Fiddling while Ebola burns
The Editor of The Lancet Infectious Diseases looks at how Ebola turned into an epidemic, and what measures should – and should not – be taken to stop it
By John McConnell Posted on 13 October 2014
Despite the cases of Ebola virus disease diagnosed recently in Dallas and Madrid, the virus poses no meaningful epidemic threat to the United States, Spain or, indeed, any country with a comprehensive healthcare system and good disease surveillance. However, the disease is raging like a wildfire through three countries of West Africa — Guinea, Liberia and Sierra Leone — and sparks will continue to spread until the fire is quenched.
There is no specific treatment or vaccine for Ebola, although experimental therapies have been tried, and the current outbreak has generated much activity in developing new drugs. The mortality rate of Ebola can be as high as 90 percent, but around 50 percent is more usual. The incubation period (time from infection to symptoms appearing) is 2 to 21 days, so someone harboring the disease could travel anywhere in the world without knowing they were infected. However, the virus is not transmitted during the asymptomatic period. Indeed, infection can only occur by direct contact with a sick infected person or their bodily fluids. Unlike colds, flu, or measles, for example, infection is not airborne. And, despite what you've seen in the movies or read on social media, the virus is vanishingly unlikely to mutate to become infectious by the airborne route.
The origins of Ebola
The first cases of Ebola virus diseases occurred in Zaire (now the Democratic Republic of the Congo) in 1976. The disease is named after the Ebola River — a tributary of the Congo — near which the virus was first identified.
The natural hosts of Ebola virus are almost certainly fruit bats living in the forests of Africa, although we cannot be certain of this because live virus has never been isolated from bats. Bats appear to be unaffected by the virus, but when transmitted to forest antelope, porcupines, monkeys, and apes — including human beings — the virus causes severe disease.
Human epidemics probably start when people hunt and consume bats or other forest animals infected with the Ebola virus,
Ebola disease symptoms
In people, Ebola presents with flu-like signs and symptoms of fever, fatigue, muscle pain, headache and sore throat, which progress to diarrhea, vomiting, rash, impaired kidney and liver function, high fever and bleeding — so called hemorrhagic fever. Bleeding occurs because the virus attacks the endothelial cells that line blood vessels and the vessels become leaky. Thus victims can bleed internally (hence blood in vomit and feces) and from bodily orifices where skin or mucosa is thin. Death probably results from fluid loss and shock.
The 2014 West African epidemic is just the 25th known outbreak, but it has sickened and killed more people that all previous outbreaks combined. The first case in West Africa was probably a 2-year-old boy (it's not known how he became infected with Ebola) living in Meliandou in the Guéckédou Prefecture of Guinea, near the border with Liberia and Sierra Leone, who died on December 6, 2013. The boy's relatives also became sick and died, but not before they had travelled and transmitted the virus to other people.
Various factors combined to allow the epidemic to spread before it was eventually identified as Ebola.
- The region is experiencing the aftermath of decades of conflict, so it is impoverished with weak health infrastructure, a lack of healthcare workers, and no routine disease surveillance system.
- Access to clean water to help control infection is limited.
- Local customs predispose to physical contact with the dead.
- Ebola had not previously been reported in the region, so sick patients were initially thought to have diseases more often seen locally such as Lassa (another type of hemorrhagic fever) cholera, or malaria.
Only on March 25, 2014, did Guinea's government report the Ebola outbreak to the World Health Organization (WHO). The first cases were reported in Liberia soon after and in Sierra Leone on May 25. Subsequently, an infected traveler caused an outbreak in Nigeria, which appears to have been contained, and single cases have been exported to Senegal and the US.
On October 6, a Spanish nurse, who had treated two Ebola patients flown back from Sierra Leone in a Madrid hospital, was diagnosed with the disease, becoming the first person to catch it outside West Africa.
In the three worst affected countries, numbers of cases and deaths continue to climb steeply, reaching 8,399 cases and 4,033 deaths as of October 8, according to the latest report by WHO. Predictions of future case numbers vary greatly but include a truly alarming 1.4 million in Liberia and Sierra Leone alone by January 20, 2015, if there are no improvements in control interventions, researchers estimate in the CDC's Morbidity and Mortality Weekly Report.
