Natural Disasters

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Natural Disasters

• Part One Pathophysiology
• Part Two Environmental Physiology

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Part One - Pathophysiology

• Definition The functional changes associated
  with or resulting from disease or injury the
  study of such changes (distinguished from s
  structural defect)
• Web site on medical physiology pathophysiology
  textbook http//www.mfi.ku.dk/ppaulev/content.htm
  

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Infectious Disease in the Aftermath of a Natural
Disaster

• Widespread outbreaks of infectious disease such
  as cholera or typhoid after hurricanes are not
  common in areas where such diseases do not
  naturally occur i.e. pre-existing level of
  disease in a community affected by disaster is a
  significant parameter, however there was a
  discovery of an endemic focus of Vibrio cholerae
  in the US
• A disease may be brought into a disaster area
  from elsewhere even by relief workers e.g. 1976
  Guatemalan Earthquake occurred in the winter
  influenza season in North America thus relief
  workers from NA could have brought influenza with
  them (however, most outbreaks that occur are
  almost always from diseases that were already in
  the disaster-affected area before the disaster
  struck)

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Infectious Disease in the Aftermath of a Natural
Disaster

• Communicable disease outbreaks of diarrhea
  respiratory illness can occur when water sewage
  systems are not working personal hygiene is
  difficult to maintain as a result of a disaster
  food storage water purification become major
  issues as is adequate shelter and warmth

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Infectious Disease in the Aftermath of a Natural
Disaster

• Decaying bodies create very little risk for major
  disease outbreaks
• Short bouts of diarrhea/upset stomach
  colds/respiratory diseases sometimes occur among
  those living in large groups in shelters (close
  contact with minimal sanitation available clean
  water)
• Drowning (after hurricane/flooding) may be more
  of a risk than contacting infectious disease
• Clean water (boiled minimum of 1 minute), food
  stored properly and personal hygiene (including
  handwashing clean wound management) very NB

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Can a Natural Disaster Lead to an Epidemic?

• Web page for discussion ( photos)
• http//ndms.chepinc.org/data/files/3/84.pps
• (disease after disaster on web browser
  Infectious Disease Issues in Natural Disasters)
• Phases of a Disaster
• Impact phase (0-4 days) extrication some soft
  tissue infections
• Post impact Phase (4 days-4 weeks) airborne,
  food-borne, waterborne diseases
• Recovery Phase (gt4 weeks) those with long
  incubation periods of chronic disease

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Can a Natural Disaster Lead to an Epidemic cont?

• Environmental Factors
• Climate (cold airborne warm water-borne)
• Season (e.g. US winter influenza summer
  enterovirus
• Rainfall e.g. El Nino years increase malaria
• Geography e.g. isolation from resources

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Types of Disasters types of Problems

• Earthquake crush penetrating injuries
• Hurricane flooding water contamination,
  vector borne diseases
• Tornado crush injuries
• Volcano water contamination airway disease

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Examples of Epidemics after Disasters a Short
History

• San Francisco 1907 Fire Plaque (quarantine
  failure)
• Duluth, Mn. 1918 Forest Fire Influenza
  (crowding, epidemic)
• Haiti 1963 Hurricane malaria (vector
  control stopped)
• Italy 1976 Earthquake Salmonella Carriers
  (water sanitation stopped)
• Dominican Republic 1976 - Hurricane typhoid,
  GI, hepatitis, measles (crowding, flooding,
  chronic disease)

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Examples of Epidemics after Disasters a Short
History

• Popaya, Colombia 1983 Earthquake viral
  hepatitis (water sanitation)
• Equador 1983 Flooding Malaria (vector
  increase)
• US 1992 Hurricane Andrew
• SE Asia 2004 Tsunami
• US 2005 Hurricane Katrina Rita
• Pakistan 2005 - Earthquake

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Infectious Disease in the Aftermath of a Natural
DisasterSpecial Considerations/Example Mold

• After flooding/hurricanes, massive mold
  contamination of buildings submerged in water
  likely a certainty especially for
  buildings/structures soaked for gt48 hours (e.g.
  after Katrina, 60-80 of residential structures
  in New Orleans sustained severe flood damage)
• Exposure routes can vary but primarily are
  aerosol and ingestion (also through open skin
  wounds is a possibility) people can be infected
  by either spores or mycelial fragments

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Infectious Disease in the Aftermath of a Natural
DisasterSpecial Considerations Mold

