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Infectious Diseases : 

Infectious Diseases A Global View

Why learn about problems that mostly affect people elsewhere?: 

Why learn about problems that mostly affect people elsewhere? Addressing the most important problems of human health is part of a university education in medicine In a global context, it is Edmonton that is “exotic”, not malaria Canada is a nation of immigrants Some of you will work or study overseas There is much to learn, which may be applicable locally, from studying these diseases and disease patterns in other settings It can be exciting and rewarding

Objectives : 

Objectives A global perspective on the frequency and impact of communicable diseases Appreciation of the distribution of various representative communicable diseases An understanding of some of the determinants of disease distribution An introduction to the principles and practice of communicable disease control An introduction to the idea that International Health can be fascinating and rewarding NOT: To teach the pathophysiology or life cycle of various tropical and communicable diseases

Causes of Death 1998 (WHO): 

Causes of Death 1998 (WHO)

Disability Adjusted Life Years Lost, WHO 1998: 

Disability Adjusted Life Years Lost, WHO 1998

Communicable Disease: Impact: 

Communicable Disease: Impact Even in the U.S., deaths due to all infections increased 1980-1992 to #3 cause (after CV disease and malignancy)

Rank of Infectious Diseases Cause of Death millions % : 

Rank of Infectious Diseases Cause of Death millions %

Global Distribution of DiseaseWhat can it Teach Us?: 

Global Distribution of Disease What can it Teach Us? What to look for when a patient comes from there What to watch out for when a traveller goes there Evidence concerning the causes and determinants of disease

Malaria Distribution:: 

Malaria Distribution: Temperature, (therefore latitude and altitude) Distribution of most efficient vector species Control measures

Slide12: 

Distribution of Chagas’ Disease Trypanosoma cruzi

Slide13: 

“Reduvid bug”, Vector of Trypanosoma cruzi—Chagas’ Disease

Distribution of Lyme Disease in the US : 

Distribution of Lyme Disease in the US

Slide16: 

Distribution Of Loa Loa

Infections with well-defined geographic distributions: 

Infections with well-defined geographic distributions Schistosomiasis (200 million people, 4 species) Vector snails and their habitat Lyme disease Ixodes tick and mouse and deer hosts Hookworm and Strongyloides Warm soil, poor sanitation, bare feet

Universal Human Diseases: 

Universal Human Diseases Rotavirus Most respiratory viruses Herpes simplex I Herpes zoster Most STD’s Epstein Barr virus Staphylococcus aureus, Streptococcus pyogenes

Distribution due to Socioeconomic Development, Poor Sanitation, etc.: 

Distribution due to Socioeconomic Development, Poor Sanitation, etc. Hepatitis A Typhoid fever Helicobacter pylori Other bacterial diarrheas TB

Slide21: 

Basic Water Supply

Other factors: 

Other factors Measles—requires minimum population pool Hydatid disease (Echinococcus granulosus) herbivore & canid & human contact Hepatitis C may require iatrogenic transmission Brucella: consumption unpasteurized milk Paragonimus: ingestion of uncooked crab

Slide26: 

H E A L T H Of R E F U G E E S

Distribution of Burkitt’s lymphoma: 

Distribution of Burkitt’s lymphoma

Worldwide distribution of penicillin resistant pneumococcus: 

Worldwide distribution of penicillin resistant pneumococcus

Diseases of Evolving Distribution: 

Diseases of Evolving Distribution HIV and other Emerging Infectious Diseases The great historical epidemic diseases: Plague and Cholera TB and Leprosy

Plague (Bubonic plague, Black Death): 

Plague (Bubonic plague, Black Death) Yersinia pestis is endemic in rodents in many parts of Asia, Africa and N. America Justinian plague 542-767 AD---toll: 40 m. Black Death 1347 X 300 yrs---toll: ¼ Europe’s population Origin: ? Central Asia Spread: trade & shipping routes & war Risks: rats and poor hygiene (fleas) Last plague epidemic, San Francisco: 1908 Most recent epidemic: Surat, India 1994

Cholera (Vibrio cholerae): 

Cholera (Vibrio cholerae) 6 “Pandemics” since 1817— due to V. cholerae 01 Can be both endemic and epidemic Risks: poor water supply, sanitation & hygiene Major problem in Western cities in 19th century e.g. John Snow & the Broad Street pump 7th Pandemic 1961-present—new strain: El Tor Cholera returned to Americas (starting in Peru) 1991 after >100 years absence Other recent outbreaks: 1992: new species V. cholerae 0139

Slide35: 

The TB Epidemic in the Western World

Tuberculosis: 

Tuberculosis Decrease in Western countries from the most common cause of death in 1900 to <5/100,000 in Canadian-born, non-aboriginals +/- 5X increase in TB incidence in HIV-affected communities Increasing TB in former Soviet Union Increasing drug resistance Leprosy: Formerly endemic in Europe, now imported only

Slide37: 

HIV vs. Other Causes of Death in the U.S.

