Message #215:
From: AzTeC SW Archaeology SIG
To:   "'Matthias Giessler'" 
Subject: Chacoan Mice Cause the Great Puebloan Fall?
Date: Tue, 09 Jul 96 12:20:00 MST
Encoding: 190 TEXT

[Some years ago the book "Hitchhiker's Guide to the Galaxy" humorously 
posited that life on earth simply was a giant experiment directed by white 
laboratory mice.  Based on the information provided below, the old archy 
fieldschool song about who caused "the great Puebloan fall" may need 
revision, or at least a new stanza of verse ]


 -- SASIG Ed.


From: Michael "Smoke" Pfeiffer

From: Charles Calisher

Nancy Hawkins forwarded to me the interesting conversations about 
hantaviruses and their possible relationship with flight from Chaco. 
Nancy's husband and my wife attended graduate school together (they are 
psychologists); that's how I know her.  I am a virologist, so the comments 
that follow are virologically sound but archaeologically without standing. 
That is, I am outstanding in my field but my wife says I am "out, standing 
in my field."  It is hard to get a wife to take one seriously; they know us 
too well.  Nonetheless, I am not shy, so I am writing to fill in some blanks 
here and there and perhaps provide a bit of enlightenment about 
hantaviruses. First a bit of background about hantaviruses.

1. Within the (very large) virus family Bunyaviridae are five genera. One of 
these is the genus |Hantavirus|.  There were eight recognized hantaviruses 
when I got to work this morning but there might be more by now because these 
things are being discovered at an awesome clip, certainly because of the 
interest in Hantavirus Pulmonary Syndrome.  The first recognized hantavirus 
likely (all we know is from atncient Japanese military records) is what we 
call Hantaan virus.  This was isolated in 1976 from a patient with Korean 
hemorrhagic fever and the discoverer of the virus, Ho Wang Lee, named the 
virus after the river that divides north from south Korea.  The disease KHF 
has been called Hemorrhagic fever with renal syndrome in Russia and 
elsewhere in Europe and Asia and is known as Epidemic hemorrhagic fever in 
China-- all the same thing and all caused by the same virus.  There are at 
least 50,000 cases of HFRS each year.

2. After the tehniques for isolating Hantaan virus became more well- known, 
other hantaviruses (the generic term for any virus within the genus) were 
isolated.  One, Puumala virus, was isolated from bank voles (|Clethrionomys 
rutilus|) and causes Nephropathia Epidemica, a milder form of HFRS, in 
northern Europe.  Seoul virus was isolated from a rat in Seoul, Korea and 
has been associated with human illness; variants of Seoul virus have been 
isolated from rats in port cities in many countries, including the U.S. 
(Baltimore, New Orleans, Houston, Philadelphia, included).  Prospect Hill 
virus was isolated from a meadow vole (|Microtus pennsylvanicus|) in 
Maryland but has not been associated with human illness... and so on-- 
clearly, there is an association of individual virus types and individual 
species of rodents.

3. If you are still awake, read on. It gets better.

4. When the 1993 epidemic of Hantavirus Pulmonary Syndrome (HPS) occurred in 
the Four Corners area (where Arizona, New Mexico, Colorado, and Utah meet), 
hantaviruses were not suspected because these viruses had been known to 
cause human illness with primarily renal involvement; HPS is a primarily 
pulmonary disorder.  So the hantavirus etiology of HPS was a surprise to 
everyone.  The mortality rate for HPS is about 50%, yet few people have been 
shown to have antibody.  This suggests high mortality, low infectivity, 
which may have some archaeological significance in light of the questions 
asked by James Carucci.

It soon became clear that the deer mouse, |Peromyscus maniculatus|, the most 
common mammals in North America, is the vertebrate host of a hantavirus that 
causes HPS.  This virus has now been isolated and named Sin Nombre virus, a 
place location, not a comment.  Other hantaviruses have been isolated from 
or detected in western harvest mice, rice rats, cotton rats, white-footed 
mice, and other rodents, each virus being associated with a distinct species 
of rodent.  Whereas rice rats, cotton rats, and harvest mice do not occur 
peridomestically, deer mice and white-footed mice are known to live side by 
side with humans, particularly those who store corn, grains, and other dried 

5. I retired from the Centers for Disease Control in 1992, having been the 
Director of the W.H.O. Reference Centre for Arbovirus (arthropod- borne 
viruses) Reference and Research but I had had some experience with 
hantaviruses, which are not arthropod-borne but are related genetically to 
viruses which are.  Shortly after I came aboard at Colorado State 
University, the outbreak of HPS occurred and we obtained funding from the 
CDC/Atlanta to pursue longitudinal studies of Sin Nombre and other 
hantaviruses in rodents in Colorado.  This is a rather large area and it 
would be impossible for us to cover all of it, so we focus on three sites: 
one on an Army facility in southeastern Colorado, one on C.S.U. property in 
southwestern Colorado, near Durango, and one in west central Colorado, on 
private property east of Grand Junction; the latter two sites were chosen 
because of their proximity to fatal human cases, the former because it is 
gorgeous and in the middle of a short-grass prairie.

