What you actually need to know about Ebola...
Dr. Jamie Jordan has a special interest in infectious diseases and when we asked him to write about Ebola based on the latest cases found in Uganda.
Key information
- Ebola Virus Disease is an acute, severe viral illness which is often fatal.
- The virus spreads from animal hosts to humans, then from human to human by direct contact with blood or body fluids. It is not generally spread through casual social contact between asymptomatic people.
- Early symptoms include fever, headache and muscle aches, progressing to severe diarrhoea and vomiting, haemorrhage and septic shock.
- Outbreaks occur regularly in Central and West Africa. No significant outbreaks have occurred in countries outside of Africa.
- Ebola should be considered in any patient presenting with fever who has travelled to an area where Ebola is known to occur within the last 21 days.
- The spread of infection can be prevented by quarantining infected individuals, careful barrier nursing, safe handling of the deceased, environmental decontamination and safe waste disposal.
- Vaccines offering protection against one species of Ebola have been licensed but are not yet widely available.
Where is Ebola found?
Ebola virus was discovered in 1976 near the Ebola River in Zaïre, now the Democratic Republic of Congo. There have since been numerous outbreaks in tropical sub-Saharan countries across Central and West Africa. The largest outbreak to date occurred in 2014-2016 when the Zaïre ebolavirus spread from Guinea to nine other countries, infecting 28,000 people and causing around 11,000 deaths. Cases have been exported to Europe and the USA but no sustained transmission has yet occurred outside of Africa.
How does the disease spread?
Fruit bats are thought to be the natural reservoir of the Ebola virus, but human infections have arisen from contact with various other animals including non-human primates, porcupines and antelopes. Transmission occurs when the blood or body fluid of an infected animal comes into contact with a person’s mucous membranes or broken skin.
The virus spreads from symptomatic individuals to other people through contact with blood or body fluids including urine, faeces, saliva, sweat and vomit. Healthcare workers or family members caring for the sick are at particular risk, and traditional burial practices involving handling of human remains are a common factor in propagating outbreaks.
Ebola virus can survive outside the body for several hours on dry surfaces or for several days in fluids such as blood spills, allowing indirect spread through contact with contaminated clothing or bedding.
Individuals who survive EVD may continue to harbour the virus within their bodies for many weeks. Ebola virus has been isolated from body fluids such as semen and breast milk in apparently healthy people several months after clinical recovery, and several incidents of sexual transmission are thought to have occurred.
What are the symptoms?
Symptoms usually develop eight to ten days after contact with the virus, though the incubation period can range from two days to three weeks.
Patients generally experience sudden-onset flu-like symptoms including fever, headache, muscle pains, sore throat and weakness. These may be followed by severe vomiting and diarrhoea, chest pain and shortness of breath. As the disease progresses patients often develop internal and external bleeding causing them to cough or vomit blood, pass blood in their stool, bleed into the whites of their eyes and bleed excessively from wounds such as needle injection sites.
On average EVD is fatal in around 50% of cases. This figure has varied from 25% to 90% in different outbreaks depending on a range of factors including the baseline population health, provision of medical care and the species of Ebola virus involved.
Death is frequently due to shock from fluid loss and bleeding, generally occurring within six to sixteen days of symptom onset.
How is Ebola diagnosed?
Early symptoms of EVD are difficult to distinguish from other common illnesses such as COVID-19, influenza or malaria. EVD should be suspected in people who develop a fever within 21 days of visiting an area where there is a current outbreak, visiting caves/mines inhabited by bats or eating primates, antelopes or bats in regions where Ebola is known to occur.
Formal diagnosis requires laboratory analysis of a blood sample, though a bedside rapid antigen test produced by OraSure Technologies has recently been approved by the Food and Drug Administration (FDA).
How is Ebola treated?
The main treatment for EVD is intensive supportive care with intravenous fluids, oxygen, blood pressure support and management of vomiting, fever and pain.
Two biological treatments have been approved by the FDA to treat EVD, ‘Inmazeb’ and ‘Ebanga.’ These have been shown to significantly reduce mortality in patients with Zaïre ebolavirus and are now recommended by the World Health Organisation (WHO), but their availability is limited.
Should you suspect a case of Ebola onboard then containment is essential until you can medically evacuate them. Take every available precaution to protect the rest of the crew and keep the patient isolated and only enter their cabin if absolutely necessary and whilst wearing full Personal Protective Equipment.
Ebola is a notifiable disease and therefore must be entered onto the Maritime Declaration of Health. Port Health will work with you to develop a management plan so early notification is key.
How can Ebola be contained?
Travellers in West and Central Africa should avoid contact with bats, antelopes and nonhuman primates, and should avoid ‘bushmeat’ prepared from these or any unknown animal.
The risk of Ebola transmission can be reduced by avoiding contact with the blood or body fluids of anybody who is unwell. Suspected cases should be isolated in access-controlled rooms and nursed using strict barrier precautions. Healthcare staff should use comprehensive personal protective equipment (PPE) including gloves and gown covering all exposed skin, a face visor, goggles and respiratory protection such as an FFP3 mask. Careful adherence to best practice procedures when donning and removing PPE are vital.
Ebola virus is deactivated by chlorine and alcohol or by exposure to high temperatures. Exposed hard surfaces can be decontaminated using bleach solution, whilst contaminated fabrics can be washed at high temperature or incinerated. Waste from infected patients must be incinerated or treated at high temperature and pressure in an autoclave.
Several vaccines against EVD have recently been developed, with three approved for human use. The ‘Ervebo’ vaccine is known to give a high level of protection against Zaïre ebolavirus and has been distributed to help control outbreaks in Central and West Africa. The US government now recommends vaccination of American healthcare workers who are at risk of exposure, but the vaccine is not yet in common use throughout the rest of the world and is not generally available to the public.
Current outbreak
A case of fatal EVD was detected in Uganda in September 2022 in a 24 year-old man from Mubende, 80 km from the capital city Kampala. As of October 12th a further 53 cases have been identified, with 19 deaths including a recent case in Kampala.
The outbreak is caused by the Sudan ebolavirus strain, for which no licensed vaccine or biological treatment currently exists. The Ugandan government and WHO are implementing testing and isolation measures and the USA has begun screening all air passengers arriving from Uganda. Five previous outbreaks of Ebola have been successfully contained in Uganda since the year 2000.
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