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A group of researchers publishing in the Lancet Infectious Diseases journal have applied modelling methods to examine the potential areas for future Zika virus outbreaks, based on air travel patterns from virus-affected areas and locations of the mosquito vector. They reported which countries in Africa and the Asia-Pacific region are vulnerable to the virus.
All our previous output on this subject can be seen here. The SMC also produced a Factsheet on the Zika virus.
Dr Derek Gatherer, Lecturer in the Division of Biomedical and Life Sciences, Lancaster University, said:
“Bogoch and co-authors use air travel patterns from Zika-affected parts of Latin America to regions of the world that either have active dengue infections or suitable mosquito vectors. Dengue distribution is used on the fair assumption that anywhere that can sustain one flavivirus outbreak, could probably sustain another, especially where the same insects do the spreading. They also make no assumptions about pre-existing immunity in other parts of the world. This is a crucial factor, as the consequences of Zika transmission from the Americas to other parts of the tropical world is critically dependent on this factor. If Zika immunity is widespread, introduced Zika will fizzle out fast, on the other hand if it enters another unprotected population, we may see a repeat of what we have already seen in Brazil and other parts of Latin America.
“Leaving this aside, it is clear from the analysis where the greatest risks lie: Portuguese-speaking Angola has its dengue season from November to February and is the major direct entry point from Brazil to Africa. In Asia, there are rather more potential targets – the cities of India and south-east Asia and the Asian Pacific coast as far north as Shanghai. Bogoch et al have produced a helpful guide to where our surveillance should be concentrated.
“Although their paper is on Zika and South America, one cannot help wondering if they are preparing something similar on yellow fever and its potential to spread from Africa to Asia. This would also be crucial given the current yellow fever situation in Angola and Congo.”
Prof. Jonathan Ball, Professor of Molecular Virology, University of Nottingham, said:
“The main message is that travel, and indeed trade, are the human activities that will help spread Zika virus around the world. While this study reminds us that many parts of the world have ideal conditions for the virus to take hold it can’t pinpoint exactly where this will happen.
“Key factors that will determine if a Zika outbreak occurs in other parts of the world are whether or not the species of mosquito that are able to transmit virus are present, which is why African and Asian countries have been identified in this research, and also whether the native human populations are susceptible to the virus. This is a virus that has circulated for years in parts of Africa and Asia and so many of these people may already have been exposed and have protective immunity.
“We can only determine which countries are most likely to be affected in future by doing science on the ground – finding out the numbers of people that are susceptible to infection and also understanding which mosquitoes can and are transmitting the virus. Unfortunately Zika reminds us that there are severe health inequalities around the globe and only when we tackle these will be able to defend ourselves against future viral outbreaks.”
Prof. Trudie Lang, Director of the Global Health Network, University of Oxford, said:
“This is an important and timely paper from an experienced group. The have applied well-regarded modelling methods that have been used extensively in other diseases such as malaria and dengue to conclude these findings. The research community are working hard to try and implement studies and plan for potential clinical trials of Zika interventions and management strategies; whilst we are still learning more all the time about this disease and the implication on newly exposed communities. We, the research community, rely heavily on modelling data such as this to help inform and guide our work and where resources are needed. This work demonstrates the range of evidence and data that are essential to tackle and prevent the devastating impact of outbreaks such as Zika. This modelling work is a very important part of the jigsaw of evidence in helping the public health and research community develop strategies and plans to reduce the burden and impact of this disease.”
‘Potential for Zika virus introduction and transmission in resource-limited countries in Africa and the Asia-Pacific region: a modelling study’ by Isaac I Bogoch et al. published in the Lancet Infectious Diseases on Thursday 1 September 2016.
Declared interests
Prof. Jonathan Ball and Dr Derek Gatherer declare no conflicts of interest.
Prof. Trudie Lang: “Trudie is Professor of Global Health Research at the University of Oxford, is a member of the ISARIC (International Severe Acute Respiratory and Emerging Infection Consortium) network and director of the Global Health Network.”