Just An FYI:
Hantaviruses are newly recognized in the "new world", several strains
have been known in the "old world" for a long time. The old world
strains cause a different clinical presentation called HFRS (hemorrhagic
fever with renal syndrome). The HFRS strains affect thousands of
people in Asia & Europe every year (China reports 40,000-100,000
cases per year), and those people in the USA who were connected
in one way or another to the Korean Conflict may have heard the
word "Hantavirus" because both native Koreans and U.N. troups were
affected by the HFRS strains.
The word "Hantavirus" in the new world is primarily connected to
previously unrecognized strains and a newly recognized clincal presentation
which affects the lungs and is called "HPS" (Hantavirus Pulmonary
Syndrome).There have already been four strains identifed in the
United States which affect the lungs, and many other strains which
have not been associated with human illness. Each strain appears
to be rather host (rodent) specific, and the strain causing most
publicity and most human illness is called "Sin Nombre" and is primarily
associated with the Deer Mouse; the Deer Mouse is found in most
parts of North America except for the Southeastern U.S. Habitat
studies (11 different biomes @ 13 sites) done in 1994 in Arizona
found Deer Mice infected with "Sin Nombre" throughout the state,
from the North Rim of Grand Canyon to the lower Sonoran desert;
in other words, all over the place.
Over 270 HPS cases have been reported in the U.S., with a distribution
of 31 states. HPS does not get its reputation because it affects
a lot of people, it gets its notoriety from what it can do to you.
Since 1994, the case fatality rate has improved, but is still over
30%. Is it worth avoiding contact with rodents? Always has been,
even before we knew about HPS. The Deer Mouse is also a significant
resevoir for plague and other diseases. HPS is a special problem
because the body has to beat the virus, and most persons infected
will require specialized hospital support systems during the process.
The CDC's All
About Hantavirus web page is highly recommended.
To date there has been one case of HPS epidemiologically connected
to the bottom of Grand Canyon, 31 cases in Arizona, 6 cases in Coconino
County (1 fatal), with 1 case in the County this year. There will
be ups and downs with Deer Mouse populations, and not all Deer mice
are necessarily infected, but since they don't get sick from it,
why take the chance. The virus is shed in the urine, saliva and
feces of infected mice. The virus is known to have an airborne transmission,
and human cases have primarily been connected to enclosed areas
with poor ventilation. The virus is highly susceptible to sunlight.
The jury is still out on whether or not ingestion is a possible
mode of transmission; another reason to keep our food out of reach
of the rodents while backpacking.
Worth taking some precautions? Odds look real good, but statistics
won't mean much if you (or someone close) is the victim!
Our group encountered lots of mice (nothing new) during our Deer
Creek/Tapeats Creek trip in October; perhaps that had something
to do with seeing 3 rattlers on the river route?
December 12, 2000
Blair Davis works with zoonotic diseases in his job at the Coconino
of Health Services.