What is Monkeypox Virus?
Monkeypox is a viral zoonotic disease caused by infection with monkeypox virus. Monkeypox virus is an enveloped double-stranded DNA virus from the Ortho-poxvirus genus in the family Poxviridae. It shares the same genus with the variola virus which causes smallpox, the vaccinia virus which was used for the development of smallpox vaccine, cowpox virus, and camel pox virus. Known as a less lethal and infectious relative of the smallpox virus, monkeypox has developed into two strains, namely the Central African strain, and the West African strain. Although infections with Central African strain have been known to be more severe and transmissible, the spread of monkeypox virus had been limited to tropical rainforest regions of Central and West Africa until 2003. Since then, although the virus was occasionally exported to other areas, it was quickly contained.
The recent outbreaks of the monkeypox virus in several non-endemic countries has caused major concern. As of May 21, 2022, 92 confirmed cases and 28 suspected cases of monkeypox infection were reported from 12 non-endemic countries including Australia, Belgium, Canada, France, Germany, Italy, Netherlands, Portugal, Spain, Sweden, the UK, and the US. Read along to find out more about monkeypox virus, its transmission routes, its symptoms, and preventive measures.
What is the natural host of monkeypox virus?
Monkeypox virus is a zoonotic pathogen, meaning that it spreads between non-human animals and humans. Although monkeypox was named after its initial discovery in monkeys in a Danish laboratory in 1958, various animal species have identified as susceptible to monkeypox virus, such as rope squirrels, tree squirrels, Gambian pouched rats, and dormice. Still, further research is required to determine the exact reservoirs of the virus.
How does monkeypox virus transmit?
Monkeypox virus spreads through close contact with infected animals and humans, or contaminated materials. The virus may enter through broken skin, respiratory tract, and mucous membranes such as the eyes, nose, or mouth.
Animal to human transmission of monkeypox may be through contact with blood, bodily fluids, and lesion material of an infected animal, including wounds such as bites and scratches. Consuming inadequately cooked meat and other products from infected animals is also considered a potential route for contamination.
Human to human transmission is possible through contact with respiratory secretions, bodily fluids, and skin lesions of an infected person. Again, contact with recently contaminated objects can also cause transmission. Apart from close contact, monkeypox can also transmit from mother to fetus through the placenta. While close physical contact has been identified as a transmission route, data remains insufficient to determine whether monkeypox spreads directly through sexual intercourse.
What are the signs and symptoms of Monkeypox?
The symptoms of monkeypox resemble a milder version of the symptoms of smallpox. Its initial symptoms include fever, headache, muscle aches, back pain, swollen lymph nodes, chills, and exhaustion. Around 1 to 5 days following the initial symptoms, the patient usually develops a rash which often begins from the face and spreads to the rest of the body. In time, the rash from small blisters, following with scabs before falling off. The incubation period between the initial contact and the development of symptoms is 5 to 21 days, and symptoms typically last for 2 to 4 weeks.
How common are monkeypox outbreaks?
Although monkeypox is a relatively rare disease, it is not a novel occurrence. The first human case of monkeypox was detected in 1970 in the Democratic Republic of the Congo (DRC). Since then, the virus has mostly affected populations in rural and rain forest regions in Central and Western Africa, with human cases reported in 11 African countries including the Democratic Republic of the Congo, Nigeria, Cameroon, the Central African Republic, Benin, Liberia, Gabon, Sierra Leone, Cote d’Ivoire, South Sudan, and the Republic of the Congo.
The first monkeypox outbreak outside of Africa occurred in 2003 in the US. Linked to pets imported from Ghana, the outbreak led to more than 70 human cases in total. More recently, monkeypox cases linked to international travel have been reported in Israel (2018), Singapore (2019), the UK (2018 and 2019), and the US (2021).
Which countries have monkeypox disease?
In May 2022, several cases of monkeypox were detected in various non-endemic countries. As of May 21, 2022, the World Health Organization (WHO) reports 92 confirmed cases and 28 suspected cases of monkeypox infection from 12 non-endemic countries including Australia, Belgium, Canada, France, Germany, Italy, Netherlands, Portugal, Spain, Sweden, the UK, and the US.
How dangerous is monkeypox?
As mentioned above, infections with the monkeypox virus are not typically as transmissible or severe as smallpox infections. Most people are known to recover on their own within a few weeks. However, some people such as children, pregnant women, and immunocompromised persons can develop more severe illness. The true burden of monkeypox is not clear. Still, the virus has been reported to have caused deaths in Africa, with a fatality rate potentially as high as 1 in 10 infected persons. Future research is required to determine the exact risks and risk groups associated with the monkeypox disease.
Is there a vaccine for monkeypox?
Due to cross-protection afforded for the immune response to ortho-poxviruses, both monkeypox and smallpox vaccines have been developed in formulations based on the vaccinia virus. Vaccination was demonstrated to be around 85% effective in preventing monkeypox. In 2019, a newer two-dose vaccine based on a modified attenuated vaccinia virus was approved for use against monkeypox. Thanks to cross-protection, prior smallpox vaccination is also thought to reduce symptom severity.
Apart from vaccines, although the data on their effectiveness is scarce, antiviral agents such as cidofovir and tecovirimat may also be used in the treatment of monkeypox, as both agents have proven to be effective against poxviruses. Developed originally for smallpox, tecovirimat was recently licensed by the European Medical Association (EMA) for use against monkeypox based on human and animal studies.
What can you do to protect yourself?
In order to protect yourself and others, you should avoid close contact with wild animals, stray animals, and animals that seem to be unwell in general. Touching or consuming bush meat may also lead to contamination. You should also make sure to not eat inadequately cooked meat. You should also refrain from coming into close contact or sharing belongings such as towels or bedding with people who may have monkeypox. Finally, you should always make sure to apply rules of personal hygiene and wash or sanitize your hands regularly.
Is diagnostic testing for monkeypox available?
Alongside vaccines and antiviral treatments, diagnostic technology has also been developed for monkeypox virus. Several IVD companies in China have developed monkeypox virus nucleic acid detection kits based on PCR-fluorescent flow method. As these viral detection kits do not currently have a registration certificate, they are used exclusively for research and disease control purposes.
References
- Sklenovská, N. (2020). Monkeypox Virus. Livestock Diseases and Management, 39–68. https://doi.org/10.1007/978-981-15-2651-0_2
- Formenty, P., Muntasir, M. O., Damon, I., Chowdhary, V., Opoka, M. L., Monimart, C., Mutasim, E. M., Manuguerra, J. C., Davidson, W. B., Karem, K. L., Cabeza, J., Wang, S., Malik, M. R., Durand, T., Khalid, A., Rioton, T., Kuong-Ruay, A., Babiker, A. A., Karsani, M. E., & Abdalla, M. S. (2010). Human Monkeypox Outbreak Caused by Novel Virus Belonging to Congo Basin Clade, Sudan, 2005. Emerging Infectious Diseases, 16(10), 1539–1545. https://doi.org/10.3201/eid1610.100713
- Isidro, J., Borges, V., Pinto, M., Ferreira, R., Sobral, D., Nunes, A., & Santos, J. D. (2022, May 20). First draft genome sequence of Monkeypox virus associated with the suspected multi-country outbreak, May 2022 (confirmed case in Portugal). Virological. Retrieved May 22, 2022, from https://virological.org/t/first-draft-genome-sequence-of-monkeypox-virus-associated-with-the-suspected-multi-country-outbreak-may-2022-confirmed-case-in-portugal/799
