Unusual outbreaks of monkeypox are affecting several countries around the world. On Monday, 17 suspected cases had been identified in the Montreal region. Should we be worried about it? Overview in six questions.
What is monkey pox?
Monkeypox is an infectious disease caused by a virus. It first causes fever, muscle aches and swollen glands. A few days later, it causes pustular rashes that last for a few weeks.
Monkeypox is a disease that looks a lot like smallpox—eradicated in 1980—but it’s usually less severe. In Africa, where the disease is endemic, mortality rates of 1 to 10% have nevertheless been reported.
“It’s not a trivial disease,” says microbiologist-infectiologist Alexandre Carignan, from the Sherbrooke University Hospital Center. However, he adds, most of the African victims were children without access to basic care and sometimes suffering from malnutrition. “We would expect, in Western populations, that mortality would be significantly lower,” he says.
How is it transmitted?
Monkeypox is usually transmitted from animals to humans. Contact with infected animals – during the preparation of wild meat, for example – would be the main route of transmission of the virus.
According to what we know so far, this virus is not easily transmitted from one human to another; very close comparisons are necessary. The disease can be transmitted through respiratory droplets, body fluids or contact with a lesion.
Where is the disease circulating?
In recent decades, the majority of monkeypox cases have been reported in Africa, primarily in the Democratic Republic of Congo. Travelers or infected animals have occasionally caused small outbreaks elsewhere in the world. For example, in 2003, an outbreak of 47 cases occurred in the United States; all of these patients had been infected through animals, and none of them had died.
In recent days, public health authorities in several countries in Europe and North America have documented dozens of cases of monkeypox. In Montreal as elsewhere, several have been listed in men who have had sex with other men. The true extent of the wave is very nebulous at this time.
Is this a new strain of the disease?
The current outbreaks of cases are thought to be attributable to transmission between humans, not from animals. In Montreal, connections have been established between several suspected cases; there are also links to a case seen in the US state of Massachusetts.
In the UK, the public health agency’s senior medical adviser, Susan Hopkins, said on Wednesday that “the latest cases, together with reports from countries in Europe, confirm our initial concerns that there would be transmission of monkeypox in our communities”.
“We can think that the virus has changed, at least that it demonstrates an ability to transmit itself a little more efficiently from human to human, but it is still early. I believe that we will need more data to establish it, ”said virology expert Benoit Barbeau, professor at UQAM.
The Dr Carignan points out that the manifestation of the disease in patients of the current wave is something “unheard of and very intriguing”: the rash appears on the genitals of the patients, whereas it is usually spread all over the body.
How to treat or prevent the disease?
There are currently no treatments designed specifically for monkeypox. Drugs for human smallpox would, however, be effective against it. For its part, the smallpox vaccine given to Canadians born before 1972 prevents 85% of monkeypox.
However, more than 50 years after its administration, this vaccine inevitably loses effectiveness, notes the Dr Carignan, especially since the proportion of the population that received it is shrinking from year to year. These two factors could have created a “storm” which favors the current emergence of the virus, he observes.
Normally, smallpox drugs will only be needed to treat severe cases, explains the specialist. Vaccines can be used for “post-exposure prophylaxis”, that is to say to protect people who have been in close contact with a patient.
What will be the next steps to better understand the current outbreak?
Samples taken from the 17 suspected cases in Quebec are currently being tested in the laboratory to confirm that they are indeed monkeypox. Sequencing the whole genome of the virus would then make it possible to know whether it is identical to the previous virus or whether it is a new strain. Public Health is also carrying out an in-depth examination of the chains of transmission between patients.