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Ebola in the US and Spain
Given the interconnectedness provided by international air travel, it was inevitable that a large outbreak of Ebola would lead to cases being exported. Presciently, a mathematical modelling study published early in September suggested that the US had about a 20 percent chance of receiving at least one case of imported Ebola virus disease by the 22nd of the month. That prediction came to pass on September 20 when Thomas Eric Duncan, a 42-year-old Liberian national, arrived in Dallas from Monrovia, Liberia, via transit stops in Brussels and Washington Dulles airports.
Before leaving Monrovia, on September 15, Duncan had been in contact with a woman sick with Ebola who subsequently died. Duncan was well while travelling and when he arrived in Dallas, but he began feeling ill on September 24 and went to the emergency room at Texas Health Presbyterian Hospital on the evening of September 25. The hospital had not only received the protocol from the US Centers for Disease Control and Prevention (CDC) on how to deal with a patient reporting travel from West Africa, it had even rehearsed its response. So it is hard to explain why, when Duncan's travel history was noted, the appropriate actions of keeping him under observation and testing for Ebola were not taken. Instead, he was given a diagnosis of low-grade viral illness and sent home with a prescription for antibiotics, a senseless action because antibiotics are ineffective against viruses.
By September 28, Duncan was vomiting and he was taken by ambulance back to the emergency room at Texas Health Presbyterian Hospital. A diagnosis of Ebola virus disease was confirmed on September 30. Duncan died on the morning of October 8 despite being treated with the experimental antiviral drug brincidofovir.
The CDC is monitoring 48 people who came into contact with Duncan for signs of infection, and will do so for 21 days, the maximum incubation period of the disease.
On October 12, a nurse who treated Duncan extensively at Texas Health Presbyterian Hospital tested positive for Ebola — the first known case to have been contracted within the US. In a press conference yesterday, CDC Director Dr. Thomas Frieden cited a "breach in protocol" as the reason for her becoming infected despite wearing full protective gear, and said the CDC was investigating.
Meanwhile, the Spanish nurse, Teresa Romero Ramos, started to feel ill on September 30, and infection with Ebola was confirmed six days later. How she became infected is unknown because she is reported to have followed all the infection prevention measures. Romero Ramos is being cared for at Carlos III Hospital in Madrid, and about 10 people, including her husband, have been admitted to the hospital as a precautionary measure. More than 50 people are reported to be under observation in Spain.Contact tracing and monitoring are key to preventing spread of Ebola; US and Spain have the infrastructure and resources to take necessary control measures, making wider outbreaks highly unlikely.
How to avoid Ebola when traveling
There is no FDA-approved vaccine available for Ebola. If you travel to or are in an area affected by an Ebola outbreak, make sure to do the following:
- Practice careful hygiene. For example, wash your hands with soap and water or an alcohol-based hand sanitizer and avoid contact with blood and body fluids.
- Do not handle items that may have come in contact with an infected person's blood or body fluids (such as clothes, bedding, needles, and medical equipment).
- Avoid funeral or burial rituals that require handling the body of someone who has died from Ebola.
- Avoid contact with bats and nonhuman primates or blood, fluids, and raw meat prepared from these animals.
- Avoid hospitals in West Africa where Ebola patients are being treated. The U.S. embassy or consulate is often able to provide advice on facilities.
- After you return, monitor your health for 21 days and seek medical care immediately if you develop symptoms of Ebola.
Putting Ebola in perspective
In the past decade, the US has had five imported cases of hemorrhagic fevers similar to Ebola (one Marburg virus, four Lassa virus), none of which have resulted in local transmission. Indeed, the perceived risk from Ebola needs to be contrasted with the vastly greater threats to health from heart disease, high blood pressure, obesity, smoking, lack of physical activity, traffic accidents, and gunshots (a particular US problem). The fact that the US Ebola patient was given a useless prescription for antibiotics highlights the real and growing threat of antibiotic-resistant infections, which kill tens of thousands of Americans every year and are caused by excessive and inappropriate use of antibiotics. Yet we don't have CNN helicopters hovering above hospitals where patients are treated for multidrug-resistant tuberculosis.
Controlling the spread of Ebola – what works and what doesn't?
