MICROBIOLOGY

  • Zika virus (ZKV): Aedes spp. mosquito-borne arbovirus of the genus Flavivirus (related to yellow fever and Dengue viruses)
    • Single-stranded, positive sense RNA virus
    • In same clade (closest relationship) as Spondweni virus.
      • The next nearest "relatives" among the flaviviruses are St. Louis encephalitis virus, Ilheus virus and Rocio virus.
  • Phylogenetic analysis reveals two main lineages based on sequencing of non-structural protein gene (NS5):
    • African lineage [38] (predominantly zoönotic cycle between non-human primates and arboreal Aedes spp; also transmitted Aedes spp - human - Aedes spp cycle in urban areas):
      • Uganda
      • Central African Republic
      • Nigeria
      • Senegal
      • Believed to likely circulate throughout tropical sub-Saharan Africa in rural areas.
    • Asian: (zoonotic cycle between non-human primates and arboreal Aedes spp; also transmitted Aedes spp - human - Aedes spp cycle in urban areas)
      • Asia: single cases reported in returning travelers as well as endemic clusters of human cases without obvious sustained transmission.
      • The Americas: widespread epidemic activity in urban and rural areas since 2015; additional human case clusters.
        • United States: local acquisition in Florida (July 2016), Puerto Rico.
  • 12 nucleotide (3 amino acid) insertion in structural envelope gene noted in Asian lineage virus; unknown if this represents evolution and/or possible virulence factor. [48]
  • The virus demonstrates neurotropism both in vivo and in in vitro systems [16] [11]
  • Viral culture systems demonstrated as permissive for Zika virus growth in vitro, (using isolate from French Polynesia) [23]:
    • Immature dendritic cells
    • Human dermal fibroblasts: demonstrated enhanced viral replication
    • Epidermal fibroblasts
  • Zika virus infection activates an antiviral innate immune response with production of type 1 interferons in infected cells.
  • ZKV appears to be inactivated by:
    • KMNO4
    • Ether
    • Temperature >60oC
    • No effect from 10% ethanol.

CLINICAL

Modes of transmission:

  • Mosquito bite: Aedes spp mosquitoes, most commonly Ae. aegypti (Asia and the Americas) and Ae. africanus (sub-Saharan Africa)
    • Ae. aegypti: Usually bites from dawn to dust but may bite at any time, both indoors and outdoors.
    • Efficiency of Ae. albopictus as a transmission vector is currently unclear but appears to be less than Ae. aegypti
  • Vertical transmission: causal link between ZKV in mother and microcephaly or other adverse effects in the fetus or newborn has increasing evidence of linkage (see Clinical Spectrum).
    • There is no risk to the fetus if ZKV has cleared the mother’s body prior to conception.
    • Risk appears greatest if acquired during first trimester but abnormalities including CNS have been reported also in second > third trimesters.
  • Breast milk: no documented transmission but virus has been isolated from breast milk. [28]
  • Sexual transmission:
    • Male-to-female (M2F) vaginal-penile intercourse [29] [44].
    • M2F sexual transmission may occur for several months after onset of symptoms in the male. [29] [15]
    • Male-to-male (M2M) via insertive anal intercourse [21].
    • Female-to-male (F2M) is suspect based upon a single report of RT-PCR positive secretions in cervical mucus and on an endocervial swab collected from a symptomatic patient [17] and a single suspected case in New York City [20].
  • Blood transfusion: possible.
    • During an outbreak in French Polynesia in 2014, 2.8% of blood donors tested positive for Zika. [39]
    • See recommendations below re: blood donation deferral.
  • Endemic transmission locations
    • Sub-Saharan Africa: initial identification in the Zika Forest in Uganda in 1947 in primates; Uganda and other African location infections in humans.
    • Asia
    • Oceania
    • The Americas: North America (Mexico and Southern Florida); the Caribbean including Puerto Rico; Central America; South America

Clinical Spectrum:

