Mpox is a zoonotic disease caused by the monkeypox virus. This virus is a DNA virus, unlike the SARS-CoV-2 virus which is an RNA virus. It belongs to the pox family of viruses which causes smallpox, cowpox, variola and vaccinia (chicken pox is not a true pox virus).

“Mpox has been around for a long time,” pointed out WHO medical epidemiologist Otim Patrick Ramadan, during a Live Q&A session on August 22. The virus was first discovered in monkeys kept for research in Denmark in 1958 and the first reported case of infection in a human was in 1970, a nine-month-old baby in the Democratic Republic of the Congo.

Ever since the end of smallpox vaccination around the world (after its eradication in 1980), mpox has been affecting humans, though it was usually limited to central, east and west Africa. The first time there was a global outbreak was in 2022.

“During the 2022 outbreak, there were 30 cases in India, including in Kerala,” said Adarsh AK, who heads the Infectious Diseases and Adult Immunization department at Amala Institute of Medical Sciences, Thrissur. WHO confirmed during its live session on Thursday that there are 11 countries with active outbreaks at the moment, though only two - the Democratic Republic of Congo and Burundi - have over 50 cases. There has been no confirmed case in India so far.

What’s different this time

What sets the 2024 mpox outbreak apart is that it is being driven by a different subtype of the virus called clade 1b, which seems to be deadlier and spreading faster than clade 2 which caused the 2022 outbreaks. As a result, the disease has reached countries where it has never reached before, like Burundi, Uganda, Rwanda and Kenya. On Thursday, Thailand became the first Asian country to report a case of mpox clade 1b. Sweden was the first.

Though there are many symptoms, the three primary ones according to Ramadan are fever, swelling of lymph nodes and lesions. Mpox can affect anyone, but it spreads largely via skin-to-skin contact. As a result, the transmission of the virus currently seems to be within the household as well as through sexual networks.

Also at risk are the immunocompromised. “Because the last outbreak was most commonly seen among men who had sex with men, there was a big stigma around the disease,” explained Adarsh. In reality, he pointed out, even people without these risk factors were developing the disease. “The current outbreak, caused by clade 1b, is affecting many children below 15 years of age,” he added.

The case fatality rate of clade 1b appears to be alarmingly high; some reports say 3% and this goes up to 10% in children. However, Rajib Dasgupta, a professor of community health at Jawaharlal Nehru University, warns that these figures are likely to be influenced by the fact that the surveillance rate is still low. “The number of diagnoses is less. As more cases are detected, these rates come down. But that doesn’t mean we can discount this outbreak. 3% is still a high mortality rate,” he said

Vaccines and vigilance

There are two vaccines currently in use for mpox, both are also smallpox vaccines. WHO is reportedly working on priority to ensure access to these vaccines to the countries that are most at risk.

At his hospital in Thrissur, Kerala, Adarsh and his colleagues have to be vigilant. “There has to be a high index of suspicion, especially with patients who have travelled from areas where mpox has been reported. In such scenarios we will take their sample and send it for testing,” he said. There are currently 32 labs equipped for testing, including one in ICMR-NIV’s Kerala Unit in Alleppey, according to Adarsh. He added that they would be following the mpox advisory issued earlier this week by AIIMS Delhi and also the national guidelines from 2022.

“India receives relatively less traffic from African countries, but like with Covid, the disease can spread through air hubs such as the middle-east,” said Dasgupta. What is critical, he emphasised, is that cases are detected and contacts are traced. “In the past, mpox cases in India were contained pretty well. It’s not rocket science. We must acknowledge and appreciate that since Covid, these things are much stronger than they were five years ago.”

The biggest hurdle in controlling mpox is likely to be the stigma associated with the disease. Part of this comes from the nature of the symptoms. “The way it presents, the lesions, the rashes on the face and body - people fear to come out in public,” said Ramadan. Then there is also the matter of sexual transmission.

“In the 2022 outbreak, patients were migrants from elsewhere, for example, countries in the Middle East. But most of them were not ready to disclose their exact exposure. They denied sexual exposure, but we could not be sure if it's true because of the stigma,” said Adarsh. The danger of this situation is that patients may not come forward to receive a diagnosis and adequate care, and the disease will likely spread further.

The mpox outbreak is not another Covid-19, stressed WHO experts. It’s a completely different virus, and more importantly, spreads primarily via intimate contact - such as sexual contact, breathing the same air, or sharing clothes.

“Covid-19 was spread through respiratory droplets. You could contract it if you were standing even six feet away from a patient, and even airborne spread was suspected. With mpox, you are unlikely to contract it from a person in the same room,” said Adarsh.

“Anyone can get mpox if they are in contact [with an infected person], but it doesn’t mean that everyone will,” said Maria Van Kerkhove, from WHO. “There is lots we can do here to interrupt transmission… but it has to be a global effort. We need the right information, resources, diagnostics and therapeutics. When vaccines are used, it has to be done in a targeted way, focusing on the at-risk population. This is not the ‘new’ anything. This is mpox, and we have experience with it.”

Nandita Jayaraj is the co-author of Lab Hopping: A Journey to Find India's Women in Science, which explores the gender gap in Indian science. The views expressed are personal