Trends of chicken pox in children: an ode to the robust network of surveillance system with laboratory support

BACKGROUND Chicken pox (varicella) is the primary infection caused by Varicella Zoster Virus (VZV) and it predominantly affects children, with highest incidence in the 1-9 years old age group.VZV transmission mainly occurs from direct contact, inhalation of aerosols from vesicular fluid of skin lesions of varicella or zoster, and possibly through infected respiratory secretions and its aerosols. Varicella outbreaks are frequently reported from various regions of India. In India about 74 outbreaks of chicken pox was reported in 2022. The objective of this research to describe the distribution and characteristics of Chicken pox outbreaks in Karnataka region during 2022 & 2023 in 7 districts, an observational study. METHODS Total of 213 suspected cases from February 2022 to February 2023 were included in the study. Samples from various districts of Karnataka were received in reference laboratory BMCRI under IDSP. Laboratory confirmation was performed in the State level viral research and diagnostic laboratory, BMCRI on representative samples sent from each district for VZV. IgM antibodies against VZV were detected by ELISA (NovaLisa). RESULTS A total of 213 suspected cases were observed from February 2022 to February 2023. Towards the end of the year in 2022, 58 cases were reported in Kolar.8 representative samples were sent and all were positive for VZV IgM ELISA. A total of 47 cases were reported from Tumkur throughout the year.47 samples were sent in total of which 43 tested positive for VZV. 48 cases were reported in Mandya,10 representative samples were positive.12 cases in Koppal.29 cases from Hassan and all 7 representative samples were positive for IgM. 8 cases were reported from Davanagere and confirmed positive for IgM VZV through ELISA. CONCLUSION Karnataka has an ideal setting for the spread of VZV. The ambient temperature in the winter, early spring & closely placed population aids in the spread of infection. The number of chickenpox cases were higher amongst the children compared to the adults. This may be due to the fact that adult population already developed natural acquired immunity against chickenpox.Timely identification by surveillance and referral of samples by the district public health laboratories helped in early detection and treatment of the cases.The Chicken pox Vaccination has not been incorporated into the National immunization schedule as of now. A programme of varicella vaccination can potentially change the epidemiology of varicella and limit its burden childhood as well as its social and financial cost.