| Zika virus | |
|---|---|
| |
| Estimated importations of Zika virus infections via travellers from Brazil to Europe in the year 2015. | |
Virus classification 
| |
| (unranked): | Virus |
| Realm: | Riboviria |
| Kingdom: | Orthornavirae |
| Phylum: | Kitrinoviricota |
| Class: | Flasuviricetes |
| Order: | Amarillovirales |
| Family: | Flaviviridae |
| Genus: | Flavivirus |
| Species: | Zika virus
|
The Zika Virus (ZIKV) is a mosquito-borne infectious disease which has been known to prevale within a narrow equatorial belt from Africa to Asia. In the Middle- and Southern-Americas, more specifically in the Caribbean and the southern part of Northern-America there was a major outbreak in 2015 and 2016, which has led the World Health Organisation (WHO) to declare ZIKV infection and its suspected link to birth defects a Public Health Emergency of International Concern (PHEIC). On November 18, 2016 this declaration was lifted[1]. Because of the fact that the virus is sexually transmittable, most cases in Europe are imported cases through travellers getting infected in foreign countries. However, mosquito populations of Aedes Albopictus are expanding in the Southern Europas and three cases of directly infected people have been reported in Hyères city, France. In 2019 the outbreak was as good as over and by now the risk of being infected with the Zika virus has declined significantly.[2]
Cause and transmission edit
The main causes of infection with the ZIKV are mosquito bites and sexual transmission. Other, less common paths of transmission are tranmission through infected blood products by for example blood transmission, transmission from mother to child, during laboratory work, breastfeeding, transplantation and through saliva[1].
Mosquitos edit
The Zika virus is being transmitted mainly through mosquito bites, and mainly from the Aedes aegypti and Aedes Albopictus species. Even though the former’s presence in European countries is limited or not established, its distribution is expanding. In the coming decades, circumstances like climate change could result in further northern and southern expansion of Aedes Aegypti and its establishment in several European countries[1]. Also, Aedes Albopictus has spread through the Mediterranean coast being established in countries like Greece, France and Spain. It is suggested that the Eastern Adriatic, Portugal and Turkey coast are the most likely places for establishment and future mosquito expansion, among others[3].
Sexual transmission edit
ZIKV transmission by sexual intercourse has first been suggested in 2008 and a high ZIKV RNA load and replicative ZIKV in semen samples was first detected in the ZIKV outbreak in French Polynesia in 2013[4]. Sexual transmission through semen occurs from subjects both symptomatic and asymptomatic.
Epidemiology Europe edit
In Europe, imported cases without the possibility of ongoing mosquito transmission have been reported in the countries of France, Spain and United Kingdom. 48 percent of these cases were reported in France. During the peak of the outbreak in 2016, the majority of the imported cases were reported in travellers returning from Guadeloupe (463), Martinique (413) and the Dominican Republic (153)[5].
Prevention edit
In order to repel endemic Aedes species areas in ZIKV affected countries, the World Health Organisation (WHO) has developed guidelines to ensure the description of geographical distributions of Aedes mosquito resistance to select appropriate insecticides for vector control [6]. Along with insecticides, there are additional measures in environmental management taken in order to suppress the mosquito populations in Europe. Environmental modification through reducing the habitats of the Aedes species has been proposed for urban and rural areas. Mainly, these modification measures to produce unfavorable conditions for the mosquitos include regulation of water level in reservoirs, vegetation removal and water salinity.
The Centres for Disease Control (CDC) provide specific guidelines to personally prevent mosquito bites [7], including advise for travellers to wear covering clothes as a physical barrier and use anti-mosquito spray which contains DEET.
Also, Centres for Disease Control (CDC) have proposed “Interim Guidelines for prevention of sexual transmission of ZIKV”, that has recently included updated recommendations for both men and women, applied time intervals to the condom use and abstinence recommendations. For Europeans, it recommends the use of condoms by men after travelling through ZIKV areas during at least six months after the travel (when not showing symptoms) and if they show symptoms, at least six months after the beginning of the travels. For women, the use of condoms is proposed for at least 8 weeks after the travel and 8 weeks after the beginning of the symptoms if it is the case[7].
Vaccines edit
The low genetic variation in ZIKV strains allows to develop a single safe and protective vaccine that is effective against all ZIKV strains. Although there have been tests with different vaccine formats showing that have protected mice or non-human primates against ZIKV infection[8], the development of a ZIKV vaccine for humans is likely to be achievable in next years[1].
Future challenges edit
Aedes albopictus is capable of hosting the Zika virus and is considered a potential vector for Zika transmission among humans. Three incidences of locally acquired Zika virus disease in France have been reported so far[9]. The European Centre for Disease Control and Prevention (ECDC), has proposed to consider communicating the risks of ZIKV to the general public.[5] For now, the completion of development of a ZIKV vaccine for humans and supressing the Aedes mosquito populations in Europe seem to be Europe's main concerns.
References edit
- ^ a b c d Diaz-Menendez, M. and Crespillo-Andujar, C. (2017). "Zika virus infection: risk of spreading in Europe" (PDF). Retrieved 20 October 2019.
{{cite web}}: CS1 maint: multiple names: authors list (link) CS1 maint: url-status (link) - ^ National institute for public health and the environment (RIVM). "Zikavirus". www.rivm.nl. Retrieved 2019-10-22.
- ^ Benedict, MQ (2007). "Spread of the tiger: global risk of invasion by the mosquito Aedes Albopictus". Vector Borne Zoonotic Dis. 7(1): 76–85.
- ^ Musso, D., Roche, C., Robin, E., Nhan, T., Teissier, A. and Cao-Lomeau, VM. (2015). "Potential sexual transmission of Zika virus". Emerging infectious diseases. 21(2): 359–361.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b "Zika virus transmission worldwide" (PDF). European Centre for Disease Prevention and Control. 9 April 2019. p. 5. Retrieved 21 October 2019.
{{cite web}}: CS1 maint: url-status (link) - ^ WHO (2016). "Monitoring and managing insecticide resistance in Aedes mosquito population. Interim guidance for entomologists" (PDF). Emergencies preparedness. Retrieved 21 October 2019.
- ^ a b Brooks, JT., Friedman, A., Kachur, RE., LaFlam, M., Peters, PJ. and Jamieson, DJ. (2016). "Update: interim guidance for prevention of sexual transmission of Zika virus-United States". Morbidity Mortality weekly rep. 65(29): 745–747.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Pierson, TC. and Graham, BS. (2016). "Zika virus: immunity and vaccine development". Cell. 167(3): 625–631.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ "Epidemiological update: third case of locally acquired Zika virus disease in Hyères, France". European Centre of Disease Prevention and Control. 31 October 2019. Retrieved 3 November 2019.