Global Warming and Malaria: 

Global Warming and Malaria

Selected Communicable Diseasesof Global Importance: 

Selected Communicable Diseases of Global Importance Acute Respiratory Infection (ARI) Diarrheal Disease Malaria Causes of Blindness

ARI (Acute Respiratory Infection, pneumonia) : 

ARI (Acute Respiratory Infection, pneumonia) #1 Cause of death in under 5’s in Low Income Countries Multiple organisms: pneumococcus, Hemophilus, viruses, coliforms and Pneumocystis in the HIV-infected, pertussis, measles Risks Malnutrition, HIV, non-vaccination, vitamin A deficiency, indoor air pollution, residential crowding

ARI: Prevention & Management: 

ARI: Prevention & Management Prevention: Socioeconomic development, improved nutrition, HIV prevention programs, breast feeding, reduced indoor pollution, vaccination (pertussis, measles) ? Hemophilus and pneumococcal vaccine Management: Prompt recognition of pneumonia by family and 1e health care workers (in functioning 1e care system) Rapid treatment with (implies availability of) antibiotics Rapid recognition and referral of the sickest kids

Diarrheal Disease: 

Diarrheal Disease # 2 cause of death in under 5’s in LIC’s (cholera and others can cause epidemic diarrhea in adults) Multiple organisms Rotavirus and other viruses, various types of E. coli, Salmonella, Shigella, Campylobacter, giardia, cryptosporidia, ? helminths etc. Different types/patterns of diarrhea: acute watery, dysentery, chronic Main mechanism of death, esp. in acute watery dd Dehydration Risks: unsafe drinking water, poor sanitation, unavailable washing water, malnutrition, not breast feeding, probably HIV, traditional treatment practices, and misuse of medication

Diarrhea: Prevention & Management: 

Diarrhea: Prevention & Management Prevention: Better drinking water, better sanitation, more washing water, food safety, hygiene, breast feeding & food safety, immunization ??rotavirus vaccine Management Oral rehydration with appropriate fluid (cereal-based ORS probably better) Continued breast (or other feeding if weaned) Avoid dangerous traditional practices (withholding oral intake, purges etc.) Train health workers that ORS, not medicines, is the treatment (except for dysentery).

Slide48: 

HIV: How fast can it spread? San Francisco gay men 0-50% in +/- 5 years Edinburgh IVDU 0-50% in 3 years Nairobi prostitutes 0-85% in 6 years Chiangmai (Thailand) prostitutes--incidence 10% per month Harare (Zimbabwe) young adults--.2%–20% in 5 years

Malaria (mainly P. falciparum): 

Malaria (mainly P. falciparum) Impact: > 2 billion people at risk +/- 300 million cases/yr +/- 2 million deaths/yr., mainly African kids Biology: Vector-borne (Anopheles mosquito) Gradually acquired, incomplete immunity

Malaria: Control: 

Malaria: Control Bednets, especially when insecticide-treated Early diagnosis & treatment requires access to functioning lab, effective drugs Domiciliary spraying Control of larval breeding Environmental, chemical, biological Chemoprophylaxis of selected groups Vaccine (don’t hold your breath)

TB: Mycobacterium tuberculosis: 

TB: Mycobacterium tuberculosis Impact: 2nd most common cause of death due to a specific microbial pathogen species 2 billion people infected 8 million active cases/year 3 million deaths/year Exploding epidemic in HIV-affected pop’s Increasing drug resistance

TB treatment and control: 

TB treatment and control Infectious TB is readily diagnosed with simple microscopic exam >95% cure of drug-sensitive disease with 6 months treatment if compliance assured In TB, cure of infectious cases is the main means of disease control Well structured programs (DOTS) can cure patients, prevent transmission and avoid drug resistance TB treatment/control among the most cost-effective of all health interventions

Travel & Immigration: 

Travel & Immigration Canada, with no local malaria transmission has > 1,000 reported cases of malaria/year Over 60% of Canada’s TB cases each year are foreign-born

A tropical disease in the comfort of your own home: 

A tropical disease in the comfort of your own home The food we eat is increasingly grown elsewhere, often in low-income countries 2X outbreaks of cyclosporiasis in the U.S. and Canada, >700 people affected in each—source: Guatamela raspberries Cholera in Maryland from Thai cocoanut milk Botulism in the U.K. from Canadian salmon

Communicable Disease Control, Global and Local: Methods: 

Communicable Disease Control, Global and Local: Methods **Immunization (measles and many more) Chemotherapy (STD’s, TB) Water, sanitation & washing (many) Vector control (malaria, yellow fever etc.) Education/behaviour change (HIV etc. etc.) Regulatory measures (pasteurization, quarantine etc.) **Socioeconomic development

Slide59: 

Impact of Immunization

Slide60: 

A Recent Vaccine Success—H. influenzae in Canada

Slide68: 

Disease Eradication— A Rash Idea?

Slide69: 

First Published Report of Vaccination

Disease Eradication: 

Disease Eradication The best kind of disease control Smallpox eradication (last case 1977) Huge reduction in morbidity and mortality (4million Deaths/year in 1950) Indefinitely compounded savings ($120m/yr in U.S. alone while whole eradication program cost $300m.)

Disease Eradication: 

Disease Eradication Wild polio virus transmission halted in Western Hemisphere—progress occurring in Asia, Africa Dracunculus (guinea worm) Dramatic reductions in the remaining endemic areas Possible future considerations: Measles, hepatitis B, hepatitis A, rubella, lymphatic filariasis, Hemophilus influenzae

Slide73: 

Sub-national Immunization Day Program in South Sudan

Cost Effectiveness of Interventionsassuming consistent, correct use: Heymann, WHO.: 

Cost Effectiveness of Interventions assuming consistent, correct use: Heymann, WHO.

Lessons Learned from International Experience: 

Lessons Learned from International Experience TB treatment Oral rehydration in the management of diarrhea Epidemiology of heterosexual HIV Doing more with less

Objectives : 

Objectives A global perspective on the frequency and impact of communicable diseases Appreciation of the distribution of various representative communicable diseases An understanding of some of the determinants of disease distribution An introduction to the principles and practice of communicable disease control An introduction to the idea that International Health can be fascinating and rewarding NOT: To teach the pathophysiology or life cycle of various tropical and communicable diseases