  • Asymptomatic: most infections (75-80%)
  • Incubation period: 3-12 days after bite of an infected mosquito
  • Mild illness: accounts for > 95% symptomatic infections
    • Common symptoms (based upon outbreaks in Yap Island and French Polynesia):
      • Low-grade fever (65-73%)
      • Arthralgia (65-75%)
      • Non-purulent conjunctivitis (55-63%)
      • Diffuse, erythematous maculopapular skin rash, often pruritic, which usually begins on the trunk and spreads to the arms and legs, palms and soles are spared (90-95%)
      • Less common
        • Myalgia
        • Headache
        • Retro-orbital pain
        • Peripheral edema [44] [31]
    • Duration of symptoms: several days to 1 week
    • Hospitalization or death: rare
  • Severe illness or death: little data available, but potential risk factors may include:
    • Immunocompromised status: persons requiring chronic steroids (rheumatologic conditions, others); unknown if HIV is a risk factor for poor outcome
      • Only 1 confirmed Zika virus infection reported in an HIV-infected person (mild case, pt w/ suppressed viral load x 10 years, CD4 >700 cells/mm3 [18]).
    • Alcoholism
  • Neurological syndromes, temporally related to ZKV infection:
    • Fetal microcephaly and other neurological syndromes following maternal infection during pregnancy.
      • Unknown if risk exists only in the first trimester before the neural tube closes at about the sixth week of pregnancy.
      • Some data suggest that adverse outcomes other than microcephaly may occur even with infection as late as the 3rd trimester of pregnancy [19].
        • Therefore, all pregnant women with a confirmed infection during any trimester of pregnancy should be followed (see diagnosis section below).
      • Spontaneous abortion and full-term infants with microcephaly and other neurological deformities have been reported in areas where epidemic ZKV is circulating.
      • Guillain-Barré syndrome (GBS)
        • Autoimmune, acute, ascending polyradiculoneuropathy
          • Only reported to be associated with the Zika outbreaks since 2007
          • Bilateral, lower, symmetrical sensorimotal deficit with associated generalized areflexi
          • Antecedent clinical syndrome consistent with ZKV infection 7 to 15 days before onset of GBS
          • Case fatality from complications occurring during the acute phase: 3.5% to 12.0%; average 5% even with optimal care
          • Recovery may take weeks to months
        • Miller-Fisher variant of GBS
          • Clinical triad: ophthalmoplegia, areflexia, and ataxia
          • May be due to inflammation of nerves post-infection.
  • Diagnostic testing: ZKV nationally notifiable disease in U.S. as of 2016.
    • General Concepts
      • CDC and several state and local health departments are testing for Zika virus infection.
        • Instructions for submitting diagnostic specimens through a state health department to the Division of Vector Borne Diseases, Arbovirus Diagnostic Laboratory at CDC can be found at: www.cdc.gov/zika/hc-providers/diagnostic.html
      • There are NO FDA-approved diagnostic tools for the diagnosis of Zika virus infection. However, the FDA has issued an Emergency Use Authorization (EUA) for several diagnostic tools for diagnosis that have been or will be distributed to qualified laboratories. These include:
        • Trioplex Real-Time PCR (rRT-PCR): to detect Zika virus, dengue virus and chikungunya virus RNA
        • Zika IgM Antibody Capture Enzyme-Linked Immunosorbent Assay (Zika MAC-ELISA): for qualitative detection of IgM antibodies in serum or CSF (see below)
      • Testing of samples in the United States is limited to those collected from patients meeting CDC criteria. The CDC Testing Algorithm can be found at: http://www.cdc.gov…
    • Testing modalities
      • Culture: not available outside of research laboratories.
      • Molecular Tests = definitive diagnosis
        • Symptomatic persons: Zika RNA can sometimes be detected early in the course of illness. rRT-PCR should be performed on serum collected < 14d after symptom onset (urine may be positive longer).
          • Urine should ALWAYS be collected with a patient-matched serum sample.
          • A positive rRT-PCR on any sample confirms infection and NO additional test is needed. However, a negative rRT-PCR does NOT exclude Zika infection.
          • Serum should be analyzed for IgM (serological testing) as described below.
        • Asymptomatic PREGNANT women who have traveled to an area of known active Zika transmission: rRT-PCR testing of serum and urine
          • Within 2 weeks of the data of the last possible exposure
          • Present for care >/=2 weeks after exposure and are found to be IgM positive
        • Asymptomatic PREGNANT women who LIVE in an area of active Zika transmission: IgM testing recommended as routine obstetrical care in the first and second trimesters of pregnancy with reflex rRT-PCR of any who test positive.
        • Duration of rRT-PCR positivity in pregnant women: appears that women with affected fetuses may have prolonged detection of Zika virus in RNA in serum [1]
      • Serological Testing = presumptive diagnosis
        • General concepts: Zika virus-specific IgM and neutralizing antibodies develop by about the end of the first week of illness.
          • IgM levels are quite variable but generally may be detectable as early as the fourth day of illness and remain elevated for about 12 weeks.
          • If rRT-PCR is negative on serum and urine: IgM antibody testing for Zika, Dengue and chikungunya viruses should be done
          • If no previous testing done and illness commenced 14 or more days ago, then serum should be tested for Zika, dengue and chikungunya IgM
          • Cross reacting antibodies from other flaviviruses may cause false positives, including persons who have received yellow fever, Japanese encephalitis, and tick-borne encephalitis virus vaccines.
          • Past natural infections with Dengue, West Nile virus, St Louis encephalitis viruses and other less common flaviviruses may also cross react with the serological test
          • See Section: "Other Information" for CDC guidance on test result interpretation
        • Zika MAC-ELISA
          • It is a qualitative test for the detection of Zika IgM antibody in serum or CSF
          • It cross reacts with other flaviviruses making results difficult to interpret
          • Presumed positive, equivocal or inconclusive tests must be forwarded for confirmation by plaque-reduction neutralization testing (PRNT), which is only performed at CDC or at a CDC-designated laboratory. This testing is arranged in consultation with local or state health department.
          • See Section: "Other Information" for CDC guidance on test result interpretation
        • Plaque reduction neutralization test: this complex test provides more substantive evidence of infection, particularly to distinguish cross-reacting antibodies in initial serological testing. Discuss the use of this test with your state or local health department should you think it is indicated. See Section: "Other Information" for CDC guidance on test result interpretation
    • Amniotic Fluid Testing
      • May be tested alongside patient-matched serum and urine samples using molecular methods described above (definitive testing) and can be requested following onset of symptoms in a pregnant woman meeting testing criteria. Amniotic fluid testing of asymptomatic pregnant women if clinically indicated (see above)
    • Tissue Specimen Testing: Testing of fixed or frozen tissue for Zika, Dengue and chikungunya viruses is available at CDC. Request should be coordinated through the provider’s state or local health department. Collection and submission guidance can be found at: http://www.cdc.gov….

