Zika virus: Difference between revisions

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'''Zika virus''' ('''ZIKV''') is a member of the ''[[Flaviviridae]]'' virus family and the ''[[Flavivirus]]'' genus, transmitted by ''[[Aedes]]'' [[mosquito]]es. In humans, it causes a mild illness known as [[Zika fever]], Zika, or Zika disease, which since the 1950s has been known to occur within a narrow equatorial belt from Africa to Asia. In 2014, the virus spread eastward across the Pacific Ocean to [[French Polynesia]], then to [[Easter Island]] and in 2015 to South America, Central America, and the Caribbean and is now considered [[pandemic]].<ref>{{cite web|title=Zika Virus: A New Threat and a New Kind of Pandemic|url=http://phenomena.nationalgeographic.com/2016/01/13/zika-2/|website=Phenomena|accessdate=18 January 2016}}</ref> The illness is like a mild form of [[dengue fever]],<ref name="Infection">{{cite web | title=Zika virus infection | url=http://ecdc.europa.eu/en/healthtopics/zika_virus_infection/Pages/index.aspx | website=ecdc.europa.eu | accessdate=18 January 2016}}</ref> is treated by rest,<ref>{{cite web | title=Zika Virus: Symptoms, Diagnosis, & Treatment | url=http://www.cdc.gov/zika/symptoms | website=www.cdc.gov | accessdate=22 January 2016}}</ref> and cannot be prevented by drugs or vaccines.<ref>http://www.cdc.gov/zika/symptoms/index.html</ref> Zika disease is related to [[yellow fever]] and [[West Nile virus|West Nile disease]], which are caused by other arthropod-borne flaviviruses.<ref name="Infection"/> A link to [[microcephaly]] in newborns of infected mothers is now thought possible.<ref>{{cite web|title=Epidemiological update: Outbreaks of Zika virus and complications potentially linked to the Zika virus infection|url=http://ecdc.europa.eu/en/press/news/_layouts/forms/News_DispForm.aspx?ID=1342&List=8db7286c-fe2d-476c-9133-18ff4cb1b568&Source=http%3A%2F%2Fecdc%2Eeuropa%2Eeu%2Fen%2Fpress%2Fepidemiological_updates%2FPages%2Fepidemiological_updates%2Easpx|publisher=European Centre for Disease Prevention and Control|accessdate=18 January 2016}}</ref> In January 2016, the CDC issued travel guidance on affected countries, including the use of enhanced precautions and considering postponing travel, and guidelines for pregnant women.<ref>http://wwwnc.cdc.gov/travel/notices/alert/zika-virus-caribbean</ref><ref>{{cite web|title=Interim Guidelines for Pregnant Women During a Zika Virus Outbreak — United States, 2016 {{!}} MMWR|url=http://www.cdc.gov/mmwr/volumes/65/wr/mm6502e1.htm|website=www.cdc.gov|accessdate=22 January 2016}}</ref>
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'''Zika virus''' ('''ZIKV''') is a member of the ''[[Flaviviridae]]'' virus family and the ''[[Flavivirus]]'' genus, transmitted by ''[[Aedes]]'' [[mosquito]]es. In humans, it causes a mild illness known as [[Zika fever]], Zika, or Zika disease, which since the 1950s has been known to occur within a narrow equatorial belt from Africa to Asia. In 2014, the virus spread eastward across the Pacific Ocean to [[French Polynesia]], then to [[Easter Island]] and in 2015 to South America, Central America, and the Caribbean and is now considered [[pandemic]].<ref>{{cite web |last=McKenna |first=Maryn |title=Zika Virus: A New Threat and a New Kind of Pandemic |work=Germination |url=http://phenomena.nationalgeographic.com/2016/01/13/zika-2/ |website=Phenomena |date=13 January 2016 |accessdate=18 January 2016}}</ref> The illness is like a mild form of [[dengue fever]],<ref name="Infection">{{cite web | title=Zika virus infection | url=http://ecdc.europa.eu/en/healthtopics/zika_virus_infection/Pages/index.aspx | website=ecdc.europa.eu | accessdate=18 January 2016}}</ref> is treated by rest,<ref name=CDC_Sympt>{{cite web |work=Zika Virus |title=Symptoms, Diagnosis, & Treatment |url=http://www.cdc.gov/zika/symptoms |publisher=DVBD, NCEZID, Centers for Disease Control and Prevention }}</ref> and cannot be prevented by drugs or vaccines.<ref name=CDC_Sympt/> Zika disease is related to [[yellow fever]] and [[West Nile virus|West Nile disease]], which are caused by other arthropod-borne flaviviruses.<ref name="Infection"/> A link to [[microcephaly]] in newborns of infected mothers is now thought possible.<ref>{{cite web|title=Epidemiological update: Outbreaks of Zika virus and complications potentially linked to the Zika virus infection|url=http://ecdc.europa.eu/en/press/news/_layouts/forms/News_DispForm.aspx?ID=1342&List=8db7286c-fe2d-476c-9133-18ff4cb1b568&Source=http%3A%2F%2Fecdc%2Eeuropa%2Eeu%2Fen%2Fpress%2Fepidemiological_updates%2FPages%2Fepidemiological_updates%2Easpx|publisher=European Centre for Disease Prevention and Control|accessdate=18 January 2016}}</ref> In January 2016, the CDC issued travel guidance on affected countries, including the use of enhanced precautions and considering postponing travel, and guidelines for pregnant women.<ref>{{cite web |title=Zika Virus in the Caribbean |date=15 January 2016 |work=Travelers' Health: Travel Notices |publisher=Centers for Disease Control and Prevention |url=http://wwwnc.cdc.gov/travel/notices/alert/zika-virus-caribbean}}</ref><ref>{{cite journal |first=Emily E. |last=Petersen |first2=J. Erin |last2=Staples |first3=Dana |last3=Meaney-Delman |first4=Marc |last4=Fischer |first5=Sascha R. |last5=Ellington |first6=William M. |last6=Callaghan |first7=Denise J. |last7=Jamieson |title=Interim Guidelines for Pregnant Women During a Zika Virus Outbreak — United States, 2016 |journal=MMWR Morb Mortal Wkly Rep |volume=65 |issue=2 |pages=30–33 |url=http://www.cdc.gov/mmwr/volumes/65/wr/mm6502e1.htm |doi=10.15585/mmwr.mm6502e1}}</ref>
   
