Sweden’s national epidemiologist does not rule out the possibility of more cases of the new strain of mpox reaching Sweden. Contact tracing has been activated and containment plans have been prepared.

“There is no new confirmed case in Sweden at the moment apart from the already reported patient with mpox clade 1b virus,” Magnus Gisslén, an infectious disease professor and Sweden’s national epidemiologist at the Public Health Agency, told Euractiv on Monday.

Since the case was detected last Thursday, intensive contact tracing has been carried out by regional infectious disease doctors.

However, the result of this work so far does not give reason to suspect that an outbreak will kick off in Sweden, according to Magnus Gisslén.

“At the same time, it is best to be prepared for the worse case [scenario]”, he said.

Controlling possible outbreaks

The national epidemiologist does not rule out the possibility of new import cases occurring in Sweden or elsewhere outside Africa which could lead to outbreaks if not controlled early and with high speed.

“To be successful, it is crucial to act quickly, diagnosing, isolating and tracing. However, the most important effort is supporting African countries by distributing vaccines and helping to halt the spread.”

At the same time, the situation is challenging as there is no mpox vaccine that is yet approved for children and adolescents.

The Swedish case is still the only one reported outside Africa.

“But what are the chances that this is the only case? There are probably other cases outside Africa, perhaps not in Sweden, but elsewhere that have not yet been detected,” Magnus Gisslén said, urging health personnel to remain vigilant.

The patient treated in Stockholm had travelled to parts of Africa with a severe clade 1b outbreak. Exactly which country the person visited hasn’t been publicly disclosed.

The new strain

The clad 1b mpox strain is believed to have emerged in the eastern Democratic Republic of Congo in September 2023 and then spread to Rwanda and Burundi. It is described as being more virulent and deadly than clade 2, the mpox virus that caused an outbreak in Europe in 2022.

“At the same time, data are still lacking to fully confirm these characteristics”, Gisslén said.

The incubation period lasts between six and 21 days, but symptoms usually appear within a week or two. The most common ones are painful blisters or sores on the body, fever, headache and muscle pain, swollen lymph nodes and bowel problems.

One challenge for doctors is that the infectious routes are not being totally clarified.

“These routes have not yet been thoroughly analysed. However, we do know that the clad 1a strain could be transmitted through household contacts with a high proportion of infections occurring in children,” Magnus Gisslén explained.

“But infections can also spread via sexual contact, and there have been some reports of the mpox transmissions via sheets and towels,” he added.

Meanwhile, it is unclear whether clade 1b is airborne and if it infects people via small particles in the air – called aerosols – at close range.

“We don’t know that at the moment, but the virus has been found in the respiratory tracts,” Magnus Gisslén told Euractiv.

This means there is still no worldwide consensus on how contagious the clade 1b is.

Sweden plans ahead

Swedish health officials are now preparing action plans in line with a range of possible scenarios.

The Swedish Pubic Health agency is analysing the existing research reports to assemble more knowledge, Gisslen told Euractiv.

The discovery of a clade 1b in Sweden rapidly led to a raised alert level around the world. The European Center for Disease and Prevention Control (ECDC) situated in Stockholm raised its level of risk for Mpox, also saying more import cases were to be expected, Euractiv reported.

Sweden’s Public Health Agency issued travel recommendations for people going to areas with an outbreak of clade 1b. The recommendations aim to help travellers avoid infection and also provide guidance if people develop symptoms.

They will be made more explicit later this week, according to Magnus Gisslén, who considers travel restrictions not useful at this time.

The Swedish government is said to be planning a meeting in its strategic crisis group, led by Prime Minister, Ulf Kristersson.

[By Monica Kleja, Edited by Vasiliki Angouridi, Brian Maguire | Euractiv’s Advocacy Lab]

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EU public health body lifts mpox risk alert level after new strain found in Sweden

The European Centre for Disease Prevention and Control (ECDC) on Friday (16 Aug) raised its risk level for mpox, after global health officials confirmed one case of infection in Sweden, the first outside Africa.