New variant of chickenpox-causing virus found first time in India

Clade 9 strain detected during survillence for monkeypox in India

File Public school student Julio Valenzuela, 11, grimaces as he gets a vaccination at a free immunization clinic for students before the start of the school year (AFP via Getty Images)

A new variant of chicken pox virus, known as clade 9, has been detected in India for the first time, health officials said.

The National Institute of Virology (NIV), an Indian virology research institute, said it encountered clade 9 variants of chickenpox-causing varicella-zoster virus (VZV) while conducting surveillance for mpox (formerly known as monkeypox) cases.

“During the surveillance of mpox, we encountered cases of Varicella Zoster Virus (VZV) in suspected mpox cases amongst children & adults,” the study said.

It said that out of 331 suspected cases of mpox, 28 cases were found positive for VZV.

Clade 9 is the most common strain of chickenpox-causing virus in countries such as Germany, UK and the US. While other variants of VZV – clade 1 and clade 5 – have been previously found in India, it is the first time that clade 9 has been detected.

According to the World Health Organisation (WHO) the VZV causes highly contagious chickenpox. It is generally transmitted through contact with infected droplets, aerosols, or direct contact with respiratory secretions.

It can cause mild symptoms in children and tends to be more severe in adults. The WHO characterizes it by symptoms such as “an itchy rash, usually starting on the scalp and face and initially accompanied by fever and malaise".

The common symptoms of clade 9 infection include rashes, headache, appetite loss and overall sense of ill health and appear only two to three weeks after exposure to the virus.

In rare cases, VZV can cause severe complications after progressing to the central nervous system of the body.

“It is critical to distinguish chickenpox from measles, bacterial skin infections, scabies, syphilis, medication–associated allergies, and Mpox viral disease,” study researchers said.

Although there wasn’t a significant sign of increased disease severity, these recombination patterns have prompted researchers to strongly advocate for the monitoring and surveillance of VZV infections in the country.