 
==Virology==
 
==Virology==
   
Along with other viruses in this family, Zika virus is [[Viral envelope|enveloped]] and [[icosahedral]] with a nonsegmented, single-stranded, positive-sense [[RNA]] genome. It is most closely related to the [[Spondweni virus]] and is one of the two viruses in the Spondweni virus [[clade]].<ref name="Fields">Fields Virology, 5th Edition</ref><ref>{{cite journal|last1=Faye|first1=Oumar|last2=Freire|first2=Caio C. M.|last3=Iamarino|first3=Atila|last4=Faye|first4=Ousmane|last5=de Oliveira|first5=Juliana Velasco C.|last6=Diallo|first6=Mawlouth|last7=Zanotto|first7=Paolo M. A.|last8=Sall|first8=Amadou Alpha|last9=Bird|first9=Brian|title=Molecular Evolution of Zika Virus during Its Emergence in the 20th Century|journal=PLoS Neglected Tropical Diseases|date=9 January 2014|volume=8|issue=1|pages=e2636|doi=10.1371/journal.pntd.0002636}}</ref>
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Along with other viruses in this family, Zika virus is [[Viral envelope|enveloped]] and [[icosahedral]] with a nonsegmented, single-stranded, positive-sense [[RNA]] genome. It is most closely related to the [[Spondweni virus]] and is one of the two viruses in the Spondweni virus [[clade]].<ref name="Fields">{{cite book |first=David M. |last=Knipe |first2=Peter M. |last2=Howley |title=Fields' Virology |url=http://books.google.com/books?id=5O0somr0w18C |year=2007 |publisher=Lippincott Williams & Wilkins |isbn=978-0-7817-6060-7 |edition=5th |pages=1156, 1199}}</ref><ref>{{cite journal|last1=Faye|first1=Oumar|last2=Freire|first2=Caio C. M.|last3=Iamarino|first3=Atila|last4=Faye|first4=Ousmane|last5=de Oliveira|first5=Juliana Velasco C.|last6=Diallo|first6=Mawlouth|last7=Zanotto|first7=Paolo M. A.|last8=Sall|first8=Amadou Alpha|last9=Bird|first9=Brian|title=Molecular Evolution of Zika Virus during Its Emergence in the 20th Century|journal=PLoS Neglected Tropical Diseases|date=9 January 2014|volume=8|issue=1|pages=e2636|doi=10.1371/journal.pntd.0002636 |pmid=24421913 |pmc=3888466}}</ref>
   
The virus was first isolated in 1947 from a [[rhesus macaque]] in the [[Zika Forest]] of [[Uganda]] and in 1968 was isolated for the first time from humans in [[Nigeria]].<ref name="EID">{{Cite journal | last1 = Hayes | first1 = E. B. | title = Zika Virus Outside Africa | doi = 10.3201/eid1509.090442 | journal = Emerging Infectious Diseases | volume = 15 | issue = 9 | pages = 1347–1350 | year = 2009 | pmid = 19788800 | pmc =2819875 }}</ref> From 1951 through 1981, evidence of human infection was reported from other African countries such as Uganda, [[Tanzania]], [[Egypt]], the [[Central African Republic]], [[Sierra Leone]], and [[Gabon]], as well as in parts of Asia including [[India]], [[Malaysia]], the [[Philippines]], [[Thailand]], [[Vietnam]], and [[Indonesia]].<ref name="EID"/>
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The virus was first isolated in 1947 from a [[rhesus macaque]] in the [[Zika Forest]] of [[Uganda]] and in 1968 was isolated for the first time from humans in [[Nigeria]].<ref name="EID">{{Cite journal | last1 = Hayes | first1 = E. B. | title = Zika Virus Outside Africa | doi = 10.3201/eid1509.090442 | journal = Emerg Infect Dis | volume = 15 | issue = 9 | pages = 1347–50 | year = 2009 | pmid = 19788800 | pmc =2819875 }}</ref> From 1951 through 1981, evidence of human infection was reported from other African countries such as Uganda, [[Tanzania]], [[Egypt]], the [[Central African Republic]], [[Sierra Leone]], and [[Gabon]], as well as in parts of Asia including [[India]], [[Malaysia]], the [[Philippines]], [[Thailand]], [[Vietnam]], and [[Indonesia]].<ref name="EID"/>
   
The pathogenesis of the virus is hypothesized to start with an infection of [[dendritic cell]]s near the site of inoculation, followed by a spread to [[lymph node]]s and the bloodstream.<ref name="Fields"/> Flaviviruses generally replicate in the [[cytoplasm]], but Zika virus antigens have been found in infected cell nuclei.<ref>{{Cite journal | pmid=2841406 | year=1988 |
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The pathogenesis of the virus is hypothesized to start with an infection of [[dendritic cell]]s near the site of inoculation, followed by a spread to [[lymph node]]s and the bloodstream.<ref name="Fields"/> Flaviviruses generally replicate in the [[cytoplasm]], but Zika virus antigens have been found in infected cell nuclei.<ref>{{Cite journal | pmid=2841406 | year=1988 |last=Buckley | first=A | title=Detection of virus-specific antigen in the nuclei or nucleoli of cells infected with Zika or Langat virus | journal=Journal of General Virology | volume=69 issue=8 | pages=1913–20 | last2=Gould | first2=E. A. | doi=10.1099/0022-1317-69-8-1913}}</ref>
author1=Buckley | first1=A | title=Detection of virus-specific antigen in the nuclei or nucleoli of cells infected with Zika or Langat virus | journal=Journal of General Virology | volume=69 ( Pt 8) | issue=8 | pages=1913–20 | last2=Gould | first2=E. A. | doi=10.1099/0022-1317-69-8-1913}}</ref>
 
   
 
==Transmission==
 
==Transmission==
Zika virus is transmitted by daytime-active mosquitoes and has been isolated from a number of species in the genus ''[[Aedes]]'', such as ''[[Aedes aegypti|A. aegypti]]'', and [[arboreal]] mosquitoes such as ''[[Aedes africanus|A. africanus]]'', ''[[Aedes apicoargenteus|A. apicoargenteus]]'', ''[[Aedes furcifer|A. furcifer]]'', ''[[Aedes hensilli|A. hensilli]]'', ''[[Aedes luteocephalus|A. luteocephalus]]'', and ''[[Aedes vitattus|A. vitattus]]''. Studies show that the extrinsic incubation period in mosquitoes is about 10 days.<ref name="EID"/> The vertebrate hosts of the virus are primarily [[monkey]]s and humans. Before the current [[pandemic]], which began in 2007, Zika virus "rarely caused recognized 'spillover' infections in humans, even in highly [[enzootic]] areas".<ref name=nejm>Anthony S. Fauci, David M. Morens [http://www.nejm.org/doi/full/10.1056/NEJMp1600297?query=TOC Zika Virus in the Americas — Yet Another Arbovirus Threat] The New England Journal of Medicine, Vol. 374 No. 2, January 14, 2016, DOI: 10.1056/NEJMp1600297</ref>
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Zika virus is transmitted by daytime-active mosquitoes and has been isolated from a number of species in the genus ''[[Aedes]]'', such as ''[[Aedes aegypti|A. aegypti]]'', and [[arboreal]] mosquitoes such as ''[[Aedes africanus|A. africanus]]'', ''[[Aedes apicoargenteus|A. apicoargenteus]]'', ''[[Aedes furcifer|A. furcifer]]'', ''[[Aedes hensilli|A. hensilli]]'', ''[[Aedes luteocephalus|A. luteocephalus]]'', and ''[[Aedes vitattus|A. vitattus]]''. Studies show that the extrinsic incubation period in mosquitoes is about 10 days.<ref name="EID"/> The vertebrate hosts of the virus are primarily [[monkey]]s and humans. Before the current [[pandemic]], which began in 2007, Zika virus "rarely caused recognized 'spillover' infections in humans, even in highly [[enzootic]] areas".<ref name=nejm>{{cite journal |first=Anthony S. |last=Fauci |first2=David M. |last2=Morens |title=Zika Virus in the Americas — Yet Another Arbovirus Threat |journal=N Engl J Med |volume=374 |issue=2 |pages= |date=14 January 2016 |doi=10.1056/NEJMp1600297 |url=http://www.nejm.org/doi/full/10.1056/NEJMp1600297 |pmid=26761185}}</ref>
   
