The document discusses infectious diseases in tropical environments, highlighting their transmission routes and impacts, particularly in developing countries. Specific diseases mentioned include cholera, schistosomiasis, and tuberculosis, alongside their transmission methods and symptoms. It emphasizes the importance of environmental factors, sanitation efforts, and coordinated health strategies in combating these diseases and reducing mortality rates.

1. Infectious Disease Transmission in Tropical Environments Mary Dain ESPM 194 Spring 2007

2. Worldwide Infectious Disease World Health Organization at http://www.who.int/whosis/whostat2006highlights/en/index4.html

3. What is an infectious disease? American Heritage Stedman's Medical Dictionary - infectious disease ( n.) A disease resulting from the presence and activity of a pathogenic microbial agent. Four main types of infectious disease carrying-pathogens: bacteria, viruses, protozoa, and helminths

4. Bacteria single-celled, free-living, ubiquitous prokaryotes Such as tuberculosis, salmonella, cholera, leprosy, plague Illinois Department of Health: http://www.idph.state.il.us/public/hb/hbsam.htm

5. Viruses Parasitic, eukaryotic Such as measles, smallpox, hepatitis, HIV Scientific American, 1995. At: http://www.wellesley.edu/Chemistry/Chem101/hiv/HIV-1.html

6. Protozoa Single-celled, no cell walls, larger than bacteria and more complex, frequently use vectors Such as malaria, leishmania, giardia Helveticum Instituticum Tropologicum, at: http://www.infektionsbiologie.ch/parasitologie/index.html

7. Helminth Multi-cellular worms, free-living or parasitic Such as schistosomiasis, guinea worm, hookworm CDC Public Health Image Library http://phil.cdc.gov/phil/quicksearch.asp

8. Communicable Diseases in the Environment Most common in developing countries, particularly in warmer climates Still very prevalent: under-5 child mortality rate is 168 for every 1,000 live births in Sub-Saharan Africa (source: World Bank, HNP statistics 2004) The environment has direct impacts on the transmission of almost all communicable diseases in the developing world

9. Transmission All infectious diseases transfer themselves along one of the following routes: Fecal/oral Respiratory Blood borne/sexual By contact

10. Water-borne Diseases

11. Cholera Commonly known for pandemics in England (1817) and New York city (1830’s) Yet still very common today – there were 100,000 cases of cholera worldwide in 2004, causing 2,300 deaths in 56 different countries

12. Cholera’s habits Water-borne bacterium ( Vibrio cholera ) Seasonal: warm weather promotes growth Forms bacterial reservoirs in brackish waters Photo curteosy of Sudan Watch blog: http://sudanwatch.blogspot.com/2006/02/drilling-for-sudans-drinking-water-is.html

13. What it does: Alters activity of G proteins in intestinal cells, so that they become “stuck” in an activated state, pumping water continuously out of cells and into the intestines Severe diarrhea and dehydration result Dr. Wim Hol, U Washington at: http://depts.washington.edu/biowww/faculty/hol.html

14. This results in: Loss of 20 liters of water/day over 5 to 8 days Shock and/or death Bacteria exits the body in feces, contaminates local drinking water and the cycle continues Most commonly occurs in children, afterwards develop base immunity

15. Human Defenses Malnourishment, parasitic infection contribute to likelihood of contracting cholera First-infection can produce long-term immunity Endemic area resistance

16. The Future of Cholera Global case-fatality down 47% from 1961 Oral Rehydration Therapy: glucose, potassium, salt Evolving pathogen Improved coordination of relief efforts Improved sanitation systems

17. Schistosomiasis Water-borne helminth with a complex life-cycle Dependent upon one genus of snail ( Biomphalaria spp. ) to survive

18. Transmission Takes the form of cercariae that carry out part of lifecycle in water, in snails, and in a human host as worms Enters the body through the skin, in water contaminated with cercariae Shistosomiasis Forum, Human Diseases and Conditions, at: http://www.humanillnesses.com/Infectious-Diseases-My-Si/Schistosomiasis.html