• Symptoms/Disease effects can range from
  immunologic/allergic response to
  hyper-sensitivity pneumonitis to long-term
  ingestion of toxins (which could lead to cancer
  not likely a serious consequence after a flood)
• Pathophysiology of mold then due to either an
  immunological, infectious or toxic interaction
  with host
• It is common for several of these mechanisms to
  contribute to pathogenesis of a fungal-induced
  disease

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Infectious Disease in the aftermath of a Natural
DisasterSpecial Considerations Mold

• Immunological response IgE-mediated (allergic)
  responses (IgE is an immunoglobulin (antibody)
  protein in nature secreted by plasma cells (some
  Igs secreted by lymphocytes) whose production is
  elicited by exposure to an allergic substance
  (allergen in this case, mold spores or
  mycellium) mostly bound to mast cells
  basophils that have a IgE specific receptor (it
  has a high CHO content) IgE attaches to foreign
  substance assists in destroying them IgE is 1
  of 5 major classes of Immunoglobulins present
  primarily in skin mucous membranes mediates
  type 1 hypersensitivity (can be involved in
  allergy, asthma, eczema, allergic conjunctivitis,
  allergic rhinitis and anaphylaxis)

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Infectious Disease in the aftermath of a Natural
DisasterSpecial Considerations Mold cont

• Atopy (genetic predisposition to form IgE
  responses to aeroallergens) is a risk factor
• Normal immune response to an antigen is to
  produce antibodies which mark the foreign
  substance for removal by phagocytosis
• Pathophysiology of an allergic response is
  primarily due to repeated exposure to antigen in
  which IgE molecules attached to mast cell
  recognize bind again to the allergen but this
  time causing degranulation of the cell (triggered
  by cross-linking of adjacent IgE molecules)
  this stimulates release of histamine other
  chemicals

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Infectious Disease in the aftermath of a Natural
DisasterSpecial Considerations Mold cont

• histamine cause dilation increased permeability
  of small blood vessels leading to typical allergy
  symptoms (sneezing, runny nose, tearing eyes
  smooth muscle contractions that can lead to
  breathing difficulties (antihistamines are used
  to treat these symptoms) a decrease in blood
  pressure
• Histamine is a physiologically active amine which
  can also be released after tissue injury as well
  as during neutralization of foreign material
• its release in skin, causes edema (swelling), can
  cause acute urticaria (rapidly appearing hives
  accompanied by sever itching)

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Infectious Disease in the aftermath of a Natural
DisasterSpecial Considerations Mold cont

• Anaphylaxis an acute allergic response which
  may lead to a whole-body, life-threatening
  reaction that can occur within seconds of
  exposure to an allergen develops when
  widespread mast cell degranulation triggers
  abrupt dilation of peripheral blood vessels,
  causing a precipitous drop in blood pressure -
  death may occur within minutes (more often seen
  with exposure insect venom, peanuts or allergy to
  Penicillin than to molds seen after flooding)

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Infectious Disease in the aftermath of a Natural
DisasterSpecial Considerations Mold cont

• Infectious response (either humoral /or
  cell-mediated immune responses) (exposure to
  mold after sever flooding/hurricane can result in
  2 types of inhalation fevers a. humidifier fever
  b. organic dust toxic syndrome both can be
  characterized by fever, flu-like symptoms,
  general weakness, headache body chills, coughing)
  these are not thought to be associated with
  immune response but rather a nonspecific
  inflammatory response usually removal from
  antigen is sufficient for recovery - not to be
  confused with hypersensitivity pneumonitis which
  is based on an immune response accurate history
  is of paramount importance) next pages on
  immune response

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Humoral Cell-mediated Immunity (associated
with response to infective agents)

• Humoral immune response involves the activation
  clonal selection of B cells (B lymphocytes),
  resulting in the production of secreted
  antibodies that circulate in blood and lymph
• Cell-mediated immune response involves the
  activation colonal selection of cytotoxic T
  cells (T lymphocytes) which directly destroy
  certain target cells
• Central to the acquired immune response is the
  helper T cell which responds to peptide antigens
  displayed on antigen-presenting cells ion turn
  stimulates the activation of nearby B cells
  cytotoxic T cells

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Cytotoxix T cells a response to infected cells
( cancer cells)

• Effectors of cell-mediated immunity
• Eliminate body cells infected by viruses or other
  intracellular pathogens ( cancer cells
  transplanted cells)
• When binds to specific antigen complexes on an
  infected body cell, these cells are activated
  differentiated into an active killer
• Cytokines secreted from nearby helper T cells
  promote this activation
• Activated cytotoxic T cells secrete proteins that
  act on bound infected cell leading to its
  destruction

