The World Health Organisation’s decision to declare the latest Ebola outbreak in the Democratic Republic of Congo (DRC) and Uganda a global health emergency has once again revived fears of cross-border epidemics.
So far, as of Tuesday afternoon, at least 130 deaths and more than 500 cases have been reported in the Democratic Republic of Congo in Central Africa, while neighbouring Uganda has confirmed one death and another case.
WHO officials say the outbreak, linked to the Bundibugyo strain of the virus, has already spread into urban centres, including Kampala in Uganda and parts of eastern Congo. Health authorities are especially worried because the strain has no approved vaccine and limited treatment options.
The renewed alarm has inevitably triggered comparisons with other deadly viral threats, from the hantavirus cluster linked to the MV Hondius cruise ship earlier this month to the COVID-19 pandemic caused by SARS-CoV-2.
But while all three diseases can spark international concern, scientists say their transmission patterns, fatality rates and ability to overwhelm healthcare systems are dramatically different.
“Ebola cases have been reported from two major cities in Africa and the genuine concern is that many have been missed,” Dr Gautam Menon, professor of biology and physics at Ashoka University, told India Today.
He warned that weak diagnostics and strained surveillance systems are making the current outbreak harder to contain.
DIFFERENT VIRUSES, DIFFERENT TRANSMISSION PATTERNS
The biggest distinction between Ebola, hantavirus and SARS-CoV-2 lies in how they spread.
Ebola is transmitted through direct contact with bodily fluids such as blood, vomit, saliva or diarrhoea from infected people. Transmission can also occur during burial rituals or through contaminated surfaces and medical equipment.
Unlike COVID-19, Ebola is not considered an airborne virus under normal conditions. That means outbreaks can often be controlled through aggressive isolation, contact tracing and protective equipment – provided health systems move quickly enough.
Hantavirus behaves differently. Most hantaviruses spread from rodents to humans through exposure to urine, droppings or saliva.
The Andes strain linked to the cruise ship outbreak is unusual because it can spread between humans, although scientists say such transmission remains relatively limited compared to respiratory viruses like COVID-19.
SARS-CoV-2, the virus behind COVID-19, proved far more efficient at spreading because it primarily travels through respiratory droplets and airborne particles.
People could transmit the virus even before symptoms appeared, allowing infections to move rapidly through crowded cities, workplaces and international travel networks. That airborne transmission helped turn COVID-19 into the deadliest pandemic in a century.
Dr Gagandeep Kang, leading virologist and director of global health at the Gates Foundation in the US, said the current Ebola outbreak is particularly concerning because the Bundibugyo strain differs significantly from the better-known Zaire strain.
“In any infectious disease, the declaration of a public health emergency depends on its potential to spread, case fatality rate and how difficult it is to control,” she told India Today.
FATALITY RATES TELL A STARK STORY
While COVID-19 infected hundreds of millions worldwide, its average fatality rate remained far lower than Ebola’s.
According to the WHO and US Centre for Disease Control and Prevention (CDC) data from previous outbreaks, Ebola’s case fatality rate can range from around 25 percent to as high as 90 percent, depending on the strain and the availability of treatment.
The Bundibugyo strain responsible for the current outbreak has historically killed roughly 30 percent of infected patients.
Hantavirus infections can also be severe.
Hantavirus Pulmonary Syndrome, reported mainly in the Americas, has a fatality rate of roughly 30–40 percent, according to the CDC. However, outbreaks are usually smaller and less sustained because the virus does not spread easily between humans.
By comparison, global estimates for COVID-19’s infection fatality rate generally remained below percent, although the sheer scale of transmission caused millions of deaths worldwide.
The pandemic demonstrated that a virus with lower lethality but extremely efficient transmission can still devastate health systems and economies.
TREATMENT AND VACCINES REMAIN UNEVEN
Another major difference lies in the availability of vaccines and treatments.
For COVID-19, vaccines were developed within a year of the virus emerging, while antiviral drugs and improved intensive care significantly reduced mortality over time. Scientists also benefited from unprecedented global cooperation and funding.
Ebola treatment has improved in recent years, especially for the Zaire strain, for which licenced vaccines and antibody therapies now exist. But experts say the Bundibugyo strain presents a fresh challenge because those medical tools may not work as effectively.
WHO officials have acknowledged that there are currently no approved vaccines specifically targeting this strain.
“There are currently no reliable diagnostics for this particular strain of the Ebola virus,” Dr Menon said, adding that delayed detection could allow transmission chains to widen unnoticed.
For hantavirus, treatment options remain limited largely to supportive hospital care, including oxygen therapy and intensive monitoring. There is no widely approved vaccine for hantavirus infections in most countries.
Scientists stress that despite the fears surrounding Ebola, it is still far less transmissible than COVID-19.
But the current outbreak is unfolding in conflict-hit regions with weak healthcare systems, porous borders and delayed surveillance – conditions that can allow a deadly virus to spread silently before authorities gain control.
That, experts say, is precisely why the latest Ebola outbreak has unsettled global health agencies more than the recent hantavirus cluster, and why memories of the 2014 West Africa epidemic continue to loom large.
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