Reservoirs of Disease

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Reservoirs of Disease

• By Allison Smock

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What exactly are reservoirs of disease?

• Animate or inanimate sources which harbor
  disease-causing organisms and thus serve as
  potential sources of disease outbreaks.
• Reservoirs are distinguished from vectors and
  carriers, which are agents of disease
  transmission rather than continuing sources of
  potential disease outbreaks.

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Categories of Disease Reservoirs

• Reservoir- Refers to the place in nature where a
  disease normally lives or is always found in
  significant numbers
• Zoonoses- Reservoir of diseases in animals
  (usually other than humans however, don't be too
  offended but epidemiologists consider humans just
  another animal), that can be transmitted to
  humans (e.g. Ebola, Lassa fever, Lyme disease and
  probably the original HIV now the HIV reservoir
  is humans). These are the most common types of
  reservoirs since pathogens are pathogens because
  they metabolize other living organisms who fail
  to appreciate their activities. Rabies is a
  classical case of a nonhuman animal reservoir.
• Inanimate- With few exception, inanimate
  reservoirs are secondary or accidental
  reservoirs. For example, you can catch a cold by
  handling a virus-laden Kleenex or a doorknob
  infected by someone's spit or snot with the flu
  virus, but the main reservoir of cold and flue
  are infected persons. The soil serves as a
  reservoir for pathogens like Clostridium
  perfringens, Clostridium tetani and Bacillus
  anthrax spores, but the ultimate reservoirs again
  are the hosts they reproduce in. Clostridium
  botulinum, as well as some fungal diseases, have
  their reservoirs in the soil and mostly live in
  the soil, probably on dead matter that is,
  living organisms are rare,?accidental hosts.

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Terms associated with Disease Reservoirs

• Disease vector Invertebrates or non-human
  vertebrates, which transmit infective organisms
  from one host to another.
• Fomites Inanimate objects that carry pathogenic
  microorganisms and thus can serve as the source
  of infection. Microorganisms typically survive on
  fomites for minutes or hours. Common fomites
  include clothing, tissue paper, hairbrushes, and
  cooking and eating utensils.

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Terms Continued

• Carrier State The condition of harboring an
  infective organism without manifesting symptoms
  of infection. The organism must be readily
  transmissible to another susceptible host
• Transplantation disease transmission
  transmission of infectious disease as a
  consequence of transplant procedures this
  includes introduction of a new pathogen from a
  source animal into a human or other species or
  from a human introduced into another species
  includes diseases transmitted through
  transplantation of cells, tissues, organs, or
  blood transfusion, etc.

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Animals and Disease Reservoirs

• Animals can act as disease reservoirs.
• Deer carry the bacteria that causes lyme disease
  and can infect humans. Ticks feed off the blood
  of deer and mice and then transfer the disease to
  us when they latch onto us and bite us.

HIV, Ebola, SARS - any of the world's most
horrifying diseases are caused by animal viruses
that made the jump to humans.
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Humans and Disease Reservoirs

• TYPHOID FEVER is caused by Salmonella enterica
  typhi and it typically has a human reservoir. It
  is usually transmitted by drinking (oral
  ingestion) or immersion in water that has been
  contaminated by fecal matter, especially in
  drinking water.

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Transmission

• Infectious agents may be transmitted through
  either direct or indirect contact. Direct contact
  occurs when an individual is infected by contact
  with the reservoir, for example, by touching an
  infected person, ingesting infected meat, or
  being bitten by an infected animal or insect.
• Transmission by direct contact also includes
  inhaling the infectious agent in droplets emitted
  by sneezing or coughing and contracting the
  infectious agent through intimate sexual contact.
  
• Some diseases that are transmitted primarily by
  direct contact with the reservoir include
  ringworm, AIDS, trichinosis, influenza, rabies,
  and malaria.
• Indirect contact occurs when a pathogen can
  withstand the environment outside its host for a
  long period of time before infecting another
  individual. Inanimate objects that are
  contaminated by direct contact with the reservoir
  (for example, a tissue used to wipe the nose of
  an individual who has a cold or a toy that has
  been handled by a sick child) may be the indirect
  contact for a susceptible individual. Ingesting
  food and beverages contaminated by contact with a
  disease reservoir is another example of disease
  transmission by indirect contact.

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Works Cited

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