19. CDC: http://en.wikipedia.org/wiki/Image:Schistosomiasis_Life_Cycle.jpeg

20. Effects Acute symptoms: Lethargy, fever, liver damage Chronic symptoms: distended belly, cirrhosis of the liver/colon http://www.mansfield.ohio-state.edu/~sabedon/black11_files/image023.jpg

21. Blood in Urine www1.imperial.ac.uk/.../schisto_children.jpg

22. Infection Process Shistosome eggs are laid in feces, and hatch when they reach fresh water Common to find shistosomiasis in freshwater sources around the globe, particularly large pools or slow-moving water Any person in the water is at risk of infection

23. Remediation Cercariae removal not really possible Snail populations are too hardy to be eliminated Base education about the presence of snails Boot-wearing Septic tank systems, water purification http://www.photographersdirect.com/stockimages/y/yangze.asp?ms=y

24. Dam-Building Reservoirs create a snail habitat Can create a bridge between endemic areas If reservoir is infiltrated, Yangtze river could become breeding ground for shistosomes after the building of the Three Gorges Dam http://www.schillerinstitute.org/economy/phys_econ/phys_econ_3_gorges.html

25. Future of Schistosomiasis Ending dam-building will hinder snail population growth Large-scale irrigation projects must be checked to avoid circariae breeding grounds New drug: praziquantel is effective way to treat symptoms, stop human egg-shedding Vaccine in 10-20 years

26. Guinea Worm Water-borne helminth that lives out a very long portion of its lifecycle inside the human host Has seen a major reduction in recent years, down from 3.5 million cases in 1986 to 16,000 in 2004

27. Guinea Worm Lifecycle

28. Problem: Communal Water Source Blisters that form are very painful, requiring the victim to submerge the affected limb in water, releasing more larvae The importance of waste water treatment and clean water management cannot be overstated

29. Eradication is on the Horizon Three-quarters of the remaining cases of Guinea Worm exist in Southern Sudan 1995 Jimmy Carter Guinea Worm cease-fire Recent success stories www.medgaget.com , with permission published by wikipedia.org

30. Respiratory Infections

31. The Big Respiratory Threat of 2007: Tuberculosis Mycobacterium tuberculosis Leading cause of death among young adults worldwide – 2 billion people are currently infected, 300,000 of them are drug resistant Commonly associated with slums, poverty, and high population density Transmitted through the respiratory route

32. What it Does: TB enters the lung Gets encased in macrophages, forms a tubercle, which prevents spreading Remains as such for years When immune system is compromised, tubercle melts and TB comes out and multiplies

33. Tuberculosis at large Symptoms: cough, chest pain, fever, weakness, dramatic weight loss http://www.pbs.org/wgbh/rxforsurvival/series/diseases/tuberculosis.html Very infectious, but only 5-10% of healthy people infected with TB develop the disease

34. 80% of TB cases are in 22 underdeveloped countries TB is the number one killer of HIV infected people, prevalance of co-infection is highest in Africa

36. MDR-TB 4 medications are used widely to treat TB Inexpensive, but must be taken regularly for six to eight months Skipping any dose causes MTB to mutate 80% of all cases of MDR-TB are superstrains, so they are resistant to at least 3 out of 4 drugs used to treat the disease

37. DOTS World Health Organization’s “Directly Observed Treatment” DOTS campaigns have yielded 85 - 100% cure rates in many clinics 90% in studies in Peru; 100% in Haitian sites BUT today, less than 25% of TB patients worldwide are treated with DOTS Strategy 25% of TB infected have no access to DOTS

38. The Future of Tuberculosis “ Tuberculosis has not reemerged, it has reemerged from the poor.” –Dr. Paul Farmer

39. Malaria Water-related, vector-borne, world’s number one parasitic disease 300 – 500 million infections per year 1-3 million deaths per year, 90% are African 3,000 child deaths per day (WHO, 2002)

40. Effects Transmitted mostly from mosquito bites, also from blood transfusions, mother/child transmission, organ transplant Symptoms: flu, fever, chills, mouth sores, loss of consciousness, death www.worldpress.org/Africa/2293.cfm