SITES OF INFECTION

  • Virus injected by mosquito into dermis.
    • Virus replication begins in dendritic cells near the inoculation site; then is carried to lymph nodes and onto the bloodstream.
  • Viremia occurs in symptomatic persons and is assumed to be lower-grade in asymptomatic infection.
    • Viral nucleic acid has been identified up to 11 days after illness onset.
    • Viral nucleic acid has been identified in asymptomatic pregnant women
  • Infection of neural tissue has been confirmed in spontaneously aborted fetuses born to mothers in the epidemic area of Brazil and in neonatal deaths as well as elective termination of pregnancy among women with affected fetuses. [16] [13]

TREATMENT

General

  • No Zika virus-specific antiviral treatments available.
  • Symptomatic measures for fever and pain.

Mild, uncomplicated infection

Supportive measures only:

  • Rest
  • Fluids to prevent volume depletion
  • Fever, arthralgia, myalgia
    • AVOID aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) until Dengue virus infection can be ruled out due to risk of hemorrhagic features associated with Dengue infection.
    • Acetaminophen or paracetamol every 4 to 6 hours as needed in persons without contraindication.

Guillian-Barre syndrome

Consider neurology and/or infectious disease consultation to assist in management

  • Care is optimal in the intensive care setting.
  • Acute phase: immunotherapy (less known if helpful with ZKV-related disease)
    • Plasma exchange: most benefits noted if initiated within 7 to 14 days of onset of symptoms.
    • Intravenous immunoglobulin: hastens recovery; provide within 2 weeks of symptom onset.
  • Complications associated with death in persons with GBS.
    • Sepsis
    • Unexplained cardiac arrest
    • Pulmonary embolus

Prevention

  • Pre-Travel:
    • CDC has issued a travel alert (Level 2-Practice Enhanced Precautions) for people traveling to regions and certain countries where Zika virus transmission is ongoing. This list of countries and U.S. areas is updated by CDC as needed.
      • Women:
        • In any trimester of pregnancy should consider postponing travel to areas where ZKV transmission is ongoing.
        • Trying to conceive: consider not traveling and discuss with their health care provider.
      • There is NO vaccine available to prevent ZKV infection although Phase I clinical trials are beginning
  • Travel-related measures:
    • Mosquito bite precautions is key (see: www.cdc.gov/chikungunya/pdfs/fs_mosquito_bite_prevention_travelers.pdf).
      • Aedes spp. mosquito can bite at any time of day, although it prefers darkness and shade, and can bite outdoors and indoors.
      • Mosquitoes can bite through clothing, therefore treatment of outerwear and exposed skin with repellents is important.
        • Breastfeeding and pregnant women should use only EPA-registered repellents and follow the product label.
        • Most insect repellents can be used on children.
        • Avoid combination sunscreen-repellent products as they are not optimally effective for either purpose.
          • Apply sunscreen first, allow to dry and then apply repellent to skin.
          • Effective repellents contain one of the following:
            • DEET
            • Picardin
            • IR3535
          • Treat outer clothing with either permethrin or purchase permethrin-impregnated clothing.
          • When possible wear light-colored, long-sleeved shirts, long pants, and socks.
      • Sleep in air conditioning or a fully screened location to exclude mosquitoes.
        • If this is not possible, sleep under a bed net.
      • To reduce mosquitoes near where the traveler will sleep or live, empty containers with standing water (breeding sites for mosquitoes).
  • Prevention of spread to others when infected:
    • For at least 11-14 days after illness onset the virus can be found in blood.
      • Avoid mosquito bites during this period.
    • Practice safer sex or abstinence until all symptoms have resolved and possibly for at least 6 months for men and at least 2 months for women [44] [8]
    • Men or women with a pregnant partner: Men or women who reside in or have traveled to an area of active Zika virus transmission who have a pregnant partner should abstain from sexual activity or consistently and correctly use condoms during sex (i.e., vaginal intercourse, anal intercourse, or fellatio) for the duration of the pregnancy.
    • Unintended transmission to the fetus: avoidance of unintended pregnancy among adolescent females and women residing or traveling to an area of active Zika transmission. [22]
    • Health care settings: blood and surfaces contaminated with blood. [54]
      • ZKV is NOT killed by 10% ethanol.
      • Effectively killed by: KMNO4; temperatures >60oC, and ether.
      • Standard precautions are recommended for use in health care settings including in labor and delivery settings [5]
    • Blood donor deferrals: the FDA recommendations continue to evolve as more information about the dynamics of transmission are known and as improved diagnostic testing becomes available. The most updated recommendations can be found at: http://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Guidances/Blood/default.htm

