Will it become endemic in the Philippines?
CLINICAL MATTERS
As more cases of monkeypox are discovered in the Philippines, many people are asking if it will become endemic. While the death rates for the current monkeypox outbreak have been low, its unprecedented spread globally has prompted WHO to declare a Public Health Emergency of International Concern (PHEIC). The last disease to be designated a PHEIC was Covid-19. Therefore, it is understandable that people are anxious about how the current monkeypox outbreak will turn out.
Monkeypox has been an endemic disease in Africa for decades. The first human cases were described and reported in 1970. It had likely been circulating in communities a lot longer than that, especially since it can infect other animals, which can be reservoirs of infection. Monkeypox is a virus that is related to smallpox (Variola) and cowpox (Vaccinia). The smallpox vaccine, which is derived from cowpox virus, is 85 percent protective against monkeypox.
Monkeypox is a DNA virus. DNA is more stable than RNA when used as a repository of genetic information. Unlike SARS-CoV-2, which uses RNA, monkeypox is less prone to mutation and errors. It is not expected to generate as many variants. There are currently two major groups, or clades, of monkeypox. The Central African clade, which is endemic to the Congo Basin, has a high fatality rate but has limited distribution. The West African clade is endemic to West Africa and is much less deadly. Fortunately, the West African clade seems to be the origin of the virus that is spreading globally, resulting in a low case fatality rate.
One of the likely reasons for monkeypox’s relatively limited distribution is that smallpox vaccination protected populations from monkeypox infection during the 1900s. Since routine vaccination for smallpox ended following its eradication in 1980, there is now a large population susceptible to monkeypox infection worldwide. There have been sporadic outbreaks of monkeypox in different parts of the world. The first outbreak outside Africa was in the American Midwest in 2003. I was training in Milwaukee, Wisconsin during this outbreak and some of the cases ended up in our hospital. The outbreak caused a lot of panic since it was so similar to smallpox. There were wild rumors that a bioterrorism attack might have occurred with weaponized smallpox. It turned out that that outbreak was caused by imported infected African rodents, which infected prairie dogs in a pet store. Using proper infection control measures, the outbreak was controlled. There was no documented human-to-human transmission and all the cases were infected through animal contact.
At the time of this writing, there have been four reports of monkeypox infection among Filipinos. The Department of Health has been very careful in limiting the release of personal information about these patients in order to protect their privacy. The cases are young people in their 20s and 30s, but their sexes have not been revealed. Three of the cases were found to have traveled to a country reporting monkeypox cases. The fourth case, however, had no such risk factor. There was also no report of close contact to a confirmed case, which brings up the possibility of hidden community transmission.
When we suspected Covid-19 community transmission in March 2020, a major part of the response was massive lockdowns to prevent the collapse of the healthcare system. This was done because Covid-19 is very contagious, had no effective vaccines at that time, and had no known treatment. There was not much data on how it was transmitted, and we had very little understanding of how it caused severe disease. The case fatality rate in vulnerable populations during the early days of the outbreak was as high as 10 percent.
Does this mean we should lock down again due to the potential community transmission of monkeypox? Absolutely not. Monkeypox is not Covid-19. Prior to the current outbreak, monkeypox transmission was mostly through contact with infected animals. While human-to-human transmission was documented in endemic areas, it was not the major mode of infection. What makes the current outbreak concerning is that the virus is predominantly being transmitted between humans. But it is nowhere near as contagious as SARS-CoV-2.
Monkeypox in its current iteration spreads mostly through close direct personal contact. It is not efficiently transmitted in the air. Many of the infections seem to have occurred through sexual contact. Current masking protocols for Covid-19 are expected to protect against monkeypox. Practicing safe sex through the consistent use of condoms will help mitigate the spread. Proper hand hygiene will also help control the outbreak. The current clade of monkeypox spreading worldwide has a very low case fatality rate, and there have been no deaths locally.
There are currently different types of smallpox vaccines, including newer, safer, and nonreplicating vaccines and these are all expected to work against monkeypox. The Philippine government is in negotiations to procure a stockpile of these vaccines. The general public does not need to be vaccinated at this time. The people who will benefit the most from vaccination if the outbreak progresses are healthcare workers because of their risk of exposure, as well as the vulnerable populations who are more likely to develop severe disease. Since monkeypox has a relatively long incubation period (up to three weeks), even exposed individuals can still be vaccinated shortly after exposure to decrease their risk of developing disease. This is the most rational use of the smallpox vaccines and it is also what is being practiced in most countries.
Most people who contract monkeypox will not require any specific treatment other than supportive care and they will recover naturally. It is important to minimize the number of close contacts during the infectious phase of the disease in order to interrupt transmission. Individuals remain infectious until the vesicles have dried out. This can take up to four weeks. There are antivirals, such as tecovirimat, that can be used to treat people with severe disease but these are not widely available.
According to the latest data in countries with the greatest number of imported monkeypox cases, the number of new cases seem to be plateauing or dropping (figure on next page). While it is too early to relax, the public health measures being employed against monkeypox seem to be working. These same measures, along with those against Covid-19, are sufficient to arrest the spread of monkeypox if properly implemented. With proper protocols and cooperation between our government and our people, it is unlikely that monkeypox will become endemic in the Philippines.
