Dear Colleagues,
as a follow up to a
posting on skin anomaly observed
in a bottlenose dolphin off La Gomera (Canary islands, see http://m-e-e-r.de/511.1.html ), I
would like to summarize the feedback by many of you. Thanks to
everyone who
provided advice and suggestions. I appreciate that it is very
difficult to
diagnose on the basis of a photographic image.
Persistent remora damage
was suggested by several
researchers. In Hawaii, researchers observed an individual young
Tursiops with
a skin "rash" that looked like the one in our photo. Each time
the animal was seen, it was with an attached remora. In some
remora
species at least, the dorsal sucker disk contains several rows
of modified
spines that actually protrude beyond the flesh of the disk, and
therefore will
penetrate the skin of the host animal. In the case of the
dolphins, this
could cause abrasions of the skin, leading to the apparent rash.
(Good photographic
evidence from Hawaii can be found
at: http://www.cascadiaresearch.org/hawaii/OctNov2011.htm
Others suggested the
lesion could be caused by Blastomyces spp., a kind of
fungi that is found
on stressed (and thus immunodepressed) animals. Another fungal disease which is contagious to humans is
"Lobomycosis", it shows very similar skin irregularities as
seen from
the pictures.
Some colleagues also
speculated about bacterial
infections (e.g. marine vibrios).
Still others thought it
looks like a trauma-induced
condition, i.e. some type of trauma may have abraded the skin
and then an infection,
possibly fungal, may have set in. Again, there would be a
relation to reduced
immune function.
Hence,
vibrio bacteria, Papillomavirus, Herpesvirus, Morbillivirus and
Poxviruses, or
a fungus as well as Parasites could all cause these lesions. I
have to stress
that there were divergent valuations about almost all of these
potential
causes.
So,
as a synthesis, I suggest the following to be the most likely
scenario:
After
the remora can be clearly seen on the image, and given its
location, the skin
of the dolphin may have suffered from its attachment. We have
seen many
emaciated dolphins this year and therefore some individuals
probably are
stressed by missing feeding opportunities, i.e. they were prone
to immunodepression.
In this situation, a damage of the skin (e.g. by the remora or
other causes)
has triggered a secondary infection - either viral, fungal or
bacterial or
through parasites – but a definite identification of the
eliciting agent is not
possible via photographic images only.
If anyone has additional suggestions, we will
be happy to hear them.
Cheers,
Fabian
-- Fabian Ritter -/President- M.E.E.R. e.V. Bundesallee 123 D-12161 Berlin T/F: (0)30-644 97 230 e-Mail: ritter@m-e-e-r.de www.m-e-e-r.org --- The dolphins were having a great relaxed time and there were no major answers they wished to know the questions to... (After Douglas Adams)