have been specified in the WHO International health regulations.

15 October 2003Emerging Infectious Diseases15 EMERGING INFECTIOUS DISEASES EMERGING INFECTIOUS DISEASES Microbes and vectors 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).

15 October 2003Emerging Infectious Diseases16 Factors contributing to emergence or re-emergence of infectious diseases 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. 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. Breakdowns of sanitary and other public health measures in overcrowded cities and in situations of civil unrest and war.

15 October 2003Emerging Infectious Diseases17 Factors contributing to emergence or re-emergence of infectious diseases (continued) Economic development and changes in the use of land, including deforestation, reforestation, and urbanization. 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. Other human behaviors, such as increased use of child-care facilities, sexual and drug use behaviors, and patterns of outdoor recreation.

15 October 2003Emerging Infectious Diseases18 Factors contributing to emergence or re-emergence of infectious diseases (continued) International travel and commerce that quickly transport people and goods vast distances. 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. Changes in food processing and handling, including foods prepared from many different individual animals and transported great distances.

15 October 2003Emerging Infectious Diseases19 Factors contributing to emergence or re-emergence of infectious diseases (continued) Evolution of pathogenic infectious agents by which they may infect new hosts, produce toxins, or adapt by responding to changes in the host immunity. 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. Development of resistance of infectious agents such as Mycobacterium tuberculosis and Neisseria gonorrhoeae to chemoprophylactic or chemotherapeutic medicines.

15 October 2003Emerging Infectious Diseases20 Factors contributing to emergence or re-emergence of infectious diseases (continued) Resistance of the vectors of vector- borne infectious diseases to pesticides. 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. Immunosuppression of persons due to medical treatments or new diseases that result in infectious diseases caused by agents not usually pathogenic in healthy hosts.

15 October 2003Emerging Infectious Diseases21 Factors contributing to emergence or re-emergence of infectious diseases (continued) Deterioration in surveillance systems for infectious diseases, including laboratory support, to detect new or emerging disease problems at an early stage. Deterioration in surveillance systems for infectious diseases, including laboratory support, to detect new or emerging disease problems at an early stage. Antimicrobial drug resistance as a major factor in the emergence and re-emergence of infectious diseases deserves special attention. Antimicrobial drug resistance as a major factor in the emergence and re-emergence of infectious diseases deserves special attention.

15 October 2003Emerging Infectious Diseases22 Factors contributing to emergence or re-emergence of infectious diseases (continued) Biowarfare/bioterrorism: An unfortunate potential source of a new or emerging disease threat. Biowarfare/bioterrorism: An unfortunate potential source of a new or emerging disease threat.

15 October 2003Emerging Infectious Diseases23 Examples of emerging infectious disease threats 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. 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.

15 October 2003Emerging Infectious Diseases24 Examples of emerging infectious disease threats (continued) 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. 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.

15 October 2003Emerging Infectious Diseases25 Examples of emerging infectious disease threats (continued) 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. 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.

15 October 2003Emerging Infectious Diseases26 Examples of emerging infectious disease threats (continued) 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. 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.

15 October 2003Emerging Infectious Diseases27 Examples of emerging infectious disease threats (continued) 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. 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.

15 October 2003Emerging Infectious Diseases28 Examples of emerging infectious disease threats (continued) 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. 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.

15 October 2003Emerging Infectious Diseases29 Examples of emerging infectious disease threats (continued) 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. 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.

15 October 2003Emerging Infectious Diseases30 Examples of emerging infectious disease threats (continued) 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 previous standard diagnostic tests are ineffective. 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 previous standard diagnostic tests are ineffective.

15 October 2003Emerging Infectious Diseases31 Examples of emerging infectious disease threats (continued) SARS is the most recent example of how devastating a newly emerging disease can be in terms of economic impact and how, in the absence of vaccines, chemoprophylaxis, or chemotherapy “old” measures of quarantine and isolation may be the only “tools” we in public health have to combat disease. SARS is the most recent example of how devastating a newly emerging disease can be in terms of economic impact and how, in the absence of vaccines, chemoprophylaxis, or chemotherapy “old” measures of quarantine and isolation may be the only “tools” we in public health have to combat disease.

15 October 2003Emerging Infectious Diseases32 Final thoughts It is only through worldwide concerted action will the effort to control infectious disease be effective (analogy). It is only through worldwide concerted action will the effort to control infectious disease be effective (analogy).

15 October 2003Emerging Infectious Diseases33 Final thoughts (continued) We have now entered an era where, as Nobel Laureate Dr. Joshua Lederberg has stated, “The microbe that felled one child in a distant continent yesterday can reach yours today and seed a global pandemic tomorrow” We have now entered an era where, as Nobel Laureate Dr. Joshua Lederberg has stated, “The microbe that felled one child in a distant continent yesterday can reach yours today and seed a global pandemic tomorrow”