In 2009, Brian Foy, a biologist from the Arthropod-borne and Infectious Diseases Laboratory at [[Colorado State University]], [[Sexually transmitted infection|sexually transmitted]] the Zika virus to his wife. He visited [[Senegal]] to study mosquitoes and was bitten on a number of occasions. A few days after returning to the United States, he fell ill with Zika, but not before having had unprotected intercourse with his wife. She subsequently showed symptoms of Zika infection with extreme sensitivity to light. Foy is the first person known to have passed on an insect-borne virus to another human by sexual contact.<ref>{{Cite journal | last1=Foy | first1=B. D. | last2=Kobylinski | first2=K. C. | last3=Foy | first3=J. L. C. | last4=Blitvich | first4=B. J. | last5=Travassos Da Rosa | first5=A. | last6=Haddow | first6=A. D. | last7=Lanciotti | first7=R. S. | last8=Tesh | first8=R. B. | doi=10.3201/eid1705.101939 | title=Probable Non–Vector-borne Transmission of Zika Virus, Colorado, USA | journal=Emerging Infectious Diseases | volume=17 | issue=5 | pages=880–882 | year=2011 | pmid=21529401 | pmc=3321795 }}</ref><ref name="Science Magazine">{{cite news | title=Sex After a Field Trip Yields Scientific First | author=Enserink, M. | url=http://news.sciencemag.org/sciencenow/2011/04/sex-after-a-field-trip-yields-sc.html?ref=hp | newspaper=Science Magazine | date=April 6, 2011}}</ref>
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In 2009, Brian Foy, a biologist from the Arthropod-borne and Infectious Diseases Laboratory at [[Colorado State University]], [[Sexually transmitted infection|sexually transmitted]] the Zika virus to his wife. He visited [[Senegal]] to study mosquitoes and was bitten on a number of occasions. A few days after returning to the United States, he fell ill with Zika, but not before having had unprotected intercourse with his wife. She subsequently showed symptoms of Zika infection with extreme sensitivity to light. Foy is the first person known to have passed on an insect-borne virus to another human by sexual contact.<ref>{{Cite journal | last1=Foy | first1=B. D. | last2=Kobylinski | first2=K. C. | last3=Foy | first3=J. L. C. | last4=Blitvich | first4=B. J. | last5=Travassos Da Rosa | first5=A. | last6=Haddow | first6=A. D. | last7=Lanciotti | first7=R. S. | last8=Tesh | first8=R. B. | doi=10.3201/eid1705.101939 | title=Probable Non–Vector-borne Transmission of Zika Virus, Colorado, USA | journal=Emerg Infect Dis | volume=17 | issue=5 | pages=880–2 | year=2011 | pmid=21529401 | pmc=3321795 }}</ref><re>{{cite web | title=Sex After a Field Trip Yields Scientific First |last=Enserink |first=M. |url=http://www.sciencemag.org/news/2011/04/sex-after-field-trip-yields-scientific-first |work=Science News |publisher=AAAS | date=6 April 2011 }}</ref>
 
 
In 2015, Zika virus RNA was detected in the amniotic fluid of two fetuses, indicating that it crossed the placenta and could cause fetal infection.<ref>Gretchen Vogel. [http://news.sciencemag.org/health/2015/12/fast-spreading-virus-may-cause-severe-birth-defects Fast-spreading virus may cause severe birth defects] Science Magazine American Association for the Advancement of Science. 3 December 2015, retrieved 7 January 2016</ref> On 20 January 2016, scientists from the state of Paraná, Brazil, detected genetic material of Zika virus in the placenta of a woman, who had undergone an abortion due to the fetus' microcephaly, which confirmed that the virus is able to pass the placenta.<ref>{{cite web | title=Caso de aborto confirma que zika consegue atravessar a placenta | url=http://g1.globo.com/bemestar/noticia/2016/01/caso-de-aborto-confirma-que-zika-consegue-atravessar-placenta.html | publisher=Globo Comunicação e Participações S.A | date=20 January 2016}}</ref>
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In 2015, Zika virus RNA was detected in the amniotic fluid of two fetuses, indicating that it crossed the placenta and could cause fetal infection.<ref>{{cite web |first=Gretchen |last=Vogel |title=Fast-spreading virus may cause severe birth defects |date=3 December 2015 |work=Science News |publisher=AAAS |url=http://news.sciencemag.org/health/2015/12/fast-spreading-virus-may-cause-severe-birth-defects |doi=10.1126/science.aad7527}}</ref> On 20 January 2016, scientists from the state of Paraná, Brazil, detected genetic material of Zika virus in the placenta of a woman, who had undergone an abortion due to the fetus' microcephaly, which confirmed that the virus is able to pass the placenta.<ref>{{cite web | title=Caso de aborto confirma que zika consegue atravessar a placenta | url=http://g1.globo.com/bemestar/noticia/2016/01/caso-de-aborto-confirma-que-zika-consegue-atravessar-placenta.html |work=Bem Estar |language=Portuguese | publisher=globo.com | date=20 January 2016}}</ref>
   
 
==Clinical==
 
==Clinical==
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Common symptoms of infection with the virus include mild headaches, [[maculopapular rash]], fever, malaise, [[conjunctivitis|pink eye]], and [[arthralgia|joint pains]]. The first well-documented case of Zika virus was described in 1964, began with a mild headache, and progressed to a maculopapular rash, fever, and back pain. Within two days, the rash was fading, and within three days, the fever resolved and only the rash remained. Thus far, Zika fever has been a relatively mild disease with limited scope, with only one in five persons developing symptoms, with no fatalities, but its true potential as a viral agent of disease is unknown.<ref name="EID"/>
 
Common symptoms of infection with the virus include mild headaches, [[maculopapular rash]], fever, malaise, [[conjunctivitis|pink eye]], and [[arthralgia|joint pains]]. The first well-documented case of Zika virus was described in 1964, began with a mild headache, and progressed to a maculopapular rash, fever, and back pain. Within two days, the rash was fading, and within three days, the fever resolved and only the rash remained. Thus far, Zika fever has been a relatively mild disease with limited scope, with only one in five persons developing symptoms, with no fatalities, but its true potential as a viral agent of disease is unknown.<ref name="EID"/>
   
{{As of| 2016}}, no vaccine or preventive drug is available. Symptoms can be treated with [[acetaminophen]] or paracetamol, while [[aspirin]] and other [[nonsteroidal anti-inflammatory drug]]s should only be used when dengue has been ruled out to reduce the risk of bleeding.<ref>[http://www.cdc.gov/zika/hc-providers/clinicalevaluation.html Zika Virus For Health Care Providers: Clinical Evaluation & Disease] CDC, June 1, 2015, retrieved January 8, 2016</ref>
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{{As of| 2016}}, no vaccine or preventive drug is available. Symptoms can be treated with [[acetaminophen]] or paracetamol, while [[aspirin]] and other [[nonsteroidal anti-inflammatory drug]]s should only be used when dengue has been ruled out to reduce the risk of bleeding.<ref>{{cite web |title=For Health Care Providers: Clinical Evaluation & Disease |date=19 January 2016 |work=Zika Virus |publisher=DVBD, NCEZID, Centers for Disease Control and Prevention |url=http://www.cdc.gov/zika/hc-providers/clinicalevaluation.html}}</ref>
   
