Frequently asked questions about Phocone Distemper Virus (PDV)
Nature of the virus and its effects
Risk of infection to humans and animals
Action being taken
Vaccination and Exclusion
Communications
The Nature of the Disease and its Effects
What types of seals the virus is affecting?
COMMON SEAL: Phoca vitulina
Males grow up to 185cm, 130kg: females are generally smaller
GREY SEAL: Halichoerus grypus
Males grow up to 230cm, 310kg: females are generally considerably smaller
How many seals are there?
Both common seals and grey seals are found around the UK coast. There
are currently over 3,000 common seals in the area of the Wash, with small
groups further up the east coast and a few along the south coast of England.
There are large populations around Scotland.
What causes the disease?
The disease is caused by a virus similar to distemper virus caught by
dogs, but distinct from it. It is called the Phocine Distemper Virus (PDV)
because it was first found in phocid seals. The virus incubation period
is 10 to 14 days. The virus is infectious.
What are the symptoms?
Symptoms - None of the symptoms listed are specific or diagnostic for
this virus. Symptoms include respiratory problems - coughing, nasal discharge,
discharge from the eyes. Also, a reluctance to move, subcutaneous emphysema
(air bubbles under the skin) of the head and neck and occasional problems
of the nervous system causing disorientation. Possible vomiting/diarrhoea.
Animals become unable to dive to feed themselves. The disease is confirmed
by blood testing diseased animals or tissue sampling dead animals (which
is why the diagnosis of the UK outbreak took a while). PDV affects the
immune system of the seal, leaving it susceptible to other infections
such as pneumonia.
How does the disease spread?
The disease spreads as infected animals moved around. It spreads between
animals in close contact in the same way a cold spreads in humans - by
inhalation of the virus or through contact with secretions such as mucus,
or faeces. In 1988 the disease spread from Scandinavia. It took 2-3 months
to reach the UK from the original outbreak in the eastern coastal areas
of Denmark. It first spread to the Waddensea around Germany and the Netherlands
and from there it reached the UK, first appearing around July and leading
to high mortalities in August in the Wash.
How many seals died in 1988?
Common seals are far more susceptible to the disease - over 50% of common
seals may die whereas around 10% of grey seals. Around Europe over 18,000
seals died. Around the UK reported counts were:
Scotland: about 1,300
Irish Sea: about 330
South west England: around 50
North east England: around 60
South east England (Suffolk, Kent, Sussex): about 24
East Anglia (The Wash): around 1,300
Estimates were higher, with over 1,500 disappearing from the Wash alone.
What proportion of seals wash up on the shore dead?
In areas such as the Wash where seals haul out on sandbanks away from
shore, sick animals will not appear on the beaches immediately. Most animals
that wash in to the beaches will be dead already. The sick animals will
remain out on the sandbanks and possibly be in extremely poor condition
when they turn up on beaches.
Have there been any cases reported in British waters during this recent
outbreak?
Tissue samples taken from dead seals at the end of July by the RSPCA,
returned positive on 13th August 2002, confirming our fear that the highly
infectious virus is now spreading through the common seal population in
the UK.
What effect will the virus have on our seal population, especially
as it is the breeding season?
In 1988 up to 60% of seals were killed by PDV around Denmark, Sweden and
the Netherlands. The major population of common seals in the Wash was
hit very hard, about 50% or around 1,500 animals died in this area alone.
The scale of deaths in Denmark and Sweden - the estimate on 11 July is
over 1,400 animals dead [updates of these numbers obtainable from Wildlife
Department: 0870 7540 205, or from website www.waddensea-secretariat.org]
- suggests that immunity to the disease is low. The seals in the UK may
also be susceptible. The virus kills adults and pups, and it causes pregnant
females to lose their pups. The recovery rate of infected adults can be
as low as 20%. England could once again lose up to half of its common
seal population. The Wash population was slower to recover than other
populations in Europe though after 14 years it is back up to its pre-PDV
1988 level. There have been small pockets of the disease in common seal
groups since 1988. This may mean that some residual resistance exists
and animals may not be as susceptible as in 1988.
What about grey seals?
Grey seals were far less susceptible to the disease in the last outbreak.
Pregnant females lost their pups and over 100 adults died, but this was
nothing like the scale of the common seal deaths. It would be impossible
to vaccinate the grey seal population.
Is this the first time the virus has threatened the UK seal population
since the 1988 outbreak?
This is the first time the disease has reappeared on this scale since
the 1988 outbreak, however it has been present in small pockets in the
European seal population.
Does it threaten seals anywhere else in the world?
It has been suggested that this disease poses a threat to the endangered
Monk Seal. A remaining population on the Mauritanian coast of Africa suffered
high mortalities a few years ago and PDV was suggested as one of the causes.
