Archives for posts with tag: West Africa

A Harvard researcher who tracks Ebola’s evolution remembers being “totally shocked” when he learned that Zaire ebolavirus was behind reports of a mysterious hemorrhagic fever cropping up in Sierra Leone last January. Lassa fever or even the rare Côte d’Ivoire Taï Forest strain of Ebola would have been more logical pathogens according to him, and the question remains:  how exactly did the most lethal form of Ebola – which was previously restricted to Central Africa – suddenly appear thousands of miles away on the edge of West Africa? Researchers may never be able to provide a precise explanation, but they have developed several theories as to how Zaire ebolavirus “jumped” across the continent.

Some background on the basic evolutionary biology of Ebola is necessary to appreciate the mystery presented by this mammoth leap. Moving down the tree of evolutionary similarity, the Filoviridae family encompasses the Ebolavirus genus, of which there are five distinct (known) species: Zaire ebolavirus, Sudan ebolavirus, Reston ebolavirus, Bundibugyo ebolavirus, and Taï Forest ebolavirus. All are found in Africa except for Reston, which has only appeared in a Virginia lab.

Despite widespread reports that the current Ebola outbreak is West Africa’s first instance of the virus, one previous case of Ebola was recorded in the region prior to last December. The case occurred when a female Swiss ethologist contracted the disease while conducting a necropsy on an infected Chimpanzee in the Taï Forest region of Côte d’Ivoire that borders Liberia. She survived what virologists eventually determined to be a separate species of Ebola, and this year’s outbreak in Liberia, Guinea, and Sierra Leone surprisingly has no connection to that species now known as Taï Forest ebolavirus.

The culprit of this year’s outbreak, Zaire ebolavirus has likely circulated in the forests of Central Africa for hundreds of years. The first confirmed case occurred only in 1976 near the Ebola River in Zaire, but based on the virus’s mutation rate, Ebola likely split from Marburg virus – another deadly member of the Filoviridae family – around 800 years ago. Further evidence for the long history of Ebola in Central Africa comes from the virus’s presence in stored samples collected from Gabon primates prior to 1976. Previous cases likely went internationally undetected in part because of long practiced indigenous protocols such as isolating infected people outside of villages in addition to community-wide dietary restrictions during times of unusually severe afflictions (see Matthew Barry’s anthropological research on Ebola).

After 1976, Zaire ebolavirus went eerily quiet but reemerged again in the mid-1990s, beginning a series of semi-annual outbursts that continue to this day in Central Africa (the recent 2014 DRC outbreak is the latest instance and is unconnected to the West Africa outbreak). Contrary to many recent news reports, these sporadic episodes have affected bustling cities (Gulu, Kikwit) and have spread via air travel (from Gabon to South Africa), but the initial index cases have always originated in Central Africa, and the outbreaks have never eclipsed more than a few hundred cases.

The 2014 West African outbreak broke this pattern. Scientists have now traced its origin back to a two year old boy who was likely exposed to fruit bats last December in Guinea, ruling out an immediate cause of an infected person bringing the virus directly from Central Africa.

The connection of fruit bats to an Ebola outbreak is not unusual, and bats have been linked to several other index cases over the years. As a result, bats are the leading suspect for the elusive and long sought “reservoir” animal that asymptomatically harbors the virus between human outbreaks. Tests on thousands of animals in Central Africa have yet to find definitive traces of ebolavirus, perhaps because the virus is also rare amongst animals or else only flares up for short spells.

Even within a single species of Ebola, the virus’s DNA constantly mutates each time it jumps from animal to animal, or animal to human. Thankfully the mutation rate for Ebola is much lower than other RNA viruses such as HIV/AIDS, providing more hope for a sustainable cure. Based on its slow rate of mutation, the genetic structure of the Zaire strain ravishing West Africa seems to have separated from its Central African parent strain of Zaire ebolavirus about a decade ago.

This estimate gives scientists about a ten-year window within which to speculate as to how Zaire ebolavirus ended up in West Africa. Here again, bats present the most likely link.

