The spread continues. The recent Ebola epidemic in West Africa has so far claimed more than 670 lives in what is now the worst outbreak of the disease . Cases have already been recorded in Sierra Leone, Guinea and Liberia. Now it has reached Lagos in Nigeria. Patrick Sawyer seemed to be alright when he boarded a flight from Liberia on 20 July, but was showing symptoms of the disease by the time he arrived in Lagos. He died on Friday.
With Lagos being Africa's largest city, boasting a population of around 21 million, an outbreak there could be disastrous. Many of the residents of the city live in cramped conditions, which could aid spread of the disease further.
So what is Ebola?
Ebola is a haemorrhagic virus; it causes extensive internal bleeding, and can lead to those infected dying from shock. Initially, those infected experience a sudden onset of fever, muscle pain, weakness, headaches, a sore throat and vomiting and diarrhoea.
As the infection worsens, it leads to external and internal bleeding, as the virus breaks down the epithelial cell wall of blood vessels, causing them to leak fluid.
How does Ebola spread?
Ebola is highly contagious and can be transmitted even after those infected have died, because the virus is
transmitted via bodily fluids. It has a 90% fatality rate.
The virus is thought to be transmitted between species: fruit bats (Nature , doi:10.1038/438575a) may be the
natural hosts of the virus, and may be the reason the virus has spread across Africa.
So how are people trying to stop its spread?
Liberia has announced it has closed all but its major crossings and is also quarantining all affected villages.
Nigerian officials are now screening passengers arriving at the international airports. However, such mechanisms vary from simply asking people if they have experienced symptoms to taking traveller's temperatures: no diagnostic blood tests are being done despite symptoms being very similar to that of other diseases.
Daniel Bausch at Tulane University School of Public Health and Tropical Medicine in New Orleans, Louisiana,
who has recently returned from Sierra Leone, says thepriority should be to trace all contacts of the infected man.
"Lagos is not a particularly international link, but nevertheless knowing where these other travellers could be is difficult. It seems simplistic, but logistics of tracing contacts of those infected is more complex," Bausch says.
How far could the virus spread?
Bausch thinks it is unlikely that the outbreak will spread through Europe or the US if someone infected gets on
an international plane to these places. "Could it happen?
I think it could. Would we get sustained transmission? I don't think we would. Screening at airports is important, but we don't have to panic about one case spreading as long as healthcare officials are taking the usual precautions."
Can the virus be treated?
Currently, there is no cure. Treatment generally involves simply relieving the symptoms of the disease.
How long will the outbreak last?
For a few more months at least, says Bausch.
"The key challenges are to stop the spread of the disease is to ensure that we identify all the contacts of those infected and isolate them, although this requires both a lot of resources and a cooperative population," he says. "It is still difficult to put any sort of temporal prediction on this, as you simply can't model all of the factors involved in the spread, so you just have to hope you have it under control."
How are people in West Africa responding to the outbreak?
"It's been a very grim scene in Sierra Leone," says Bausch. "We've really been trying to fight a very difficult situation, but we haven't had adequate resources due to quite a number of healthcare workers infected , which is tough on people's morale."
It seems that there is a general mistrust of health workers in Sierra Leone. It has been reported that a woman who tested positive for the disease was removed from hospital by her family. The 32-year-old hairdresser was the first known case among residents in the capital city. She later died in the ambulance taking
her back to hospital.
Bausch says there are some nurses in Sierra Leone who have been told by landlords not to return home because
they risk bringing the disease back with them. Not only that, but resources are scarce in the affected areas: one ward was reported as having 55 confirmed patients but only one nurse because some were on strike and others were infected.
Despite this, Bausch is optimistic. "Hopefully bringing in more external support in the next week or two will see an increase in scale of support of this outbreak to allow us to gradually gain control of the situation."