However it was not confirmed that PDV caused the mortalities. The virus
also affected the Lake Baikal Seal, a seal unique to this lake in Russia,
in 1988. A similar disease has been found in dead porpoises from the North
Sea.
Is this the worst virus to affect seals (in the UK/worldwide)?
Yes, as far as we know.
What is the worst case/best case scenario when the virus hits?
The disease may kill as many seals as last time - there could be 1500
dead seals in the Wash alone. The animals that survived in 1988 and bred
may have passed on some immunity to later generations however deaths in
Scandinavia suggest that the population has not maintained much immunity.
However seals closer to the UK, e.g. in Belgium, have been more recently
exposed to the virus so there may be sufficient immunity in local North
Sea animals to limit the spread of the disease.
They are wild animals, shouldn't we let nature take its course?
If we let nature take its course it would ensure that the animals that
survived were naturally the strongest. However, large numbers of seals
will be washed up alive and we should act in the interests of their welfare.
This could mean either putting them to sleep, or rehabilitating them.
Does the spread/introduction of the virus have anything to do with
man?
Impossible to say. There is no evidence that the disease came from canine
distemper virus. However there is circumstantial evidence that links the
spread of the disease with pollution.
Is pollution to blame?
There was some scientific research done after the last outbreak that suggested
that there might have been higher mortality rates in areas where seals
were more contaminated with pollutants but a full-scale comprehensive
study was not carried out and results were inconclusive.
Risk of Infection to Humans and Animals
How does the virus spread?
It spreads between seals mainly through coughing whereby other seals inhale
the virus. Dung, mucus and food waste can also harbour residues of the
virus.
Is the virus dangerous to humans?
The virus itself does not present a danger to public health. However,
pathogens such as bacterial infections can develop in the carcasses of
the seals as in other animals, which present a risk to health. It is therefore
advisable not to touch dead seals.
Can I still go to the beach?
There is no reason to avoid the beach as long as you steer clear of any
dead or dying animals on the beach. If the animal is still alive, do not
approach it as it could bite or carry pathogens (other than the virus)
which could be harmful to your health. You should never touch a dead animal
- ring the helpline 08712 447999.
What do I do if I've touched a sick or dying seal?
The virus itself is not dangerous to people, but the seal could be harbouring
other bacterial or viral infections which are transmittable to people.
If you do contract certain symptoms, it is important to tell your doctor
you have been in contact with a sick or dying seal.
How sick can an infected person get? Do drugs exist to treat the disease
in humans?
The virus itself does not transmit to humans. But a seal might be carrying
other bacterial or viral pathogens, which could make you sick. How sick
someone becomes will depend upon the nature of the infection, sometimes
drugs will be prescribed to combat an infection.
Is the virus dangerous to animals?
The virus may infect dogs. Pet owners need to be aware of this. Dogs inoculated
against canine diseases are not at risk.
Do dogs die of the virus?
The virus may be fatal to infected dogs, which have not been inoculated.
As with the seals, some dogs will survive the virus, but they may suffer
brain damage.
Is there a risk of an epidemic among fish or birds?
No, the virus is not transmitted to fish or birds.
Are fishermen or people walking on the mud flats at risk?
The virus does not present a risk to public health. However, like everyone
else, fishermen and walkers should stay away from dead or sick seals because
they may harbour other pathogens.
Is a dead seal a greater threat to health than a sick seal?
It makes no difference. In any case, do not touch, but call the helpline
- 08712 447999. Bear in mind that a live seal can inflict quite a serious
wound on a human.
Action being taken
What is Defra doing?
Drawing on the lessons that have been learned during the last outbreak,
DEFRA is helping voluntary organisations prepare and cope with the PDV
outbreak as it hits UK waters. Discussions have been held about the disposal
and vaccinations options for seal carcasses
and a resulting guidance note can be seen on the website.
Defra have commissioned the Institute of Zoology (Zoological Society of London) to monitor, report and produce information about the progress of the virus. The helpline is funded by DEFRA and the devolved administrations (NAWAD, SEERAD and DoE NI)
We are working closely with voluntary organisations and other government departments these include; The Royal Society for the Prevention of Cruelty to Animals (RSPCA), The Scottish Society for the Prevention of Cruelty to Animals (SSPCA), The Institute of Zoology (IOZ), Scottish Executive Environment Rural Affairs Department (SEERAD), National Assembly of Wales Agriculture Department (NAWAD), The Department of Environment (Northern Ireland) (DoE NI), The Sea Mammal Research Unit (SMRU).
What is the Institute of Zoology doing?
