Threats of Zika virus transmission for Asia and its Hindu-Kush Himalayan region

Asia and its Hindu Kush Himalayan(HKH)region is particularly vulnerable to environmental change,especially climate and land use changes further influenced by rapid population growth,high level of poverty and unsustainable development.Asia has been a hotspot of dengue fever and chikungunya mainly due to its dense human population,unplanned urbanization and poverty.In an urban cycle,dengue virus(DENV)and chikungunya virus(CHIKV)are transmitted by Aedes aegypti and Ae.albopictus mosquitoes which are also competent vectors of Zika virus(ZIKV).Over the last decade,DENV and CHIKV transmissions by Ae.aegypti have extended to the Himalayan countries of Bhutan and Nepal and ZIKV could follow in the footsteps of these viruses in the HKH region.The already established distribution of human-biting Aedes mosquito vectors and a naïve population with lack of immunity against ZIKV places the HKH region at a higher risk of ZIKV.Some of the countries in the HKH region have already reported ZIKV cases.We have documented an increasing threat of ZIKV in Asia and its HKH region because of the high abundance and wide distribution of human-biting mosquito vectors,climate change,poverty,report of indigenous cases in the region,increasing numbers of imported cases and a naïve population with lack of immunity against ZIKV.An outbreak anywhere is potentially a threat everywhere.Therefore,in order to ensure international health security,all efforts to prevent,detect,and respond to ZIKV ought to be intensified now in Asia and its HKH region.To prepare for possible ZIKV outbreaks,Asia and the HKH region can also learn from the success stories and strategies adopted by other regions and countries in preventing ZIKV and associated complications.The future control strategies for DENV,CHIKV and ZIKV should be considered in tandem with the threat to human well-being that is posed by other emerging and re-emerging vector-borne and zoonotic diseases,and by the continuing urgent need to strengthen public primary healthcare systems in the region.

Climate change and its association with the expansion of vectors and vector-borne diseases in the Hindu Kush Himalayan region:A systematic synthesis of the literature

Observed weather and projected climate change suggest an increase in the transmission of vector-borne diseases(VBDs)in the Hindu Kush Himalayan(HKH)region.In this study,we systematically explore the literature for empiric associations between the climate variables and specific VBDs and their vectors in the HKH region.We conducted a systematic synthesis of the published literature on climate variables,VBDs and vectors in the HKH region until the 8th of December 2020.The majority of studies show significant positive associations of VBDs with climatic factors,such as temperature,precipitation,relative humidity,etc.This systematic review allowed us to identify the most significant variables to be considered for evidence-based trend estimates of the effects of climate change on VBDs and their vectors in the HKH region.This evidence-based trend was set into the context of climate change as well as the observed expansion of VBDs and disease vectors in the HKH region.The geographic range of VBDs expanded into previously considered non-endemic areas of highlands(mountains)in the HKH region.B ased on scarce,but clear evidence of a positive relationship of most climate variables and VBDs and the observed climatic changes,we strongly recommend an expansion of vector control and surveillance programmes in areas of the HKH region that were previously considered to be non-endemic.