Ebola’s re-emergence, a wake-up call

The past two decades have seen the world experiencing, with alarming regularity, outbreaks of viral diseases like Severe Acute Respiratory Syndrome (SARS), bird flu and swine flu. These have caused alarm and spread panic not only in populations that are directly affected but also in places away from the locations of these outbreaks. Even before memories of these outbreaks have faded, there are new outbreaks; the recent re-emergence of the Ebola virus, for example, has underscored the fact that humans are increasingly and continuously at risk from life-threatening viral diseases, and that the unexpected can be expected anytime. These emerging infectious diseases that occur in most parts are generally connected with a rapid growth in population. Human activities like changes in land use, increased urbanisation and high population density in cities, increased contact with wild animal reservoirs, climate change and a deterioration in health-care systems, particularly in developing and poor countries are the major causes.

Spread and impact

The current outbreak of the Ebola virus in some West African countries is unprecedented and seems to have spun out of control. What started in three of the poorest countries in West Africa — Guinea, Liberia and Sierra Leone — already ravaged by political turmoil and civil war, has now spread beyond their borders. The epidemic — which the World Health Organization (WHO) says has affected more than a million humans — has already claimed more than a thousand lives. Although officially reported cases are between 2,000-3,000, it is quite likely, as it often happens in such cases, that the actual number of those affected is much more.

India, China and Brazil, which have a highly developed scientific and pharmaceutical industrial base, should work towards solutions to such diseases

In the current outbreak, the first reported case was that of a two-year-old boy who died on December 6, 2013, which was soon followed by the deaths of his mother, his three-year-old sister and his grandmother. By the end of March 2014, the disease had erupted in many locations and the outbreak was termed as “unprecedented.” By end July, it had caused widespread panic, fear and disruption, including steps that led to the closure of borders between the affected countries. The death of a nurse in Lagos, Nigeria, on August 6 and, since then, several more cases in that country, have added an entirely different dimension to this extraordinary health threat.

The Ebola disease is severe, with mortality rates as high as 90 per cent, caused by rapidly acquired haemorrhagic fever. The Ebola virus was identified in 1976 in two different outbreaks — one in Sudan, and the other in the Democratic Republic of Congo (Zaire), in a village close to the Ebola river from which the disease derives its name. Five species of the Ebola virus characterised so far have been named after the locations of their emergence: Zaire (EBOV), Bundibugyo (BDBV), Sudan (SUDV), Taï Forest (TAFV) and Reston (RESTV). Several outbreaks in Africa were caused by the first three species. The current, and by far the worst, outbreak in West Africa is caused by the most lethal of the above five species — the EBOV. These outbreaks have infected both human and non-human primates including the chimpanzee and the gorilla, causing a substantial loss of lives among these species. What exactly triggers the Ebola outbreaks remains poorly understood, but periodic and unpredictable outbreaks are followed by the disappearance of the virus into its natural reservoirs, though only to reappear.

After an incubation period of two to 20 days, the Ebola infection shows a sudden onset of the disease resulting initially in flu-like symptoms: fever, chills and malaise. As the disease progresses, it results in multi-system involvements indicated by the person experiencing lethargy, nausea, vomiting, diarrhoea and headache. Haemorrhagic conditions usually set in at its peak, resulting in uncontrolled bleeding, shock, convulsions and severe metabolic disorders. Fatal clinical signs come up early, with death occurring within about two weeks. In non-fatal cases, the fever resolves itself and is generally co-related with the host’s ability to mount an antibody response, suggesting the possibility of a protective mechanism.

The transmission route

The African fruit bat is considered to be the natural host for the Ebola viruses as well as the major source of human infection. The chimpanzee and the gorilla can also carry the virus and infect humans but they are merely accidental hosts and not natural reservoirs. How the human first gets infected in an outbreak is not clear but close contact with bats is considered to be the major reason. Ebola then spreads through direct contact with body fluids of an infected person which includes blood, urine, saliva, semen and indirect contact with environments contaminated with such fluids. Close contact with infected dead persons can also cause the infection. However, unlike flu viruses, Ebola does not spread through air.

