Mapping the cryptic spread of the 2015–2016 global Zika virus epidemic

Abstract

Background Zika virus (ZIKV) emerged as a global epidemic in 2015–2016 from Latin America with its true geographical extent remaining unclear due to widely presumed underreporting. The identification of locations with potential and unknown spread of ZIKV is a key yet understudied component for outbreak preparedness. Here, we aim to identify locations at a high risk of cryptic ZIKV spread during 2015–2016 to further the understanding of the global ZIKV epidemiology, which is critical for the mitigation of the risk of future epidemics. Methods We developed an importation simulation model to estimate the weekly number of ZIKV infections imported in each susceptible spatial unit (i.e. location that did not report any autochthonous Zika cases during 2015–2016), integrating epidemiological, demographic, and travel data as model inputs. Thereafter, a global risk model was applied to estimate the weekly ZIKV transmissibility during 2015–2016 for each location. Finally, we assessed the risk of onward ZIKV spread following importation in each susceptible spatial unit to identify locations with a high potential for cryptic ZIKV spread during 2015–2016. Results We have found 24 susceptible spatial units that were likely to have experienced cryptic ZIKV spread during 2015–2016, of which 10 continue to have a high risk estimate within a highly conservative scenario, namely, Luanda in Angola, Banten in Indonesia, Maharashtra in India, Lagos in Nigeria, Taiwan and Guangdong in China, Dakar in Senegal, Maputo in Mozambique, Kinshasa in Congo DRC, and Pool in Congo. Notably, among the 24 susceptible spatial units identified, some have reported their first ZIKV outbreaks since 2017, thus adding to the credibility of our results (derived using 2015–2016 data only). Conclusion Our study has provided valuable insights into the potentially high-risk locations for cryptic ZIKV circulation during the 2015–2016 pandemic and has also laid a foundation for future studies that attempt to further narrow this key knowledge gap. Our modelling framework can be adapted to identify areas with likely unknown spread of other emerging vector-borne diseases, which has important implications for public health readiness especially in resource-limited settings.

Which Plagues are Coming Next?

“…Current research suggest Zika will be around until the foreseeable future with research indicating ZIKV actually circulates in areas previously unknown. Moreover, in 2019 Europe's first autochthonous case [31] was identified and further confirmed the importance of vector control and public health programs. Like the flaviviruses mentioned above, ZIKV's main vectors are Ae.…”

“…One of the most famous infectious diseases of recent decades, Zika came into the international spotlight during its 2015 epidemic. Although Zika virus (ZIKV) was discovered in a Ugandan forest over 50 years ago, in 2015 it emerged as a global epidemic affecting multiple countries and causing widespread panic [31]. In 2016, Which Plagues are Coming Next?…”

“…aegypti and Ae. albopictus placing a large proportion of the global population at risk of infection; therefore, threatening International Health Security [31,33]. Although Aedes mosquitos are the confirmed vector for ZIKV, Culex genera mosquitoes, mostly Culex quinquefasciatus, are theorized to be capable to transmit Zika, further expanding its geographic reach [34].…”

Temporal and coevolutionary analyses reveal the events driving the emergence and circulation of human mamastroviruses

“…This evokes another lesson learned from the current COVID-19 pandemic, in which the emergence of variants of concern (VOC) or variants of interest (VOI) were linked to the circulation of SARS-CoV-2 in immunocompromised patients[ 34 ]. Thus, this type of individual represents an ideal niche for the expansion of viral diversity and the acquisition of viral fitness [ 35 ], characterized by an increased mutational profile [ 36 ] that favours its further spread across the susceptible population, either cryptically [ 37 ] or with clinical manifestations [ 38 ]. An important limitation of this study is the low number of sequences from this genotype.…”

Towards Understanding and Identification of Human Viral Co-Infections

“…They are obligate intracellular parasites that rely on host cells for replication and survival and can cause a wide range of diseases [4,5]. In recent years, several major viral outbreaks, such as Ebola, Zika, COVID-19, and monkeypox, have posed significant threats to global public health [6][7][8][9], highlighting the importance of understanding virus-host interactions and developing effective prevention and control strategies.…”