In a French Polynesian epidemic, 73 cases of [[Guillain–Barré syndrome]] and other neurologic conditions occurred in a population of 270,000, which may be complications of Zika virus.<ref name=nejm/> The European Centre for Disease Prevention and Control issued in December 2015 a comprehensive update on the possible association of Zika virus with congenital microcephaly and this syndrome.<ref name=rrr>{{cite web | title=Rapid risk assessment: Zika virus epidemic in the Americas: potential association with microcephaly and Guillain-Barré syndrome | url=http://ecdc.europa.eu/en/publications/Publications/zika-virus-americas-association-with-microcephaly-rapid-risk-assessment.pdf | publisher=European Centre for Disease Prevention and Control. | accessdate=9 January 2016 | location=Stockholm | pages=14 | format=pdf | date=10 December 2015}}</ref>
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In a French Polynesian epidemic, 73 cases of [[Guillain–Barré syndrome]] and other neurologic conditions occurred in a population of 270,000, which may be complications of Zika virus.<ref name=nejm/> The European Centre for Disease Prevention and Control issued in December 2015 a comprehensive update on the possible association of Zika virus with congenital microcephaly and this syndrome.<ref name=rrr>{{cite web | title=Rapid risk assessment: Zika virus epidemic in the Americas: potential association with microcephaly and Guillain-Barré syndrome | url=http://ecdc.europa.eu/en/publications/Publications/zika-virus-americas-association-with-microcephaly-rapid-risk-assessment.pdf | publisher=European Centre for Disease Prevention and Control. | accessdate=9 January 2016 | location=Stockholm | pages=14 | format=PDF | date=10 December 2015}}</ref>
   
 
===Microcephaly===
 
===Microcephaly===
 
Data suggest that newborns of mothers who had Zika virus infection during early pregnancy are at an increased risk for microcephaly. Since December 2015, it has been suspected (but not proven) that a transplacental infection of the fetus may lead to microcephaly and brain damage.<ref name=darlington>{{cite news | url=http://www.cnn.com/2015/12/23/health/brazil-zika-pregnancy-warning | author=Darlington S | title=Brazil warns against pregnancy due to spreading virus | publisher=CNN | date=December 23, 2015 | accessdate=December 23, 2015}}</ref>
 
Data suggest that newborns of mothers who had Zika virus infection during early pregnancy are at an increased risk for microcephaly. Since December 2015, it has been suspected (but not proven) that a transplacental infection of the fetus may lead to microcephaly and brain damage.<ref name=darlington>{{cite news | url=http://www.cnn.com/2015/12/23/health/brazil-zika-pregnancy-warning | author=Darlington S | title=Brazil warns against pregnancy due to spreading virus | publisher=CNN | date=December 23, 2015 | accessdate=December 23, 2015}}</ref>
   
In November 2015, Zika virus was isolated in a newborn from the northeastern state of [[Ceará]], Brazil, with microcephaly and other congenital issues. In 2015, 2,782 cases of microcephaly occurred compared with 147 in 2014 and 167 in 2013.<ref>{{cite news | title=Alarm Spreads in Brazil Over a Virus and a Surge in Malformed Infants | url=http://www.nytimes.com/2015/12/31/world/americas/alarm-spreads-in-brazil-over-a-virus-and-a-surge-in-malformed-infants.html?smid=nytcore-ipad-share&smprod=nytcore-ipad&_r=0 | accessdate=31 December 2015 | publisher=New York Times | date=30 December 2015}}</ref><ref>Folha de S.Paulo: [http://www1.folha.uol.com.br/cotidiano/2015/11/1710303-em-uma-semana-casos-de-microcefalia-crescem-85-no-pais.shtm In just one week, microcephaly cases increase 85% in Brazil.] {{dead link|date=January 2016}}</ref> ''The Lancet'' reported in January 2016 that the Brazilian Ministry of Health had only "confirmed 134 cases of microcephaly believed to be associated with Zika virus infection — a further 2,165 cases in 549 counties in 20 states are under investigation".<ref name=lancet>{{cite journal | author1=Marcia Triunfol | title=A new mosquito-borne threat to pregnant women in Brazil | journal=The Lancet | date=9–15 January 2016 | volume=387 | issue=10014 | pages=96 | doi=10.1016/S1473-3099(15)00548-4 | accessdate=9 January 2016}}</ref>
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In November 2015, Zika virus was isolated in a newborn from the northeastern state of [[Ceará]], Brazil, with microcephaly and other congenital issues. In 2015, 2,782 cases of microcephaly occurred compared with 147 in 2014 and 167 in 2013.<ref>{{cite news | title=Alarm Spreads in Brazil Over a Virus and a Surge in Malformed Infants | url=http://www.nytimes.com/2015/12/31/world/americas/alarm-spreads-in-brazil-over-a-virus-and-a-surge-in-malformed-infants.html?smid=nytcore-ipad-share&smprod=nytcore-ipad&_r=0 | accessdate=31 December 2015 | publisher=New York Times | date=30 December 2015}}</ref><ref>Folha de S.Paulo: [http://www1.folha.uol.com.br/cotidiano/2015/11/1710303-em-uma-semana-casos-de-microcefalia-crescem-85-no-pais.shtm In just one week, microcephaly cases increase 85% in Brazil.] {{dead link|date=January 2016}}</ref> ''The Lancet'' reported in January 2016 that the Brazilian Ministry of Health had only "confirmed 134 cases of microcephaly believed to be associated with Zika virus infection — a further 2,165 cases in 549 counties in 20 states are under investigation".<ref name=lancet>{{cite journal |first=Marcia |last=Triunfol | title=A new mosquito-borne threat to pregnant women in Brazil | journal=Lancet | date=9–15 January 2016 | volume=387 | issue=10014 | pages=96 | doi=10.1016/S1473-3099(15)00548-4 |pmid=26723756 |url=http://linkinghub.elsevier.com/retrieve/pii/S1473-3099(15)00548-4}}</ref>
   
