Ask A Scientist© Molecular Biology Archive

 name        Heather

Question -  How do Animal's spread diseasis to Humans?

>An infectious disease that is spread to humans by
>animals is called a zoononis. The animals are the
>reservoir for the micro-organisms, and may or may not
>suffer from the infection. One common route is
>fecal/oral, which means fecal contamination of water
>or food spreads contagious microorganisms. For
>instance direct contamination with fecal material from
>cats can cause toxoplasma infections to humans.
>Anohter example: certain Leptospira infections are
>caused by (recreational) water contaminated with
>excrements from rodents.  Contamination of food
>products of animal origin, like meat, milk and eggs,
>is another common route. Food products are often
>contaminated during slaughter and processing
>procedures. Some diseases are spread by  insects that
>live on humans and animals (with Plague as a classic
>example). Rabies is spread by bites of the infected
>animals themselves. There are fewer examples of
>diseases spread by droplets (aerosols) directly from
>animals (mammals or birds) to humans. Since humans are
>just another species of mammals, each possible route
>of transmission between hosts has been explored by
>certain infectious micro-organisms.
>
>The latest catastrophy are prion-caused diseases like
>Scrapy (in sheep) and BSE (in cattle) that apparently
>can spread to humans by consumption of infected
>meat/organs, as we have seen in the UK the last few
>years. In this case the contagion is not a
>microorganism but a protein that is wrongly folded,
>and forces our own proteins to fold in the same, wrong
>way.
>
>Trudy Wassenaar
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