The virus strain in the current monkeypox outbreak in non-endemic countries was likely separated from the monkeypox virus that caused an outbreak in Nigeria in 2018-19 and has many more mutations than expected, several that increase transmission , according to a study published today in Nature Medicine. .
The study comes from Portugal’s National Institute of Health in Lisbon, which was the first institution to genetically sequence the current strain behind more than 3,000 cases of monkeypox in Europe, North America and other regions that had never seen the virus until now. year.
The researchers found that the current strain differed from the original strain by 50 single nucleotide polymorphisms (SNPs), and several mutations made the virus more transmissible. The strain belongs to clade 3 of the West African virus strain, which is less lethal than the Congo Basin clade. Outbreaks of clade 3 monkeypox are typically reported from western Cameroon to Sierra Leone and generally have a case fatality rate of less than 1%.
The authors said the outbreak was probably not caused by silent undetected spread, or by an animal-to-human crossover event. Instead, “current data points for a scenario of more than one single-origin introduction, with superspreading events (eg, saunas used for sexual encounters) and foreign travel likely to trigger rapid global spread.”
The authors also said that the 50 SNPs that differ from the original strain are much more (approximately six to 12 times more) than would be expected from previous estimates of the rate of replacement of orthopoxviruses, which typically have 1 to 2 substitutions per site per year. .
Modeling Study Shows Potential Outbreak Growth
In another study, published today in The Lancet Microbe, scientists use modeling to predict what will happen in non-endemic countries if public health measures are not taken to curb ongoing outbreaks.
They predict that, without interventions, introducing 3 cases into a country could cause 18 secondary cases, 30 could cause 118 secondary cases, and 300 cases could cause 402 secondary cases.
Contact tracing and surveillance, isolation of symptomatic cases, and ring vaccination would reduce the number of secondary cases by up to 86.1% and the duration of the outbreak by up to 75.7%, the authors conclude.
The authors also said the outbreak is of moderate international concern. Consultants to the World Health Organization are currently weighing whether the outbreak constitutes an international public health emergency during a two-day meeting.
USA and Portugal add more cases
In the United States, the Centers for Disease Control and Prevention said the national total is now 173 in 24 states, an increase of 17 cases since yesterday.
A New York City sexual health clinic offering the monkeypox vaccine to men who have sex with men was forced to close due to overwhelming demand. Many men sought out the vaccine in the days leading up to the Pride celebrations.
Portugal now has 348 cases of monkeypox, with 20 new cases in the last 24 hours. Along with Spain and the UK, Portugal has the most cases in Europe.
In other news, Croatia and Taiwan each reported their first cases of the virus.
Source: www.cidrap.umn.edu