Ebola virus disease (EVD) or Ebola hemorrhagic fever (EHF) is a viral hemorrhagic fever caused by ebolaviruses in humans and other primates.
WHAT IS EBOLA VIRUS DISEASE?
Ebola virus disease (EVD) is a deadly disease that primarily affects the African continent with occasional outbreaks. People and nonhuman primates are the most common victims of EVD (such as monkeys, gorillas, and chimpanzees).
An infection with a group of viruses belonging to the genus Ebolavirus causes it:
• Ebola virus (species Zaire ebolavirus)
• Sudan virus (species Sudan ebolavirus)
• Taï Forest virus (species Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus)
• Bundibugyo virus (species Bundibugyo ebolavirus)
• Reston virus (species Reston ebolavirus)
• Bombali virus (species Bombali ebolavirus)
Only four of these viruses (Ebola, Sudan, Ta Forest, and Bundibugyo) have caused disease in humans. The Reston virus can infect nonhuman primates and pigs, but no human cases have been reported. The Bombali virus was first discovered in bats in 2018, and experts are still unsure whether it causes disease in animals or humans.
In 1976, near the Ebola River in what is now the Democratic Republic of Congo, the Ebola virus was discovered for the first time. Since then, the virus has infected people on a regular basis, causing outbreaks in a number of African countries. The source of the Ebola virus is unknown to scientists. They believe EVD is animal-borne, with bats or nonhuman primates being the most likely source, based on similar viruses. Infected animals, such as apes, monkeys, duikers, and humans, can spread the virus to other animals.
The virus is transmitted to humans through direct contact with animal blood, body fluids, and tissues. The Ebola virus then spreads to others through direct contact with the body fluids of someone who is sick or has died from the disease. This can happen if a person comes into contact with infected body fluids or contaminated objects. The virus then enters the body through abrasions on the skin or mucous membranes in the eyes, nose, and mouth. Sexual contact with someone who is sick with EVD or has recovered from it can spread the virus. After recovery from the illness, the virus can be found in certain body fluids, such as sperm.
IS IT THE CASE THAT, I COULD CATCH EBOLA BY SITTING NEXT TO SOMEONE WHO HAS IT?
According to the CDC, the chances of this happening are extremely unlikely. The Ebola virus does not spread like the flu; it is spread by direct contact with ill people's blood, secretions, or other bodily fluids. It can also be spread through "indirect contact," such as coming into contact with contaminated needles.
IS EBOLA THE MOST DANGEROUS DISEASE THAT HUMANS HAVE EVER ENCOUNTERED?
This isn't the case. While the current outbreak's mortality rate is around 55%, the total number of people who have died as a result of the outbreak is around 1,400. The Plague killed 30 to 60 percent of Europe's population in the 1300s. According to the World Health Organization, 36 million people have died as a result of HIV/AIDS since the first cases were reported in 1981, with 1.6 million people dying in 2012.
EMERGENCE OF EBOLA IN HUMANS
When two outbreaks of fatal hemorrhagic fever occurred in different parts of Central Africa in 1976, the Ebola virus disease (EVD), one of the deadliest viral diseases, was discovered. The first outbreak was in a village near the Ebola River in the Democratic Republic of Congo (formerly Zaire), which gave the virus its name. The second outbreak occurred about 500 miles (850 kilometres) away, in what is now South Sudan.
Initially, public health officials assumed that these outbreaks were caused by a single infected person travelling between the two locations. The two outbreaks, however, were caused by two genetically distinct viruses: Zaire ebolavirus and Sudan ebolavirus, according to scientists. Scientists concluded that the virus originated from two different sources and spread to people in each of the affected areas independently after this discovery.
Viral and epidemiologic evidence suggests that the Ebola virus existed long before the outbreaks that have been documented. The spread of the Ebola virus may have been aided by factors such as population growth, encroachment into forested areas, and direct contact with wildlife (such as bushmeat consumption).
The majority of cases and outbreaks of Ebola Virus Disease have occurred in Africa since its discovery in 1976. The Ebola outbreak in West Africa from 2014 to 2016 began in a rural setting in southeastern Guinea, quickly spread to cities and across borders, and became a global epidemic within months.
IDENTIFYING A HOST
Scientists studied thousands of animals, insects, and plants in search of the virus's source after it was discovered (called reservoir among virologists, people who study viruses). When the first cases of EVD in humans are discovered, gorillas, chimps, and other mammals may be blamed. They, like humans, are “dead-end” hosts, which means the organism dies after infection and does not survive to spread the virus to other animals. Despite the virus being present in its organs, tissues, and blood, the reservoir host animal of Ebola virus may not experience acute illness, as with other viruses of its kind. As a result, the virus is most likely kept alive in the environment by spreading from host to host or via intermediate hosts or vectors.
African fruit bats are likely to be involved in Ebola virus transmission and may even be the source animal (reservoir host). Scientists are still looking for conclusive evidence of the bat's role in Ebola transmission. 1 Bombali virus, the most recent Ebola virus to be discovered, was discovered in bat samples collected in Sierra Leone. 2
UNDERSTANDING PATHWAYS OF TRANSMISSION
During the first outbreaks, the use of contaminated needles and syringes allowed the Ebola virus to spread and multiply. Nurses at the Yambuku mission hospital in Zaire (now the Democratic Republic of Congo – DRC) reportedly used five syringes for 300 to 600 patients per day during the first outbreak. During early Ebola outbreaks, close contact with infected blood, reuse of contaminated needles, and poor nursing techniques were the main sources of human-to-human transmission. 3
Reston ebolavirus was discovered in research monkeys imported into the United States from the Philippines in 1989. Scientists later confirmed that the virus was spread throughout the monkey population in the facility by droplets in the air (aerosolized transmission). However, such airborne transmission has not been shown to play a significant role in human Ebola outbreaks. 4 The discovery of the Reston virus in these Philippine monkeys revealed that Ebola was no longer limited to African settings, but had also spread to Asia.
