[Editorial] The Monkeypox virus: origins and outbreaks

Context: With cases being reported from across the world, monkeypox has caught everyone’s attention. The present outbreak has a toll of over 220 confirmed cases spread across 19 countries. U.K., Spain and Portugal are leading the pack with the highest number of confirmed cases but no deaths reported to date.

What is the Monkeypox virus?

• Monkeypox is not a new virus. The virus, belonging to the poxvirus family of viruses, was first identified in monkeys way back in 1958, and therefore the name.
• The first human case was described in 1970 in the Democratic Republic of Congo and many sporadic outbreaks of animal to human as well as human to human transmission have occurred in Central and West Africa in the past with significant mortality.
• After the elimination of smallpox, monkeypox has become one of the dominant poxviruses in humans, with cases increasing over years along with a consequent reduction in the age group affected.

Transmission and incubation period

• Since the transmission occurs only with close contact, the outbreaks have been in many cases self-limiting.
• Since in the majority of affected people, the incubation period ranges from five to 21 days and is often mild or self-limiting, asymptomatic cases could transmit the disease unknowingly.

Does the virus mutate?

• Monkeypox virus is a DNA virus with a quite large genome of around 2,00,000 nucleotide bases.
• While being a DNA virus, the rate of mutations in the monkeypox virus is significantly lower (~1-2 mutations per year) compared to RNA viruses like SARS-CoV-2.
• The low rate of mutation, therefore, limits the wide application of genomic surveillance in providing detailed clues to the networks of transmission for monkeypox, unlike what was possible for SARS-CoV-2.

What do the genomes say?

• With over a dozen genome sequences of monkeypox now available from across the world due to the current outbreak, it is reassuring that the sequences are quite identical to each other suggesting that only a few introductions resulted in the present spread of cases.
• Additionally, almost all genomes have come from the West African clade, which has much lesser fatality compared to the Central African one.
• This also roughly corroborates with the epidemiological understanding that major congregations in the recent past contributed to the widespread transmission across different countries.
• While, unlike COVID-19, the slow rate of mutations precludes us from using genomic sequences for fine-tracing of the contact networks, the sequences largely belong to the West African lineage of the virus, which has shown to be associated with lesser virulence.

Does it have an effective vaccine?

• It is reassuring that we know quite a lot more about the virus and its transmission patterns.
• We also have effective ways of preventing the spread, including a vaccine.
• Smallpox/vaccinia vaccine provides protection.
• While the vaccine has been discontinued in 1980 following the eradication of smallpox, emergency stockpiles of the vaccines are maintained by many countries.
• Younger individuals are unlikely to have received the vaccine and are therefore potentially susceptible to monkeypox which could partly explain its emergence in younger individuals.

Practice question for Mains

1. Often confused with chickenpox, monkeypox is a rare viral infection that does not spread easily between people and is usually a mild “self-limiting illness” and most people recover within a few weeks. Discuss. (150 Words, 10 Marks).