One theory picked up by those with a taste for primitiving Africa, postulates that Africans’ supposed appetite for bat meat (and bush meat in general) has led to the illegal smuggling of infected bats or chimpanzees from Central Africa to West Africa. While it is true that infected primates acted as vectors for bringing Reston ebolavirus to the US and Marburg virus to Germany, there is no evidence of an elaborate black market for bush meat criss-crossing Africa. Assuming a thriving bush meat trade is to misunderstand the driving factor behind wild game consumption in Africa: poverty. West Africans don’t import chimpanzees and bats from Central Africa as exotic delicacies—hungry villagers hunt small game in the forest to add protein to their diets, as other forms of meat are often prohibitively expensive. The average annual income in Guinea is $416 (World Bank).

A more likely scenario for Ebola’s jump involves the long distance migration of bats. Bats are unique amongst mammals in their ability to fly, and recent research tracking their flight patterns has uncovered that they often travel hundreds of miles a year in search of insects. Just about everything about bats from their migration routes to their immune systems is notoriously understudied.

According to the few published studies, scientists know that there are “metapopulations” of bats – separate colonies (whose members can run into the millions) that interact on some level. In other words, large populations of bats come into contact with other large populations of bats at the fringes of their territories or as they migrate, allowing pathogens to pass between them. Along such a metapopulation network, Zaire ebolavirus could have worked its way up the coast of West Africa. Preliminary positive tests for Zaire ebolavirus in bats found in Ghana – about halfway between the DRC and Guinea – support this theory of a gradual passing on of Ebola.

One factor that complicates this picture of bat-born Ebola is the fact that human outbreaks seem to only occur in regions of Africa where large primates are found. This remains a puzzling mystery, but one possible explanation floated is that Ebola needs to be – in a sense – shaken back and forth between bats and non-human primates before it mutates into a form that can be picked up by humans. An intriguing theory and time will tell if index cases eventually do emerge from areas without non-human primates.

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Creating a mashup of aerial images of African cities is something I’ve wanted to do for a while now and today I finally had a minute to put the satellite images together. Here’s the link: Afrian_metropolises. I downloaded all of the images from Google Earth Pro at the same size and scale (from 34.7 miles). The top row shows six of West Africa’s largest cities, the middle row shows East and Central African cities, and the bottom shows southern Africa plus New York and Boston for familiar comparisons (for me at least). A few striking first glance observations include the size of the South African giants Johannesburg and Cape Town, and Nigeria’s neighboring megalopolises Lagos and Ibadan (especially these two Nigerian cities in comparison to Kano, which recent (politically motivated) censuses have given population figures equal to Lagos. This is not to say geographic size of a city is determinant of its population, but the aerial difference between these three cities is readily apparent). Also interesting to note is how obvious (but obviously not a scientific method) it is to tell how paved a city is or is not based on where the city lies on the scale between brown (dirt) and grey (asphalt). There’s a limit to how useful images/maps like this actually are, but it’s fun to look at and helpful to have a for developing a mental imprint of the relative geographic sizes and shapes of African cities. 

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(Mark Duerksen 2014)

This is the final post in an eight part series on the history of Ebola. For immediate information about how to help prevent the further spread of Ebola and keep yourself safe please consult and share the Ebola Facts website.

As we are well aware, this year the two-decade trend of isolated outbreaks in Central Africa every few years has been broken by a much larger and more prolonged series of cases in West Africa. The outbreak began when a two-year-old child in southeastern Guinea contracted the most deadly species of the virus (Zaire ebolavirus) in early December last year, putting into motion the initially slow and then progressively faster spread of the virus to Liberia, Sierra Leone, and now Nigeria. Unlike the past twenty year’s string of Central African outbreaks that were each unique and separate despite initial speculation otherwise, this year’s West African outbreak does seem to be the result of a single index case followed by human-to-human transmission. Here’s a good time-lapse map of that transmission through West Africa. Summaries of the specifics of this year’s outbreak are widely available online, so I won’t go into too much detail here, but I will offer a few pieces of analysis based on the history I’ve covered in the previous posts.

IMG_5260Matt Ridley gets it all wrong for The Times

First there’s a need to correct a couple of pieces of misinformation that continue to circulate with this year’s outbreak. A more minor error is that this is not in fact the first time that there has been a West African case of Ebola as many news outlets have reported. Previously a zoologist working in Cote d’Ivoire caught the Tai Forest species of the virus and then fully recovered in Switzerland. Second and more importantly, the virus has not been previously restrained to only rural, remote areas of Central Africa. As we’ve seen, two of the deadliest previous outbreaks occurred when the virus struck the relatively large cities and regional hubs of Kikwit and Gulu. These Central African cities might not have quite the same level of road infrastructure linking them to other urban centers as West African cities do (although I know plenty of people board buses every day in Gulu bound for several cities and countries), but these two cases do provide a precedent for urban outbreaks of Ebola. And although these previous urban outbreaks were incredibly deadly, the cities were able to eventually contain the virus’s spread within a matter of months. So, in searching for a reason why this year’s outbreak has spread so far and killed so many, the answer is not as simple as stating that this is the first time the virus has appeared in an urbanized setting.

