Recent Outbreak of Zika in Kerala State, India; is Zika Virus Re-Emerging as a Distinct Genetic Lineage in India? (original) (raw)

2023

Abstract

Background: An outbreak of Zika fever occurred in Thiruvananthapuram City, Kerala, India during 2021. We investigated the same, on request of Kerala state health administration towards proposing containment strategies. Methods: Epidemiological and entomological investigations as well as genome analysis of ZIKA Virus (ZIKV) involved in the infections were performed, targeting crucial and phylogenetically important mutations in the Capsid-pre Membrane, Envelope and Non-Structural protein -5 gene sequences. Results: A clustering pattern of cases was observed during the outbreak, with the presumed index case from a multi-speciality hospital, in Thiruvananthapuram city. The causative ZIKV belonged to the Asian strain, however, distinct from the pandemic American lineage. The predominant Aedes albopictus (65.55%), Aedes aegypti (22.0%) and Aedes vittatus (12.0%) species were found naturally infected with ZIKV, the Minimum Infection Rates being 17.9, 7.8 and 3.6 respectively. Also, trans-ovarian transmission was recorded in Ae. albopictus. Conclusions: ZIKV isolates presented with four unique non synonymous mutations viz., “I22T” & “I160M” (pre-Membrane) and “D348N” & “V473L” (Envelope) during the outbreak which’s implications remains to be investigated. Phylogenetic analysis of the gene sequences indicated the emergence of a distinct genetic lineage of ZIKV in India. Our investigations evince the urgent need of development of a systematic country-wide surveillance strategy, towards the prevention/ preparedness/ containment of a massive outbreak of this emerging arbo-viral disease. Funding: This study was performed utilizing intramural funds of Indian Council of Medical Research-Vector Control Research Centre. Declaration of Interest: The authors declare no known competing financial interests or personal relationships/interests that could have appeared to influence the work reported in this manuscript. Ethical Approval: As the study was an outbreak investigation carried out on the request of the Department of Health Services, Government of Kerala. India, institutional ethical approval was not essential the time of investigation. Most of the samples processed were from mosquito specimens. Informed consent forms were obtained from all the four patients from whom blood samples were obtained during the investigation. However, towards on going further investigations institutional ethical approval was obtained retrospectively.

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