Anthrax: Key Facts
In
this issue, we take a short break from exploring creativity
in animal intelligence to discussing some pertinent observations
about anthrax.
Introduction
Anthrax is a disease that mainly affects ungulates or in
other words cloven footed animals like domestic and wild
herbivores. Animals that are most likely to suffer from
anthrax under natural circumstances are all the grass eating
animals like elephants, deer, cattle, sheep, goats, pigs
etc. However, it may be noted that all animals can suffer
from anthrax. Humans of course are as vulnerable to anthrax
as any other species. However, understanding anthrax becomes
simpler if you know some key facts about how the disease
occurs, the manner in which it is spread and preventive
and treatment measures.
Causative
organism
Anthrax is fortunately not caused by a virus. It is a bacterial
infection caused by a bacteria called Bacillus anthracis.
Under the microscope, the organisms appear like small elongated,
rectangular structures. Microbiologists describe the bacteria
as having a rod shaped form, covered by a capsule and with
an ability to form spores.
However,
although anthrax is caused by bacteria, the disease is considered
a deadly and dangerous one because, often affected people
and animals simply do not survive long enough to get treatment.
This form of anthrax is the most dangerous and is called
the peracute form.
Once
the bacteria enter the body, it attacks and in a matter
of a few hours, affected individuals may be found dead.
There may be no external signs or symptoms except sometimes
a slight swelling of the neck or dark, tarry looking blood
oozing from the natural orifices like the ear.
Spore
formation
An unusual feature of this bacteria is that it can convert
to another form called sporulated form and remain dormant
in the soil for years. In the sporulated form, what really
happens is that the bacteria acquire a small capsule like
structure which protects it from heat, drying up, excessive
humidity, rainfall and other environmentally adverse conditions.
Climatic
conditions
Therefore, scientists and doctors who study anthrax and
its method of spread have marked out certain areas where
the disease is more likely to spread. In fact, in some villages
and towns where people are very vigilant, most of the towns
folk can almost correctly predict when the next anthrax
outbreak is likely. This is because they are basing their
conclusions on observations like the humidity, a hot dry
summer followed by a heavy rainfall. High soil temperatures,
high humidity, severe drought and alkaline soil can also
precipitate an outbreak of anthrax. Anthrax is a very dangerous
disease because the spores can remain dormant in the soil
for very long periods of time, sometimes for even as long
as 15 years or even longer.
Methods
of spread
There are many different methods by which anthrax may be
spread - besides the current reports of spores being sent
in letters and personal mail. The earlier conventional and
natural methods by which anthrax was spread included the
following:
Drinking
of water and food contaminated by anthrax.
Through contact with wounds of anthrax affected animals
and individuals.
Through the bites of the large biting flies seen in stables
and barns. The biting flies are different from the houseflies
Through inhalation: anthrax spores can be breathed in to
cause the deadly disease.
Vaccination: In some cases of vaccination failures, the
spores which are injected to provide protection to the animal
can get reactivated and cause the disease. Other ways in
which anthrax can be spread include: by the movement of
wild animals and birds, especially those species that scavenge
on the carcasses of anthrax infected dead animals. Contaminated
hides, bone meal, hides and wool. In earlier days, the people
who worked in the wool shearing and sorting industry were
most vulnerable to getting infected with anthrax. The chances
of coming down with the disease was so high and so common
that anthrax was also referred to as wool sorter's disease.
The disease was also called as splenic fever or charbon.
Time
period for appearance of disease
The time from being exposed to the disease to actual appearance
of infection may be as short as one day or it may be as
long as two weeks. However, when the disease is transmitted
by biting flies, the time period may be as short as one
or two days.
Common
signs in domestic animals
Normally, death occurs within 12 -36 hours after the appearance
of symptoms.In most of the cases, no signs or symptoms may
be seen. This form where death of the animals occurs within
a few hours of the appearance of signs is called the per-acute
form. The animal may just collapse with a slight swelling
around the neck or tarry, blood oozing out from the natural
orifices like the ear etc. In animals that survive a little
longer, there may be a slight rise in temperature, depression,
diarrhoea, difficulty in breathing and in cattle a swelling
in the brisket, flank and throat. In horses, in addition,
colic may be seen. In dogs pharyngitis with swelling of
head, neck and face may be more prominently seen. In birds,
swelling of the throat, wattles, comb and head along with
dysentery, fits and fever may be seen . Anthrax is extremely
rare in cats although they too can get anthrax.
Precautions
If you suspect any animal to be suffering from anthrax,
immediately quarantine the animal from all the other affected
animals and contact your veterinarian immediately. Avoid
eating foods containing any animal products. Always make
sure that the leather shoes and jackets and woolen garments
are purchased from very reliable and quality conscious manufacturers.
Avoid using any canned food, either for yourself or for
your pets. Talk to your doctor and veterinarian and find
out whether outbreaks of anthrax have occurred in your neighbourhood
in the past few months or years. Check the soil and water
in your garden or farm for pH and presence of anthrax spores.
If
you suspect any animal in your neighbourhood or belonging
to you to have died of anthrax, do not open the carcass.
Consult your veterinarian immediately. If the carcass is
opened, spores will be formed, then the spores will persist
in the environment and soil for long periods of time, varying
from a few months to several decades.
If
you have a lot of pets or farm animals living on your farm,
consult your veterinarian about vaccination schedules.
Vaccination
For some decades now, several vaccines have been available
to help protect animals and humans from anthrax. A significant
degree of reduction has been noticed in many affected countries
of the world with the use of vaccination. However, vaccination
like any other invasive medical intervention process carries
its own set of small risks like the occurrence of adverse
events and the likelihood of spores being reactivated and
an anthrax outbreak occurring. Consult your veterinarian.
Compulsory
vaccination for all US military personnel
The U.S. Department of Defense (DoD) on December 15, 1997,
announced that it was mandatory for all US military personnel
to be vaccinated. Under the Anthrax Vaccine Immunization
Program (AVIP) until April 12, 2000, 425,976 service members
had received 1,620,793 doses of anthrax vaccine adsorbed
(AVA) (Bioport, Inc., Lansing, Michigan).. AVIP plans to
have total force protection against anthrax by 2004.
References
