Nation-wide vector surveillance did not indicate transmission of the “American lineage pandemic ZIKA virus” in India

Abstract

Background In wake of the global health emergency declared by the World Health Organization (WHO) during 2016, on the outbreak of ZIKA pandemic, Indian Council of Medical Research (ICMR) carried out countrywide vector surveillance for ZIKA and DENGUE viruses (ZIKV & DENV) in India, as a preparedness measure. Methods The study incorporated high-risk zones distributed to 49 Districts in 14 states/ Union Territories (UT) of India during 2016-2019. Seven ICMR Institutions undertook the study, following a uniform Standard Operating Protocol. Aedes specimens sampled on weekly intervals were processed by multiplex Reverse transcriptase PCR for ZIKV/DENV and Real time RT-PCR of ZIKV, among few samples distributed to all the Districts. Results Altogether, 79492 specimens of Aedes mosquitoes in 6492 pools were processed for both ZIKV and DENV infections. Among these, three and 63 pools respectively were found positive for ZIKV and DENV. ZIKV infections were recorded from Aedes aegypti sampled during 2018 sporadic ZIKA outbreak in Jaipur, Rajasthan, which belonged to the Asian lineage, already circulating in the Country. Both Ae. aegypti and Aedes albopictus were found infected with DENV and were distributed to ten states/ UTs. Both male and female specimens of Ae. albopictus recorded DENV infections indicating trans-ovarial transmission of DENV in the species. Conclusion This national vector surveillance study evinced no active transmission of the “American lineage - pandemic ZIKA virus” in India during 2016-2019, although Asian lineage of the virus already circulating in the Country was detected from Ae. aegypti from Jaipur, Rajasthan.