What we now know about ebola

Source: WHO.

Update: As of October 20, two nurses who had cared for the index patient have caught ebola. There are allegations that the hospital was not properly prepared for the case, and they did not have proper equipment while they looked after him.

Update: The news broke on October 11 and 12 that a nurse who had cared for the first (index) case of ebola in the US had caught ebola herself. It is worrying because she had worn the full hazmat gear in caring for the patient, and that she cannot remember committing any breach of security, unlike a nurse in Spain who said she had accidentally touched her face with a gloved hand. The US Centers for Disease Control and Prevention is firm that some breach of 'protocol' did occur; the question is where, or whether ebola is not well-understood enough.

The World Health Organization shared a list of ways in which the ebola virus may be transmitted on 6 October. While it's known that the virus is transmitted among humans through close and direct physical contact with infected bodily fluids, the most infectious are blood, faeces and vomit, the WHO said.

The virus has also been detected in breast milk, urine and semen. In a convalescent (recovering) male, the virus can persist in semen for at least 70 days; one study suggests persistence for more than 90 days. This implies that the virus can remain in semen for a longer period, but it remains unclear whether the virus can be transmitted through this method.

WHO also says that saliva and tears may also carry some risk of infection. However, the studies implicating these additional bodily fluids were extremely limited in sample size and the science is inconclusive. In studies of saliva, the virus was found most frequently in patients at a severe stage of illness. 

The whole live virus has never been isolated from sweat. This implies that sweat from a victim cannot transmit the virus.

The ebola virus can also be transmitted indirectly, by contact with previously contaminated surfaces and objects. The risk of transmission from these surfaces is low and can be reduced even further by appropriate cleaning and disinfection procedures.

Ebola virus disease is not an airborne infection. Airborne spread among humans implies that you can catch the virus from inhaling a suspended cloud of small dried droplets. This mode of transmission has not been observed during extensive studies of the ebola virus over several decades.

Theoretically, bigger droplets from a heavily infected individual, who has respiratory symptoms caused by other conditions or who vomits violently, could transmit the virus – over a short distance – to another nearby person. This could happen when virus-laden droplets are directly propelled, by coughing or sneezing (which does not mean airborne transmission) onto the mucus membranes or skin with cuts or abrasions of another person.

However, observation to date is that the spread of the virus via coughing or sneezing is rare, if it happens at all. Epidemiological data emerging from the outbreak are simply not consistent with the pattern of spread seen with airborne viruses, like those that cause measles and chickenpox, or the airborne bacterium that causes tuberculosis.

WHO is not aware of any studies that actually document this mode of transmission. On the contrary, good quality studies from previous ebola outbreaks show that all cases were infected by direct close contact with symptomatic patients.

There are also fears that the disease could change its mode of transmission. The WHO says scientists are unaware of any virus that has dramatically changed its mode of transmission. Speculation that ebola virus disease might mutate into a form that could easily spread among humans through the air is just that: speculation, unsubstantiated by any evidence.

For example, the H5N1 avian influenza virus, which has caused sporadic human cases since 1997, is now endemic in chickens and ducks in large parts of Asia. That virus has probably circulated through many billions of birds for at least two decades. Its mode of transmission remains basically unchanged.

The WHO is calling for more to be done to implement – on a much larger scale – well-known protective and preventive measures. Abundant evidence has documented their effectiveness, it says.

WHO downplays possibility of global ebola epidemic

The World Health Organization (WHO) provided an overview of the spread of Ebola virus disease (EVD) in West Africa on 11 August and stressed that in countries with well-developed health systems, an epidemic is highly unlikely "given the epidemiology of the Ebola virus and experiences in past outbreaks".

The organisation noted that fear has led to a very high level of vigilance and clinical suspicion worldwide, stating that "such a high level of alert further increases the likelihood that any imported case will be quickly detected and properly managed, limiting onward transmission."

On the downside, the WHO observes that the same fear is compromising outbreak control when it causes airlines to refuse to transport personal protective equipment and courier services to refuse to transport properly and securely packaged patient samples to a WHO-approved laboratory.

Facts about Ebola

• The Ebola virus is highly contagious, but is not airborne. 
• Transmission requires close contact with the bodily fluids of an infected person, as can occur during health-care procedures, home care, or traditional burial practices. 
• The incubation period ranges from two to 21 days, but patients become contagious only after the onset of symptoms. As symptoms worsen, the ability to transmit the virus increases. As a result, patients are usually most likely to infect others at a severe stage of the disease, when they are visibly, and physically, too ill to travel. 
• There is no cure. 
• Early detection and supportive care greatly improve prospects for survival. 

Read about the WHO announcement of the gravity of the EVD situation here, and how India and Singapore have prepared for the disease.

World Health Organization calls Ebola outbreak a public health emergency of international concern

The World Health Organization (WHO) has warned 8 August that the Ebola outbreak in West Africa is a Public Health Emergency of International Concern (PHEIC).

As of 4 August 2014, there have been 1,711 cases (1,070 confirmed, 436 probable, 205 suspect) of Ebola virus disease (EVD), including 932 deaths. Between 5 and 6 August 2014, a total of 68 new cases of EVD (laboratory-confirmed, probable, and suspect cases) as well as 29 deaths were reported from Guinea, Liberia, Nigeria, and Sierra Leone.

On 6 August, a Saudi man suspected of being infected with the Ebola virus passed away at 8.45am at a specialised hospital in Jeddah, Saudi Arabia. The patient had been admitted to the intensive care unit late on 4 August after exhibiting symptoms of viral hemorrhagic fever following a business trip to Sierra Leone, Saudi's Ministry of Health said. The cause of the infection is still under investigation, and people who had been in contact with the man are being traced or monitored for symptoms of Ebola.

The WHO further provides the following recommendations for states which are currently not affected by EVD nor adjacent to a state which is affected:

• There should be no general ban on international travel or trade; restrictions outlined in recommendations regarding the travel of EVD cases and contacts should be implemented.
• States should provide travelers to Ebola affected and at-risk areas with relevant information on risks, measures to minimise those risks, and advice for managing a potential exposure. 
• States should be prepared to detect, investigate, and manage Ebola cases; this should include assured access to a qualified diagnostic laboratory for EVD and, where appropriate, the capacity to manage travelers originating from known Ebola-infected areas who arrive at international airports or major land crossing points with unexplained febrile illness (fever). 
• The general public should be provided with accurate and relevant information on the Ebola outbreak and measures to reduce the risk of exposure. 
• States should be prepared to facilitate the evacuation and repatriation of nationals (e.g. health workers) who have been exposed to Ebola. 

On 11 August, WHO will convene a panel of medical ethics experts to begin looking at the use of experimental treatments in the ongoing EVD outbreak in West Africa. At this time, there are no registered medicines or vaccines against this deadly virus, though several experimental options are currently under development.

Emirates has already suspended flights to Conakry in Guinea until further notice due to the Ebola outbreak, the company said on its website. "We apologise for any inconvenience caused to our customers, however the safety of our passengers and crew is of the highest priority and will not be compromised," the company stated, asking affected customers to contact their travel agent or Emirates Call Centres for rebooking options, and visit the website for further updates.

Airlines flying to Sierra Leone include British Airways and Air France. British Airways has cancelled flights to Sierra Leone and Liberia till August 31. Air France also flies to Guinea, while Lufthansa flies to Nigeria.

Gulf Business has also reported that hajj visas are not being issued to pilgrims of the affected countries.

View the latest FAQ on EVD here.
Read about Singapore's preparedness activities here. Read about what India is doing about tracking nationals exposed to Ebola here.