In January 2016, a baby in [[Oahu]] was born with microcephaly, the first case in the United States of brain damage linked to the virus. The baby and mother tested positive for a past Zika virus infection. The mother, who likely had acquired the virus while traveling in Brazil in May 2015 during the early stages of her pregnancy, had reported her bout of Zika. She recovered before relocating to Hawaii. Although her pregnancy had progressed normally, the baby's condition was not known until birth.<ref>{{cite web | last1=Jr | first1=Donald G. Mcneil | title=Hawaii Baby With Brain Damage Is First U.S. Case Tied to Zika Virus | url=http://www.nytimes.com/2016/01/17/health/hawaii-reports-baby-born-with-brain-damage-linked-to-zika-virus.html?_r=0 | website=The New York Times | date=16 January 2016}}</ref>
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In January 2016, a baby in [[Oahu]] was born with microcephaly, the first case in the United States of brain damage linked to the virus. The baby and mother tested positive for a past Zika virus infection. The mother, who likely had acquired the virus while traveling in Brazil in May 2015 during the early stages of her pregnancy, had reported her bout of Zika. She recovered before relocating to Hawaii. Although her pregnancy had progressed normally, the baby's condition was not known until birth.<ref>{{cite news | last1=Jr | first1=Donald G. Mcneil | title=Hawaii Baby With Brain Damage Is First U.S. Case Tied to Zika Virus | url=http://www.nytimes.com/2016/01/17/health/hawaii-reports-baby-born-with-brain-damage-linked-to-zika-virus.html?_r=0 | newspaper=New York Times | date=16 January 2016}}</ref>
   
 
==History==
 
==History==
In 1947, scientists researching yellow fever placed a rhesus macaque in a cage in the Zika Forest (''zika'' meaning "overgrown" in the Luganda language), near the [[Uganda Virus Research Institute|East African Virus Research Institute]] in [[Entebbe]], Uganda. The monkey developed a fever, and researchers isolated from its serum a transmissible agent that was first described as Zika virus in 1952. It was subsequently isolated from a human in Nigeria in 1954. From its discovery until 2007, confirmed cases of Zika virus infection from Africa and Southeast Asia were rare.<ref name=eid14>{{cite journal | last=Various | date=June 2014 | title= Etymologia: Zika Virus | url= http://wwwnc.cdc.gov/eid/article/20/6/et-2006_article | journal= Emerg Infect Dis [Internet] | publisher=CDC | volume=20 | issue=6 | doi=10.3201/eid2006.ET2006 | accessdate=19 June 2014}}</ref>
+
In 1947, scientists researching yellow fever placed a rhesus macaque in a cage in the Zika Forest (''zika'' meaning "overgrown" in the Luganda language), near the [[Uganda Virus Research Institute|East African Virus Research Institute]] in [[Entebbe]], Uganda. The monkey developed a fever, and researchers isolated from its serum a transmissible agent that was first described as Zika virus in 1952. It was subsequently isolated from a human in Nigeria in 1954. From its discovery until 2007, confirmed cases of Zika virus infection from Africa and Southeast Asia were rare.<ref name=eid14>{{cite journal | last=Various | date=June 2014 | title= Etymologia: Zika Virus | url= http://wwwnc.cdc.gov/eid/article/20/6/et-2006_article | journal= Emerg Infect Dis | volume=20 | issue=6 | doi=10.3201/eid2006.ET2006 |page=1090 |pmid=24983096 |pmc=4036762}}</ref>
   
In April 2007, the first outbreak outside of Africa and Asia occurred on the island of [[Yap]] in the [[Federated States of Micronesia]], characterized by rash, conjunctivitis, and arthralgia, which was initially thought to be dengue, [[Chikungunya]], or [[Ross River virus|Ross River disease]].<ref>{{cite news | title=Little-Known Virus Challenges a Far-Flung Health System | author=Altman, L. K. | url=http://www.nytimes.com/2007/07/03/health/03virus.html?_r=0 | newspaper=The New York Times | date=July 3, 2007}}</ref> However, serum samples from patients in the acute phase of illness contained RNA of Zika virus. There were 49 confirmed cases, 59 unconfirmed cases, no hospitalizations, and no deaths.<ref>{{Cite journal | last1=Duffy | first1=M. R. | last2=Chen | first2=T. H. | last3=Hancock | first3=W. T. | last4=Powers | first4=A. M. | last5=Kool | first5=J. L. | last6=Lanciotti | first6=R. S. | last7=Pretrick | first7=M. | last8=Marfel | first8= M. | last9=Holzbauer | first9=S. | doi=10.1056/NEJMoa0805715 | last10=Dubray | first10=C. | last11=Guillaumot | first11=L. | last12=Griggs | first12=A. | last13=Bel | first13=M. | last14=Lambert | first14=A. J. | last15=Laven | first15=J. | last16=Kosoy | first16=O. | last17=Panella | first17=A. | last18=Biggerstaff | first18=B. J. | last19=Fischer | first19=M. | last20=Hayes | first20=E. B. | title=Zika Virus Outbreak on Yap Island, Federated States of Micronesia | journal=New England Journal of Medicine | volume=360 | issue=24 | pages=2536–2543 | year=2009 | pmid=19516034}}</ref>
+
In April 2007, the first outbreak outside of Africa and Asia occurred on the island of [[Yap]] in the [[Federated States of Micronesia]], characterized by rash, conjunctivitis, and arthralgia, which was initially thought to be dengue, [[Chikungunya]], or [[Ross River virus|Ross River disease]].<ref>{{cite news | title=Little-Known Virus Challenges a Far-Flung Health System | author=Altman, L. K. | url=http://www.nytimes.com/2007/07/03/health/03virus.html?_r=0 | newspaper=New York Times | date=July 3, 2007}}</ref> However, serum samples from patients in the acute phase of illness contained RNA of Zika virus. There were 49 confirmed cases, 59 unconfirmed cases, no hospitalizations, and no deaths.<ref>{{Cite journal | last1=Duffy | first1=M. R. | last2=Chen | first2=T. H. | last3=Hancock | first3=W. T. | last4=Powers | first4=A. M. | last5=Kool | first5=J. L. | last6=Lanciotti | first6=R. S. | last7=Pretrick | first7=M. | last8=Marfel | first8= M. | last9=Holzbauer | first9=S. | doi=10.1056/NEJMoa0805715 | last10=Dubray | first10=C. | last11=Guillaumot | first11=L. | last12=Griggs | first12=A. | last13=Bel | first13=M. | last14=Lambert | first14=A. J. | last15=Laven | first15=J. | last16=Kosoy | first16=O. | last17=Panella | first17=A. | last18=Biggerstaff | first18=B. J. | last19=Fischer | first19=M. | last20=Hayes | first20=E. B. | title=Zika Virus Outbreak on Yap Island, Federated States of Micronesia | journal=New England Journal of Medicine | volume=360 | issue=24 | pages=2536–43 | year=2009 | pmid=19516034}}</ref>
   
 
More recently, epidemics have occurred in Polynesia, Easter Island, the [[Cook Islands]], and [[New Caledonia]].<ref name=eid14/>
 
More recently, epidemics have occurred in Polynesia, Easter Island, the [[Cook Islands]], and [[New Caledonia]].<ref name=eid14/>
   