Treatment options

Although the very thought of Ebola raises and creates fear and panic, the risk of infection from a visit to an Ebola affected area is extremely low. The risk even for health-care providers who directly deal with Ebola patients also remains low if all basic precautions are taken. In this context, media reports about some doctors making a bid to leave hospital locations in Ebola-affected countries not only comes as a surprise but also raises medical, ethical issues.

While Ebola virus infections can be easily diagnosed with certainty in laboratories through standard tests like ELISA and RT-PCR assay, obtaining samples from patients is extremely risky and can only be conducted under highly sophisticated containment facilities. Unfortunately, Ebola infections have occurred in places where these facilities are not readily available. Another difficulty experienced in its detection is that initial symptoms are similar to those of many other fever-causing diseases like influenza, malaria, typhoid, cholera and other viral haemorrhagic fevers.

Currently, there is no vaccine or drug that can prevent or cure the disease. Experimental vaccines are being developed but they are in early stages of development. Since working with a virus as lethal as Ebola is extremely hazardous, research and developmental activities can only be undertaken in high-level bio-safety laboratories. Therefore, it is very difficult to carry out these activities in countries with poor scientific infrastructure. Developing countries like India, China and Brazil, which have a highly developed scientific and pharmaceutical industrial base, and skilled manpower, should take the initiative in working towards solutions to diseases like Ebola. However, even when drugs and/or vaccines are developed, testing for their efficacy will pose serious scientific and ethical challenges. These are still early days of research and a highly coordinated approach and leadership will be required to find cures.

Two American aid workers who contracted the disease in West Africa and their treatment in Atlanta, U.S., are being closely watched by world health agencies. This represents the first example in modern medicine of the treatment of patients with therapeutic agents yet to be tested in humans; unusual situations leading to unusual methods! Such unprecedented measures, recently also endorsed by WHO, raise ethical issues and simultaneously capture both the hopelessness as well as the helplessness of the current situation.

How and why did the present outbreak spin out of control? Why did the world neglect what was happening in West Africa? Perhaps lessons learnt from previous Ebola outbreaks, particularly in Uganda in 2000 and in Gabon and Congo in 2001-3, about the disease being greatly reduced through education and increased awareness led to some complacency. There are no simple explanations about why the epidemic was allowed to spread as far as it has, except for the fact that this time, the epidemic occurred in extremely poor countries with very fragile health care and poor infrastructure. Contrast this with the SARS outbreak in 2003 in China and Hong Kong which threatened to spread to the western world, when highly coordinated control and prevention efforts were put in place in record time. The present negligence around the containment of the Ebola outbreak becomes even more intriguing when one finds that the horrors of Ebola infections are well-known enough to become themes of Hollywood films like “Outbreak.”

Containment measures

The current outbreak has shown no signs of abatement. The immediate need is to reach out to the communities living through its horrors. Given that there is no effective treatment or vaccine, raising awareness through educative messages and providing much needed health care has to be the top priority. Public health messages should focus on reducing the risk of animal-to-human, as well as human-to-human transmission, particularly through body fluids. Containment measures, including burial of the dead, should be strictly enforced. Given that this outbreak is happening in very poor settings, the provision of basic supplies including gloves, masks, disinfectants and basic drugs must be immediately ensured. Equally, or perhaps even more important, is the setting up of active surveillance systems to detect the early onset of the disease in susceptible animals and humans. Travel to and from locations where the Ebola epidemic continues to rage should be done with care, and anyone developing fever on account of such travel should immediately be reported to the health authorities for observation and treatment, if necessary.

The current outbreak is sure to subside, though unfortunately only after consuming many lives. At the same time, it is bound to reappear somewhere, sometime, and mostly for man-made reasons. Unfortunately, it might happen before long. Would the world have learnt from the present deadly outbreak? If and when Ebola strikes again, would it be able deal with it better? Hopefully during the lull, scientists, researchers and the industry would treat Ebola as a common enemy that must be defeated with modern medicine and better health-care infrastructure. Modernisation and development should not become the key reasons for viruses to take centre stage.

(Prof. Virander S. Chauhan, former director of the International Centre for Genetic Engineering and Biotechnology, New Delhi, is an active researcher in infectious diseases and vaccinology.)

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Printable version | Oct 29, 2020 1:51:37 PM | https://www.thehindu.com/opinion/lead/lead-article-ebolas-reemergence-a-wakeup-call/article6357471.ece

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