The Changing Patterns of Infectious Diseases in South Asia: A Personal Journey Richard A. Cash, MD, MPH Harvard School of Public Health 9 September 2013

Outline—IDs That Are…… Eradicated, eliminated, or controlled Deceasing in incidence and severity Continuing high incidence but decreasing mortality Linked to long-term consequences New or reemerging

Agent Host Environment Age Sex Genotype Behaviour Nutritional status Health status Infectivity Pathogenicity Virulence Immunogenicity Antigenic stability Survival Weather Housing Geography Occupational setting Air quality Food SE status Politics Factors Influencing Disease Transmission

ID’s Eradicated, Eliminated, or Controlled and Primary Intervention Smallpox (vaccine) Guinea worm (environment/behavior) Polio (vaccine) Neonatal tetanus (vaccine) Diphtheria (vaccine and treatment) Leprosy (treatment)

ID’s Decreasing in Incidence with Significant Reduction in M & M from Disease or Associated Conditions Measles (vaccine-esp with 2 nd dose) Rheumatic fever (treatment and development?) Hepatitis B (vaccine) Helicobacter pylori and Peptic Ulcers(treatment, H2 blockers)

ID’s with a Higher Incidence but Reductions in Mortality and Morbidity Diarrhea (treatment) Lower respiratory infection (treatment, vaccines--measles, DP) Tuberculosis (?) (treatment) Malaria (bed nets and treatment)

ID’s—Long-term Consequences Hepatitis B-cancer and chronic hepatitis (vaccine, treatment?) Human papilloma virus (HPV)-cervical cancer (screening and vaccine) Hepatitis C-cancer and chronic hepatitis (safe injections) JE—mental health problems/retardation-(vaccine and environment)

ID’s—New and Reemerging HIV/AIDS SARS H5N1 “Avian” Flu & H1N1 “Swine” Flu Nipah Dengue Hepatitis C MDR/XDR TB, malaria and other a drug resistant organisms

Nipah—Case Definition Confirmed case –Fever –Headache or altered level of consciousness –Positive antibody test (IgM or IgG) Probable cases –Consistent symptoms –Epidemiologically linked

Nipah—Risk Factors in Malaysia The outbreak was concentrated among pig farmers—(92% of cases reported contact with pigs) Compared to controls, persons with Nipah encephalitis were –5.6X more contact with pigs. –3.7X more contact with sick pigs

Nipah—Outbreak Control in Malaysia Outbreak stopped following the culling of over 2 million pigs –Fruit trees were no longer permitted above pig pens –Pork industry decimated No cases of Nipah recognized in people or animals since these measures were taken

How Often do Bats Visit Date Palm Trees? Identified tree 500 meters from P. giganteus roost Mounted silent infrared wildlife camera 49 bats visited the tree –26 drank sap from the shaved part of the tree Photo by Salah Uddin Khan

Zoonoses are Expensive BSE—UK $9 Billion Plague—India $1.7 Billion Nipah—Malaysia $540 Million SARS—China >$50 Billion Avian flu (H5N1)—Global $Billions

Factors Enhancing ID Spread Increased population density Inadequate infrastructure especially for water/sanitation Movement of people through travel or social disruption Centralized food production Antibiotic and other drug overuse, under treatment and counterfeit drugs Ineffective government control

Factors to Reduce the Incidence and Improve the Control of IDs Increase and maintain high levels of immunization and introduce new vaccines when cost-effective Reduce environmental risks, especially water/sanitation and air pollution Improve local and national surveillance and laboratory support Train and employ more epidemiologists and public health experts

Reducing Incidence and Improving Control of ID (II) Vector control in urban and rural areas Improve and enforce guidelines for antibiotic use Develop an approach to control that is consistent with local realities Seek greater global and local equity in the distribution of vaccines and drug

Factors that Favor the Ability to Limit the Impact of NRE IDs Increased knowledge of epidemiology, microbiology, treatment, and behavior and access to information Vaccines and drugs Better nutrition Democratization of pathogens Surveillance

Lessons from Quotes and History “ Chance favors the prepared mind.” Louis Pasteur “You cannot step in the same river twice.” Heraclitus “Everything should be as simple as possible but not one bit simpler” Albert Einstein