FOLLOW UP

  • Non-pregnant patient with uncomplicated ZKV infection: none
  • Pregnant women: per the interim guideline---all pregnant women with exposure to an area of active Zika transmission [10] [3]
    • A useful algorithm for providers can be found at: http://www.cdc.gov/zika/pdfs/testing_algorithm.pdf
  • Infant born to at-risk mother testing positive for Zika virus during pregnancy: should be followed by an Maternal-Fetal Medicine Specialist
  • Guillain-Bare Syndrome patients: as outlined under "Treatment"

OTHER INFORMATION

For latest information, please also check references below:

CDC GUIDANCES AND RECOMMENDATIONS

INTERIM GUIDANCE HEALTH CARE PROVIDERS RE: CARING FOR PREGNANT WOMEN WITH POSSIBLE ZIKA EXPOSURE
INTERIM GUIDANCE FOR PREVENTION OF SEXUAL TRANSMISSION OF ZIKA VIRUS
INTERIM GUIDANCE FOR INTERPRETATION OF ZIKA VIRUS ANTIBODY TEST RESULTS
CONTRACEPTIVE USE AMONG NON-PREGNANT AND POST-PARTUM WOMEN AT RISK FOR UNINTENDED PREGNANCY: ZIKA VIRUS PREPAREDNESS.
  • 41 states with potential range of Ae. aegypti or Ae, albopictus mosquitoes.
  • Unintended pregnancy rates are high, particularly among younger women in the child-bearing range (18-44 years)
  • CDC recommends contraception for the prevention of unintended pregnancy be optimized [22]. See http://www.cdc.gov…

Basis for recommendation

  1. Brooks JT et al: Update: Interim Guidance for Prevention of Sexual Transmission of Zika Virus - United States, July 2016. MMWR Morb Mortal Wkly Rep 65:745, 2016  [PMID:27466758]

    Comment: The interim guidance is distilled in the Box for couples in which one or both partners have traveled to or reside in an area with active Zika transmission. If the woman is pregnant. Barrier methods shoudl be used against infection for the duration of pregnancy. For couples who are not pregnant and are not planning pregnancy then recommendations are based on the presence of symptomatic vs asymptomatic infection and gender as well as residence vs non residence in the endemic area.

  2. Food and Drug Administration. Recommendations for Donor Screening, Deferral, and Product Management to
    Reduce the Risk of Transfusion Transmission of Zika Virus. Guidance for Industry. 16 Feb 2016. Available at: http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm486359.htm

