This morning you woke up feeling a
little unwell. You have no appetite,
your head is aching, your throat is
sore and you think you might be
slightly feverish. You don’t know it
yet, but Ebola virus has started to
attack your immune system, wiping
out the T-lymphocyte cells that are
crucial to its proper function.
These are the same cells that the AIDS virus
( HIV-1) attacks, but Ebola virus kills them far more
aggressively. Exactly when and where you caught
Ebola virus is unclear, it can take anything
between two and 21 days from initial infection to
the first symptoms. What is more certain is that
you are now infectious yourself. Your family,
friends and anyone in close contact with you are
all in mortal danger.
The next week or so will determine if you are one
of the lucky minority who survive. In the 24 Ebola
virus outbreaks prior to the present one, a
cumulative total of 1,590 people, two-thirds of all
cases, have died.
The current outbreak, which began in the village
of Meliandou in eastern Guinea in early
December 2013, and which has now spread
across Guinea and into the neighbouring
countries of Sierra Leone and Liberia, has killed
251 people as of June 5, nearly half of the
identified cases.
The west African Ebola epidemic is now the
largest outbreak seen since Ebola virus was
discovered in 1976. The World Health
Organisation issued its first communiqué on the
situation on March 23, and since then has been
producing regular reports.

Over the next few days your condition
deteriorates. Your body aches all over, you have
chronic abdominal pain, the fever intensifies and
you start to vomit and develop diarrhoea. After
anything between a couple of days and a week of
misery, you will have reached the crisis point –
now the symptoms will either gradually recede or
you will progress to the horrors of “cytokine
storm”, a convulsion of your ravaged immune
system that will plunge you into the terminal
phase of Ebola virus disease known as
haemorrhagic fever.
Cytokine storm releases a torrent of
inflammatory molecules into your circulatory
system. Your own immune system, now
completely out of control, attacks every organ in
your body. Tiny blood vessels burst everywhere
and you begin slowly to bleed to death. The
whites of your eyes turn red, your vomit and
diarrhoea are now charged with blood and large
blood blisters develop under your skin. You are
now at the peak of infectiousness as Ebola virus
particles, ready to find their next victim, pour out
of your body along with your blood.
Fortunately, however, it seems you have survived.
Rehydration therapy kept you strong in the initial
phase and pure luck saved you from
haemorrhagic fever. Understanding why some
Ebola virus patients avoid the terminal phase is
an active area of research, and one possible
answer is that those whose T-lymphocytes survive
the initial attack of the virus possibly retain
sufficiently intact immune systems. Even when
you are merely in the first phase of feeling
vaguely unwell, it may be possible to determine if
you will live or die.
Even though you are feeling much improved, and
perhaps even ready to return to work, you will
remain infectious for a while. All your bodily fluids
will still contain virus. In particular, the virus can
be sexually transmitted, especially if you are a
man, up to 40 days after recovery.
Epidemiological modelling studies have shown
that Ebola virus is about as infectious as influenza
or very slightly more so – each infected person
will probably infect two to four others. That’s not
tremendously infectious compared to some of
the super-infectious viruses such as measles or
polio, which have corresponding numbers of five
to 18, but it is nevertheless enough to sustain a
pandemic. The question of why we haven’t seen a
worldwide pandemic of Ebola in pre-modern
times therefore becomes rather perplexing.