Other explanations have included the slow recognition and response time of international medical teams. Again, a look at the history of the virus shows that response time is not a unique factor in considering why this outbreak is so much worse. In the cases of the 1976 Sudan and Zaire outbreaks and several subsequent episodes, international teams were slow to recognize the virus’s appearance and did not arrive on the scene until after the local communities had already contained the spread of the virus. This fact suggests that one reason for the extent and deadliness of this year’s outbreak might be partly found in the local community’s responses. As Hewlett observed in Gulu, the DRC, and Gabon, many communities in Central Africa possess long practiced social procedures such as quarantine and modified burial practices that they employ when their communities recognize that they are dealing with an especially virulent affliction. I do not know if communities in West Africa have similar procedures, but it would not be surprising if they don’t due to the fact that they’re not used to seeing diseases like Ebola, or alternatively that they did previously possess similar response techniques but that the long civil wars in Liberia and Sierra Leone destroyed that local knowledge as violence and insecurity ripped communities apart.

Whatever the cause(s) behind the severity of this year’s outbreak, the fact is Zaire ebolavirus’s path through West Africa has been more deadly than all previous Ebola cases combined, and I have to admit that when I initially heard that the virus had arrived in Lagos—the impetus for this series of posts—I feared that Ebola might finally find in the fast life, international networks, and rancid infrastructure of Sub-Saharan Africa’s largest city what HIV/AIDS found in the reused medical needles, sex trade, and migrant networks of 1970s Kinshasa and Brazzaville—that is, the lethal mixture of social and environmental conditions that would allow the virus to eventually explode into a global epidemic.

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Trash disposal in Lagos (Mark Duerksen 2014)

Being a Central African originating RNA virus linked to primates and transmitted through body fluids, comparisons of Ebola to HIV/AIDS were bound to occur. However there are several important differences that will likely yet prevent Ebola from boiling into an epidemic the way HIV/AIDS did. The first significant difference is the length of time from infection to fatality (or recovery for 10-60% of Ebola patients). HIV can hole up and multiply inside an infected person’s immune system for months, years, or even a decade, slowly destroying T-cells until it has killed so many that doctors consider the person to have developed AIDS. Over these months or years while HIV festers into AIDS, a person with HIV may be completely asymptomatic, but all the while still able spread the virus through sexual contact or blood transfusions. This slow and silent development timeline means that an HIV carrier might not even realize that he or she has become infected for years or even a decade and all the while be transmitting the virus to numerous people, allowing HIV to creep into a critical mass of carriers before it is even detected. This quiet buildup of an infected mass of people is exactly what happened for decades in Central Africa, and by the time doctors “discovered” HIV/AIDS, it was already an epidemic throughout the region.

Ebola on the other hand asymptomatically incubates for a few days or up to a few weeks, during which time the victim cannot transmit the virus to another person. Once symptoms develop after the incubation period, the patient’s health declines quickly and death is then generally a matter of days away, leaving only a very small window to further spread the virus (although it can still be contracted from infected corpses, so that is an additional concern and why burial practices are crucial to containing Ebola). One important note here is that those who recover from Ebola can still transmit the virus through semen or possibly breast milk for a number of weeks. While Ebola is easier to transmit during its small contagious window than HIV/AIDS is during its prolonged window, Ebola still has a low transmission rate,[1] requiring direct contact with infected bodily fluids, and the virus cannot be transmitted through the air the way respiratory diseases can be. Despite the horrific extent and fatality numbers of Ebola in West Africa, the virus will likely burn itself out due to its short contagious window (although it might take severe quarantine and curfew measures as we’re now seeing in West Africa) before it ever reaches a critical, completely uncontrollable mass in the way HIV did.

