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The World Health Organization has urged European countries to prepare themselves for cases of Zika virus, as it warns that every country which Aedes mosquitoes are present are at risk.
All our previous output on this subject can be seen here.
Dr Clive McKimmie, British Society for Immunology spokesperson and Research Fellow at the University of Leeds, said:
“In South America and the Caribbean, the Zika virus is most likely being transmitted by the Aedes aegypti mosquito, which is widespread in tropical and sub-tropical climates. This mosquito species is not presently found in Europe, including the UK. However, a related mosquito species, called Aedes albopictus (also called the Asian Tiger Mosquito) has established itself successfully in much of Southern Europe and the USA. It is currently not known if the Aedes albopictus mosquito can transmit the Zika virus to people, although it is known to transmit other mosquito-borne viruses such as those that cause Chikungunya and Dengue. Indeed, the presence of this invasive mosquito species most likely enabled an outbreak of Chikungunya in northern Italy in 2007, when an infected person travelled from an endemic region to Italy.
“As the extent of international travel increases, so does the probability of a mosquito-borne virus spreading to new geographical locations that have mosquitoes capable of transmitting these viruses. It will be important to find out whether the European resident Aedes albopictus mosquito is capable of transmitting Zika virus, or whether the Zika virus can easily mutate to infect these mosquitoes as otherwise it is not possible for us to predict the likelihood of a Zika outbreak in southern Europe. Finally, it is worth noting that climate change is predicted to increase the geographic range in which these mosquitoes can thrive, suggesting that as our climate changes, the risk to human health posed by these viruses will increase.”
Dr Louise Sigfrid, Clinical Research Fellow, PREPARE, University of Oxford, said:
“For a majority of the population in Zika-affected countries there is no need for concern, the disease is asymptomatic in a majority of cases, only about in 1 of 4 infected develop mild symptoms (mild fever, skin rash, sometimes red eyes, muscle or joint pain) without need for medical care. Until further research is available later in the spring to establish if Zika virus infection in pregnancy can lead to microcephaly (smaller than normal head size), and other birth anomalies, pregnant women in currently affected areas are urged to take pre-cautions against mosquitos. If the link is confirmed, there is also need for rapid research into the risk of birth anomalies if infected in different stages of pregnancy. There are also studies being set up to review risk of post-viral Guillain-Barre’ syndrome, which has been reported in some cases and if any populations, e.g. people with underlying medical conditions are at higher risk of Zika virus complications or more severe disease.
“The risk of an outbreak in Southern Europe is considered low, but travel imported cases have already emerged. If cases or any outbreaks emerge in Southern Europe in the summer season, the health systems will be prepared to detect cases early and to take rapid action to control and to contain outbreaks. The EU funded European Platform for European Preparedness Against (Re-) emerging Epidemics (PREPARE) are currently collaborating with experts across Europe to strengthen preparedness to any emerging arbovirus infections (viruses spread by insects or parasites) in Europe, including Zika virus, by setting up collaborative networks of hospitals, primary care and laboratories across Europe, with a focus on Southeastern Europe. PREPARE have developed research tools for identification, diagnostics and rapid research responses, and are running training in the early identification, diagnostics, management and European outbreak response exercises for physicians and laboratory staff across Southeastern Europe, to strengthen European preparedness and rapid response to control Arbovirus infections including Zika virus.”
Prof. Michael Bonsall, Professor of Mathematical Biology, University of Oxford, said:
“Aedes aegypti is the mosquito implicated in the current epidemic in Brazil. Aedes albopictus is currently established in Italy, and is on the move northwards. We don’t know how efficient albopictus is at transmitting Zika. Aedes aegypti is much more efficient at spreading dengue than albopictus.
“It is very unlikely that these mosquitoes could live in the UK because they are a tropical and subtropical beast. There are around 30 other species of mosquitoes in the UK of which about 1/2 are in the Aedes genus (group) but are different species – and most of these don’t interact with humans. Species of Culex mosquito can be easily mis-identified as Aedes.
“Aedes mosquitoes are implicated in the spread of Zika. The ability of specific species to transmit Zika remains to fully determined so sensible precautions (using insect repellents, long clothing etc) to avoiding mosquito bites (the principal transmission route for Zika) should always be taken.”
Prof. Matthew Baylis, Chair of Veterinary Epidemiology; Head of the Liverpool University Climate and Infectious Diseases of Animals (LUCINDA) group; Head of the Department of Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, said:
“I think this statement by Dr Jakob is somewhat regrettable, as it is very unspecific about the mosquitoes that should concern us. Most and probably all European countries will have Aedes mosquitoes of one species or more – there are hundreds worldwide. The classification is complicated and for some mosquito species it is not even clear if they should be classed as Aedes or not.
“The mosquitoes that should concern us are the Yellow Fever mosquito (Aedes aegypti) and the Asian Tiger mosquito (Aedes albopictus). Both species are present in parts of Europe. Aedes aegypti is present in the island of Madeira (where it has transmitted dengue in the last few years) and the eastern side of the Black Sea. It was distributed more widely in southern Europe in the past, but is now limited to these places.
