Water Borne Diseases2 - Medical Ecology

1 Water - Borne DiseasesCourtesy NASA20% Of The Earth s Liquid Fresh Water Is In Just One PlaceLake Baikal, SiberiaBathymetryMaximum depth: 1,632 mUSAID Save The Children ProgramAccess to safe drinking Water is everyone s rightWater Borne Infectious DiseasesClinical SyndromesType Ia. Noninflammatory (enterotoxin, etc.)b. Proximal small bowelc. Watery diarrhead. Examples:RotavirusVibrio choleraeGiardia lambliaCryptosporidium parvumCyclopsora cayetanensisType IIa. Inflammatory (invasive, cytotoxin)b. Colonc. Dysentery (bloody diarrhea)d. Examples:Salmonella enteriditisClostridium difficileCampylobacter pyloriEnatmeba histolyticaType IIIa.

2 Penetratingb. Distal small bowelc. Examples:Salmonella typhiYersinia enterococolithicaCholera toxinGiardia lambliaSalmonella typhiEntameba histolyticaDiscoverer Of The First Water BorneInfectious Disease: Giardia lambliaAnton Von LeeuwenhoekWater Borne Infectious Diseases:VirusesRotavirusPolio Hepatitis AHepatitis EPolio virusRotavirusHepatitis virusWater Borne Infectious Diseases:BacteriaVibrio choleraeEscherichia coli 0157 Salmonella typhiShigella flexneriCampylobacter pyloriChlamydia trachomatisEscherichia coliVibrio choleraeChlamydia trachomatisSalmonella typhiShigella flexneriCampylobacter pyloriWater Borne Infectious Diseases.

3 ProtozoaGiardia lambliaEntameba histolyticaCryptosporidium parvumCyclospora cayetanensisBalantidium coliCyclospora cayetanensisEntameba histolyticaCryptosporidium parvumGiardia lambliaBalantidium coliWater Borne Infectious Diseases:HelminthsStrongyloides stercoralisDracunculus medinensis Schistosoma mansoniSchistosoma japonicumSchistosoma haematobiumSchistosome adult Strongyloides stercoralisWater Borne Infectious Diseases:BacteriaVibrio choleraeEscherichia coli 0157 Salmonella typhiShigella flexneriCampylobacter pyloriChlamydia trachomatisEscherichia coliVibrio choleraeChlamydia trachomatisSalmonella typhiShigella flexneriCampylobacter pyloriCholeraDistribution Of EstuariesTrophic Relationships Of The Mangrove EstuaryFrom: E.

4 Odum Fundamentals Of EcologyNew Cholera Outbreaks Frequently OccurIn Communities Adjacent To BloomEnvironmental Conditions Favoring Growth Of Nutrient phytoplankton by zooplankton by a cholera outbreakBecause Vibrio cholerae and its relatives are marine microbes, fully integrated into their respective food copepod with Vibrio cholerae attached to egg of PathogenicityMonsoons1. lower the salinity of the estuary2. bring nutrients to the estuary3. raise the ambient Water temperature of the estuaryWater Borne Infectious Diseases:ProtozoaGiardia lambliaEntameba histolyticaCryptosporidium parvumCyclospora cayetanensisBalantidium coliCyclospora cayetanensisEntameba histolyticaCryptosporidium parvumGiardia lambliaBalantidium coliGiardia lambliaSEM of Giardia lamblia in situClinical Disease:1.

5 Diarrhea (steatorrhea)2. Weight loss3. Constipation4. FatiguePathogenesis:Trophozoites induce malabsorption of (s) correlate: Flattened villiDiagnosis:1. Identify trophozoites and cysts by microscopic examination of stoolTrophozoiteCyst 8 mDiagnosis:2. Antigen Capture ELISA using stool sample3. PCR4. IHA serology:Intestinal - 95% predictive of active infectionExtra-intestinal - 100% predictive of active infectionDrug Of Choice:MetronidazoleMode Of Action:Inhibits Against All Anaerobic OrganismsEntameba histolyticaMorphologyTrophozoiteCyst RBCsNucleiChromatoidal barNucleus15 mGross pathology of large intestine due to Entameba histolyticaFlask-shaped ulcer due to infectionwith Entameba histolyticaTrophozoites of Entameba histolyticain situ in flask-shaped ulcerAmebaeEntameba histolytica in culturewith Chinese hamster ovary cellsSEMTEMEhCHOP athogenesis:1.

