The haemorrhagic fever caused by the Ebola virus may finally be curable as two experimental drugs have shown survival rates of as high as 90 per cent in a clinical trial, which was carried out in the Democratic Republic of Congo (DRC).
On July 17 the World Health Organisation (WHO) declared the Ebola outbreak in DRC as a Public Health Emergency of International Concern (PHEIC), the highest declaration of alarm used by the organisation.
A brief history of the disease
Ebola outbreaks in DRC are not new. The first outbreak of the virus was recorded in the year 1976, when over 318 cases of the disease were reported as per the National Centre for Biotechnology Information (NCIB).
The virus derives its name from the 250-km long Ebola river which flows through Congo and at a point is over 60-km from Yambuku, the rural Congolese area where some of the first patients of the disease were reported. So that the Yambuku community was not stigmatised, the scientific director of the International Commission, Karl Johnson suggested that the virus be called “Ebola”. Johnson’s suggestion was formally accepted in 1977 at a meeting in London.
Before the virus was given the name, “Ebola”, it was simply referred to as the “mystery” disease, for in August 1976 patients who were reporting to the Yambuku Mission Hospital in northwestern DRC (then Zaire) were affected by this then-unknown disease and were presenting symptoms including headache, abdominal pain and bleeding.
As per the NCIB, it is possible that the first known case of this species of the Ebola virus contracted it from an antelope or smoked monkey meat that a 42-year old individual purchased in 1976.
In the same year in late September, a similar outbreak was reported in Sudan by the WHO. However, it was eventually concluded that the Ebola virus in Sudan was different from the Ebola virus in Zaire as the fatality rates were higher for Zaire, at 88 per cent as compared to 53 per cent for Sudan.
The Ebola virus (EBOV) is one among the four related species of the genus Ebolavirus—the Sudan virus, Tai Forest virus, Bundibugyo virus and Reston virus.
How is the disease transmitted?
Since Ebola is a viral disease, transmission occurs upon contact with the bodily fluids of an infected animal or human being, either directly through a needle or from exposure through broken skin.
Present status of treatment and drug development
According to the NCIB, “Drug development for Ebola virus (EBOV) has been in progress for several decades, primarily fueled by concerns about the potential use of the Category A agent as a bioweapon.” However, the 2014-2016 West African outbreak focused efforts on “medical countermeasures” for Ebola virus disease (EVD).
While no drugs exist to treat the disease, several clinical trials have been initiated since the 2014-2016 outbreak. These clinical trials are carried out in three phases, where every phase differs in its scope and objectives. While some of these trials are stopped after they complete phase 1 due to safety concerns, others are flagged because of their designs, which are not randomly sampled.
A successful drug should stop the virus from making copies of itself. The majority of clinical trials and drug development efforts until now have been projected towards controlling EBOV Zaire.
Latest clinical trial
The ongoing outbreak in DRC started in 2018, due to which 1,650 have died and over 12 cases are reported every day as per the WHO. Militia violence and local people’s resistance to acknowledge help from outside have also been a barrier in controlling the breakout.
The recent clinical trial began in November 2018 and has been sponsored by the National Institute for Allergy and Infectious Diseases (NIAID). In this trial, participants will be screened with questions, blood tests, and their medical history.
Four drugs were tested in this trial to seek treatment from EBOV Zaire. Out of these, two experimental drugs, called REGN-EB3 and mAb114 have shown promising results. If administered shortly after the infection is contracted (when levels of virus in the blood is low), the survival rate may be as high as 90 per cent. The former drug is developed by Regeneron Pharmaceuticals based in the United States, while the latter is developed by the NIAID.
Preliminary data from the first 499 patients enrolled in the study shows that when administered with REGN-EB3, 29 per cent patients died as compared to 34 per cent deaths when the patient was administered mAb114.
Both the drugs are made up of antibodies, which are Y-shaped proteins produced by the immune system in response to foreign substances called antigens. While REGN-EB3 is made up of three monoclonal antibodies (types of antibodies made in the laboratory such that they bind with only one substance, also used to carry drugs to cancer cells), mAb114 is derived from a single antibody retrieved from the blood of a person who survived the disease in the 1995 breakout in DRC.
In case of the other two drugs tested in the trial, 53 per cent of patients who received the antiviral drug “remdesivir” died as compared to 49 per cent deaths in case of those people who received the antibody treatment ZMapp.
Researchers associated with the trial hope that with such a success rate, people with symptoms will seek treatment sooner. As per WHO, after noticing the first symptoms, people are waiting on average for 5-6 days before visiting an Ebola centre. In order to seek regulatory approval, researchers will continue to collect data on REGN-EB3 and mAb114. As many as 681 patients have been enrolled as part of this trial so far, which hopes to enroll a total of 725 patients. This is the tenth recorded outbreak of the disease as per the NIAID.