Ebola
Ebola virus disease, which used to be called Ebola haemorrhagic fever,
was named after the river in the Democratic Republic of the Congo, where
one of the first two villages to report cases in 1976 was located. The
other was in Sudan. Ebola is a severe viral illness with a sudden onset
that comes from direct contact with infected living or dead rainforest
animals, including chimpanzees, gorillas, monkeys, fruit bats, forest
antelope and porcupines. It kills up to 90% of those who are infected.
Transmission
The virus is passed from one human to another, carried in blood and
bodily fluids and secretions, but also beds, sheets, clothes or other
surfaces that a sick person has touched. Burial ceremonies that involve
touching the body are also a risk. The virus enters the body through
broken skin or mucous membrane.
The group at highest risk are
health workers, caring for those with Ebola. They have to wear full
protective clothing, including facemasks and goggles, and should change
their gloves between one patient and the next.
Symptoms
The early signs are sudden fever, intense weakness, muscle pain,
headache and a sore throat. Vomiting and diarrhoea follow, raising the
chances that the sick man or woman will infect somebody else. The kidney
and liver are affected and there can be both internal and external
bleeding, which is why it was originally called Ebola haemorrhagic
fever. Patients are infectious once the symptoms show, which is two to
21 days after
they have contracted the virus.
Treatment
There is very little treatment. Patients will need intensive supportive
care, with intravenous fluids or oral rehydration salts. They must be
kept in isolation and their nurses and visitors must wear full
protective suits. If people are to be nursed at home, their carers need
instructions and equipment to safeguard themselves. There are no drugs
to treat the disease or vaccine to prevent it, although research on a
vaccine is under way.
Cure
It has proved very hard to find drugs to treat viral diseases from
animals, from influenza to HIV. Although the death rate is high,
outbreaks of ebola are infrequent and have so far been contained each
time. As with many of the so-called neglected tropical diseases, there
is not a potentially lucrative market for drug companies, so they will
be reluctant to invest in research and development.
Control
They can be contained in human populations but the viral reservoir still
exists in animals. There will always be a risk that hunters will kill
infected animals or that people will pick up those that have died of the
infection in the forest and the virus will be reintroduced to the human
population.
Closed borders
Containment is key to the strategy against ebola. Quarantine has been
used in some outbreaks for the relatives of people who become sick.
Because people are not infectious until they become obviously ill, it
should in theory be possible to focus efforts on the community where the
outbreak began. In the past, that has usually been villages in close
proximity to rainforests.
Confirmation of a case in a city such as
Lagos is a real concern, but transmission must involve direct contact
with a sick individual, so is more likely in a family setting or a
hospital. The biggest worry is probably that somebody showing symptoms
will be taken to hospital where nursing staff are unprotected, because
the disease is not recognised, sparking an outbreak that spreads to
their families in turn.
Closing borders may not help keep the disease out because borders are permeable in much of Africa. The World Health Organisation says closures may hinder travel and trade without detecting cases.
World threat
Clearly somebody infected with the virus could theoretically get on a
plane and spark an outbreak – probably in a hospital – anywhere in the
world. However, as with the Mers virus, which arrived in London via a
patient who was taken to St Thomas' hospital, infection control measures
are so stringent in more affluent countries that it is probable the
virus would be very rapidly contained.