6 Attachment of amebae to target cells mediated bygalactose, then pore-forming protein disruptstarget cell membrane:2. Cell-cell contact induces synthesis of lysosomalenzymes in amebae at interface with target cells. Cell death ensues. From: Ravdin, (1995) Amebiasis (Review). Clin. Infect. Dis. 20: 1453-1466 Clinical Disease:A. Intestinal:1. Diarrhea2. Dysentery (bloody diarrhea)B. Extra-intestinal:1. Liver abscess (most common site)2. Lung abscess3. Brain abscess (usually fatal)Diagnosis:1. Identify trophozoites and/or cysts in feces. Cannotdistinguish E. histolytica from E. dispar by morphology unless cytoplasm contains : CDCRBCsDrugs of Choice:1.

7 Intestinal:Metronidazole and Iodoquinol2. Extra-intestinalHigh doses of MetronidazoleCryptosporidium parvumHistologic section of small intestine of patientsuffering from HIV/AIDS, infected withCryptosporidium J. LefkowitchPathogenesis:Secretory diarrhea. May produce up to 10 liters ofwatery stool per day! Mechanism of Cryptosporidium parvumDiagnosis:Find oocysts in stoolWater Borne Infectious Diseases:HelminthsDracunculus medinensisStrongyloides stercoralis Schistosoma mansoniSchistosoma japonicumSchistosoma haematobiumSchistosome adult Strongyloides stercoralisStrongyloides stercoralisParasitic female Strongyloides stercoralisHeadTailEggs60 mStrongyloides stercoralis in :Worms invade epithelial cells, induce celldeathClinical Disease:1.

8 Diarrhea2. Malabsorption syndrome3. Secondary bacteremia/septicemia as larvae migrate throughout body and defecate microbes that they ingested in large Death due to overwhelming bacterial :1. Microscopical examination of feces (X6)2. String testLarva of Strongyloides stercoralisDrug of choice:IvermectinMode of Action:Blocks Cl(-) ion channels, inhibits !-aminobutyric acidreceptor medinensisOrigins Of The Cadeusus?DracunculusLesion On LegAdult WormDracunculus and Step Well EcologyCyclopsDracunculus infective larvaeExtraction of dracunculus adultStep WellDrug Of Choice:MetronidazoleMode Of Action:Inhibits Oxidoreductase EnzymeMedical EcologyStatement of purpose: Medical Ecology is an emerging science that defines those aspects of the environment thathave a direct bearing on human health.

9 The concept of ecosystem functions and serviceshelps to describe global processes that contribute to our well-being, helping to cleanse the airwe breathe, the Water we drink, and the food we eat. Environmental degradation often leadsto alterations in these aspects, leading to various states of ill health. The term MedicalEcology was first coined by the eminent microbiologist, Rene Dubos, who intended it toembrace the concept that natural systems, if explored fully, would provide for many of ourneeds, as for example, quinine did regarding the treatment of malaria. Dubos discoveredgramicidin in 1939, a powerful topical anti-microbial agent.

10 Together with AlexanderFleming s discovery of penicillin in 1928, these findings led the way into the modern era ofanti-microbial therapy, in which soil organisms played a dominant Ecology as described here is re-defined to a much broader level. We believe thatecological principles, when applied to the human condition will offer a resolution to thedichotomy of the "man versus nature" paradigm. In fact, humans are an integral part ofnature, but most of the time we are unaware of our connectedness to the rest of the Ecology links natural processes with living on earth, from the point of view of beinghuman. The environment in which we live is characterized by countless physical, chemical,and biological systems, and it is in this complex setting that we carry out our lives, whetherwe are aware of them or not.