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B Cells A Response to Extracellular Pathogens

• Antigens that elicit a humoral immune response
  are typically proteins polysaccharides present
  on surface of bacteria or incompatible
  transplanted tissue
• Activation of B cells is aided by cytokines
  secreted from helper T cells activated by the
  same antigen
• B cell proliferates differentiates into a clone
  of antibody-secreting plasma cells clone of
  memory B cells depending on type of antibody
  produced, various mechanisms of disposal of
  antigens are initiated (e.g. viral
  neutralization, agglutination of antigen-bearing
  particles precipitation of soluble antigens
  enhances removal by phagocytosis often by
  neutrophils) where as activation of complement
  system pore formation lead to cell lysis)

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Infectious Disease in the aftermath of a Natural
DisasterSpecial Considerations Mold cont

• Toxic response many common molds can produce
  metabolites with a wide range of toxic activities
  such as antibiotic (e.g. penicillium),
  immune-suppressive (e.g cyclosporine),
  carcinogenic (e.g. aflatoxins), emetic and
  hallucinogenic (e.g. ergot alkaloids) ingestion
  is a common route (but inhalation dermal
  contact also possibilities) mycotoxin
  production depends on species strain of mold
  plus environmental conditions (e.g. temperature,
  water activity, light) growth substrate huge
  variability in pathophysiology of mycotoxins
  ranging from disruption of membrane permeability
  functioning of ion channels (e.g. leakage of K
  influx of Na) to changes

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Infectious Disease in the aftermath of a Natural
DisasterSpecial Considerations Mold cont

• Toxic reaction cont to changes in pH to DNA
  breaks, chromosomal abnormalities inhibition of
  protein synthesis (can be a biological weapon)
  several theories on how a mycotoxin can inhibit
  protein synthesis one is related to toxins
  affinity for a part of the ribosomal subunit,
  therefore inhibiting protein synthesis at the
  initial step while another theory suggests that
  it is due to inactivation of peptidyl transferase
  which inhibits the terminal step of protein
  synthesis

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Opportunistic organisms

• Many organisms do not cause disease and live
  basically symbiotically with humans
• However, provided the right environmental
  conditions, some organisms not originally
  pathogenic (disease-causing) become pathogenic
  capitalizing on the opportunity e.g.
  Pseudomonas after a sever burn to the skin
• Natural disasters may provide ideal environments
  for opportunistic organisms to cause disease

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Infectious Disease in the aftermath of a Natural
DisasterSpecial Considerations Mold cont

• Greatest risk posed to those with impaired host
  defense systems (immunodeficity diseases, organ
  transplant recipients, stem cell recipients,
  cancer-themotherapy patients, individuals taking
  corticosteroids, etc.) in which exposure to mold
  could lead to death

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Infectious Disease in the aftermath of a Natural
DisasterSpecial Considerations/Example Cholera

• Causitive agent Vibrio cholerae (gram negative
  bacterium
• Major symptom severe watery diarrhea with 50
  mortality if untreated
• Bacterial model for toxin mediated disease

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Infectious Disease in the aftermath of a Natural
DisasterSpecial Considerations Cholera cont

• Pathophysiology
• Organisms enter small bowel colonize pilus
  required hemagglutanins accessory colonizing
  factor porin like proteins
• Produces toxin A with 5 B subunits A cleaves
  to A1, activates adenylate cyclase (enzyme
  involved with converting ATP to cAMP) leads to
  increase Cl secretion decreased Na absorption
  resulting in a net flow of H2O, K HCO3 into the
  bowel

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Infectious Disease in the aftermath of a Natural
DisasterSpecial Considerations Cholera cont

• May be asymptomatic most cases show no symptoms
  before diarrhea - some people develop rapid
  diarrhea (with some emesis) most sever day 1-2
  (usually stops by day 6 or individual may lose
  10 body weight in 2 days (children elderly at
  risk) with accompanying thickening of blood,
  shoke death occurring in 2-48 hours (18
  average) infected people are carriers until
  they develop diarrhea, then they have cholera
• (e.g. Of non-cholera dysentery Giardia, E. coli,
  Salmonella, Shigella, Campylobacter, Yersinia,
  Viral hepatitis)

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Importance of Other Related Sciences/Studies
their Definitions