Export of more cases of Ebola is inevitable until the epidemic is brought under control at its source. Hence there have been calls for passengers arriving at airports to be screened for signs of illness and for travel restrictions. However, studies indicate that screening all passengers would be ineffective and disruptive. Thomas Duncan's infection would not have been detected by screening on arrival in the US because he was not yet ill. Likewise, when millions of passengers were screened at Asian and Australian airports during the 2003 outbreak of severe acute respiratory syndrome (SARS) no cases were detected. There might be some value in screening passengers arriving on flights directly from the affected countries in West Africa (no direct flights arrive in the US), but better still would be screening before departure from airports in those countries. This departure screening is already happening, and it is where resources should be directed to improve detection. Nevertheless, the US government has decided to screen passengers arriving from the three most affected countries at five airports. I suspect that governments will succumb to pressure to introduce widespread passenger screening regardless of its limited value.
Similarly, travel bans risk being not just ineffective but positively counterproductive. Modelling shows that even an 80 percent reduction in travel from affected countries (which is highly unlikely) would only delay cases being exported by a few weeks, according to a new report by the MOBS-LAB at Northeastern University in Boston. Isolating affected countries will make it harder to deploy medical supplies and personnel to stop the spread of Ebola, and because people will be forced to travel in clandestine ways, their movements will be harder to track. Both WHO and CDC advise against travel restrictions. Advocates of such restrictions are divorced from the scientific evidence and the realities of the 21st-century world.
What's needed to contain Ebola in West Africa?
Our response to Ebola must be directed to controlling the epidemic at its source. The international community was slow to respond to the outbreak in West Africa after it was first reported at the end of March. Indeed, the world didn't really start to pay attention until two American aid workers caught the disease while working in Liberia and were flown to the US for treatment early in August. On August 8, WHO declared the outbreak a Public Health Emergency of International Concern — only the third time such a declaration had been made. Following a vote at the United Nations general assembly on September 19, the UN Mission for Ebola Emergency Response (UNMEER) was formed, the first time the UN has established a mission in response to a health emergency. UNMEER's role is to coordinate the efforts of government and non-government agencies to produce a coherent response to the Ebola crisis.
As in the past, the current outbreak has taken a particular toll on healthcare workers. WHO reports that 416 have been infected and 233 have died as of October 8. So as well as financial and logistical responses, relief efforts must involve sending well trained and well equipped staff to West Africa. Unlike previous outbreaks, which tended to take place in isolated, rural settlements, the current epidemic has become embedded in the community in urban settings. Thus containment in such communities is key, which will involve providing community clinics, educating people on how to avoid infection, supplying adequate sanitation in areas where it's rare, and changing cultural practices such as the tradition of washing dead bodies.
Many more hospital beds are needed to treat the sick, and to this end the US military will set up 100-bed treatment centers at 17 locations in Liberia and train 500 health-care workers a week. British troop are building a 62-bed treatment center in Sierra Leone, and the UK government will fund 1,000 treatment beds and has sent the hospital ship RFA Argus to the country. Canada and China have sent mobile laboratories and staff to the region, France and Germany have established treatment centers, and hundreds of healthcare workers have been sent from Cuba.
WHO estimates that the cost of containing Ebola in West Africa will be at least $1 billion, which seems a considerable underestimate given the commitments already made as described above. The World Bank puts the economic impact at $3.8 billion to $32.6 billion, depending on how quickly it is contained, which will be felt most severely in the three worst affected countries but also across the wider west African region. These countries, already among the world's poorest, cannot afford such an economic setback.
The West Africa Ebola outbreak shows clearly how poverty, underdevelopment, and weak healthcare systems in seemingly distant countries can affect all our lives by allowing dangerous infections to flourish. Rather than hasty reactions to disease threats, global health security depends on improving quality of life and access to healthcare for all human beings.
Read the latest research on Ebola
To assist health workers and researchers working under difficult and dangerous conditions to bring this outbreak to a close, The Lancet has created an Ebola Resource Centre. This hub brings together existing Ebola content from The Lancet and Cell Press journals and will feature the latest Ebola research as it is published. It is intended to be a comprehensive Ebola resource for clinicians, public health professionals, and anybody else who needs access to existing Ebola research and latest developments.
All content on the site is free to access.
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John McConnell (@JohnSMcConnell) has been an editor at The Lancet since 1990 and was founding Editor of The Lancet Infectious Diseases in 2001. After graduating with a degree in clinical microbiology and parasitology, he was a researcher at the Royal Postgraduate Medical School, Hammersmith Hospital, in London, for six years before switching to science publishing.