The Ebola outbreak in western Uganda over the past two weeks reveals how violent conflict, porous borders and poor healthcare infrastructure have created the perfect storm to make the region particularly susceptible to the deadly disease.

The latest outbreak has deepened the puzzle for scientists who are wondering why in recent years the epicentre of the haemorrhagic fever appears to have shifted from the Congo and Central African Republic to Uganda.

The entire region is now on high alert with concern rising that the virus could spread to Kenya and Tanzania given the frequent movement of people between the three countries.

Two suspected cases are under investigation in Tanzania in Kagera Region near the border with Uganda, and another two suspected cases in Kenya—one in Central and the other in Western Province. None of the cases have been confirmed to be Ebola.

The latest outbreak in Uganda has been linked an influx of an estimated 20,000 refugees from the eastern Democratic Republic of Congo fleeing fighting in North Kivu province. But a direct cause-and-effect link between the entry of refugees and the outbreak of the disease has not been established.

Still, porous borders are a feature of the entire East African region, particularly when violent conflict pushes large numbers of people across borders.

Apart from the eastern DRC-Uganda border, other borders that have recently experienced the pressure of conflict are the Uganda-South Sudan border; the Kenya-Somalia border; and the Tanzania-Burundi border.

But it is not just conflict that drives people across borders; the search for better economic opportunities, too, has driven people to neighbouring countries in the EAC, particularly with the inauguration of the Common Market Protocol.

READ: EA in panic as Ebola strikes again in Uganda

Even though scientists cannot put a finger on the next country that is likely to be hit, they consider Kenya and Tanzania, and to a smaller extent, Rwanda and Burundi, to be out of the Ebola virus’s geographical distribution.

According to Medecins Sans Frontiers’ Paul Roddy, despite the three instances in Uganda, claiming nearly 300 lives in total, the greater East African region largely remains free of Ebola because the virus’s concentration is in the Central Africa region.

Like Marburg, Ebola is a virus that is passed on from and/or by primates to humans, but the puzzle that scientists are trying to unravel is why especially Uganda, South Sudan and DR Congo, are the most susceptible to Ebola outbreaks.

Dr Roddy said that recent research shows that the geographical distribution of Ebola stretches across the African continent from Uganda to Gabon, and from Sudan all the way to Angola.

However, “evidence from individual cases shows that the virus is in circulation from Central African Republic.”   

In essence, other regions in the greater East Africa are not prone to the Ebola virus because they lie out of its geographical loop despite the fact that humans in those regions also interact with the forests.

Ebola is classified as a Category “A” biological terrorism agent by the US Centres for Disease Control as well as being considered a select agent that has the “potential to pose a severe threat to public health and safety".

As a terrorist weapon, Ebola has been considered by members of Japan’s Aum Shinrikyo cult, whose leader, Shoko Asahara, led about 40 members to Zaire in 1992 under the guise of offering medical aid to Ebola victims in what was presumably an attempt to acquire a sample of the virus.

About 40-50 per cent of people who are exposed to the Ebola virus contract the disease, and about 40-90 per cent of those who contract the disease die.

It depends on many factors — the strain of the virus contracted, the route of infection, the amount of contaminated fluid that a person comes in contact with, and even the genetic make-up of the patient.

Medical journals report that the same viral strain, acquired in the same way at the same time from the same infectious patient, can kill one person, while simply giving another a headache.

But is Uganda the last place to be hit by the outbreak?

“To be able to predict where the next outbreak is going to be, you have to know what carries the virus. Right now, the reservoir animal is not known; it could be an animal, insect or fruit bats,” says Dr Julius Lutwama, the principal research officer and head of National Influenza Centre at the Uganda Virus Research Institute (UVRI).

“You have to look at the other places where Ebola first occurred before Uganda, mainly Sudan and the Congo. There is no healthcare system in these areas; it is possible that people contract the Ebola virus and just die.

