The poxviruses are highly relevant to human beings, among which the orthopoxviruses are the best-known. These include the smallpox virus (variola virus, VARV), the monkeypox virus (MPXV), the cowpox virus, and the vaccinia virus.
Introduction
All of these cause newly emerging endemic diseases, especially in developing countries. Monkeypox (MPX) leaped into the limelight recently with a threatening outbreak of rapidly spreading infections almost completely confined to the community of men who have sex with men (MSM).
A new review published sheds light on the origins of this virus and recently acquired knowledge about its disease mechanism and the preventive and therapeutic measures appropriate in this situation.
Prevention and Treatment
Two smallpox vaccines are available that may confer 85% protection against MPX. Both are live virus-based. One, ACAM2000, is capable of replication and can cause serious complications, such as progressive vaccinia infection, eczema, myocarditis and pericarditis, and encephalitis. ACAM2000 requires a single dose, with peak protection at 28 days.
The second, JYNNEOS, is safer and can be used in immunocompromised individuals and potentially in pregnant women. Two doses are required 28 days apart, with full protection being present only 14 days after the second dose.
Post-exposure prophylaxis with these vaccines has been reported, and ring vaccination is being practiced at present in the USA, UK, and Canada to arrest the MPX epidemic. However, one dose of this vaccine may not be protective against MPX, and data on adverse effects is very limited.
Severe cases may require treatment, including those with severe confluent lesions, hemorrhagic disease, sepsis, encephalitis, immunocompromised individuals, pregnant or lactating mothers, children, those with severe skin disease, and those with secondary bacterial infection of the lesions, and those with dehydration secondary to vomiting, diarrhea or other causes, MPX lesions in the eyes, mouth, genitals or anus. The last category includes almost all patients in the current outbreak.
Drugs like tecovirimat, which inhibits viral replication and has been approved for smallpox treatment, brincidofovir and cidofovir, both of which are DNA polymerase inhibitors, are being used off-label for MPX cases. The first is under a non-research expanded access investigational new drug protocol for non-smallpox orthopoxvirus infections, while the others were approved in 2021 for smallpox. Vaccinia immune globulin intravenous (VIGIV) is approved to treat vaccinia vaccine-related complications and is also under an expanded access protocol for orthopoxvirus infections.
Conclusion
The MPX outbreak seems to be losing force at last. However, its initial rapid spread within the MSM community, despite the known inefficiency of MPXV transmission, exposed some chronic failings of the public health system. It also lends force to the arguments for sticking to a single sexual partner, irrespective of sexual orientation.
The virus has likely acquired beneficial mutations, and new strains have emerged by natural selection to take advantage of a naïve human population. Effective responses to this virus must be implemented, building on experience gained from the coronavirus disease 2019 (COVID-19) pandemic.
Source:
https://www.news-medical.net/news/20220831/The-most-recent-evidence-about-phylogenesis-pathogenesis-prevention-and-treatment-for-monkeypox.aspx