“Aedes albopictus is more widespread: it is found across a wide swathe of southern Europe, and some specimens have been found further north.
“In one laboratory study, Aedes albopictus appeared to be as good as Aedes aegypti at transmitting Zika; but it is still too early to be sure of this. It may turn out to be a vector, but not as good a vector. This is believed to be the case for dengue virus.
“In my view, the areas of greatest risk of Zika transmission in Europe will be those with Aedes aegypti present. There may be a risk in places with Aedes albopictus present, but it might be a lower risk. Further research is urgently needed on this particular aspect.
Dr Derek Gatherer, Lecturer in the Division of Biomedical and Life Sciences, Lancaster University, said:
“We know from studies carried out in Africa about a decade ago, that Aedes albopictus specifically can be a vector for Zika virus. We also know from earlier studies that Aedes of various other species are Zika vectors in Africa. The areas of Europe in which A. albopictus are found is most of Italy, southern France along the coast and up the Rhone valley, the Spanish Med coast and the eastern shore of the Adriatic. It is also found around Sochi in Russia. A. albopictus was the vector for the Italian chikungunya epidemic in 2007. Chikungunya did not establish itself in Italy, since richer countries do not have the urban habitat conditions that are required for such diseases to become endemic, such as stagnant water, communal wells, open sewers etc. For similar reasons, neither dengue nor chikungunya have established themselves in Gulf Coast regions of Texas or Florida, and probably Zika will not either.
“There is no Zika virus established in any part of Europe and so no reason to be concerned about any European continental holidays. The Foreign and Commonwealth Office website has an alphabetical list of countries and their current status, not just for Zika, but for many other diseases. Travelers should use this as their main source of travel advice. The WHO have not recommended any travel restrictions to or from South America. Pregnant women, and those contemplating starting a pregnancy either while on a trip or after returning, need to consider if their journey is really necessary, given the possible microcephaly risk. However, for healthy individuals who are not in that category, Zika is only a minor concern. The major tropical travel concern worldwide remains malaria, and for that reason any individuals returning from a tropical holiday with a fever, or who have had a fever while abroad, or who develop one after returning, must consult a doctor immediately. Because of the slight risk of sexual transmission of Zika, travellers should avoid unprotected sex with the local population while in Zika infected areas.”
Prof. Jimmy Whitworth, Professor of International Public Health at the London School of Hygiene & Tropical Medicine, said:
“While Aedes aegypti is not present in western Europe, a related mosquito, Aedes albopictus does occur in the southern parts of western Europe. This mosquito is a competent vector for zika virus, as well as for chikungunya and dengue.
“Aedes albopictus is already found in Spain and in southern France during the summer and seems to be steadily increasing its spread northwards. Outbreaks of chikungunya occurred in Spain and France (in the Carmargue) last summer. It is possible that zika virus could be introduced into European Aedes albopictus and cause similar outbreaks in the future.
“It is important that Spain and France establish effective anti-mosquito measures to control Aedes albopictus and so prevent outbreaks of zika, chikungunya and dengue. Although Aedes albopictus is currently not found in the UK, contingency plans should be established in case the mosquito extends its range further north in future years.”
Prof. Peter Horby, Professor of Emerging Infectious Diseases and Global Health, Centre of Tropical Medicine and Global Health, said:
“Aedes albopictus is certainly present in Southern Europe. Whilst A. albopictus has been implicated in Zika transmission in previous outbreaks, we don’t yet know how good this mosquito is at transmitting Zika virus. Understanding the ‘competence’ of A. albopictus to transmit the virus is therefore critical. Through the European Commission funded project ‘PREPARE’ we are leading a clinical study that will begin this summer and will tell us if Zika virus is causing illnesses in Southern Europe. This clinical study needs to be complemented by studies of vector biology.”
Declared interests
Dr Clive McKimmie: “No interests to declare.”
Prof. Michael Bonsall: “I was the Specialist Adviser to the inquiry on Genetically Modified Insects by the House of Lords Science and Technology Committee, and am a member of ACRE (Defra’s committee on releases into the environment). The Advisory Committee on Releases to the Environment is independent scientific committee that through EU derivatives and national UK legislation is mandated to provide the UK government/ministers with advice on the environmental risks (to wider receiving environments/human health) of non-native and GM releases. I have been a member of this committee since December 2007. I have carried out occasional consultancy work for WHO, NIH, and EFSA, including work on GM-based control methods for mosquitoes. I have received research funding from BBSRC (including working with Oxitec on GM insects), Oxford Martin School, NERC, the Royal Statistical Society, and the Royal Entomological Society. For full details off all my interests, please see: http://www.parliament.uk/documents/lords-committees/science-technology/GMInsects/michael-bonsall-specialist-adviser-interests.pdf.”
Prof. Matthew Baylis: “I receive grant funding from BBSRC and NIHR for studies of viruses spread by insects to people and animals.”
Dr Derek Gatherer: “No relevant conflicts of interest.”
Prof. Jimmy Whitworth: “No competing interests.”
Prof. Peter Horby: “No relevant interests to declare.”
No others received.