Since April 2015, a large, ongoing outbreak of Zika virus has occurred in Brazil. In the district of [[Camaçari]] and the neighbor city [[Salvador, Bahia|Salvador]], capital of the state of [[Bahia]], a previously unknown disease affecting around 500 patients with flu-like symptoms followed by rash and arthralgia was proven to be Zika fever by researchers from the [[Federal University of Bahia]] using [[RT-PCR]] technique.<ref>http://g1.globo.com/bahia/noticia/2015/04/identificado-virus-causador-de-doenca-misteriosa-em-salvador-e-rms.html</ref> Local authorities suspected the outbreak was due to an increased influx of foreign visitors attending the [[2014 FIFA World Cup]], coupled with the large population of ''Aedes aegypti'' and ''A. albopictus'' mosquitoes in the region. The spread followed a similar pattern to an outbreak of Chikungunya virus in the same region, another disease previously unknown to the local population. French Polynesian researchers argued that none of the Pacific countries with circulating Zika participated in the soccer games and have suggested that the outbreak is more likely linked to the [http://www.worldsprints.com/2014-brazil.html Va'a World Sprint Championship canoe race] in August 2014. Besides Zika, a high incidence of the autoimmune disease Guillain–Barré syndrome was noted in French Polynesia and later in Brazil.<ref name=lancet/>
+
Since April 2015, a large, ongoing outbreak of Zika virus has occurred in Brazil. In the district of [[Camaçari]] and the neighbor city [[Salvador, Bahia|Salvador]], capital of the state of [[Bahia]], a previously unknown disease affecting around 500 patients with flu-like symptoms followed by rash and arthralgia was proven to be Zika fever by researchers from the [[Federal University of Bahia]] using [[RT-PCR]] technique.<ref>{{cite web |title=Identificado vírus causador de doença misteriosa em Salvador e RMS |date=29 April 2015 |language=Portuguese |work=Bahia |publisher=globo.com |url=http://g1.globo.com/bahia/noticia/2015/04/identificado-virus-causador-de-doenca-misteriosa-em-salvador-e-rms.html}}</ref> Local authorities suspected the outbreak was due to an increased influx of foreign visitors attending the [[2014 FIFA World Cup]], coupled with the large population of ''Aedes aegypti'' and ''A. albopictus'' mosquitoes in the region. The spread followed a similar pattern to an outbreak of Chikungunya virus in the same region, another disease previously unknown to the local population. French Polynesian researchers argued that none of the Pacific countries with circulating Zika participated in the soccer games and have suggested that the outbreak is more likely linked to the [http://www.worldsprints.com/2014-brazil.html Va'a World Sprint Championship canoe race] in August 2014. Besides Zika, a high incidence of the autoimmune disease Guillain–Barré syndrome was noted in French Polynesia and later in Brazil.<ref name=lancet/>
   
 
In December 2015, the [[Pan American Health Organization]]/[[World Health Organization]] noted that [[Transmission (medicine)|transmission]] of Zika virus infection had occurred within nine countries: Brazil, [[Chile]] (specifically Easter Island), [[Colombia]], [[El Salvador]], [[Guatemala]], [[Mexico]], [[Paraguay]], [[Suriname]], and [[Venezuela]].<ref name=PAHO2015>{{Cite web | author=Pan American Health Organization / World Health Organization | title=Epidemiological Alert. Neurological syndrome, congenital malformations, and Zika virus infection. Implications for public health in the Americas | date=1 December 2015 | url=http://www.paho.org/hq/index.php?option=com_docman&task=doc_view&Itemid=270&gid=32405&lang=en | access-date=2 December 2015}}</ref><ref name=CIDRAP2015>{{cite news | last=Schnirring | first=Lisa | date=1 December 2015 | title= PAHO issues Zika virus alert | url=http://www.cidrap.umn.edu/news-perspective/2015/12/paho-issues-zika-virus-alert | newspaper=CIDRAP (Center for Infectious Disease Research and Policy) News | location=Minneapolis, MN | access-date=2 December 2015}}</ref> The organizations made recommendations for [[Disease surveillance|surveillance]], case management, and prevention.<ref name=PAHO2015/><ref name=CIDRAP2015/>
 
In December 2015, the [[Pan American Health Organization]]/[[World Health Organization]] noted that [[Transmission (medicine)|transmission]] of Zika virus infection had occurred within nine countries: Brazil, [[Chile]] (specifically Easter Island), [[Colombia]], [[El Salvador]], [[Guatemala]], [[Mexico]], [[Paraguay]], [[Suriname]], and [[Venezuela]].<ref name=PAHO2015>{{Cite web | author=Pan American Health Organization / World Health Organization | title=Epidemiological Alert. Neurological syndrome, congenital malformations, and Zika virus infection. Implications for public health in the Americas | date=1 December 2015 | url=http://www.paho.org/hq/index.php?option=com_docman&task=doc_view&Itemid=270&gid=32405&lang=en | access-date=2 December 2015}}</ref><ref name=CIDRAP2015>{{cite news | last=Schnirring | first=Lisa | date=1 December 2015 | title= PAHO issues Zika virus alert | url=http://www.cidrap.umn.edu/news-perspective/2015/12/paho-issues-zika-virus-alert | newspaper=CIDRAP (Center for Infectious Disease Research and Policy) News | location=Minneapolis, MN | access-date=2 December 2015}}</ref> The organizations made recommendations for [[Disease surveillance|surveillance]], case management, and prevention.<ref name=PAHO2015/><ref name=CIDRAP2015/>
   
Also in December 2015, the first confirmed Zika virus case occurred in Puerto Rico. Besides cases in returning travelers, no other locally transmitted Zika cases have been reported from elsewhere in the United States, as of 31 December 2015.<ref>{{cite web | url=http://www.cdc.gov/zika/index.html | title=Zika virus | website=CDC | date=31 December 2015 | accessdate=7 January 2016}}</ref>
+
Also in December 2015, the first confirmed Zika virus case occurred in Puerto Rico. Besides cases in returning travelers, no other locally transmitted Zika cases have been reported from elsewhere in the United States, as of 31 December 2015.<ref>{{cite web | url=http://www.cdc.gov/zika/index.html | title=Zika virus | website=DVBD, NCEZID, Centers for Disease Control and Prevention | date=31 December 2015 | accessdate=7 January 2016}}</ref>
   
 
On 15 January 2016, the [[Centers for Disease Control and Prevention]] (CDC) issued a level 2 travel alert for people traveling to regions and certain countries where Zika virus transmission is ongoing: Brazil, Colombia, El Salvador, [[French Guiana]], Guatemala, [[Haiti]], Honduras, [[Martinique]], Mexico, Panama, Paraguay, Suriname, Venezuela, and Puerto Rico.<ref>{{cite web | url=http://www.cdc.gov/media/releases/2016/s0315-zika-virus-travel.html | title=Zika virus travel | website= CDC|date= January 15, 2016 | accessdate= January 18, 2016}}</ref><ref>{{cite web | url=http://www.paho.org/hq/images/stories/AD/HSD/IR/Viral_Diseases/Zika-Virus/2016-cha-autoch-human-cases-zika-virus-ew-2.jpg?ua=1 | title=Countries and territories with confirmed cases of Zika virus in the Americas | website=paho.org | date=January 10, 2016 | accessdate=January 18, 2016}}</ref> According to the CDC, Brazilian health authorities reported more than 3,500 microcephaly cases between October 2015 and January 2016. Some of the affected infants have had a severe type of microcephaly and some have died. The full spectrum of outcomes that might be associated with infection during pregnancy and the factors that might increase risk to the fetus are not yet fully understood. More studies are planned to learn more about the risks of Zika virus infection during pregnancy.<ref>{{cite web|title=Microcephaly in Brazil potentially linked to the Zika virus epidemic, ECDC assesses the risk|url=http://ecdc.europa.eu/en/press/news/_layouts/forms/News_DispForm.aspx?ID=1329&List=8db7286c-fe2d-476c-9133-18ff4cb1b568&Source=http%3A%2F%2Fecdc.europa.eu%2Fen%2FPages%2Fhome.aspx|website=European Centre for Disease Prevention and Control|accessdate=18 January 2016}}</ref>
 
