IUBio Biosequences .. Software .. Molbio soft .. Network News .. FTP

Brown rats, black rats, spotted fever

Robin M. Weare persepha at csulb.edu
Thu Dec 12 09:09:51 EST 1996


>         One explanation for the dwindling of the Bubonic Plague in
Britain
> has been that the native black rats were replaced by the European brown
> rat.  A friend of mine and I have been batting this around.  Does anyone
> know whether we have native black rats or brown rats in America?  I assume
> that our domesticated rats are bred from the brown ones.  

In North America, we have both black rats and brown rats. Brown
rats tend to live in sewers and basements, while black rats (also
called "roof rats"> live in attics, roofs, and (at least here in
Southern California) trees. The two species CAN coexist, by
occupying separate habitats.

OTOH, it may be that by ousting the black rat from the levels
where it came into closest contact with humans, the brown rat
may have reduced human exposure to black rat fleas. Black rats
and brown rats have separate species of fleas, and while both
fleas can spread bubonic plague, supposedly the brown rat flea
is more reluctant to bite humans.

But at least in Europe, a major factor behind the waning of
black plague may have been the switch away from thatched roofs,
at least in the cities such as London. Thatched roofs are
perfect black rat habitat, and the rodents' dung and fleas
can rain down on humans living inside.

I've heard conflicting claims about which species the domestic
rat is, but I believe it's from the brown rat.

> Are spotted fever
> and bubonic plague the same thing?  Defoe mentions both names in his
> Journal of the Plague Year.  The friend at church did not have rocky
> mountain spotted fever unless there is something important I don't know
> about it.  Her baby was in a coma six hours after contracting it.

To the best of my non-expert knowledge, no, they are not the same
disease.

Incidentally, once bubonic plague infects the lungs, it can be
spread via the breath. It no longer relies on fleas for propagation.

Robin M. Weare
California State University, Long Beach





More information about the Virology mailing list

Send comments to us at biosci-help [At] net.bio.net