Zika virus infection

Zika virus infection is not currently reported to be causing major outbreaks of disease anywhere worldwide; however, local transmission still occurs in some countries, with small outbreaks occurring in others.

Majority of patients are asymptomatic; however, about 20% of infections result in a mild, self-limited illness with fever, rash, arthralgia, and conjunctivitis.

Infection may be more serious in pregnant women. There is strong scientific consensus that Zika virus is a cause of microcephaly and other congenital abnormalities. The range of abnormalities seen and the likely causal link to the virus suggest a new congenital syndrome.

Guillain-Barre syndrome and other neurological disorders are strongly associated with, and suspected to be caused by, Zika virus but the link is unproven and studies are ongoing, including to elucidate a possible mechanism.

Treatment of symptomatic infection is supportive and there are no specific antiviral therapies at this time. Prevention of mosquito bites through individual and public health measures is important to prevent infections.

A mild, usually self-limited infection when symptomatic (about 20% of infections) caused by the Zika virus (also known as ZIKV). The virus belongs to the Flaviviridae family (genus Flavivirus) and is an arbovirus (a virus transmitted by arthropods). It is named after the Zika forest in Uganda where it was first discovered in 1947.[1]Kindhauser MK, Allen T, Frank V, et al. Zika: the origin and spread of a mosquito-borne virus. Bull World Health Organ. 2016 Sep 1;94(9):675-86C. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5034643 http://www.ncbi.nlm.nih.gov/pubmed/27708473?tool=bestpractice.com

It is transmitted to humans primarily by the Aedes species of mosquito which is also a vector for dengue, chikungunya, and West Nile viruses. Sexual transmission from person to person is also possible.

Congenital Zika syndrome is a recognised pattern of congenital anomalies in infants (i.e., microcephaly, intracranial calcifications or other brain anomalies, or eye anomalies, among others) associated with Zika virus infection during pregnancy.[2]Adebanjo T, Godfred-Cato S, Viens L, et al. Update: interim guidance for the diagnosis, evaluation, and management of infants with possible congenital Zika virus infection - United States, October 2017. MMWR Morb Mortal Wkly Rep. 2017 Oct 20;66(41):1089-99. https://www.cdc.gov/mmwr/volumes/66/wr/mm6641a1.htm?s_cid=mm6641a1_w http://www.ncbi.nlm.nih.gov/pubmed/29049277?tool=bestpractice.com [3]França GV, Schuler-Faccini L, Oliveira WK, et al. Congenital Zika virus syndrome in Brazil: a case series of the first 1501 livebirths with complete investigation. Lancet. 2016 Aug 27;388(10047):891-7. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(16)30902-3/fulltext http://www.ncbi.nlm.nih.gov/pubmed/27372398?tool=bestpractice.com [4]Melo AS, Aguiar RS, Amorim MM, et al. Congenital Zika virus infection: beyond neonatal microcephaly. JAMA Neurol. 2016 Dec 1;73(12):1407-16. http://jamanetwork.com/journals/jamaneurology/fullarticle/2557231 http://www.ncbi.nlm.nih.gov/pubmed/27695855?tool=bestpractice.com [5]Moore CA, Staples JE, Dobyns WB, et al. Characterizing the pattern of anomalies in congenital Zika syndrome for pediatric clinicians. JAMA Pediatr. 2017 Mar 1;171(3):288-95. https://jamanetwork.com/journals/jamapediatrics/fullarticle/2579543 http://www.ncbi.nlm.nih.gov/pubmed/27812690?tool=bestpractice.com [6]Lucey D, Cummins H, Sholts S. Congenital Zika syndrome in 2017. JAMA. 2017 Apr 4;317(13):1368-9. http://www.ncbi.nlm.nih.gov/pubmed/28384812?tool=bestpractice.com ​ According to the World Health Organization, there is strong scientific consensus that Zika virus is a cause of microcephaly and these other congenital abnormalities.[7]Costello A, Dua T, Duran P, et al. Defining the syndrome associated with congenital Zika virus infection. Bull World Health Organ. 2016 Jun 1;94(6):406-406A. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4890216 http://www.ncbi.nlm.nih.gov/pubmed/27274588?tool=bestpractice.com The Centers for Disease Control and Prevention has also concluded that there is a causal relationship between antenatal Zika virus infections and microcephaly/other brain abnormalities.[8]Rasmussen SA, Jamieson DJ, Honein MA, Petersen LR. Zika virus and birth defects - reviewing the evidence for causality. N Engl J Med. 2016 May 19;374(20):1981-7. http://www.nejm.org/doi/full/10.1056/NEJMsr1604338 http://www.ncbi.nlm.nih.gov/pubmed/27074377?tool=bestpractice.com  Evidence to support a causal relationship has expanded in recent years; however, the total number of cases investigated in the published cohort or case-control studies remains small.[9]Counotte MJ, Meili KW, Taghavi K, et al. Zika virus infection as a cause of congenital brain abnormalities and Guillain-Barré syndrome: a living systematic review. F1000Res. 2019 Aug 14;8:1433. https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC6852328 http://www.ncbi.nlm.nih.gov/pubmed/31754425?tool=bestpractice.com

Guillain-Barre syndrome and other neurological disorders are strongly associated with and suspected to be caused by Zika virus infection but the link is unproven and studies are ongoing, including to elucidate a possible mechanism.[10]Dos Santos T, Rodriguez A, Almiron M, et al. Zika virus and the Guillain-Barré syndrome - case series from seven countries. N Engl J Med. 2016 Oct 20;375(16):1598-601. http://www.nejm.org/doi/full/10.1056/NEJMc1609015?query=featured_zika http://www.ncbi.nlm.nih.gov/pubmed/27579558?tool=bestpractice.com [11]Parra B, Lizarazo J, Jiménez-Arango JA, et al. Guillain-Barré syndrome associated with Zika virus infection in Colombia. N Engl J Med. 2016 Oct 20;375(16):1513-23. http://www.nejm.org/doi/full/10.1056/NEJMoa1605564#t=article http://www.ncbi.nlm.nih.gov/pubmed/27705091?tool=bestpractice.com [12]Frontera JA, da Silva IR. Zika getting on your nerves? The association with the Guillain-Barré syndrome. N Engl J Med. 2016 Oct 20;375(16):1581-2. http://www.nejm.org/doi/full/10.1056/NEJMe1611840 http://www.ncbi.nlm.nih.gov/pubmed/27705077?tool=bestpractice.com [13]Leis AA, Stokic DS. Zika virus and Guillain-Barre syndrome: is there sufficient evidence for causality? Front Neurol. 2016 Sep 30;7:170. http://journal.frontiersin.org/article/10.3389/fneur.2016.00170/full http://www.ncbi.nlm.nih.gov/pubmed/27746763?tool=bestpractice.com ​ Evidence to support a causal relationship has expanded in recent years; however, the body of evidence is still smaller than that for congenital abnormalities.[9]Counotte MJ, Meili KW, Taghavi K, et al. Zika virus infection as a cause of congenital brain abnormalities and Guillain-Barré syndrome: a living systematic review. F1000Res. 2019 Aug 14;8:1433. https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC6852328 http://www.ncbi.nlm.nih.gov/pubmed/31754425?tool=bestpractice.com