top of page

Lassa fever: Is this a sign of the new pandemic era?

Two Britons have been diagnosed with the virus that causes bleeding eyes and facial swelling – and it could be evidence of a changing world.

Just hours after Boris Johnson unveiled plans to lift all Covid regulations in England on Wednesday, an alert warned of a new disease threat facing Britain: two people had been diagnosed with Lassa fever, a viral haemorrhagic disease similar to Ebola.

The pathogen – which is endemic in countries including Nigeria, Sierra Leone and Ghana – is less deadly than other haemorrhagic fevers, such as Ebola or Marburg. But it is nasty, killing roughly 15 per cent of those who are hospitalised.

Symptoms of Lassa start gradually, with fever and malaise, and after a few days a headache, muscle pain and vomiting may kick in. In severe cases, the virus triggers facial swelling, fluid-filled lungs and intense bleeding from the eyes, nose and other orifices. As yet, there is no licensed vaccine and treatments are poor.

Lassa’s arrival in Britain, in travellers from West Africa, is highly unlikely to trigger a major outbreak – although scientists told The Telegraph to watch this space in the coming days. They would not elaborate, but it is possible a track and trace initiative will be launched, further cases announced or that there will be complications in the patients’ treatment.

“Fortunately, the virus is nowhere near as infectious as many other pathogens,” says Dr Michael Head, senior research fellow in global health at the University of Southampton. “While any Lassa cases within the UK are of concern, we won’t be seeing transmission on anything like the scale we have with the Covid-19 pandemic.”

Dr Head points to the reproduction (R) number, used to describe how many people each infected person passes a disease onto. For Lassa, this is estimated at between 1 and 1.6 – compared with around 3 for the original Wuhan Sars-Cov-2 strain. The more transmissible omicron variant has an R number as high as 12.

Certainly, you would be unlucky to catch the Lassa virus on a bus: unlike Covid, it spreads through direct contact with the bodily fluid of an infected person, or after contact with the urine or faeces of infected rats. As long as you were not sitting next to someone with it, there would be little cause for concern.

But, as the acute phase of one epidemic finally appears to wane - at least for now - Lassa’s re-emergence in Britain is a stark reminder that the world is entering a “new pandemic era”, as Prof Anthony Fauci, America’s top infectious disease expert, warned in August 2020.

Pandemics are nothing new - humanity has been battling infectious diseases for centuries. In 430 BC, roughly 100,000 people died in what is known as the ‘Plague of Athens’, which heralded the end of the city’s Golden Age.

A millennium later, the Justinian plague wiped out almost half of the global population, while Athenian historians claimed the third-century Plague of Cyprian, also thought to be a haemorrhagic fever like Lassa, killed up to 5,000 a day at its peak. The world has since been hit by tuberculosis, yellow fever, cholera and the Spanish flu, to name but a few.

But the idea of a pandemic era is new - it suggests that major pandemics may no longer be once-in-a-century events. Six months before the emergence of Sars-Cov-2, Dr Mike Ryan, director of emergencies at the World Health Organisation (WHO), warned the world was entering a “new normal”, when several “high-impact” disease outbreaks occur simultaneously.

Experts point to environmental changes that make it more likely that viruses will “spill over” to humans and lap the globe. This includes booming population growth, the development of previously undeveloped nations, human encroachment into jungles and forest, the growth in the international trade in wildlife and widespread travel.

But the next pandemic may not look like Covid-19. Alongside Lassa fever, the WHO’s list of priority pathogens with pandemic potential includes Crimean-Congo haemorrhagic fever (CCHF), Ebola and Marburg.

“As we come out of one pandemic, we must still look for the next pathogens,” says Dr Tom Fletcher, an infectious disease specialist at the Liverpool School of Tropical Medicine.

In terms of haemorrhagic viruses, he adds, there are gaping holes in our knowledge and our ability to respond.

“As well as not having the right drugs or diagnostics, we don’t really understand how these diseases work, or what it is that causes patients to bleed,” Dr Fletcher says, “…but if we understand this, we can target treatment and improve the analysis of new diagnostics.

“The risks are going to persist going forward, they’re not going away – and we will see cases,” he adds. “And therefore we have to prioritise and fund key research.”

Dr Fletcher points to a conference set to take place in the Ivory Coast next week, where scientists will discuss how to design and enact trials for new treatments. But funding is lacking, so conclusions will be “theoretical”. “There is a complete dearth of funding for good drugs to treat Lassa and CCHF – that is criminal,” he says.

Yet the need is clear. In 2021, Turkey reported a record number of CCHF cases – a tick-borne disease with a fatality rate as high as 40 per cent – while Marburg, which is far deadlier, was detected for the first time in West Africa last summer. Ebola outbreaks, too, are on the rise – of the 12 outbreaks seen in the Democratic Republic of Congo since 1976, half have taken place since 2014.

That Lassa has now reached Britain’s shores is not surprising. The two confirmed cases, plus a third probable infection, are members of the same family and recently visited West Africa.

“The overall risk to the public is very low,” says Dr Susan Hopkins, chief medical adviser at the UK Health Security Agency. “We are contacting the individuals who have had close contact with the cases prior to confirmation of their infection, to provide appropriate assessment, support and advice.”

Although the last infections were detected here in 2009 – with eight reported in total since 1980 – the UK has close travel ties with countries where there are outbreaks of Lassa every year. So far this year, Nigeria alone has seen 211 confirmed cases and 40 deaths.

The disease was first identified in 1969, but its true scale remains unknown. Each year, there are an estimated 100,000 to 300,000 cases of the disease and 5,000 deaths, but some 80 per cent of cases are thought to be asymptomatic.

The Coalition for Epidemic Preparedness (Cepi), an organisation that has funded several Covid vaccines, is leading a $26m (£19.2m) project in West Africa to understand the full scale of the disease.

Current knowledge is hindered by a lack of formal diagnosis and the broad range and severity of symptoms. Cases may also occur in remote regions where there is no testing. As a result, most experts believe the true toll of the disease is likely to be much higher than current estimates.

There is a treatment for the virus – ribavirin, an antiviral – but it has to be given early on to be effective. Cepi is funding six vaccines, two of which entered phase one trials in 2019, and another started human trials last year.

Cepi’s goal is to get a licensed vaccine for routine immunisation, and Dr Melanie Saville, the organisation’s director of vaccine research and development, says there “have been a number of positive developments” in the past few years. Continuing to focus on R&D is critical, she adds, because novel pathogens from the same family of viruses as Lassa could be even more contagious or deadly.

“It is important to remember that Lassa virus is just one of a number within the Arenaviridae viral family,” Dr Saville says. “Other novel viruses within this family could emerge in the future with greater transmissibility and/or fatality rates.”

As European nations move into the post-Covid phase, there is a fear we will forget the lessons of the past two years.

“There will be another pandemic just around the corner,” says Dr Head. “We just don’t know when.”

Source: The Telegraph



bottom of page