On 15 January 2016, the [[Centers for Disease Control and Prevention]] (CDC) issued a level 2 travel alert for people traveling to regions and certain countries where Zika virus transmission is ongoing: Brazil, Colombia, El Salvador, [[French Guiana]], Guatemala, [[Haiti]], Honduras, [[Martinique]], Mexico, Panama, Paraguay, Suriname, Venezuela, and Puerto Rico.<ref>{{cite web | url=http://www.cdc.gov/media/releases/2016/s0315-zika-virus-travel.html | title=Zika virus travel | website= CDC|date= January 15, 2016 | accessdate= January 18, 2016}}</ref><ref>{{cite web | url=http://www.paho.org/hq/images/stories/AD/HSD/IR/Viral_Diseases/Zika-Virus/2016-cha-autoch-human-cases-zika-virus-ew-2.jpg?ua=1 | title=Countries and territories with confirmed cases of Zika virus in the Americas | website=paho.org | date=January 10, 2016 | accessdate=January 18, 2016}}</ref> According to the CDC, Brazilian health authorities reported more than 3,500 microcephaly cases between October 2015 and January 2016. Some of the affected infants have had a severe type of microcephaly and some have died. The full spectrum of outcomes that might be associated with infection during pregnancy and the factors that might increase risk to the fetus are not yet fully understood. More studies are planned to learn more about the risks of Zika virus infection during pregnancy.<ref>{{cite web|title=Microcephaly in Brazil potentially linked to the Zika virus epidemic, ECDC assesses the risk|url=http://ecdc.europa.eu/en/press/news/_layouts/forms/News_DispForm.aspx?ID=1329&List=8db7286c-fe2d-476c-9133-18ff4cb1b568&Source=http%3A%2F%2Fecdc.europa.eu%2Fen%2FPages%2Fhome.aspx|website=European Centre for Disease Prevention and Control|accessdate=18 January 2016}}</ref>
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== References ==
 
== References ==
 
''This article contains public domain text from the CDC as cited''
 
''This article contains public domain text from the CDC as cited''
{{Reflist|3}}
+
{{Reflist}}
   
 
==External links==
 
==External links==
  +
*{{cite web |title=Zika Virus |date=19 January 2016 |work=Division of Vector-Borne Diseases (DVBD), National Center for Emerging and Zoonotic Infectious Diseases (NCEZID) |publisher=Centers for Disease Control and Prevention |url=http://www.cdc.gov/zika/index.html }}
  +
*{{cite web |title=''Zika virus'' |work=NCBI Taxonomy Browser |url=http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=64320 |id=64320}}
 
* [http://www.vbrc.org/query.asp?web_taxonomy=Flaviviridae Flaviviridae Genomes] database search results from the [http://www.vbrc.org Viral Bioinformatics Resource Center]
 
* [http://www.vbrc.org/query.asp?web_taxonomy=Flaviviridae Flaviviridae Genomes] database search results from the [http://www.vbrc.org Viral Bioinformatics Resource Center]
 
* [http://www.expasy.org/viralzone/all_by_species/43.html '''Viralzone''': Flaviviridae]
 
* [http://www.expasy.org/viralzone/all_by_species/43.html '''Viralzone''': Flaviviridae]

Revision as of 11:54, 22 January 2016

Zika virus
Aedes aegypti CDC-Gathany.jpg
Aedes aegypti is a vector transmitting the Zika virus
Virus classification
Group:
Group IV ((+)ssRNA)
Family:
Genus:
Species:
Zika virus
Zika virus
SpecialtyInfectious disease

Zika virus (ZIKV) is a member of the Flaviviridae virus family and the Flavivirus genus, transmitted by Aedes mosquitoes. In humans, it causes a mild illness known as Zika fever, Zika, or Zika disease, which since the 1950s has been known to occur within a narrow equatorial belt from Africa to Asia. In 2014, the virus spread eastward across the Pacific Ocean to French Polynesia, then to Easter Island and in 2015 to South America, Central America, and the Caribbean and is now considered pandemic.[1] The illness is like a mild form of dengue fever,[2] is treated by rest,[3] and cannot be prevented by drugs or vaccines.[3] Zika disease is related to yellow fever and West Nile disease, which are caused by other arthropod-borne flaviviruses.[2] A link to microcephaly in newborns of infected mothers is now thought possible.[4] In January 2016, the CDC issued travel guidance on affected countries, including the use of enhanced precautions and considering postponing travel, and guidelines for pregnant women.[5][6]

Virology

Along with other viruses in this family, Zika virus is enveloped and icosahedral with a nonsegmented, single-stranded, positive-sense RNA genome. It is most closely related to the Spondweni virus and is one of the two viruses in the Spondweni virus clade.[7][8]

The virus was first isolated in 1947 from a rhesus macaque in the Zika Forest of Uganda and in 1968 was isolated for the first time from humans in Nigeria.[9] From 1951 through 1981, evidence of human infection was reported from other African countries such as Uganda, Tanzania, Egypt, the Central African Republic, Sierra Leone, and Gabon, as well as in parts of Asia including India, Malaysia, the Philippines, Thailand, Vietnam, and Indonesia.[9]

The pathogenesis of the virus is hypothesized to start with an infection of dendritic cells near the site of inoculation, followed by a spread to lymph nodes and the bloodstream.[7] Flaviviruses generally replicate in the cytoplasm, but Zika virus antigens have been found in infected cell nuclei.[10]

Transmission

Zika virus is transmitted by daytime-active mosquitoes and has been isolated from a number of species in the genus Aedes, such as A. aegypti, and arboreal mosquitoes such as A. africanus, A. apicoargenteus, A. furcifer, A. hensilli, A. luteocephalus, and A. vitattus. Studies show that the extrinsic incubation period in mosquitoes is about 10 days.[9] The vertebrate hosts of the virus are primarily monkeys and humans. Before the current pandemic, which began in 2007, Zika virus "rarely caused recognized 'spillover' infections in humans, even in highly enzootic areas".[11]

In 2009, Brian Foy, a biologist from the Arthropod-borne and Infectious Diseases Laboratory at Colorado State University, sexually transmitted the Zika virus to his wife. He visited Senegal to study mosquitoes and was bitten on a number of occasions. A few days after returning to the United States, he fell ill with Zika, but not before having had unprotected intercourse with his wife. She subsequently showed symptoms of Zika infection with extreme sensitivity to light. Foy is the first person known to have passed on an insect-borne virus to another human by sexual contact.[12]<re>Enserink, M. (6 April 2011). "Sex After a Field Trip Yields Scientific First". Science News. AAAS.</ref>