    Comment: FDA Press Release RE this Guidance: As a safety measure against the emerging Zika virus outbreak, today the U.S. Food and Drug Administration issued a new guidance recommending the deferral of individuals from donating blood if they have been to areas with active Zika virus transmission, potentially have been exposed to the virus, or have had a confirmed Zika virus infection.
    “The FDA has critical responsibilities in outbreak situations and has been working rapidly to take important steps to respond to the emerging Zika virus outbreak,” said Luciana Borio, M.D., the FDA’s acting chief scientist. “We are issuing this guidance for immediate implementation in order to better protect the U.S. blood supply.”
    While there have been no reports to date of Zika virus entering the U.S. blood supply, the risk of blood transmission is considered likely based on the most current scientific evidence of how Zika virus and similar viruses (flaviviruses) are spread and recent reports of transfusion-associated infection outside of the U.S. Furthermore, about 4 out of 5 of those infected with Zika virus do not become symptomatic. For these reasons, the FDA is recommending that blood establishments defer blood donations from individuals in accordance with the new guidance.
    In areas without active Zika virus transmission, the FDA recommends that donors at risk for Zika virus infection be deferred for four weeks. Individuals considered to be at risk include: those who have had symptoms suggestive of Zika virus infection during the past four weeks, those who have had sexual contact with a person who has traveled to, or resided in, an area with active Zika virus transmission during the prior three months, and those who have traveled to areas with active transmission of Zika virus during the past four weeks.
    In areas with active Zika virus transmission, the FDA recommends that Whole Blood and blood components for transfusion be obtained from areas of the U.S. without active transmission. Blood establishments may continue collecting and preparing platelets and plasma if an FDA-approved, pathogen-reduction device is used. The guidance also recommends blood establishments update donor education materials with information about Zika virus signs and symptoms and ask potentially affected donors to refrain from giving blood.
    “Based on the best available evidence, we believe the new recommendations will help reduce the risk of collecting blood and blood components from donors who may be infected with the Zika virus,” said Peter Marks, M.D., Ph.D., director of the FDA’s Center for Biologics Evaluation and Research.
    Following the issuance of these recommendations, the FDA also intends to issue a guidance that will address appropriate donor deferral measures for human cells, tissues, and cellular and tissue-based products (HCT/Ps), given recent reports of sexual transmission of the virus.
    In addition to protecting the nation’s blood supply, the FDA is also prioritizing the development of blood screening and diagnostic tests that may be useful for identifying the presence of the virus, preparing to evaluate the safety and efficacy of investigational vaccines and therapeutics that might be developed, and reviewing technology that may help suppress populations of the mosquitoes that can spread the virus.
    The FDA, an agency within the U.S. Department of Health and Human Services, promotes and protects the public health by, among other things, assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices. The agency also is responsible for the safety and security of our nation’s food supply, cosmetics, dietary supplements, products that give off electronic radiation, and for regulating tobacco products.

  3. Hennessey M et al. Zika virus spreads to new areas---Region of the Americas, May 2015-January 2016. Morb Mortal Wkly Rprt. 2016; 65(3):55-58.

    Comment: This is a concise update of the distribution of ZIKV in the American region. By 20 Jan 2016, locally transmitted cases had been reported to the Pan American Health Organization from Puerto Rico and 19 other countries or territories in the Americas. NO local transmission has been documented in the continental US but multiple cases of ZIKV infection have been diagnosed in returning travelers from endemic areas. Therefore, in certain area of the US, especially those with Aedes aegypti mosquitos, local transmission could occur in the future. Ae. albopictus could also become a vector but its competency to become a major and sustaining virus vecctor are unknown. The report notes that although there has been a 20-fold increase in microcephalic births in Brazil since the outbreak began compared to the pre-epidemic period, it is not known how many of these case are associated with ZIKV. Specific recommendation: " until more is known, and out of an abundance of caution, pregnant women should consider postponing travel to any area where Zika virus transmission is ongoing"

  4. Meaney-Delman D et al: Prolonged Detection of Zika Virus RNA in Pregnant Women. Obstet Gynecol Jul 29  [PMID:27479770]

    Comment: Report of 5 pregnant women reported to the US Zika Pregnancy Registry with detectable Zika virus PCR products up to 46 days after symptom onset. This finding provides the rationale for the testing recommendation for women even 14 days or more after last exposure to an endemic area and who test positive by Zika IgM ELISA.

  5. Oduyebo T, Petersen EE, Rasmussen SA, et al. Update: Interim Guidelines for Health Care Providers Caring for Pregnant Women and Women of Reproductive Age with Possible Zika Virus Exposure — United States, 2016. MMWR Morb Mortal Wkly Rep 2016;65:122–127. DOI: http://dx.doi.org/10.15585/mmwr.mm6505e2.

    Comment: This updates the CDC recommendation issued < 2 weeks ago. Now all pregnant women who have traveled to the Zika affected areas should be tested for evidence of infection. The alogrithm is very helpful for providers. Working with a Maternal-Fetal Medicine specialist may assist in facilitating efficient and effective care for the patient.

  6. Oduyebo T et al: Update: Interim Guidance for Health Care Providers Caring for Pregnant Women with Possible Zika Virus Exposure - United States, July 2016. MMWR Morb Mortal Wkly Rep 65:739, 2016  [PMID:27467820]

    Comment: Some of this guidance has been updated (Other CDC recommendation by this author above) to include testing ALL pregnant women who have traveled to any area with active Zika transmission.