Each six weeks we travel to each site and trap, measure, examine, comb, and 
generally annoy our furry little friends.  We then ear tag them, take blood 
and oropharyngeal swab samples, and release them.  We are learning a great 
deal about rodents and about hantavirus transmission.

6. When I first heard of the etiology of the HPS outbreak in 1993, I 
wondered whether this virus might have been the etiology of the dispersal of 
Chacoans.  My wife and I are not nearly even amateur archaeologists but we 
have spent some time in the Four Corners area and we do read without moving 
our lips.  I knew the exodus from Chaco supposedly was over a brief period 
of time and that a drought had occurred about that time.

Droughts do not cause hantavirus outbreaks.  One of the things we have 
learned from our longitudinal studies is that rainfall is critical.  In 
brief: rain -- plants -- chemicals in plants that initiate breeding cycles 
in rodents -- breeding cycles -- breeding -- susceptible young rodents. 
 Much of the rodent transmission of Sin Nombre virus can be attributed to 
fighting among male rodents but when there ain't nothing to fight about, 
there ain't much fighting.  That is, when there is no water there must be 
another mechanism by which Sin Nombre virus persists.  We think it is 
persistent (life-long) infection, rather than acute infection.

>From my many visits to archaeological sites in the Four Corners area, I know 
that people lived closely and that they stored corn and grains near their 
living quarters.  I have seen the small corn cobs that still remain and I 
have found thigh bones of what appear to have been rodents among the 
detritus of those communities.

Molecular epidemiologic studies of North American and other hantaviruses 
indicate that evolution takes place rather quickly.  My guess is that if 
there was a hantavirus at Chaco Canyon, it isn't there any longer.  However, 
it would not be unlikely that a near relative of that virus still persists. 
I would be delighted to trap rodents at Chaco Canyon, Canyon de Chelly, 
Betatakin, Hovenweep, and Keet Seel and see what is there in the way of 
hantaviruses.  I know that CDC did a serologic survey in National Parks 
after the 1993 experience but I do not have in front of me the details as to 
which areas were tested.  Should anyone ask, I will be in the truck in a 
matter of hours.

7. The 1993 outbreak might have been a new recognition but hantaviruses are 
not new to the Americas.  The deer mouse does not occur in certain areas 
where hantaviruses have been found and in which human disease has been known 
to occur.  Therefore, not all North American hantaviruses are carried by 
deer mice.  Hantaviruses have been isolated or evidence for their presence 
has been obtained in Brazil, Argentina, Bolivia, Costa Rica, Mexico, etc. 
 These things likely have been around a long time and it was only the small 
epidemic burst that brought our attention to them.  Retrospective diagnoses 
from frozen materials indicate that people have been
dying of hantavirus infections in the U.S. since at least 1959.  Why not 
since 1259?

But does this mean that the people cleared out of Chacho Canyon because of a 
hantavirus epidemic?  Given that there does not seem to be human-to-human 
transmission, this is unlikely.  The mortality rate of Sin Nombre virus in 
rodents is zero but the mortality rate in humans is about 50%.  A case here 
and there might not have been noticed as a pattern in an early culture.

8. I do not understand the question by Carucci regarding the pattern of 
death, panic, and abandonment that might have occurred at Chaco.  I would be 
grateful if someone could tell me whether there are "burned pithouses with 
human remains, and rapidly abandoned pueblos with bodies in some rooms, corn 
and beans still stored in others".  My understanding is that the Chacoans 
left rather quickly but that whereas they did leave some corn, beans, pots, 
and other small items, they did not leave behind burned bodies and there is 
no evidence of a large human die-off at that time.

9. As for Richard Currit's comment about Navajo verbal admonitions, I wish I 
could see some book written in 1200 by a Navajo.  There being none, all we 
have to go on are what people say has been said.  I have a hard time with 
such "data".  Indeed, how do we know that anyone says anything any time, 
without a publication of some sort?  Nonetheless, I have "heard" that Navajo 
shamans had suggested keeping house and food storage areas clean and free of 
mice or "it will take your breath away".  I have also "heard" that Navajos 
believe heavy rains lead to pneumonia. Tough to trace this back 

I do go on, don't I?  Sorry.  This response should be enough to get Nancy 
kicked off the Archaeology List.

For anyone who would like more information about hantaviruses: let me know 
and I will either provide it or, if I cannot, send you to a person who can. 
If anyone has any publications reporting ancient wisdom of the Navajos, of 
course, please let me know.

Finally, don't stick your nose in any dusty places.

Charles H. Calisher, Ph.D.
Professor, Department of Microbiology
Arthropod-borne and Infectious Diseases Laboratory Foothills Campus
Colorado State University
Fort Collins, Colorado 80523
TEL: (970) 491-8604