As more cases of Monkeypox are reported locally, it seems that we can’t catch a break from new and reemerging diseases. Aside from the prodigious ability of viruses to mutate, one major reason behind this accelerated increase in outbreaks is the continued encroachment of human settlements into jungles and wildlife habitats. This phenomenon brings people and their livestock into contact with new viruses to which they do not have any immunity against. Once the new virus establishes a foothold in a human population, it can easily spread to the rest of the world due to the ease and convenience of modern travel.

Looking at the last two PHEIC’s, both mpox outbreaks started in Africa. Clade II monkeypox, the virus responsible for the 2022 PHEIC, is originally from West Africa and spread abroad in an unusual manner. For the first time ever, it was associated with sexual transmission. This unprecedented change in behavior along with distinct genetic changes led to the classification of the 2022 PHEIC monkeypox virus to its own subclade designated IIb. With a combination of intensified surveillance and judicious vaccination programs, the 2022 mpox PHEIC was brought under control and was declared over in less than a year. 

However, just like Covid-19, mpox clade IIb did not go away just because the PHEIC was over. Having established itself outside Africa, low level circulation has continued inside many countries. The virus also continues to be introduced and reintroduced as a result of widespread travel. Clade IIb Monkeypox was especially prominent among men who have sex with men (MSM) and has followed these sexual networks in a predictable manner. Widespread vaccination in the US among MSM helped contain the outbreak, but similar vaccination programs did not occur in other countries, especially in developing countries. Hence, it was just a matter of time before cases of mpox were detected as a result of the intensified surveillance from the new 2024 PHEIC.

The 2024 clade I mpox PHEIC, on the other hand, seems to be more complicated as discussed in last week’s column. With a clade Ia outbreak causing deaths in children and Clade Ib now being sexually transmitted, it is easy to understand why WHO declared a PHEIC. To further muddle things, there is a simultaneous clade IIa outbreak in West Africa plus continued clade IIb transmission worldwide. There is a lot of potential for confusion and the situation can easily get out of hand if not properly addressed. Scientists are still trying to better characterize the overlaps between the different clades and they are trying to identify the most likely transmission networks involved in the different outbreaks.

One important and very powerful tool that has come into widespread use since the COVID-19 outbreak is the use of polymerase chain reaction (PCR). This technology, along with genomic sequencing, has revolutionized the way scientists diagnose and track outbreaks. For SARS-CoV-2, RT-PCR (reverse transcription PCR) was used since it is an RNA virus. Mpox is caused by a DNA virus which is easier to diagnose with PCR since it won’t need an reverse transcription step. However, it is much harder to sequence since its genome is more than five times longer than SARS-CoV-2.

 

The monkeypox virus doesn’t mutate as fast as SARS-CoV-2 so we don’t expect as many variants to emerge. In addition, it seems that immunity to one clade confers cross-protection to the other clade and this protection lasts a very long time. This means that, unlike COVID-19 which can reinfect people multiple times, we won’t have to worry about mpox reinfection in the short term. In addition, the availability of an effective vaccine means that these vaccines can be deployed to the most at risk populations to control local outbreaks. The slow spread of the disease and the distinct symptomatology also means that detection and containment strategies are unlikely to miss new cases if properly implemented. 

Here is what we know about the transmission potential of mpox. All clades (Ia, Ib, IIa, IIb) can be transmitted by skin to skin contact and by objects contaminated with the virus. For this mode of transmission, good hand hygiene whether by hand washing or alcohol hand rub will be effective. In addition, covering exposed skin areas when in a crowd or anticipating skin to skin contact will decrease the risk of transmission. Disinfection of frequently touched surfaces like door knobs and light switches can also help prevent spread. Sexual transmission is the predominant mode of infection for clades Ib and IIb. For populations with multiple sexual partners, using condoms and careful and frequent inspection of the skin especially in the genital area are good practices to reduce risk. 

As for respiratory transmission, the current consensus is that the role of droplets and short-range aerosols is minimal. This means that there is no need to wear masks except perhaps for immunocompromised individuals. There is also no need to stay home or avoid face to face meetings. Someone who develops a rash consistent with mpox will need to get tested and isolate. Isolation can be done at home with the proper setup, unless there is a different medical indication for hospitalization.

One unfortunate consequence of the PHEIC declaration is that almost every single skin rash is flagged as a potential Monkeypox case. There are many viral and bacterial causes of rashes and so the potential for false alarms is tremendous. Just the other day, we admitted a returned traveler to the hospital with a three-week history of a rash all over his body. This flagged him as a Monkeypox suspect and he ended up getting admitted to isolation for proper diagnosis. Closer examination and questioning revealed a more likely alternative diagnosis, but we still had to do the mpox PCR and isolate the patient and wear all that PPE when taking care of him because of his recent travel history. This is costly (fortunately this patient has good health insurance) and distressing for the patient. For the doctors and nurses, it is inconvenient to have to don so much gear, and a bit distressing as it does remind us of the pandemic times. We do know and accept, as frontliners, that this is the price of vigilance and these precautions will help stop the spread of this latest outbreak. Monkeypox is not Covid-19 and so we do not anticipate any lockdowns or travel restrictions, but we do still have to follow best practices to prevent its spread. We do hope that with everyone’s help and cooperation, we can quickly control Monkeypox in our country and we can all get back to normal.