As part of a £250,000 project The Institute of Zoology (IoZ) have
been commissioned to:
- Establish systematic survey and reporting of stranded seals nation-wide,
referring reports of live animals to the welfare organisations
- Carry out post-mortem and sampling of dead seals to establish levels
of PDV infection
- Estimate the current susceptibility of UK seals to the disease, and,
with the assistance of SMRU, predict the impact of the outbreak as it
develops
- Monitor progress of the disease and produce information updates and
forecasts of seal mortality to Government and the public
- Provide a source of scientific information to assist with media enquiries.
Work has now started. Volunteers are rapidly being recruited for the systematic surveying of seals around the UK and it is hoped that the systematic surveying will begin next week.
What is the RSPCA doing?
The RSPCA Norfolk Wildlife Hospital, which is the focal point for treatment
of affected seals, is still waiting for results of samples taken from
a further 20 sick seal pups currently in care in its isolation unit. The
Society has already scaled down normal operations and prioritised manpower
to the affected areas on the English coastline to deal with the high number
of seals that could be seriously taken ill or die as a result of the virus.
Over the last few weeks, the hospital has seen a higher than average mortality
rate among pups. The RSPCA Norfolk Wildlife Hospital is currently the
only facility in the country taking in sick, potentially infected seals,
which RSPCA staff are collecting from beaches. The RSPCA is also collaborating
closely with the voluntary group, British Divers Marine Life Rescue, to
survey the seals in the Wash for widespread signs of sick or suffering
animals.
Can sick seals be brought in for treatment?
It is very difficult to catch healthy seals, so animals that are readily
captured are usually already very ill. Some of these animals will already
be close to death and beyond treatment, so immediate euthanasia is recommended.
Less severely affected animals may be suitable for transport to rehabilitation
facilities.
What is the survival rate of seals brought in for treatment?
In 1988 the RSPCA Seal Assessment Unit was established at Docking in Norfolk
to cope with the outbreak of PDV. 88 animals were brought in to this facility.
65 died and 23 were eventually released. 74% of animals brought in for
treatment died.
Does the RSPCA have facilities for treating seals?
The RSPCA Wildlife Hospital in Norfolk has specialist seal treatment facilities,
and was established specifically in response to the 1988 outbreak when
no facility of the type existed.
Vaccination and Exclusion
Can healthy seals be vaccinated?
There is a vaccine against PDV but this cannot be administered easily
to the currently healthy population - the animals are very difficult to
catch. They are also breeding. Any attempt to pursue/catch animals will
cause adults to flee from the breeding beaches. There is a high risk that
this will lead to pup abandonment. Seals currently in rehabilitation facilities,
such as orphaned pups, can be vaccinated against PDV if the vaccine is
available. Although it is proving very difficult to get hold of any PDV
vaccine. Details of the vaccination options are available in a guidance
note, which conclude that this course of action is not appropriate
at this stage.
What should I do if I find a dead or live seal? Who do I phone?
It is important that people report any dead or alive seals, which have
been washed ashore immediately. They should phone the dedicated helpline
on 0871 2447999 and it is crucial they have the following details:
- Precise location of the animal
- Time and date
- Symptoms they observed
They should never approach a sick seal and should keep dogs well away - they could contract the disease
Are there any other damage limitation techniques?
None. It is unacceptable to reduce the number of seals. Even such a cull
would not prevent the disease spreading as common seals group together
at this time of year to pup and moult. Even when the population density
is low seals regularly come into contact with one another, even over considerable
distances.
What happens to the washed up seals?
Once a sick or dead seal has been reported then experts will take a decision
about the most appropriate course of action, sick seals may be removed
to a rescue centre for treatment and carcasses will be disposed of in
the most appropriate way. A guidance note explaining
the disposal options for seal carcasses can be found on the DEFRA website.
Can the seals be moved to another location?
This is not feasible. There is no guarantee that we would be moving healthy
seals - they could already be incubating the disease so we could actually
be contributing to the spread. Seals move very widely naturally. The disease
will inevitably reach seals if they are susceptible.
Can I take a seal home and look after it?
No, it would be an offence and in any case would be very unwise. Only
expert rescue centres can provide seals with the proper care and attention
that is needed.
Can I help, perhaps by taking care of sick seals?
Rescue centres do sometimes need help from volunteers. Further information
can be found on the RSPCA
website
Can I donate money to support seal rescue efforts?
The RSPCA is a charity and welcomes all donations. Further information
can be found on the RSPCA
website
Communications
How are the public and visitors to the area informed?
A press release has been issued by Defra.
Information concerning the disease can be found on the following websites:
RSPCA - www.rspca.org.uk
The Dutch website - www.minlnv.nl
- under zeehondenziekte
Institute of Zoology - www.ioz.ac.uk
Sea Mammal Research Unit - www.smub.st-and.ac.uk
Page last modified: 9 October 2002