Fruit bats, a common link between Ebola and Nipah; urgent attention required: Doctors explain

The Nipah outbreaks in 2018 and 2023 were significantly amplified within hospitals, a pattern that A week ago, the World Health Organisation declared an Ebola virus outbreak in the African nation, the Democratic Republic of Congo, a global health emergency. A viral hemorrhagic fever that damages blood vessels, Ebola can be quite life-threatening. It will damage our body's ability to clot and will result in fever, multiorgan failure and related issues. There are many Ebola strains, and the current outbreak, which has been flagged in Congo, Uganda and South Sudan, is caused by the Bundibugyo virus. Dr A S Anoop Kumar, Director of Critical Care Medicine at Aster MIMS, Kozhikode, and Dr Smitha Menon, Community Medicine Resident at KMCT Medical College, Kozhikode, explain their history, why Kerala needs to be careful, and more. 

The story of Ebola
The first signs of Ebola were observed on June 27, 1976, in a cotton factory storekeeper in Nzara, a town in South Sudan. He was admitted to the hospital with a high fever and symptoms of haemorrhage. In that region alone, 318 people were infected, of whom 280 died during that period. Two months later, an even more devastating outbreak occurred in Yambuku village in Congo, nearly 500 kilometres away, where the disease was first identified in a teacher.

The outbreak in Nzara was identified as being caused by the Sudan Ebola virus (SUDV), while the one in Yambuku was traced to the more lethal Zaire Ebola virus (EBOV). These were separate spillover events from different sources, occurring almost simultaneously in humans. The Ebola virus genus is believed to be between 3,000 and 10,000 years old. In fact, antibodies to Ebola were found in blood samples collected from Central African populations in the 1960s and 70s. Though these communities had been exposed to the virus across generations, the cases were often misdiagnosed as malaria.

What caused its rapid spread
In 1976, three major factors contributed to the rapid spread of the virus. The first was deforestation. Extensive forest loss in Central Africa during the 1970s forced fruit bats, the natural hosts of the Ebola virus, closer to human settlements in search of food. The second was hunting, which expanded as roads cut through previously inaccessible forests, opening access to deeper regions. Hunters who came into direct contact with infected wild animals were among the earliest victims. The third was the lack of awareness within African healthcare systems. The reuse of unsterilised needles, the absence of personal protective equipment (PPE) kits and limited diagnostic facilities turned even isolated cases into large-scale outbreaks with alarming speed.

Ebola on a familiar trail, like Nipah
Fruit bats were identified as carriers of the Ebola virus only in 2005. Bats of the Pteropus genus, commonly known as flying foxes, are found to carry 8 to 12 per cent of Ebola RNA. The Indian flying fox, a subspecies of this group, is widely distributed across Kerala, Karnataka, Tamil Nadu and northeastern India. This species was also implicated in the 2018 Nipah outbreak in Kozhikode. These bats can shed the virus through saliva, urine and faeces for months without showing any symptoms. The virus is transmitted to humans through direct contact with infected bats or monkeys, or by consuming fruits contaminated with bat saliva or excreta. This is the same transmission route observed in the Nipah outbreak reported in Kerala.

Ebola's mutation
The Ebola virus belongs to the RNA virus category, which mutates at a rate nearly six times higher than that of normal cells. Continuous interaction with bats creates conditions that allow the virus to adapt genetically to the human body. This raises concerns about the possible emergence of highly virulent Ebola variants in forest regions, especially in the absence of specific treatments or vaccines, with potential mortality rates reaching up to 90 per cent.

Why the outbreak in Africa matters
Ebola outbreaks in Africa are undeniably a global public health concern. During 2022–23, the Sudan and Bundibugyo variants that spread in Uganda recorded a mortality rate of 47 per cent, while the more lethal Zaire strain, which has been circulating in Congo since October 2023, has a fatality rate of 42 per cent. Despite the availability of antiviral drugs such as remdesivir, the mortality rate remains high. This may be due to delayed hospital admissions or the virus developing resistance to treatment. The detection of multiple Ebola variants circulating simultaneously in Congo also points to ongoing zoonotic transmission and the continuous genetic evolution of the virus.

Where we fall short and what must be fixed
When Kerala faced the Nipah outbreak in 2018, the mortality rate stood at a staggering 91 per cent, while the fatality rate of Ebola ranges between 40 and 90 per cent. The possibility of an Ebola outbreak in India through Indian bats is a serious public health risk that demands urgent attention from the health system.

How can Ebola enter India?
Experts point out that there are multiple routes through which Ebola could enter India. More than 80 lakh passengers travel to India from African countries every year. If an infected person arrives during the early, asymptomatic stage of the disease, the initial symptoms could easily be mistaken for malaria or dengue. Within the 3–5 days usually taken to confirm the disease, the infection could spread to over a hundred people. If such an outbreak occurs in a major city like Mumbai or Delhi, there is an estimated 70–80 per cent likelihood that it could become uncontrollable.

Kerala is prepared, but...
This highlights the need to recognise our vulnerabilities and strengthen preparedness. After the 2018 Nipah outbreak, Kerala has established dedicated isolation wards and strict infection-control protocols, but most other states remain unprepared to handle such highly lethal viral infections. In India, RT-PCR testing facilities for confirming Ebola are available in only two or three laboratories. The 24–48 hours required to obtain test results could further accelerate the spread of infection by delaying timely isolation and treatment. There is also a severe shortage of the antiviral drug remdesivir in the country, with only 200–300 units currently available, whereas managing a large-scale outbreak would require 5,000-10,000 units.

Urgent measures India must take now
The country must establish a national rapid response force and formulate a comprehensive preparedness and containment plan. Between 5,000 and 10,000 units of remdesivir should be procured and strategically stored in major cities. Testing capacity must be expanded, with at least 15 major hospitals across the country equipped with RT-PCR testing facilities, and a minimum of 500 healthcare workers should be trained in Ebola prevention and response protocols.

The warnings from COVID-19 and monkeypox are too significant to ignore. The question is no longer whether Ebola will reach India, but when. Without losing the lessons learned from the Nipah outbreak, the country must build robust defensive systems against Ebola. The time to act is now, and any delay could come at a high cost.