Arboviral Infections in New Zealand, Australia and the Pacific Islands: Zika, Dengue and Chikungunya

Abstract

Background: Arboviruses are viruses which require blood-feeding arthropods to transmit themselves to susceptible hosts. Globally, arboviruses are responsible for some of the most important emerging infectious diseases and are classed as emerging pathogens due to their rapid geographic spread and increasing impact upon susceptible human populations. Arboviruses pose significant economic and social threats which greatly impact upon global public health. Zika (ZIKV), dengue (DENV) and chikungunya (CHKV)are arboviruses which have caused epidemics in numerous countries around the world. This study attempts to examine the trends in notified ZIKV, DENV and CHKV infections in New Zealand (NZ), Australia (Queensland) and the Pacific Islands (Fiji, French Polynesia and New Caledonia) to understand the extent to which these arboviruses are impacting the south western pacific region. Furthermore, the epidemiology of these arboviral infections in New Zealand will be analysed, with the aim of providing an evidence base for policies and practices which attempt to reduce the number of arboviruses being brought into New Zealand by travellers. Aim: 1. Estimate the disease specific annual incidence of ZIKV, DENV and CHKV among NZ travellers between 2010 - 2015. 2. Utilise disease count data to determine whether the rates of ZIKV, DENV and CHKV infections are on the increase in NZ, Australia (Queensland) and the Pacific Islands (Fiji, French Polynesia and New Caledonia). Factors which may explain the trends that are seen will be discussed. 3. Calculate the incidences of ZIKV, DENV and CHKV infections among NZ travellers arriving from Samoa, Tonga and Fiji between 2010 - 2015. 4. Analyse the characteristics of cases of arboviral infections in NZ. 5. Put forward recommendations regarding arbovirus surveillance and the prevention of arboviral infections among travellers. Methods: • NZ disease count data for the years 2010 – 2015 was utilised along with NZ traveller arrival statistics data to estimate the disease specific annual incidence of ZIKV, DENV and CHKV. • Disease count data from NZ, Australia (Queensland) and the Pacific Islands (Fiji, French Polynesia and New Caledonia was analysed from 2005 to 2015 to determine whether the ZIKV, DENV and CHKV have been increasing during this ten year period. • Disease count data from cases of ZIKV, DENV and CHKV that acquired infection in Samoa, Tonga and Fiji were analysed along with NZ traveller arrival statistics data to calculate the incidence of these three arboviruses in travellers arriving from these three countries. • Case characteristics were analysed from a line listed retrospective data set which was acquired from the NZ Institute of Environmental Science and Research (ESR). Results: • The annual incidence of ZIKV, DENV and CHKV among New Zealand travellers between 2010 – 2015 has been generally increasing. • Rates of ZIKV, DENV and CHKV virus infections are on the increase in New Zealand, Australia (Queensland) and the Pacific Islands (Fiji, French Polynesia and New Caledonia). • The annual incidence of DENV and CHKV infections among New Zealand travellers arriving from Samoa, Tonga and Fiji between 2010 – 2015 has been increasing. The annual incidence for ZIKV has only increased for Samoa. • Transnational surveillance partnerships between New Zealand, Australia and the Pacific Islands can assist the Pacific region with upgrading their surveillance system to monitor rates of ZIKV, DENV and CHKV infections. As to the majority of ZIKV, DENV and CHKV cases have been identified as entering New Zealand from the Pacific Islands, this would have great benefits for New Zealand’s health system. Prevention of arboviral infections among travellers revolves around improving traveller health education so that they have greater knowledge of precautionary behaviours that can be utilised to prevent infection.