• Etiology
• Epidemiology
• Pathology
• Pathogenesis
• Endemic vs. Pandemic vs. Epidemic
• Virology vs. Bacteriology vs. Parasitology
• Clinical Symptoms, Predisposing Factors,
  Infectivity, Carrier-state

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Part Two - Environmental Physiology - Introduction

• Provides a basic understanding of physiological
  responses to natural and man-made environmental
  conditions
• Sub-topics often studied in environmental
  physiology include comparative aspects of
  temperature regulation, the effects of altitude
  and hudrostatic pressure, life existing without
  light and the dive reflex across the species

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Introduction cont

• It is important to study animals in the context
  of their own habitat and their real needs this
  adds traditional natural history to the study of
  comparative physiology
• Primary aim of ecological or environmental
  physiology is to understand how animals function
  in and respond to their natural environments, at
  all stages of their life cycles

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Environmental Changes

• Overall, environments may be very stable on all
  timescales relevant to living organisms, e.g.
  deep seas or,
• They may vary on an evolutionary and geological
  timescale of tens or hundreds or thousands of
  years as land masses move, sea levels rise and
  fall, material erode and deposit elsewhere, an
  rivers change their courses
• There may also be changes with a regular annual,
  lunar, or daily cyclicity
• There are changes on a much shorter timescale of
  hours or minutes or seconds, as the weather
  changes

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Environmental Changes cont

• Magnitude of change is a relative phenomena
  short-term changes are especially important in
  relation to very local microenvironments
  therefore to very small animals (e.g. the
  difference between the environment above a leaf
  the environment below it may be profound, and
  both may change within seconds in relation to
  varying solar radiation insulation, air
  movements rainfall)
• Changeable environments put a high selective
  premium on versatility or tolerance in animals,
  rather than on precise adaptations to particular
  conditions (this may be particularly true where
  man has intervened in the natural ecosystem to
  put new stresses on animals, whether from habitat
  destruction, climate modification or the
  introduction of many kinds o toxic chemicals)

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Environmental Changes cont

• It is significant to note, that many animals, for
  most of their lifetime do not need extreme
  physiological adaptation reply instead on
  behavioral strategies to avoid the worst of their
  difficulties however, in the wake of a natural
  disaster (as well as in the cumulative damage
  done through pollution), their environments are
  drastically changed, some temporarily, some
  permanently

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What does an organism need from its environment?

• Source of palatable water
• Source of oxygen (note some organisms are
  anaerobic)
• Source of energy ( other nutrients)
• Climate within tolerable limits
• Shelter (including appropriate breeding
  grounds) - depends on species
• for survival of the species, access to
  potential mates protection/defense from
  predators

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Natural Disasters Change Environments often
Drastically Suddenly

• No time for evolutionary adaptations
  adjustments must be made quickly
• Relationships between animals their
  environments maybe forever changed
• Items provided by the environment may be reduced
  or totally lost (habitat, nesting grounds,
  breeding grounds, feeding grounds, prey reduction
  /or predator loss (either can upset the natural
  balance), other food source loss or reduction,
  contaminated water or water source loss,
  permanent changes to landscape (e.g. large
  crevices, river direction) may separate
  populations, environmental cues which drive
  behavior may be gone, etc.
• survival strategies no longer effective

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Natural Disasters as an Extreme Type of Abiotic
Stress

• Abiotic stress a wide range of threats to
  animal health not associated with other living
  organisms which would include nutrient
  deficiencies, nutrient non-nutrient toxicities,
  drought, temperature and salinity stresses
  (extreme weather and pollution of all types would
  be examples of abiotic stresses)
• Within limits, animals have adaptive abilities to
  cope with moderate changes in their environments,
  especially if these changes are temporary (e.g.
  seasonal temperature fluctuations) not extreme
  (e.g. some animals may hibernate, enter torpor or
  migrate) but they have limited ability to adjust
  to sudden drastic/permanent changes only
  those individual able to acclimatize to these
  extreme changes carry on

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Bottleneck Effect

• Genetic drift resulting from a reduction in a
  population, typically by a natural disaster, such
  that the surviving population is not longer
  genetically representative of the original
  population
• By chance, among the survivors certain
  individuals may be over-represented while others
  may be under-represented some may be lost
  entirely

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Bottleneck Effect

• Genetic drift may continue to have substantial
  impact for many generations

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A web site for more info

• http//www.pbs.org/wgbh/evolution/darwin/origin/in
  dex.html