The world of viruses is a turbulent one. When they find their way into human populations they can spread like wildfire and cause serious disease, before seeming to slink away again. This is the case with Ebola virus, which has emerged from the jungles of central Africa to wreak havoc in the west of the continent. A relatively rare, but incredibly deadly virus, Ebola has since its discovery in 1977 remained relatively contained in minor outbreaks in Central Africa. That is, until now. The largest and deadliest outbreak of the disease yet has reached epidemic levels in West Africa, and it is showing no signs of slowing down.
According to the Centers for Disease Control (CDC), as of 23rd July 2014 there have been 1,201 cases in this outbreak, with 672 of those having died. Though these numbers are difficult reading, it shows a rare silver lining in this outbreak as these figures represent a 56% mortality for a disease that has been known to kill 90% of those infected.
This outbreak, the extent of which (correct as of 20th July 2014) is shown on the map on the left produced by the CDC, is thought to have started in Guinea late in 2013 or early this year. It has since spread to neighbouring Sierra Leone and Liberia with ferocious speed. It has recently been reported that a Liberian official had died in the Nigerian capital of Lagos, sparking fears not only that the outbreak had spread to Africa’s most populous country but also bringing about concern that the disease had been spread to other countries through air travel without anyone knowing. Add to this the fact that Sierra Leone’s head health official has also been struck down with the disease and there are concerns that this outbreak will soon become unmanageable.
What Has Changed?
The question being asked by many is why this outbreak is so bad – as many people as all the previous outbreaks this century combined have been affected in just a few months. The reasons behind the outbreak’s severity are complex, but can be grouped into two categories. The first of these concerns the causative agent – the virus. Ebola virus disease can be caused by 5 different species of Ebola virus, a genus included in the family of Filoviridae, viruses that are long and fibrous in physiology. Each of the 5 species can cause disease in humans, but one is particularly deadly. This species, Zaire ebolavirus, is the culprit behind this outbreak. This form of the virus cause far worse symptoms, which are infamous for their horrific nature. Though the disease can result in such awful symptoms as sweeping haemhorraging, leading to serious bleeding from virtually any orifice, the disease actually begins rather inauspiciously. After an incubation period – a period where infection has started but no symptoms are apparent – of around three weeks, those infected will suffer from flu-like symptoms, such as fever, throat and muscle pains and a general malaise. This will quickly progress to more serious disease, which brings about nausea, vomiting, severe and often bloody diarrhoea along with declining kidney and liver function. It is at this stage that problems with bleeding, which are associated with a negative prognosis and a near-assurance of death, become apparent. However, contrary to belief haemorrhagic symptoms do not lead to hypovolemia (an overall decrease in the volume of blood and plasma in the body) and are not the cause of death. Instead, death occurs due to multiple organ dysfunction syndrome (MODS) – a systematic failure of all the major organs – due to fluid re-distribution, hypotension (abnormally low blood pressure), disseminated intravascular coagulation (the blockage of blood vessels due to uncontrolled clotting) and focal tissue necrosis. This huge range of symptoms are not only increased in their severity, but they are also accelerated in their onset with the species of Ebola virus at work in this outbreak. Click here to learn more about just why Ebola virus is so deadly.
The second cause of the severity of this outbreak are an often ignored in outbreaks such as these, but are incredibly important in their development – social and political factors. Though there have been a number of outbreaks in Africa before this one, this is the first to originate in and largely involve the west of the country. As such, the local health infrastructure was not prepared to deal with such a large volume of cases. There have been cases of nurses and doctors fleeing hospitals in Liberia as more and more patients arrived and fewer and fewer left. Additionally, since there have been so few cases in the region the general population suffer from a lack of education about the disease. A recent editorial in <em>Lancet</em> identified that significant social stigmas exist about the disease. This leads to fewer people who are suffering from symptoms coming forward for treatment and those who have being forcibly removed from care by their tribes or relatives, who are dubious about the intentions of hospitals in treating a condition that many see as, for example, the work of witchcraft. Furthermore, due to a lack of understanding about the nature and cause of the disease, funerals continue to be carried out as normal leading to yet further increased contact. Another result of the lack of an outbreak in this region was that local aid organisations, such as Médecins Sans Frontières, were under-prepared for this many cases. Even this giant of healthcare aid sent distress calls, admitting that they were “overwhelmed”.
What is clear about this outbreak is that it is going to get worse before it gets better. It is difficult to predict how much worse, simply because there is no precedence in this environment. Mathematical models do exist for previous outbreaks in Uganda and DR Congo, but it is difficult to predict exactly how much worse this outbreak will get based on this data. But what about predicting the future of the treatment of Ebola virus disease? Currently there is neither an effective treatment nor a vaccine available. Treatment of patients predominately involves water replacement treatments. This lack of a specific treatment contributes to this disease’s extremely high mortality rate and as such a great deal of work is going into finding ways to treat and prevent new cases. This latter aim has seen a number of potential solutions mooted, but there is yet to be a conclusive breakthrough. These potential vaccines included anti-sense therapy, which involved using laboratory generated ‘small-interfering RNAs’ to decrease the production of viral proteins and a virus (vesicular stomatitis Indiana virus) with viral glycoproteins decorated on its surface, to serve as a way of generating immunological memory before infection occurs. Though research is ongoing, the near future unfortunately does not look promising.
This is the most severe test that has been posed by Ebola. Never before have we seen an outbreak of this severity. What needs to be determined is whether this is a definitive point in our relationship with <em>Ebola virus</em>; is this a case of a perennially deadly virus now becoming more common, or is it a case of the virus affecting an area that was simply woefully unprepared for an outbreak? Regardless, this must be regarded closely, as it poses the potential for disaster.
‘Til next time…