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Infection control guidelines for Ebola

Ebola guidelines are not consistent and do not protect against airborne infection. Highly deadly infectious diseases should be treated at the highest infection control level

Bjørg Marit Andersen MD PhD

Professor in Hygiene and Infection Control,

Specialist in Medical Microbiology,

Former head of Department of Hospital Infections,

Oslo University Hospital-Ullevål, Norway

Ebola is claiming an increasing number of victims in West Africa. Up to the end of October 2014, the number of confirmed, probable and suspected cases was 9291, including 4555 deaths (49%).1 Healthcare workers (HCW) have also been seriously affected; as of 14 October, 423 HCWs have developed Ebola disease and 239 of them died (57%).1 This development, with an increasing epidemic situation, may raise some questions about international and national infection control guidelines recommended by WHO, CDC and the UK.2–4 Why did the infection control not work for patients or for HCWs?5

The guidelines recommended contact and droplet isolation within one metre

Healthcare personnel may have followed the specific infection control recommendations from WHO, CDC, or the UK.2–4

They were last updated in August and September 2014 (see Table 1).2–4 All three guidelines recommended contact and droplet isolation within one metre from an Ebola suspected or confirmed case.2–4 The spread of infection was decided to be only by contact, not airborne, except for aerosol-producing procedures.2–4 WHO, CDC and the UK recommended similar infection control precautions concerning personal protective equipment (PPE) for suspected or confirmed cases.2–4

The use of PPE in Ebola situations was insufficient2–4

For cases without uncontrolled bleeding, diarrhoea or vomiting, the recommendation of PPE when entering the room is (Table 1):

For suspected cases: Eye protection, fluid repellent gown (in the UK, plastic apron), gloves and surgical mask. Specific shoes/shoe covers are recommended only by WHO. No head/hair/neck cover is recommended.

For confirmed cases: Similar to suspected cases, but the UK is recommending a gown and respirator/N95 instead of a surgical mask. No head/hair/neck cover.

For aerosol-producing procedures: All three guidelines recommend respirator/N95, still no head/hair/neck cover, but CDC recommends shoe covers.

The three guidelines may have been followed during work with Ebola patients in West Africa most of the time in ordinary Ebola patients without bleeding, vomiting or diarrhoea, and in triage situations where there may a mixture of infected and non-infected patients.2–4 No head/hair/neck covers or respirator/N95s have been recommended for all suspected and confirmed cases in these guidelines.2–4

Even during aerosol-producing procedures, head/hair/neck covers were not recommended. This is striking information for personnel knowing that they are producing aerosols while working with a highly deadly disease.

Upgrading Ebola guidelines 20 October 2014, CDC – for US Hospitals

Two nurses were recently infected with Ebola during high-risk work with an imported Ebola patient in USA. They probably followed the CDC guidelines and still were infected. CDC then decided to strengthen the guideline of August 2014. 

The new CDC guideline of 20 October 2014 was recently made for HCWs in US hospitals (see Table 1).6 All bare skin should be covered, like the head, hair and neck, and all should put on respirator/N95s. In addition, procedures for putting on (donning) and removing (doffing) were included.6 This guideline was only made for US hospitals and is only for confirmed, not suspected, Ebola cases. 

The protective effect on contact infection is better in this guideline, but still the guide is made to inhibit contact and droplet contamination within one metre, not airborne infections.6 In the CDC October guideline the observer is not well protected in the PPE removal area. When assisting the HCW with PPE removal, the observer is not using respirator/N95 or a surgical mask at all. Virus organisms released from the contaminated HCWs during PPE doffing may be airborne and contaminate the observer which is not protected against airborne spread of Ebola. The airborne virus may also be a general risk in the PPE removal room. 

The guidelines do not protect against airborne disease

The guidelines from WHO, the UK and CDC (August 2014) do not protect against a serious disease like Ebola because they do not protect against airborne spread.2–5 The new CDC guideline (20 October 2014) is still not intended to protect against airborne disease.6

Ebola is defined as a high-risk infectious, hazard level 4 virus, but is not treated as such in the international/national guidelines.2–4,6 Ebola has been a remote and seldom illness, with small outbreaks and is not well studied.7,8 Even if the main transmission of Ebola virus is person-to-person contact and indirect contact, there is no good medical documentation for declaring that Ebola may not be transmitted by air.5,7–9 This serious situation should call for responsibility from WHO!  

