In 1976, in the north of what was then called Zaire, there was an outbreak of a new and deadly disease. It caused high fever, a rash, and bleeding from the internal organs. The disease moved for a while along the banks of the Ebola River, killing almost every person it struck. Then it disappeared again, as mysteriously as it had arrived. The disease was named for the river where it had first struck and was eventually shown to be caused by a virus.
A similar outbreak occurred about the same time in Southern Sudan, and then again in the same region some four years later. The next major outbreak was not until 1995, in the town of Kikwit in the south-west of the former Zaire. The disease caused great fear, not only where it occurred but world-wide. This fear only abated once medical and epidemiological investigations showed how it was possible to manage an outbreak.
How ebola kills
The Ebola virus must hide somewhere between outbreaks, but no-one has yet discovered where - it may be in monkeys or some other animal host, or it may be in healthy human carriers. Once an outbreak does occur the virus is spread from person to person via blood and bodily secretions. It can possibly infect a new victim via a cut or scratch on the skin, and can certainly do so through an injection with an unsterile needle. It can also be spread sexually.
A small number of people, although infected, do not develop serious disease. Most others, however, are susceptible to the virus and will fall ill. The incubation period is between four and 16 days. Once inside the body the virus multiplies and invades all the major organs. There is a high fever, headache and joint pains, vomiting and diarrhoea.
The characteristic haemorrhaging or bleeding is caused by a process called DIC - disseminated intravascular coagulation. Through this, the virus provokes massive clotting within the organs, and this leads paradoxically to bleeding because it uses up all the clotting factors in the blood. The clotting itself causes failure of the liver and kidneys, and this coupled with the haemorrhaging almost invariably leads to a fatal outcome.
Managing an ebola outbreak
Given that the virus is so highly contagious and virulent, it is essential to intervene rapidly in order to limit spread. Field volunteers and national staff need to be both trained and experienced so as to avoid becoming themselves infected.
The activities that they undertake include the following:
- confirming the diagnosis by taking blood samples from infected persons. These samples are of course themselves highly contagious and cannot be transported - they will normally only be handled by an international team of virologists brought specifically to the site of the outbreak to investigate. The diagnosis may be initially be a presumptive one, based upon the clinical picture, and control measures must never be delayed
- active case-finding, so as to isolate infected persons in hospital contact tracing, which means finding and watching over any persons in close
- contact with a patient over the previous three weeks
- setting up of on-going epidemiological surveillance so as to track who is becoming infected and perhaps work out ways of limiting spread
- urgent education of the general public on how to avoid contagion. Such an education campaign may use all media available, including loudspeakers, radio broadcasts and dissemination of information by teachers and community leaders
- training all health staff on methods of isolation, "barrier nursing" and sterilisation, and disposal of contaminated waste
- ensuring that health facilities have adequate supplies of sterile needles and syringes, so as to be certain that they are not spreading the virus.
Preventing ebola
The Ebola virus is spread by contact with blood or other body fluids. There is currently no vaccine against it.
Prevention during an epidemic relies upon reducing contact with the body fluids of infected persons:
- medical staff should wear gloves, face masks and an outer garment that is removed before they leave the hospital. Highly specialised "space suits" are not considered necessary for clinical staff;
- local authorities must intervene to ensure that relatives should not handle the corpse of any persons dying of the illness, as may happen during traditional funeral preparations;
- people should avoid receiving injections from untrained "village doctors" (who often have no health training whatsoever). Such people sometimes operate in local markets offering injections for a variety of ills, often using unsterilised needles and syringes;
- during an outbreak people must be especially careful to wash their hands when caring for people who are sick from any cause, in case the illness is the early stage of Ebola; male survivors may secrete the virus in their semen for many weeks after they are cured and thus should refrain from unprotected sexual activity for a period of three months. ;
An example - the MSF emergency intervention in Kikwit ; In 1995 there was a major outbreak of haemorrhagic fever in the town of Kikwit in the south-west of Zaire, now called the Democratic Republic of Congo.
An experienced team of MSF volunteers went to investigate and help the local authorities in setting up control measures. ; It was essential to address several issues at once - strengthening treatment facilities at the local hospitals and dispensaries; confirming the nature of the epidemic; and instituting control measures. ; The clinical features of the Kikwit disease could in theory have been caused either by yellow fever or Ebola.
However the severity and high case fatality rate seemed to point to Ebola, as did the pattern of transmission - initial epidemiological surveillance of cases seemed to implicate person-to-person transmission, rather than transmission by a mosquito vector, as is the case with yellow fever.
Indeed, the groups most affected were pregnant women and young children. A particular risk factor seemed to be living within close proximity of a health centre or hospital. And closer questioning of people affected revealed that many of the patients had received an injection during the previous days or weeks - the women against tetanus in the context of their antenatal care, and the children as part of their regular immunisations.
This information led to urgent investigation of sterilisation techniques by local medical staff and it was found that needles and syringes were being re-used without proper sterilisation.
The first intervention, therefore, and the most effective step in bringing an end to the outbreak, was to provide adequate supplies of sterile equipment and to provide also training of the staff on how to prevent contagion.
MSF treatment for ebola
There is no specific treatment against the Ebola virus. Patients are given intravenous infusions of fluid and electrolytes, but the purpose of these is merely to keep the patient hydrated while his or her immune system attempts to deal with the virus. If it is possible the patients may also be given blood transfusions, however this depends upon there being family members able to donate blood. Their blood must of course first be screened for other viruses such as hepatitis B and HIV. Because the Ebola virus is so virulent these attempts at treatment are not often successful. It follows that all efforts must be made to limit contagion, and this indeed is the major priority of MSF teams working with a disease such as Ebola.