As India's Monkeypox tally continues to rise, the National Institute of Virology (NIV) in Pune on Sunday said that after analysis of the two cases pertaining to travellers who had returned from the UAE and subsequently tested positive in July, it has been found that they were infected with virus strain A.2. They said it is related to the lineage of hMPXV-1A clade 3.

In other words, the two patients had been infected with a less seen variant of the current strain of infection and bears similarity to cases that have cropped up in several Western nations earlier this year. Clade 3 is various 'branches' of monkeypox, each of which have unique genomic signatures and varying severity. Mentioning the details, the study also showed that the 35-year-old male and 31-year-old male from UAE -- tested positive for Monkeypox -- had no traces of sexual contact.

The development came soon after the country reported two fresh cases on Friday.

"Phylogenetic analysis revealed that the two cases were infected with Monkeypox virus strain A.2 which belong to hMPXV-1A lineage of clade 3...The complete genome sequences obtained from skin lesions of cases 1 and 2 showed similarity of 99.91% and 99.96% respectively with MPXV_USA_2022_FL001 West African clade," said the ICMR-NIV study.

The term 'hMPXV' is an abbreviation for 'human monkeypox virus'. While scientists have traditionally classified monkeypox cases based on location - clade 1 for Congo Basin as it was the first to be detected and 2 for West African - many argue that the new strain (akin to the typically milder West African strain) deserves a fresh categorisation as clade 3.

Genetic data from other parts of the world however have indicated that there are at least two 'separate' monkeypox outbreaks underway outside of Africa at present, with a majority of the genomes across the world which belonging to the B.1 lineage. The A2 strain meanwhile has been detected in several Indian cases including a Kerala man who returned from the UAE who had succumbed to the virus last week.

"Case 1, a 35-year, male, resident of UAE had developed low-grade fever and myalgia on July 5 2022. On the next day, he developed multiple vesicular rashes in the oral cavity and lips followed by a single lesion on the genital organ. The lesions were umbilicated with the size 0.5 to 0.8 cm," the study explained.

Another case pertained to a 32-year-old male from Dubai who travelled to his hometown Kerala on July 13, 2022, and tested positive for Monkeypox.

According to the study, he had developed dysuria and genital swelling on July 8. The next day he developed fever with chills, myalgia, backache and headache followed by multiple vesicular rashes on the genital organ and both hands on July 10. The lesions progressed and later spread to the face, back, neck and forearm with cervical lymphadenopathy by July 15, 2022. "He did not have any co-morbidity and denied any sexual or physical contact with suspected or confirmed MPXV case," it added.

The Niv  on 6 August analysed two monkeypox cases of travellers who had returned from the UAE.

According to the study, the two cases were infected with monkeypox virus strain A.2 which is related to the lineage of hMPXV-1A clade 3.

"The complete genome sequences obtained from skin lesions of cases 1 and 2 showed similarity of 99.91 and 99.96 per cent respectively with MPXV_USA_2022_FL001 West African clade," read the ICMR-NIV study.

"Phylogenetic analysis revealed that the two cases were infected with Monkeypox virus strain A.2 which belong to hMPXV-1A lineage of clade 3," it added.

Both the cases' samples from multiple sites -- lesion fluid, lesion roof and lesion base -- were collected on the ninth post-onset day of illness i.e. 13 July, 2022, and July 16, 2022, respectively. They referred to the World Health Organization Collaborating Centre for emerging and re-emerging diseases, ICMR-National Institute of Virology, Pune, India for the MPXV diagnosis.