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Scientists comment to an unknown disease breakout in the Democratic Republic of Congo (DRC).
Dr Amanda Rojek, Senior Clinical Fellow, Pandemic Sciences Institute, University of Oxford, said:
“The exact cause of these outbreaks is unknown. While there might be one disease that explains all cases, we frequently see situations where there might be a mixture of more common illnesses contributing to case numbers. It is reassuring that tests for Ebola and Marburg virus – two viral haemorrhagic fevers with a high death rate – have returned negative so far.
“Investigations will now be underway to examine the cause of the outbreak – which could include infectious diseases, or diseases caused by exposures to toxic or contaminated substances. Local health care teams will also be trying to identify how cases might be linked to each other.
“The outbreak investigation team will be verifying reports of a bat being consumed by children who later died of their illness because this raises the possibility of a zoonotic disease – that is, a disease spread from animals to humans. However, rumours are often rife early during an outbreak, and so verification of this information is important.
“Scientific research has a crucial role to play in understanding an outbreak of this kind, to ensure that responses are evidence-based, and that national health agencies can make the best possible decisions.
“Support for local health care services will also be very important, because these outbreaks are occurring in a vulnerable area with poor healthcare infrastructure.
Dr Zania Stamataki, Associate Professor in Viral Immunology, University of Birmingham, said:
What do we know about the outbreak, potential causes, or modes of transmission?
“The symptoms shown in these infections are different to the alarming infection caused by severe malaria in the DRC in the end of last year, with patients reporting nose bleeds, vomiting blood and internal bleeding. The time from symptom onset to death is 48 hours, which is very alarming.
“We know that the patients tested negative for known haemorrhagic fever viruses such as Marburg and Ebola. Other haemorrhagic fever-causing pathogens are investigated.
“The modes of transmission are unknown. The authorities are also looking at culprits beyond infection, for example poisoning by a toxic agent.
How is the situation being controlled, Are we likely to see more cases in the coming days?
“It is possible that we will see more cases. The incidents are currently correctly treated like an outbreak of infection, but it is not known how infection is transmitted, which makes it more difficult to contain. The best way to contain the outbreak is to isolate patients and stop travel in affected regions to prevent transmission.
“Viral infections can remain silent in the body for days before we start showing any symptoms. This is called the virus “incubation period”. While infected, a person could feel well enough to travel and mix with others in social events, which aids transmission.
How likely is it that this disease will spread across borders, potentially into the UK?
“Infections know no borders and do not respect country lines. People travel and infections travel with them, either hitching a ride in a person or in animal carriers, so one cannot exclude spread outside of a country’s borders. In the UK and in other countries we need to remain vigilant and watch for symptoms. Symptoms of a haemorrhagic fever-type disease should be reported to the UK Health Security Agency via a registered medical practitioner.
Given the large number of deaths and rapid transmission how concerned should we be?
“This outbreak, as well as previous outbreaks in the DRC are of significance to the rest of the world and we need to keep a close eye and assist with diagnosis and treatment. The large number of deaths of children and young people may be worsened by malnutrition and pre-existing conditions like malaria, that could weaken the immune system.
Could the pathogen have come from a bat, and what might this tell us of the nature of the outbreak?
“There are reports of three children eating a dead bat, so people rightly ask if this outbreak could be due to a bat-related virus infection. It is unwise to seek contact with dead bats, given that they are natural reservoirs of deadly viruses. Bats carry many viruses that have previously jumped to infect humans and cause severe diseases, including viruses such as Ebola, Marburg, Nipah, Hendra severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory coronavirus (MERS-CoV) and SARS-CoV-2, which caused the COVID-19 pandemic. If the infection originated from a virus that came from a bat, this tells us that it is unlikely that we have pre-existing immunity to this new infection for humans, so we are unprotected, we suffer severe disease and even death. If the virus is similar to other viruses infecting humans, like the covid-causing virus was similar to some common cold coronaviruses, some people may stand a chance to show less severe symptoms and recover.”
Dr Michael Head, Senior Research Fellow in Global Health, University of Southampton, said:
“At time of writing, there is a huge amount of uncertainty about this outbreak.
“Outbreaks like this will happen many times around the world. Typically, such outbreaks are brought under control relatively quickly. However, here, it is concerning that we have hundreds of cases and over 50 deaths, with haemorrhagic-fever like symptoms widely reported among those cases.
“Tests have so far proven negative for Ebola and other similar viruses, but results are known for a relatively small number of cases. Tests are never 100% accurate, and it is likely that with increased testing, we will have a confirmed pathogen in some of those samples.
“The lack of healthcare infrastructure in the DRC means the public health response is more complicated. However, the country has had mpox and Ebola outbreaks in recent, so they are experienced at addressing infectious disease epidemics.”
Prof Paul Hunter, Professor in Medicine, University of East Anglia (UEA), said:
“This is another cluster of fatalities in one of the poorer African countries. These are not rare. We saw another such cluster in DRC last November/December time. That last one turned out to be malaria and the was likely more severe as a result of increased malnutrition.
“So far I am not aware of much information about the current problem other than it is in the northwest of the country there are apparently two separate clusters in the area. The earlier cluster was reported in 21 January 2025 and is centred on Boloko Village in Bolomba Health District. The more recent cluster is in Bomate Village in Basankusu Health Zone and this was reported on the 9th February. No link is known between these two clusters. So far test results are negative foe Ebola and Marburg.
“The only other bit of information is that in the earlier cluster some of the children who died had apparently consumed bat carcasses. But the relevance of that is not yet known.
“What is causing these two clusters is not yet known or indeed whether the same thing is responsible for both. It is certainly possible that we have a similar issue to last autumn with malaria and malnutrition. But we need to wait the results of ongoing investigations to know the cause.”
Declared interests
Dr Amanda Rojek “None”
Dr Michael Head “None”
Prof Paul Hunter “None”
For all other experts, no reply was received for our request for DOIs.