  7. Olson CK et al: Preventing Transmission of Zika Virus in Labor and Delivery Settings Through Implementation of Standard Precautions - United States, 2016. MMWR Morb Mortal Wkly Rep 65:290, 2016  [PMID:27010422]

    Comment: Emphasized the importance of standard precautions in health care settings to prevent inadvertent transmission from infected secretions to providers.

  8. Oster AM, Brooks JT, Stryker JE, et al. Interim Guidelines for Prevention of Sexual Transmission of Zika Virus — United States, 2016. MMWR Morb Mortal Wkly Rep 2016;65:120–121. DOI: http://dx.doi.org/10.15585/mmwr.mm6505e1

    Comment: The CDC’s interim recommendation re preventing sexual transmission of ZIKV

  9. Rabe IB et al: Interim Guidance for Interpretation of Zika Virus Antibody Test Results. MMWR Morb Mortal Wkly Rep 65:543, 2016  [PMID:27254248]

    Comment: Provides guidance for interpretation of antibody testing for suspected Zika virus infection when the test used initially was the IgM ELISA are done to detect Zika and Dengue viruses and then a Zika virus and Dengue virus PRNT are done to sort out the diagnosis. This is critically important for interpretation of the PRESUMPTIVE diagnostic IgM test results.

  10. Staples JE et al. Interim guidelines for the evalution and testing of infants with possible congenital Zika virus infection--United States, 2016. Morb Mortal Wkly Rprt. 2016; 65(3):63-67

    Comment: This document along with the companion CDC guidance related to evaluation and testing of pregnant women for Zika virus infection provide providers with a sucinct and clear guidance for use in evaluation and managment of patients.

References

  1. Balm MN et al: A diagnostic polymerase chain reaction assay for Zika virus. J Med Virol 84:1501, 2012  [PMID:22825831]

    Comment: Describes an RT-PCR method developed and utilized during the Yap Island epidemic. This is one of the tests used by CDC for definitive confirmation of infection

  2. Besnard M et al: Evidence of perinatal transmission of Zika virus, French Polynesia, December 2013 and February 2014. Euro Surveill 19:, 2014  [PMID:24721538]

    Comment: This describe perinatal transmission of Zika virus infection in mothers who were likely viremic at partruition. Although the newborns did develop mild illness, there appeared to be no other adverse effect. This finding is similar to reported perinatal transmission of dengue infection outcomes.
    Rating: Important

  3. Boulet SL et al: Contraceptive Use Among Nonpregnant and Postpartum Women at Risk for Unintended Pregnancy, and Female High School Students, in the Context of Zika Preparedness - United States, 2011-2013 and 2015. MMWR Morb Mortal Wkly Rep 65:780, 2016  [PMID:27490117]

    Comment: Important pro-active approach to prevention of mother-to-fetus Zika virus transmission through the prevention of unwanted pregnancy, which in the USA are now approximately 50% of all pregnancy. Effective contraceptive use is felt to be a key prevention strategy.
    Rating: Important

  4. Buathong R et al: Detection of Zika Virus Infection in Thailand, 2012-2014. Am J Trop Med Hyg 93:380, 2015  [PMID:26101272]

    Comment: Report of 7 laboratory-confirmed cases of Zika virus (ZIKV), 3 by sequential serological testing (IgM ELISA followed by plaque reduction neutralization test at CDC) and 4 by ZIKV RT-PCR develpm at the US Army Research Institute of Medical Sciences (AFRIMS) among Thai nationals from various locations in Thailand over from March 2012 to July 2014. The retrospective laboratory investigation of clinical illness cluster isamples (rash, conjuctivitis or arthralgias, and serum negative for dengue or chikunngunya and negative IgM for measles and rubella) was prompted by the identification of the virus in a Canadian tourist who had only visits Thailand. These 7 ZIKV infections were identified among 38 subjects (18.4%). Genomic sequencing of the non-structural 5 gene indicated the isolated virus RNA was of Asian ZIKV lineage. None to the case-patients were reported to be pregnant. None had serious illness.

  5. Calvet GA et al: First detection of autochthonous Zika virus transmission in a HIV-infected patient in Rio de Janeiro, Brazil. J Clin Virol 74:1, 2016  [PMID:26615388]

    Comment: Single report in the literature of ZIKV infection in an HIV infected person. However, the patient had a supressed viral load and a high CD4 count on antiretroviral therapy for many years. Await more data on this infection who are more immunocompromised.

  6. Cao-Lormeau VM et al: Zika virus, French polynesia, South pacific, 2013. Emerg Infect Dis 20:1085, 2014  [PMID:24856001]
  7. D'Ortenzio E et al: Evidence of Sexual Transmission of Zika Virus. N Engl J Med 374:2195, 2016  [PMID:27074370]

    Comment: This correspondence provides a case of sexual transmission from male travelers returned from an endemic area to sexual partners. Case 1 was a female sexual partner of a man who had traveled to Brazil and had engaged in both vaginal sexual intercourse (without ejaculation) and oral sex (with ejaculation). The male partner has been ill but symptoms had resolved 1 day prior to sexual contact.