41. Four types, Two hosts Four species of parasite that can infect humans There are 400 species of Anopheles mosquitoes, 30 of them carry malaria

42. Encarta pictures at: http://encarta.msn.com/media_461541582/Life_Cycle_of_the_Malaria_Parasite.html

43. Treatment Acquired immunity over time Chloroquin, quinine, mefloquin Difficult to treat because it has a large genome, and rapidly mutates Prevalance increases with population density, incidence of standing water Time Magazine image: http://img.timeinc.net/time/asia/magazine/2001/1203/refugee_camp.jpg

44. Human behavior Affects Transmission Creation of mosquito breeding sites: irrigation ditches, water buckets, puddles Deforestation decreases resting sights for mosquitoes Mass migrations (India/Pakistan border) Agricultural work Raising livestock near house Bed-net use

45. Malaria Remediation Efforts Insecticide-treated bed nets Introduction of mosquito-eating fish Filling or covering pits, puddles Pesticide use for indoor and outdoor spraying

46. DDT Persistant Organic Pollutant, phased out in POPs treaty of 2001 Persists in the environment Bioaccumulates Travels long distances Toxic to wildlife Can cause premature birth in humans Some mosquitoes develop resistance to it

47. BUT, indoor DDT use reduces malaria transmission by 90% Ten countries in Sub-Saharan Africa still use it

48. One More Factor in Infectious Disease Prevalence Most infectious disease victims are suffering already from a host of other problems Most commonly: malnutrition

49. Conclusions In the face of global climate change, warm places will only be getting warmer, and therefore facing more exposure In the face of globalization and development, public health workers, environmental scientists, and public policy workers have to work together in order to decrease mortality rates and increase health expenditures in developing countries

50. Source Material infectious disease. (n.d.). The American Heritage® Stedman's Medical Dictionary . Retrieved February 24, 2007, from Dictionary.com website: http:// dictionary.reference.com /browse/infectious disease Onchocerciasis volvalae at: http://www.vetmed.ucdavis.edu/courses/vet_eyes/eye_path/epath_s_7377.html WHO communicable diseases: http:// www.who.int /infectious-disease-news/ -neglected tropical diseases: http:// www.who.int/neglected_diseases/en / World Bank Health and Population Data, including vital statistics: http://web.worldbank.org/WBSITE/EXTERNAL/TOPICS/EXTHEALTHNUTRITIONANDPOPULATION/0,,menuPK:282516~pagePK:149018~piPK:149093~theSitePK:282511,00.html Center for Disease Control and Prevention. Department of Health and Human Services. [Online] Available at :http://www.cdc.gov/index.htm Image sources: Water-borne disease image: http://www.theirc.org/images/photoessays/drc/pe-drc-pb0506-drc9.jpg Hookworm image: http:// phil.cdc.gov/phil/quicksearch.asp G protein activation graph: http:// depts.washington.edu/biowww/faculty/hol.html The defenders image: http:// www.thehumanbody.ecsd.net/immune_system.htm Imperial College of London blood in urine image: http://www1.imperial.ac.uk/medicine/research/researchstrategy/researchthemes/publicandint/ide/groupsandcollabs/thesci/ Schistosomiasis life cycle graph, CDC: CDC: http://en.wikipedia.org/wiki/Image:Schistosomiasis_Life_Cycle.jpeg Yangtze farmer: http:// www.photographersdirect.com/stockimages/y/yangze.asp?ms =y Three gorges dam: http://www.schillerinstitute.org/economy/phys_econ/phys_econ_3_gorges.html east African river: http://www.iwmi.cgiar.org/Africa/files/RIPARWIN/05/_archive/latest.htm guinea worm extraction photo: http://seattlepi.nwsource.com/africa/worm23.shtml Malaria woman and child: www.worldpress.org/Africa/2293.cfm DDT: http://www.sciam.com/media/externalnews/2006-12-07T202947Z_01_NOOTR_RTRIDSP_2_SCIENCE-AIDS-MALARIA-DC.jpg DDR jar: http :// www.oei.es / decada / ddt.jpg