Strict isolation is needed for suspected, probable or confirmed cases of high-risk infectious diseases such as Ebola, Lassa and other haemorrhagic viruses, which are among the most dangerous microbes known. This fact should be taken into consideration when treating such patients. Personal protective equipment (PPE) for contact and airborne infections and strict isolation should always be used for these high-risk infectious diseases because of:

  • A high lethality: Ebola virus disease (EVD) may have a lethality of more than 55% in HCWs.1
  • There is a very long survival of the virus outside the body: one to two weeks as it is a robust virus.7
  • The infectious dose is probably very low: 1–10 viruses organisms by air, as shown for non-human primates.7 
  • During the initial phase of illness, there may be respiratory symptoms such as pharyngitis, coughing and hiccups. Studies have shown that when coughing and sneezing, droplets may be expelled a large distance – up to nine metres in a room.10 
  • Like other infectious disease agents, Ebola virus may be re-aerosolised from the environment, bed clothes, equipments etc., especially when caring for the patients. 
  • Airborne transmission is well documented in animal studies by PCR in air samples – from infected pigs to non-human primates.7,11 Using slit samplers to collect virus organisms from the air in patient rooms may be easy during the epidemic in West Africa with so many cases.
  • An increasing concentration of virus organisms (airborne) from skin scales, coughing and re-aerosols during work with the patients, especially without a negative pressure room, air changes and ventilation, may be a hazard to persons not well protected. 

The SARS success is a reminder

Healthcare workers and helpers should be protected with PPE as they were during the SARS epidemic.5 The SARS epidemic was an infection control success by the healthcare system in Asia in 2003. It came as a new and, in the beginning,  remote illness. 

From February to August 2003, there were more than 8000 SARS cases and approximately 10% of those died. During the first phase of SARS, more than 90% of the cases were HCWs that took care of SARS patients, using WHO’s recommendation of “contact and droplet isolation – one metre from the patient.”12 On 24 April 2003, WHO introduced “strict isolation”, airborne and contact isolation, and the epidemic was over after five to six months. However, WHO is now repeating the same failure as was done during the early phase of the SARS epidemic by using “contact and droplet isolation – one metre from the patient.”12

Separate hospitals for EVD should be built, like in China (1000 beds in eight days for SARS), and only patients with laboratory documented EVD should be cohorted. Suspected cases should be isolated separately. HCWs and helpers should be trained and especially observed concerning putting PPE on and taking it off. The observers should also use complete PPE. During the SARS epidemic, HCWs were re-contaminated by not knowing how to take off PPE correctly. 

Exposed people and patients with other diseases should be treated in professional triages to reduce the population’s fear of being infected with EVD during contact with healthcare. Exposed people should be taken care of by professional helpers. 


  • Infection control does not work since well educated persons working with the patients are infected.5,6,9 The revised CDC guidelines  (recommendations of 20 October 2014) may result in better protection against Ebola for HCWs, helpers and others, if used in West Africa, and if including suspected cases in triages. But there is no airborne protection included.
  • The general population would feel more safe and confident when observing that HCWs and helpers are not infected and that they are working in a safe way. This may probably also have an impact on bringing the epidemic under control. 
  • A high-risk infectious disease like Ebola should always be treated at the highest risk concerning infection control. And this should be done extensively and immediately from the beginning. That would spare a lot of suffering, lives and economic burden on poor countries.
  • Before infection control is raised to level 4; strict isolation (airborne and contact infection), more HCWs, helpers, families of cases and the general population may probably be exposed unnecessarily to a serious illness. 
  • There is still a need for a lot of resources, especially concerning infection control work.


  1. WHO: Ebola response roadmap update 17 October 2014.
  2. WHO. Interim infection prevention and control guidance for care of patients with suspected or confirmed filovirus haemorrhagic fever in health-care settings, with focus on Ebola. September 2014.
  3. CDC. Infection prevention and control recommendations for hospitalized patients with known or suspected Ebola haemorrhagic fever in US hospitals. August 2014.
  4. UK, Department of Health. Management of hazard group 4 viral haemorrhagic fevers and similar human infectious diseases of high consequences. September 2014.
  5. Andersen BM. Infection control is not working. Promed-mail 14 September 2014.
  6. CDC. Guidance on personal protective equipment to be used by healthcare workers during management of patients with Ebola virus disease in U.S. Hospitals, including procedures for putting on (donning) and removing (doffing). October 20, 2014.
  7. Public Health Agency Canada. Ebolavirus. August 2014. 
  8. CDC. Review of human-to-human transmission of Ebola virus. September 17, 2014.
  9. Brosseau LM, Jones R. Health workers need optimal respiratory protection for Ebola. September 17, 2014.
  10. Bourouiba L, Dehandschoewerker E, Bush JWM. Violent expiratory events: on coughing and sneezing. J Fluid Mech 2014; 845: 537–63. 
  11. Weingartl HM, Embury-Hyatt C, Nfon C. Transmission of Ebola virus from pigs to non-human primates. Scientific Rep 2. 2012; article number:811.
  12. WHO. Hospital infection control guidance for severe acute respiratory syndrome (SARS) revised 24. April 2003.