  8. DICK GW, KITCHEN SF, HADDOW AJ: Zika virus. I. Isolations and serological specificity. Trans R Soc Trop Med Hyg 46:509, 1952  [PMID:12995440]

    Comment: This is one of 2 landmark papers that discuss the isolation of the virus in non-human primates and its identification in Uganda.
    Rating: Important

  9. DICK GW: Zika virus. II. Pathogenicity and physical properties. Trans R Soc Trop Med Hyg 46:521, 1952  [PMID:12995441]

    Comment: This is the 2nd of two landmark papers by this author re: Zika vius and provides important infomation not only on the pathogenesis but on the physical properties of the virus and its response to physical agents that may be of interest/importance to infection control practitioners
    Rating: Important

  10. Davidson A et al: Suspected Female-to-Male Sexual Transmission of Zika Virus - New York City, 2016. MMWR Morb Mortal Wkly Rep 65:716, 2016  [PMID:27442327]

    Comment: A non-pregnant female who had traveled to a Zika endemic area and who developed symptoms on the day after return to the USA along with a heavier than usual menses and had documented infection with postivie real-time reverse transcriptase PCR in both urine and semen on day 3 of illness. Seven days after a single episode of condomless sexual intercourse with her male partner who had not traveled to a zika endemic area, he developed symptoms of illness consistent with Zika infection and the infection was confirmed by rRT-PCR of urine but not serum.
    Rating: Important

  11. Deckard DT et al: Male-to-Male Sexual Transmission of Zika Virus - Texas, January 2016. MMWR Morb Mortal Wkly Rep 65:372, 2016  [PMID:27078057]

    Comment: A man who developed symptomatic Zika virus infection 2 days after returning from Venezuela had condomless insertive anal sex with a male partner the day before and the day after illness onset. The male partner beame symptomaic. Both had laboratory-confirmed Zika virus infection.
    Rating: Important

  12. Diallo D et al: Zika virus emergence in mosquitoes in southeastern Senegal, 2011. PLoS One 9:, 2014  [PMID:25310102]

    Comment: ZIKV was first isolated from Ae. luteocephalus collected in 1968 in the Saboya Forest in Senegal (western part of the country) and then was isolated in a human in 1969. The ZIKV IgM seroprevalance in the western regeon among humans in 1988 and 1990 was 10.1% and 2.8% respectively suggesting possible outbreak activity in 1988. Subsequently, virus has been isolated in mosquitos in the region but there has not been ongoing human serosurveillance.

  13. Driggers RW et al: Zika Virus Infection with Prolonged Maternal Viremia and Fetal Brain Abnormalities. N Engl J Med 374:2142, 2016  [PMID:27028667]

    Comment: Case report of an affected fetus following materinal infection in the 11th week of pregnancy. The electively aborted fetus had high viral load in aminotic fluid and virus particles identified in brain tissue with substantial brain abnormalities.
    Rating: Important

  14. Duffy MR et al: Zika virus outbreak on Yap Island, Federated States of Micronesia. N Engl J Med 360:2536, 2009  [PMID:19516034]

    Comment: This is the first documented widespread transmission of ZIKV outside of Africa and Asia with transmission by the Aedes hesilli species. Much of what we know of the clinical manifestations of the infection come for the few outbreaks that have been identified and investigated. During htis outbreak there were 49 laboratory-confirmed and 59 probable cases of ZIKV infection on this island in Micronesia. The outbreak affected and estimated 73% of the population 3 years of age and older. No microcephaly was reported associated with this outbreak although the numbers may have been too small to detect its occurence should this be a causal factor in this birh defect.
    Rating: Important

  15. Dupont-Rouzeyrol M et al: Infectious Zika viral particles in breastmilk. Lancet 387:, 2016  [PMID:26944028]

    Comment: This article provides evidence of cultivable virus in breast milk collected from an symptomatic mother. Transmission to the infant was not proven
    Rating: Important

  16. Dupont-Rouzeyrol M et al: Co-infection with Zika and dengue viruses in 2 patients, New Caledonia, 2014. Emerg Infect Dis 21:381, 2015  [PMID:25625687]

    Comment: Although submitted as a letter to the journal, it importantly reminds providers that Aedes spp carry dengue, chikungunya and Zika viruses. The viruses may co-circulate and therefore, co-infection can occur. Here co-infection with both ZIKV and DEN occurred and highlights the importance of considering co-infection when transmainases are elevated and leukopenia and thrombocytopenia are seen.