Perhaps the most optimism-inspiring difference between HIV/AIDS and Ebola is the two viruses’ rates of mutation. While both likely simmered in the forests of Central Africa long before scientists officially detected and classified them, Ebola’s genetic structure has hardly changed since the first confirmed cases in 1976 while HIV/AIDS has mutated incredibly rapidly, making treatment for HIV/AIDS much more difficult to square with virus’s continually changing configuration. Ebola’s steady genetic structure makes the prospects for a cure much more promising, and as we’ve seen with the initial success of ZMapp, cures seem to be on the horizon. Now we just have to hope treatments can be produced and distributed asap because, while Ebola is not likely to become a global epidemic, it is causing untold suffering in West Africa that we likely won’t realize the true extent of for some time yet. Ebola’s destructive path through West Africa includes not only the direct victims of the virus, but also those caught in the clashes between soldiers enforcing quarantines and those trying to flee its path, survivors who are now shunned by their communities, communities that no longer trust doctors and hospitals, businesses and entire economies that have taken a massive hit, and medical infrastructure throughout the region that has been depleted, abandoned, and looted, causing other illnesses to proliferate in the absence of treatment facilities. Still it is worth noting the statistics on HIV/AIDS and other deadly diseases deaths per day dwarf Ebola deaths in the Ebola-affected countries–a reminder that those preventable diseases also require immediate attention and that serious long term work to repair medical infrastructure and communities’ relations with medical personnel will be imperative to West Africans’ health once this outbreak can be contained.

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(image source)

[1] Daniel G Bausch, et al., “Assessment of the Risk of Ebola Virus Transmission from Bodily Fluids and Fomites,” Journal of Infectious Disease, 196(), S142-S147. Available online: http://jid.oxfordjournals.org/content/196/Supplement_2/S142.full

For immediate information on how to help prevent the further spread of Ebola and how keep yourself safe, please consult and share the Ebola Facts website.

The terrible news that a man—who we now know was an American citizen on his way home to Minnesotadied from Ebola upon arriving in Lagos from Liberia jolted me when I read about it a couple of days ago. Ebola—the disease my older sister used to give me nightmares about after she read The Hot Zone—seemed oceans away when I was researching in Lagos several weeks ago, where car crashes, malaria, and Boko Haram seemed like much more immediate fears.

But now, in a matter of hours, via one single horribly unlucky man on one ill-fated flight, the disease has arrived in Nigeria’s megacity—a city where as many as 20 million or more people live without a reliable source of power, without a well functioning sanitation system, and without much infrastructure whatsoever (a topic I am currently writing another post on). The people of Liberia, Sierra Leone, and Guinea along with the health workers bravely working to treat those affected have already suffered horribly from West Africa’s first outbreak of the Zaire strain of Ebola—an outbreak that has killed at least 1,500 people since early 2014—and it is terrifying to think of the virus traveling to a major international city like Lagos where the toll could be even more horrific and from where it could more easily spread beyond West Africa (over seven million passengers traveled through Murtala Muhammed International Airport in 2011 alone).

With fear for my friends in Nigeria in mind, I decided to research more about the deadly disease, and have been writing a summary of the virus’s history because the wikipedia entry didn’t provide much information and because the double mystery surrounding Ebola and Central Africa—still imagined by many in Heart of Darkness terms—is in part why many people find the disease so terrifying. Over the next few days I’ll upload a series of posts on the history of Ebola, so check back or follow Arcade Africa for notifications of those posts.

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Murtala Muhammed International Airport (Mark Duerksen 2014)

Following up onmthe last post, here’s another article (from the August New Yorker) questioning whether Mayor Fashola is leaving behind the city’s poorer residents in his pursuit of glamorous projects like Eko Atlantic that provide clean water and reliable power for the ultra rich. The article points to the Makoko slum built over polluted water on boards and logs and asks why solutions like the floating school designed by Kunle Adeyimi isn’t being developed for the people struggling in Makoko. For a look into life in Makoko read this article on the slum’s high teenage birthrate. After years of predominately positive coverage of improvements in Lagos the media seems to definitely be going through a more negative phase…I imagine that much of Fashola’s legacy will be tied to Eko Atlantic for better or worse and making sure the project is completed is consuming the majority of his time currently. What EA will mean for the rest of Lagos is yet to be seen. I have a chance to ask Mayor Fashola a question during a group video conference next week and am thinking about what I should ask and will be sure to share his response here. The article did a nice job juxtaposing these two images of EA and Makoko:

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