Are we prepared for the emergence of new diseases? - Veterinary Practice
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Are we prepared for the emergence of new diseases?

Periscope continues the series of reflections on issues of current concern.

AT the time of writing the World Health Organisation (WHO) has declared the Ebola virus outbreak in West Africa to be an International Health Emergency. So far this year, more than 930 people have died from the disease across Guinea, Liberia, Nigeria and Sierra Leone.

Mortality rates from Ebola virus infection can reach 90% though in the current outbreak it is considerably lower than this at around 55%. The real significance of this outbreak, however, is that it is to date the largest by far with more than 1,700 cases reported, already more than four times the number of any previously recorded epidemic.

Ebola virus first came to light in 1976 when two simultaneous outbreaks occurred in Sudan and Democratic Republic of Congo, the latter in a village near the Ebola river from which the virus takes its name.

The Ebola genus belongs within the family Filoviridae and there are currently five distinct species listed on the WHO website: Bundibugyo, Zaire, Reston, Sudan and Tai Forest. The first two of these, plus the Sudan species, have been associated with large Ebola virus outbreaks in Africa whilst the other two have not.

Increasing regularity

From 1980 to 1993 no Ebola virus infections of humans were recorded but since 1994 they have occurred with regularity and in more years than not. Perhaps something of a warning then that until now had largely gone unheeded in the Western world, consigned to the school of thought that this was something that happened in faraway places with little relevance to our own well being. All that may now be about to change.

International air travel has transformed the significance of viruses such as Ebola. Whilst the risk of transmitting diseases in this way has long been recognised, the sheer volume of two-way traffic between West Africa and Europe and beyond has increased dramatically since the emergence of this particular disease.

Much of Africa has developed considerably in the last 40 years and countries such as Nigeria now have an enlarging middle class with considerable spending power and historic and familial ties with the UK and other European countries. Diseases such as Ebola can no longer be dismissed as something that happens “over there and poses no threat to us here”. The world has shrunk both in metaphorical and real terms.

Ebola is not primarily a human virus. The reservoir of infection is believed to be in fruit bats of the Pteropodidae family and the virus spills over into other animals such as non-human primates, forest antelopes, porcupinesand, of course, humans.

Outbreaks in people usually start through the handling or consumption of infected wildlife, followed by human to human spread through close contact with infected blood or other body fluids, or contact with an environment contaminated with such fluids.

Health-care workers are at great  risk when treating suspect or perhaps unknown cases of Ebola virus, particularly where appropriate protective clothing is in short supply. There is currently no licensed vaccine that can offer protection against the disease.

We are all familiar with animal viruses that spill over into humans. Avian influenza and swine influenza are two of the best known examples along with yellow fever virus and the equine encephalitides. Rabies too, of course, though this is generally a more visible disease in those countries where it remains endemic.

Viruses such as Ebola, however, can disappear from the human population (whilst remaining within the animal reservoir) and as a result drop off the radar. Only when they re-emerge as Ebola has done this year do they begin to concentrate minds and wake up those in positions of power to the potential threat posed by them.

Hoping for funds

It is to be hoped that through the WHO designating the current outbreak to be an International Health Emergency, sufficient funds will be made available not just to contain the present alarming situation but to also fund research into the search for and production of an effective vaccine.

Completely new viruses or new strains of already well documented viruses are constantly emerging. The world human population is at unprecedented levels and continues to increase. The number of people per square kilometre in our cities, particularly those in developing countries, has never been greater and represents a naive and potentially susceptible population to any new pathogens.

As a species we are probably more vulnerable to a disease pandemic than at any time in our history because of the rapid and constant movement of people over vast distances.

Taking all this into account, it would seem to be not just sensible, but indeed essential, that surveillance for the emergence of new diseases in both human and animal populations should become a priority and be given the sort of government funding that recognises its importance.

Short-term savings, such as are to be gained by the closure of AHVLA laboratories and the tendering for TB testing (that will surely be awarded to the lowest bidder) fail to look at the big picture and at what is really needed to fully keep abreast of the situation in the field.

The WHO has recognised the importance of the current Ebola virus outbreak and at a recent two-day emergency meeting in Switzerland called for a co-ordinated international response to curtail the spread of the virus. This is probably not a moment too soon since the possibility of
someone turning up at a British (or
other European) airport on a flight
from West Africa and exhibiting signs
of Ebola virus infection is a very real

Fortunately, Ebola virus containment
is relatively easy so long as the
equipment, facilities and trained personnel are in
place to implement
the necessary
measures. That
is not necessarily
going to be the
case with emerging
diseases of the
future and there
have been scares
(thankfully short-lived) with the likes of swine flu and
SARS in the relatively recent past.

So far we seem to have got away
with it but that may be down more
to luck than to judgment. We cannot
afford to be complacent. Thorough
and active surveillance for emerging
diseases (for some of the reasons
already mentioned) is probably the
most important step we can take to
ensure the survival of life as we know
it and to safeguard future human

Those in positions of influence
should be telling this to our politicians
in no uncertain terms.

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