By the time of the Cote d'Ivoire outbreak in 1994, scientists and public health officials had a better understanding of how the Ebola virus spreads, and progress had been made in reducing transmission by requiring healthcare workers to wear face masks, gloves, and gowns. In addition, disposable equipment, such as needles, was made available.
During the 1995 Ebola outbreak in Kikwit, Zaire (now DRC), the international public health community played a key role, as it was widely acknowledged that containing and controlling the virus was critical to ending outbreaks. The local community was educated on how the disease spreads; the hospital was adequately staffed and equipped; and healthcare personnel were trained on disease reporting, patient case identification, and methods for reducing transmission in the healthcare setting.
Clinically, it can be difficult to tell the difference between EVD and other infectious diseases like malaria, typhoid fever, and meningitis. Many of the symptoms of pregnancy and Ebola are very similar. Because of the risks to the unborn child, pregnant women should be tested as soon as possible if Ebola is suspected.
The following diagnostic methods are used to confirm that symptoms are caused by Ebola virus infection:
• antibody-capture enzyme-linked immunosorbent assay (ELISA)
• antigen-capture detection tests
• serum neutralisation test
• reverse transcriptase polymerase chain reaction (RT-PCR) assay
• electron microscopy
• virus isolation by cell culture.
The selection of diagnostic tests should be done with care, taking into account technical specifications, disease incidence and prevalence, and the social and medical implications of test results. Diagnostic tests that have been subjected to an independent and international evaluation are strongly recommended for use.
Survival is improved with supportive care, such as rehydration with oral or intravenous fluids, and treatment of specific symptoms. A variety of potential treatments are currently being evaluated, including blood products, immune therapies, and drug therapies.
The first-ever multi-drug randomised control trial was conducted in the DRC during the 2018-2020 Ebola outbreak to evaluate the effectiveness and safety of drugs used in the treatment of Ebola patients under an ethical framework developed in consultation with experts in the field and the DRC during the 2018-2020 Ebola outbreak.
Ebola has no known cure, though researchers are working on one. For the treatment of Ebola, two drug treatments have been approved. Inmazeb is a compound that consists of three monoclonal antibodies (atoltivimab, maftivimab, and odesivimab-ebgn). Ebanga (ansuvimab-zykl) is a monoclonal antibody that is given as an injection. It aids in the blocking of the virus's path to the cell receptor, preventing it from entering the cell.
The Ervebo vaccine has been shown to protect people against the Zaire ebolavirus species, and the Strategic Advisory Group of Experts on Immunization recommends it as part of a broader set of Ebola outbreak response tools. The vaccine was approved by the US Food and Drug Administration in December 2020, and WHO prequalified it for use in people aged 18 and up (except pregnant and breastfeeding women) for protection against Ebola virus disease caused by the Zare Ebola virus.
Under the "compassionate use" protocol, the vaccine was given to over 350 000 people in Guinea and the Democratic Republic of the Congo during the 2018-2020 Ebola virus disease outbreaks. The vaccine has been proven to be safe and effective against the Zaire ebolavirus species. Beginning in January 2021, a global stockpile of the Ervebo vaccine will be available.
In May 2020, the European Medicines Agency recommended that a 2-component vaccine called Zabdeno-and-Mvabea be approved for people aged 1 year and up.
The vaccine is given in two doses: the first is Zabdeno, and the second is Mvabea, which is given approximately 8 weeks later. As a result, this two-dose prophylactic regimen is not appropriate for an outbreak response where immediate protection is required.
PREVENTION AND CONTROL
Case management, surveillance, and contact tracing, as well as a good laboratory service, safe burials, and social mobilisation, are all important components of effective outbreak control. In order to successfully control outbreaks, community engagement is essential. Raising public awareness about Ebola infection risk factors and protective measures (such as vaccination) that individuals can take is an effective way to reduce human transmission. Several factors should be highlighted in risk reduction messaging:
Contact with infected fruit bats, monkeys, apes, forest antelope, or porcupines, as well as the consumption of their raw meat, reduces the risk of wildlife-to-human transmission. Handling animals should be done with gloves and other protective gear. Before eating animal products (blood and meat), make sure they are thoroughly cooked.
Reducing the risk of human-to-human transmission by avoiding direct or close contact with people who have Ebola symptoms, especially their bodily fluids. When caring for sick patients, gloves and other appropriate personal protective equipment should be worn. After visiting patients in the hospital or caring for patients at home, hand washing is required on a regular basis.
Outbreak containment measures include burying the dead in a safe and dignified manner, identifying people who may have come into contact with someone infected with Ebola and monitoring their health for 21 days, separating the healthy from the sick to prevent further spread, and maintaining a clean environment.
To reduce the risk of sexual transmission, WHO recommends that male EVD survivors practise safer sex and hygiene for 12 months from the onset of symptoms or until their semen tests negative twice for Ebola virus, based on further analysis of ongoing research and consideration by the WHO Advisory Group on the Ebola Virus Disease Response. Contact with bodily fluids should be avoided, and soap and water should be used to clean. Male and female convalescent patients whose blood has been tested negative for Ebola virus should not be isolated, according to the WHO.
lowering the risk of infection from pregnancy-related fluids and tissue Pregnant women who have survived Ebola disease require community support in order to attend frequent antenatal care (ANC) visits, manage pregnancy complications, and meet their sexual and reproductive health and delivery needs in a safe manner. This should be done in conjunction with Ebola and Obstetric health care specialists. Pregnant women's sexual and reproductive health decisions should always be respected.