In 2015, Zika virus RNA was detected in the amniotic fluid of two fetuses, indicating that it crossed the placenta and could cause fetal infection.[13] On 20 January 2016, scientists from the state of Paraná, Brazil, detected genetic material of Zika virus in the placenta of a woman, who had undergone an abortion due to the fetus' microcephaly, which confirmed that the virus is able to pass the placenta.[14]

Clinical

Rash on an arm due to Zika virus

Common symptoms of infection with the virus include mild headaches, maculopapular rash, fever, malaise, pink eye, and joint pains. The first well-documented case of Zika virus was described in 1964, began with a mild headache, and progressed to a maculopapular rash, fever, and back pain. Within two days, the rash was fading, and within three days, the fever resolved and only the rash remained. Thus far, Zika fever has been a relatively mild disease with limited scope, with only one in five persons developing symptoms, with no fatalities, but its true potential as a viral agent of disease is unknown.[9]

As of 2016, no vaccine or preventive drug is available. Symptoms can be treated with acetaminophen or paracetamol, while aspirin and other nonsteroidal anti-inflammatory drugs should only be used when dengue has been ruled out to reduce the risk of bleeding.[15]

In a French Polynesian epidemic, 73 cases of Guillain–Barré syndrome and other neurologic conditions occurred in a population of 270,000, which may be complications of Zika virus.[11] The European Centre for Disease Prevention and Control issued in December 2015 a comprehensive update on the possible association of Zika virus with congenital microcephaly and this syndrome.[16]

Microcephaly

Data suggest that newborns of mothers who had Zika virus infection during early pregnancy are at an increased risk for microcephaly. Since December 2015, it has been suspected (but not proven) that a transplacental infection of the fetus may lead to microcephaly and brain damage.[17]

In November 2015, Zika virus was isolated in a newborn from the northeastern state of Ceará, Brazil, with microcephaly and other congenital issues. In 2015, 2,782 cases of microcephaly occurred compared with 147 in 2014 and 167 in 2013.[18][19] The Lancet reported in January 2016 that the Brazilian Ministry of Health had only "confirmed 134 cases of microcephaly believed to be associated with Zika virus infection — a further 2,165 cases in 549 counties in 20 states are under investigation".[20]

In January 2016, a baby in Oahu was born with microcephaly, the first case in the United States of brain damage linked to the virus. The baby and mother tested positive for a past Zika virus infection. The mother, who likely had acquired the virus while traveling in Brazil in May 2015 during the early stages of her pregnancy, had reported her bout of Zika. She recovered before relocating to Hawaii. Although her pregnancy had progressed normally, the baby's condition was not known until birth.[21]

History

In 1947, scientists researching yellow fever placed a rhesus macaque in a cage in the Zika Forest (zika meaning "overgrown" in the Luganda language), near the East African Virus Research Institute in Entebbe, Uganda. The monkey developed a fever, and researchers isolated from its serum a transmissible agent that was first described as Zika virus in 1952. It was subsequently isolated from a human in Nigeria in 1954. From its discovery until 2007, confirmed cases of Zika virus infection from Africa and Southeast Asia were rare.[22]

In April 2007, the first outbreak outside of Africa and Asia occurred on the island of Yap in the Federated States of Micronesia, characterized by rash, conjunctivitis, and arthralgia, which was initially thought to be dengue, Chikungunya, or Ross River disease.[23] However, serum samples from patients in the acute phase of illness contained RNA of Zika virus. There were 49 confirmed cases, 59 unconfirmed cases, no hospitalizations, and no deaths.[24]

More recently, epidemics have occurred in Polynesia, Easter Island, the Cook Islands, and New Caledonia.[22]

Since April 2015, a large, ongoing outbreak of Zika virus has occurred in Brazil. In the district of Camaçari and the neighbor city Salvador, capital of the state of Bahia, a previously unknown disease affecting around 500 patients with flu-like symptoms followed by rash and arthralgia was proven to be Zika fever by researchers from the Federal University of Bahia using RT-PCR technique.[25] Local authorities suspected the outbreak was due to an increased influx of foreign visitors attending the 2014 FIFA World Cup, coupled with the large population of Aedes aegypti and A. albopictus mosquitoes in the region. The spread followed a similar pattern to an outbreak of Chikungunya virus in the same region, another disease previously unknown to the local population. French Polynesian researchers argued that none of the Pacific countries with circulating Zika participated in the soccer games and have suggested that the outbreak is more likely linked to the Va'a World Sprint Championship canoe race in August 2014. Besides Zika, a high incidence of the autoimmune disease Guillain–Barré syndrome was noted in French Polynesia and later in Brazil.[20]

In December 2015, the Pan American Health Organization/World Health Organization noted that transmission of Zika virus infection had occurred within nine countries: Brazil, Chile (specifically Easter Island), Colombia, El Salvador, Guatemala, Mexico, Paraguay, Suriname, and Venezuela.[26][27] The organizations made recommendations for surveillance, case management, and prevention.[26][27]

Also in December 2015, the first confirmed Zika virus case occurred in Puerto Rico. Besides cases in returning travelers, no other locally transmitted Zika cases have been reported from elsewhere in the United States, as of 31 December 2015.[28]

On 15 January 2016, the Centers for Disease Control and Prevention (CDC) issued a level 2 travel alert for people traveling to regions and certain countries where Zika virus transmission is ongoing: Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname, Venezuela, and Puerto Rico.[29][30] According to the CDC, Brazilian health authorities reported more than 3,500 microcephaly cases between October 2015 and January 2016. Some of the affected infants have had a severe type of microcephaly and some have died. The full spectrum of outcomes that might be associated with infection during pregnancy and the factors that might increase risk to the fetus are not yet fully understood. More studies are planned to learn more about the risks of Zika virus infection during pregnancy.[31]

See also

References

This article contains public domain text from the CDC as cited

  1. ^ McKenna, Maryn (13 January 2016). "Zika Virus: A New Threat and a New Kind of Pandemic". Phenomena. Retrieved 18 January 2016. More than one of |work= and |website= specified (help)
  2. ^ a b "Zika virus infection". ecdc.europa.eu. Retrieved 18 January 2016.
  3. ^ a b "Symptoms, Diagnosis, & Treatment". Zika Virus. DVBD, NCEZID, Centers for Disease Control and Prevention.
  4. ^ "Epidemiological update: Outbreaks of Zika virus and complications potentially linked to the Zika virus infection". European Centre for Disease Prevention and Control. Retrieved 18 January 2016.
  5. ^ "Zika Virus in the Caribbean". Travelers' Health: Travel Notices. Centers for Disease Control and Prevention. 15 January 2016.
  6. ^ Petersen, Emily E.; Staples, J. Erin; Meaney-Delman, Dana; Fischer, Marc; Ellington, Sascha R.; Callaghan, William M.; Jamieson, Denise J. "Interim Guidelines for Pregnant Women During a Zika Virus Outbreak — United States, 2016". MMWR Morb Mortal Wkly Rep. 65 (2): 30–33. doi:10.15585/mmwr.mm6502e1.
  7. ^ a b Knipe, David M.; Howley, Peter M. (2007). Fields' Virology (5th ed.). Lippincott Williams & Wilkins. pp. 1156, 1199. ISBN 978-0-7817-6060-7.
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