"Without the healthcare system detecting the epidemic, it is difficult to say which country has the highest incidence. By contrast, there is vigilance and a fairly better healthcare system in Uganda, which is why the virus seems to strike here more frequently,” he said.

The Entebbe-based UVRI can now test and analyse the Ebola virus as opposed to previous instances when the sample had to be flown to the Atlanta-based CDC laboratories in the US. This also accounts for the faster diagnosis and detection of the virus compared with countries whose healthcare systems are less robust.

What is certain, however, is that Uganda lies in the area where the reservoir lives, and humans often in contact with animals, insects or fruit bats that are suspected to be the carriers of the virus.

Among scientists in the region who have been spearheading the fight against Ebola are Dr Lutwama, Kenya’s Dr Rosemary Sang (Centre for Virus Research) and another Ugandan, Dr Zabulon Yoti, who now works for WHO in Brazzaville.

Ebola belongs to a family of viruses known as Filoviridae, which cause viral haemorrhagic fevers and includes the equally deadly Marburg virus.

In 2004-2005, an outbreak of Marburg fever in Angola infected 252 people and killed 227 of them—a 90 per cent fatality rate.

Other haemorrhagic fevers include dengue fever, which is transmitted by the Aedes mosquito and currently has no vaccine, though its incidence has reduced significantly in the past few decades thanks to mosquito-control campaigns; as well as yellow fever, also transmitted by the Aedes mosquito but whose deadly ravages have been tempered by vaccination campaigns against the disease.

Since the 1980s, however, the number of cases of yellow fever has been increasing, making it a re-emerging disease, likely driven by warfare and social disruption in several African nations.

Frank Kaharuza, the chief of the epidemiology branch at the Entebbe-based Centres of Disease Control (CDC) explains that this is due to a phenomenon referred to as zoonotic parasitic infections, whereby animals pass on diseases to humans. 

“Humans have ceased living in the wild for a long time, yet they are increasingly having intimate relationship with forests around them; and the more they do so, the more they are exposed to wild animals that carry these virus, thus contracting epidemics from animals,” he said.

Dr Roddy, an expert on Marburg and Ebola, is currently in Kibaale, western Uganda, battling the Ebola epidemic that has so far claimed 17 lives since last month.

The virus struck Uganda in 2000, claiming 224 lives in northern Uganda, and again in 2007, when 42 died in the west of the country. Last year, one death was reported in Luwero in central Uganda.

The outbreak in 2000 hit particularly hard as it was the first time the disease had struck in a densely populated area, with Gulu town as the epicentre.

Transport links between Gulu and other major towns in Uganda, including the capital Kampala, made a plague-like spread across the entire country a real possibility.

And one resounding tragedy was the death of Dr Matthew Lukwiya, a physician in St Mary’s Hospital Lacor in Gulu, who was at the forefront in containing the spread of the disease, only for him to succumb to Ebola himself. 

Epidemiologists who later travelled to Gulu credited Dr Lukwiya with helping to contain Ebola before it could spread, as his insistence on immediately calling senior health officials in Kampala when the diseases first broke out in Gulu jump-started the government’s public-awareness campaign.

Dr Lukwiya’s death revealed just how difficult health workers have it when trying to combat a disease as ravaging as Ebola, particularly in the African context where healthcare infrastructure is often non-existent, or moribund at best.

Protective equipment as basic as gloves can be in short supply or absent in a typical rural hospital, not to mention the kind of specialised gear needed to handle highly infectious diseases like Ebola, such as masks, caps, gowns, aprons and goggles.

Besides Marburg and Ebola, other zoonotic diseases that have struck around the world are swine flu, H1N1 (bird flu), bubonic plague and rabies. 

First discovered in 1976, Ebola is said to have come from primates out of the Philippines, but what remains unclear is the link between the Philippines and Central Africa. Over that period, there have been 2,000 individual cases.

By Julius Barigaba and Christine Mungai