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A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Wed 30 Jun 2010
From: Marcela Uhart
[Re: ProMED-mail Die-off, right whale - Argentina: (CH) RFI 20100630.2179]
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Since 2003, when the Southern Right Whale Health Monitoring Program
(SWRHMP) was established by a consortium of local NGOs, a total of
366 right whale deaths has been recorded, with peaks in 2007 (83),
2008 (95), and 2009 (79). Most (91 percent) of the dead animals have
been 1st-year calves. Necropsies conducted on dead whales have been
performed following internationally recognized standard protocols.
Samples for histopathology, serology, nutritional status,
contaminants, infectious disease and biotoxin diagnostics, genetics,
stable isotopes and fatty acid composition analysis, have been
collected, archived, and distributed to analytical laboratories.
Since 2003, nearly 3500 samples have been collected by the SRWHMP.
Over the past 7 years, gross necropsy examinations have provided
information on the cause of death for only 7 animals. This has
included blunt-force trauma (that is, rough-surf injury, boat
strikes, blows from whales), chronic degenerative lesions of the
spine, and dystocia. Given rapid decomposition of dead whales and the
fact that they come to shore at variable times after death, good
samples for histopathology have been collected on a limited number of
carcasses (approximately 20 percent of total dead whales each year).
Histologic examination has been performed on 53 of the 366 (14
percent) right whales (majority condition code 3 or 4). In these
animals, establishing a cause of death has been variably limited by
tissue preservation and availability. A variety of histologic lesions
(typically mild) have been identified in examined tissues; however,
common significant lesions or pathologic processes (such as,
infectious disease) to explain the yearly or recurrent strandings
have not been identified.
Scars and wounds from gull attacks have become an increasingly common
finding on the backs of right whales at Peninsula Valdes and are seen
in approximately 80 percent of calves. Gulls could potentially act as
vectors for infectious disease transmission or bacterial toxin
transfer. Samples of gull peck lesions have been available for
histological examination from 6 dead calves. Of those 6 samples,
wounds in 3 of the animals were associated with local inflammation
and a disseminated process, possibly related to gull peck wounds, was
present in one of these 3 animals.
Blood suitable for infectious disease serology was available from 4
calves sampled between 2004-2009. These samples were negative for
brucellosis, leptospirosis (18 serovars), influenza type A,
morbillivirus panel, and seal herpesvirus (only tested on animals
stranded in 2009). Two calves sampled in 2004 and 2005 were
serologically positive for canine herpesvirus. Mass tag (respiratory
and pan viral panels) was run on serum from 2 animals from 2009 with
negative results. Pathogens included in the respiratory panel were:
_Haemophilus influenzae_, _Chlamydophila pneumoniae_, _Neisseria
meningitis_, _Streptococcus pneumoniae_, _Legionella pneumoniae_, and
_Mycoplasma pneumoniae_. Those included in the pan-viral panel were:
adenovirus, influenza A & B, RSV [respiratory syncytial virus] A and
B, coronavirus, HPIV [human parainfluenza viruses] 1 to 4,
metapneumovirus, enterovirus. PCR for _Brucella_ sp. on ovary,
spleen, testicle, and lymph nodes was negative for 26 whales examined.
Although a limited number of samples have been tested for heavy
metals and other pollutants like organochlorines, these are likely to
be of little significance given the low trophic level and
predominantly offshore feeding habits of southern right whales.
Biotoxins from harmful algal blooms have also been considered
potential causative or contributing factors in the whale mortalities.
Blooms of the toxic dinoflagellate _Alexandrium tamarense_ and the
diatom _Pseudonitzschia_ sp. have occurred at Peninsula Valdes from
2005 through 2009; however, they have not been temporally associated
with the highest peaks in whale mortality in any year and there were
no observed die-offs of other marine mammals, marine birds, or fish
during these times. Also, although traces of domoic acid were found
in the blood of one adult female and one calf in 2005, an additional
90 samples collected from 28 dead whales since 2007 tested negative
for domoic acid and paralytic shellfish poison.
While many samples and much information has been gathered to date,
additional data are needed to determine the causes for the recent
deaths. Ongoing monitoring for independent,
multifactorial/interrelated, or concurrent disease processes,
including infectious, toxic or nutritional disease, genetic or
environmental factors including food availability, and maternal and
calf fitness are critical for establishing the cause(s) of the recent
recurrent, significant mortality of young right whales at Peninsula Valdes
A full report on the southern right whale die-offs can be found at
the International Whaling Commission website,
Note: The Southern Right Whale Health Monitoring Program (SRWHMP) is
a collaborative effort of the following NGOs: Wildlife Conservation
Society, Whale Conservation Institute, Instituto de Conservacion de
Ballenas, Fundacion Patagonia Natural, and Fundacion Ecocentro.
--
Marcela Uhart
Wildlife Conservation Society, Associate
Director Global Health Program,
Latin America. Supervisor
Southern Right
Whale Health Monitoring Program
[This is a very thorough response regarding the situation of the
right whales. Dr Uhart has presented their findings and it clearly
represents an extensive investigation into a situation that is still
baffling to everyone.
ProMED-mail wishes to apologize to our readers as this email has only
recently been brought to the attention of this moderator. ProMED-mail
also wishes to thank Dr Uhart for the continued diligence to get this
report to us. - Mod.TG]
[see also:
Die-off, right whale - Argentina: (CH) RFI 20100630.2179]
...................................tg/mj/dk
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