Not all exponential growth is equal, of course. In the case of monkeypox, we’re not talking about 10,000 cases turning into 20,000 within days, COVID-style. We are talking about 10 cases that turn into 20.
Even so, if there’s one thing we’ve learned from two years of pandemic misery, it’s that a small number of infections can quickly grow into a large number if growth continues exponentially.
Virologist Trevor Bedford has tracked monkeypox cases in various countries and spotted a worrying trend. It is possible that scientists have detected more cases recently simply because they are now looking for them. But the fact that the growth is so similar in different places suggests that the virus is actually spreading in the community. It’s not a surveillance artifact, he thinks. This is proof of transmission.
There may still be continued improvements in case detection nationally over the past 11 days in England, Portugal and Spain, but the finding of similar 8-10 day doublings in these three countries suggests that this rate growth can largely reflect the underlying transmission dynamics. 7/10
— Trevor Bedford (@trvrb) June 3, 2022
Most of this transmission is occurring in a subset of the population with high rates of sexual contact and therefore this rate of growth is unlikely to be sustained in the general population. However, this observed growth rate remains worrying. 9/10
— Trevor Bedford (@trvrb) June 3, 2022
We have all seen this movie before. The ending isn’t great.
There is good news. By CNN, 643 cases of monkeypox have now been recorded in countries outside Africa. As far as I know, not a single person died. In the early days of the global epidemic, we were told that there were two known strains of the virus in Africa, one with a death rate of around 1% and the other with a death rate of 10% (!). The fact that monkeypox is 0 in 643 outside of Africa may mean that Africa’s death rate is due more to lack of access to basic health care than to the innate virulence of the virus. Fortunately, the virus is also less likely to mutate aggressively than, say, COVID. Because its genome is made up of double-stranded DNA rather than single-stranded RNA, like SARS-CoV-2, it doesn’t change as quickly, CNN points out.
Meanwhile, evidence continues to mount that gay men are the subpopulation most at risk of infection. The number of confirmed cases in the United States doubled last week at 20but “[o]Of the 17 patients who provided detailed information to the CDC, 16 identified themselves as men who have had sex with men. This corresponds to what the scientists of other countries have seen. Monkeypox is not traditionally an STD – in the past it was spread by airborne droplets during close and sustained contact – but it turns out that an outbreak in Nigeria five years ago year also had a sexual component.
Also in Nigeria, doctors first detected hints of a new pattern that would be repeated around the world. Many patients were male and many had genital lesions, suggesting transmission through sexual contact. Four years later, many cases in Europe and the Americas also involve men and are also characterized by genital lesions. “It feels like deja vu to me,” says Dimie Ogoina, a doctor at the Niger Delta University Teaching Hospital, who treated the first and many subsequent cases of monkeypox in Nigeria in 2017. The virus was known to spread through droplets and any type of physical contact with infectious sores and scabs, but sex, in particular, had never been high on the list of transmission risks. (Past cases were usually related to wildlife or household contact.) The unusual pattern and size of the outbreak in Nigeria should have been a signal that something had changed for monkeypox. But the world ignored it until too late, and a global epidemic is now well underway.
Read that again. The same unusual type of monkeypox that seems to be spreading in the west now was spreading in Africa *five years ago*. “What happened in 2017 in Nigeria was absolutely a warning sign,” an epidemiologist told The Atlantic. But because Westerners tend to overlook epidemics in Africa (“there are always Something resources were not rushed to try to contain the spread before it broke out continent-wide and eventually into Europe and the United States
Scientists have already confirmed a link between the ‘new’ monkeypox and one that has been spreading in Africa for years. “In [new] research, genetic sequences showed that the first cases of monkeypox in 2022 appear to stem from an outbreak that resulted in cases in Singapore, Israel, Nigeria and the UK from 2017 to 2019,” CNN reports. But that’s not the only surprise in the genetic data: Apparently, the current global epidemic is actually two separate epidemics, each driven by its own distinct lineage of the virus. CDC scientists analyzed 10 virus samples from patients in the United States and found that three of them differed genetically from samples collected in Europe. All three samples were from people who had also traveled abroad to different locations – Nigeria, West Africa and East Africa/Middle East.
The best way for experts to explain the two-way epidemic for now is that monkeypox has been circulating at low levels for far longer than anyone thought. Which is…reassuring, I suppose? If it’s had years to unleash explosive exponential growth and hasn’t, that must mean transmission is difficult. On the other hand, it may have now gained enough of a foothold in Western populations that there is no way to get rid of it. New York City has only had five cases, but health officials there believe that’s strong enough evidence of community spread that it could be “too late to contain”. The nightmare scenario is that it will transition from humans to native animals, which will then become a “reservoir” for a virus endemic in the wild. It didn’t happen in the 2003 monkeypox outbreak in the US, but it did with other viruses like West Nile.
I leave you with this piece of Atlantic, raising the possibility of widespread infection leading to the evolution of the virus. It may mutate slowly but it Is mutate to become fitter. Quote: “Poxviruses tend to accumulate mutations at a fairly slow rate of one or two per year, but the 2022 genomes have 47 mutations. Curiously, almost all changes to the genetic code are from TC to TT or from GA to AA. It is unlikely that this happened through a random copy error; instead, it looks like the signature of an immune system mechanism – found in both humans and animals – that introduces mutations in an attempt to disable the virus. The more people it infects, the more mutations there will be.
#Monkeypox #spreading #exponentially