Granted, this is someone who doesn't know how to interact w ferrets,
but the reasons behind influenza (which ferrets and humans get) being
more common in winter may be better understood now according to the
Live Science article:
1. Colder and drier conditions help the virus survive better between
hosts
2. Those conditions also move away water at the virus, allowing the
virus to remain airborne longer
3. Drier conditions reduce the mucus barrier which otherwise could help
stop infection.
4. Less mucus also means an inability to expel the virus before it can
take hold.

http://www.livescience.com/health/071018-flu-season.html

The study is in PLoS (Public Library of Science, a freely available
source) Pathogens and the full article may be found here:

<http://pathogens.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.ppat.0030151>

Abstract:

BEGIN QUOTE

Influenza Virus Transmission Is Dependent on Relative Humidity and
Temperature
Anice C. Lowen1*, Samira Mubareka1, John Steel1, Peter Palese1,2*
1 Department of Microbiology, Mount Sinai School of Medicine, New York,
New York, United States of America,
2 Department of Medicine, Mount Sinai School of Medicine, New York, New
York, United States of America

Using the guinea pig as a model host, we show that aerosol spread of
influenza virus is dependent upon both ambient relative humidity and
temperature. Twenty experiments performed at relative humidities from
20% to 80% and 5 degC, 20 degC, or 30 degC indicated that both cold
and dry conditions favor transmission. The relationship between
transmission via aerosols and relative humidity at 20 degC is similar
to that previously reported for the stability of influenza viruses
(except at high relative humidity, 80%), implying that the effects of
humidity act largely at the level of the virus particle. For infected
guinea pigs housed at 5 degC, the duration of peak shedding was
approximately 40 h longer than that of animals housed at 20 degC; this
increased shedding likely accounts for the enhanced transmission seen
at 5 degC. To investigate the mechanism permitting prolonged viral
growth, expression levels in the upper respiratory tract of several
innate immune mediators were determined. Innate responses proved to be
comparable between animals housed at 5 degC and 20 degC, suggesting that
cold temperature (5 degC) does not impair the innate immune response in
this system. Although the seasonal epidemiology of influenza is well
characterized, the underlying reasons for predominant wintertime spread
are not clear. We provide direct, experimental evidence to support the
role of weather conditions in the dynamics of influenza and thereby
address a long-standing question fundamental to the understanding of
influenza epidemiology and evolution.

END QUOTE

Alternatively, a person can go to
http://www.plos.org/
select and click on the pathogen journal from the menu on the reader's
right then if it is not coming up on the first page select "more".
There are rotating first pages. At least one contains a direct link
but another is on coral.

Sukie (not a vet)

Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.afip.org/ferrets/index.html
http://www.miamiferret.org/fhc/
http://www.ferretcongress.org/
http://www.trifl.org/index.shtml
http://homepage.mac.com/sukie/sukiesferretlinks.html

[Posted in FML 5766]