Dr Gangakhedker was the head of the department of epidemiology and communicable diseases at the country’s apex Indian Council of Medical Research (ICMR) at the beginning of the COVID-19 pandemic. He is also a part of the World Health Organisation’s (WHO’s) scientific advisory group on origins of novel pathogens. He has been working on HIV/AIDS since the 1980s, contributing significantly towards the national policies in place today. He was also instrumental in handling the Nipah virus outbreak in Kerala in 2018.

There have been over 18,000 cases of Monkeypox across 78 countries in the world, with 70 per cent cases being reported from Europe and 25 per cent cases from the Americas. Even though cases have rapidly spread across the world, there have only been five deaths, that too in countries where the infection was found even before the current outbreak, according to the World Health Organisation (WHO). India has so far reported four cases – three from Kerala – all with a history of international travel – and one from Delhi without it.

Now that we have detected a case of local transmission in India, are we likely to see more cases of Monkeypox in the coming months? Can the infection spread across the country like COVID-19?

This virus does not have the classical pandemic potential. The first reason is the transmission efficiency is low. The Ro value (this is the basic reproduction number that represents the number of people who can get the infection from the affected) is far too less for a spread. It can never be like COVID-19 where the virus is transmitted rapidly through the respiratory route. This is mainly transmitted through sexual route.

Second, not everyone is at an equal risk of getting the infection. The number of people at high risk is going to be smaller.

Third, those with Monkeypox get skin lesions, with the symptoms starting between six to 13 days of getting the infection. If people are aware about the kind of lesions seen in Monkeypox, they will be careful about onward transmission.

The WHO says that the disease is transmitted through close contact with lesions, bodily fluids, respiratory droplets and contaminated materials. It is still unclear about the infection being transmitted through sexual routes. What does evidence suggest?

The transmission of Monkeypox from animals to humans is well established; the disease manifests in people living close to forests and consuming bush meat. Over the years, there has been an increase in human-to-human transmission but we still do not know everything about it.

What we have seen till now is that the Ro is higher among men who have sex with men (MSM). And the reason that perhaps happens is because most of the lesions tend to occur in the peri-genital region. Though the Monkeypox virus has been documented as being present in the semen, we don’t know if it has replication potential. The mere presence of the virus doesn’t make the infection sexually transmissible. If someone is in the incubation period and doesn’t have lesions and another person gets it from unprotected sex, then it establishes that the virus in the semen is replication competent. This is what is called a classical sexually transmitted disease.

Even otherwise, if the infections are occurring only in people where you can ascribe it to sexual activity, it is quite possible that it might emerge as a sexually transmitted infection. It took us a couple of years to establish HIV as a sexually transmitted disease, but with the speed of research these days, we might know for sure in one-and-a-half months.

However, every organism has a preferred route of transmission and an accidental one. As we have seen cases in children, clearly there is transmission through skin lesions as well. Hence, it is essential that those infected remain in isolation and maintain hygiene in a way that household transmission can be prevented.

Most of the cases reported so far are in MSM. Is there any reason men are at a higher risk of getting the infection?

We have seen fewer cases of the infection being reported in women but it isn’t unheard of. There is a case series of pregnant women who got the infection reported from Congo.

The prevalent gender inequality comes into play here. Women are less likely to seek care, especially if the lesions are in the genital area. Plus, if the infection is transmitted from the husband to the wife, and she knows that it is self-limiting, she might not seek care.

This is compounded by the fact that the infections were mostly reported in regions near the forest, meaning access to health facilities weren’t very good, and among the poor. After all, that’s why they consumed bush meat. We should not stigmatise the infection so that people who do have symptoms seek care.

What can be done to prevent the spread of the infection?

It is preferable that people avoid sexual activities with partners who are unknown or not regular. If one does have sex with an unknown partner, a condom should be used – although, we still do not know whether condom can prevent transmission of Monkeypox.

Good isolation and hygiene practices will also prevent household spread of the infection. It is always a good idea to wash hands after being outdoors.

As for healthcare workers, they should just adhere to protocols that are followed for any infection – such as wearing gloves while checking the lesions or ensuring proper disposal of bio-medical waste so that those collecting or transporting it do not get exposed.

The US is vaccinating high-risk populations post-exposure. Is there a need for vaccines here in India as well?

It is too early to talk about vaccination; we have only reported four cases. We also need to look at the impact of the disease. There is a very low risk of death – less than one per cent. And, this estimate is based on data from Africa. So far, there have been no deaths reported outside Africa in the multi-country outbreak, though the number of cases has been pretty high. Statistically, the case fatality ratio is very, very low.

The disease is not very severe, so the public health systems are unlikely to be over-burdened. Data from the Western countries shows that about 13 per cent of the cases are hospitalised. If you look at the breakup of the hospitalisations, many come in for pain management. This number is likely to be lower in India – varying among different socio-economic groups with different health-seeking behaviour. Most patients can be effectively isolated at home.

The disease is as it is mildest, so is there a need for getting a vaccine after exposure to reduce severity? Also, the vaccine being used was developed against small pox, which has been eradicated. So there is no effectiveness data for it, it only has immunogenicity data. Why use it unless necessary?

Can the smallpox vaccine, which was given to people before the elimination nearly 40 years ago, help?

Theoretically, it’s possible. But for that we have to assume that our immune system still remembers a vaccine that was given 42 years ago. We don’t have evidence for that. But, then there are vaccines like the one for measles that is needed only once.

Two genome sequences from the patients in Kerala have been uploaded by India. The infections have been caused by a different sub-lineage from the one that has been most commonly found. What does this mean?

I think we should not over analyse these phylogenetic data. There can be any number of mutations in a virus but unless there are any clinical manifestations of it, it doesn’t matter to people. It is still important data but it is too premature to talk about it now.

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