Scientists of the Indian Council of Medical Research-National Institute of Virology (ICMR-NIV) scientists have found a new variant of chickenpox-causing virus for the first time in India.
According to the World Health Organisation (WHO), Varicella-zoster is a herpes virus that causes chickenpox which is an extremely common childhood illness. It is noteworthy that Herpes zoster (HZ), commonly known as shingles, is caused by the reactivation of the varicella zoster virus (VZV).
Scientists have found that the clade 9 variant VZV is circulating in India. The findings of this study have been published in the recent issue of Annals of Medicine journal.
So far the clade 9 is the most common strain in circulation in countries such as Germany, UK and USA, as per a report by the Indian Express.
“As part of our surveillance for monkeypox cases, we encountered cases of VZV in the suspected Mpox cases among children and adults,” said Dr Pragya Yadav, senior scientist with ICMR-NIV, and one of the study authors, as quoted by Indian Express.
Dr. Yadav highlighted that their study focused on the genome characterisation of VZV in India. She also pointed out that despite the infection with VZV clade 9 strain, there were no significant indications of heightened disease severity in the patients.
In rare cases, VZV infections can progress to central nervous system involvement and severe complications.
“It is critical to distinguish chickenpox from measles, bacterial skin infections, scabies, syphilis, medication–associated allergies, and Mpox viral disease,” study researchers said as quoted by Indian Express.
Due to the similarities of the symptoms and clinical presentation, Mpox disease is frequently mistaken for VZV. Consequently, there is a need for clinical differentiation between Mpox and VZV for accurate diagnosis.
Recently, a multicentric Mpox outbreak was reported across 110 countries, with a total of 86,500 cases and 111 deaths till March 16 this year, including 22 cases and 1 death from India.
While the multi-country Mpox outbreak across the globe had led to the systematic surveillance of these cases in India, at ICMR-NIV a total of 331 Mpox suspected cases were tested for VZV through real-time PCR, and of these 28 cases with vesicular rashes were found to be positive for VZV, Indian Express reported.
The incubation period of Mpox ranges from 5 to 21 days whereas, in the case of chickenpox, it is from 10 to 21 days. The evolution of rashes occurs quite slowly over a few days in Mpox but this occurs rapidly in chickenpox, researchers said.
As there is no availability of chickenpox vaccination in the national immunisation programme, and the immunity of the population is waning to orthopoxviruses, there is a need for laboratory diagnosis and identification of different clades of circulating VZV in India.
Although clades 1 and 5 have been reported earlier, the circulation of clade 9 of VZV has been determined for the first time in India, researchers said.
It is noteworthy that these recombinant patterns have led researchers to make a strong case for disease monitoring and surveillance of VZV infections in the country.
In a study of patients with central nervous system (CNS) involvement in VZV infection from the metropolitan region of New York City, the clade 9 strains were found in areas with a higher concentration of immigrants of Middle Eastern and Indian ethnicity, indicating the presence of clade 9 circulation in India. In this study, two sequences from India belonged to clade 1 which were considered to be European and North American strains.
Clades 1 to 5 are most prevalent in the world, with clade 1 and 3 circulating in Oceania, Europe and America while clade 2 in Asia and clade 4–5 in South Asia and Africa. Most VZV infections observed in USA belong to clade 1 and 3.