  17. Enfissi A, et al. Zika virus genome from the Americas. Lancet, 2016; 387: 227-228.

    Comment: This correspondence from Suriname provides genomic data collected from 4 of the first 5 patients diagnosed with locally-acquired ZIKV infection. Complete coding the the viral genome was obtained for 1 patient and the viral envelope sequence for 3 othters. A phylogenetic analysis was conducted for the non-structural-5 protein, the envelope protein and compared against existing databases for these virus sequences from other geographic locations. The Suriname strains belong to the Asian genotype and are most closely related to the French Polynesia outbreak strains from 2013 with >99.7% and 99.9% nucleotide and amino acid identity, respectively.
    Rating: Important

  18. Fagbami AH: Zika virus infections in Nigeria: virological and seroepidemiological investigations in Oyo State. J Hyg (Lond) 83:213, 1979  [PMID:489960]

    Comment: This article provides that reader with insight into the range of endemic infections in Sub-Saharan Africa as early as the 1960s and 1970s. Notably, ZIKV infecion in non-human primates is thought to decrease the severity of yellow fever virus infection in the primates although it does not prevent disease.

  19. Faye O et al: Molecular evolution of Zika virus during its emergence in the 20(th) century. PLoS Negl Trop Dis 8:, 2014  [PMID:24421913]

    Comment: The authors report their analysis of the envelope and NS5 genes of 47 Sub-Saharan African Zika virus genes collected from mosquitoes, humans and other mammals isolated in Burkina Faso, Central African Republic, Cote d’Ivoire, and Senegal in West Africa. over a period of time from the 1960s through 2001. These data and those from early Ugandan isolates were use to examine the lineage over time. A model of geographic spread of the virus was created to estimate introductory pathways and sites. Additionally, recombination events, uncommon in flavivirus were noted with recurrent loss and gain the N-linked glycosylation site in the envelope protein which was postulated to be related to mosquito cell infectivity. The authors postulate that the changes could be related to changes in the enzootic cycle of the virus. Similar analyses of isolates from Oceania and the Americas may help in understading the explosive epidemics and adverse outcomes of human infections noted, if a putative virulence factor can be found.
    Rating: Important

  20. Fokam EB et al: Silent circulation of arboviruses in Cameroon. East Afr Med J 87:262, 2010  [PMID:23057269]

    Comment: Although the title is misleading in that infections were not "silent" per se, the report does provide important informtion regarding the circulation of ZIKV in this West African country. This study reports the results of arbovirus serological testing of sera from 102 febrile patients without malaria or typhoid fever seen at clinics in Fako Division in southwest Cameroon after the identification of both dengue and chikungunya ciruculation in the country. Although 67% of sera reacted to more than one of the 18 arboviral antigens tested; 11.2% had a monotypic response to Zika virus without cross reaction with other flaviviruses tested.
    Rating: Important

  21. Fonseca K et al: First case of Zika virus infection in a returning Canadian traveler. Am J Trop Med Hyg 91:1035, 2014  [PMID:25294619]
  22. Foy BD et al: Probable non-vector-borne transmission of Zika virus, Colorado, USA. Emerg Infect Dis 17:880, 2011  [PMID:21529401]

    Comment: This is a case report supporting likely sexual transmission of Zika virus (ZIKV) from a man to his wife after he departed Senegal and returned to the US. His wife had not traveled with him. Sexual intercourse occurred before the onset of symptoms in the traveler. His wife develop symptoms including rash, within a week of sexual contact. Both the traveler and his wife were diagnosed with presumptive ZIKV infection based upon independent testing of paired sera at different laboratories. Notably, after the traveler’s fever and rash had resolved, he developed fatigue, arthralgia, symptoms of prostatitis and hematospermia. This highlights that need to advise patient regarding possible sexual transmission and to consider use of condoms or abstinence until all symptoms of illness have resolved.
    Rating: Important

  23. França GV et al: Congenital Zika virus syndrome in Brazil: a case series of the first 1501 livebirths with complete investigation. Lancet 388:891, 2016  [PMID:27372398]

    Comment: This is a retrospective review of congenital Zika virus infections in Brazil. These data suggest that maternal infection through the third trimester may have adverse outcomes, other than microcephaly. However, more data are needd to support this retrospective observations/investigations
    Rating: Important

  24. Garcez PP et al: Zika virus impairs growth in human neurospheres and brain organoids. Science 352:816, 2016  [PMID:27064148]

    Comment: This in vitro study compared the effects of Zika virus with dengue virus infection on human neural stem cells grown as organoids (Organoids are three-dimensional organ-bud grown in vitro that shows realistic micro-anatomy. Brain organoids are derived from stem cells that mimic the developing human brain’s cellular organization). The Zika virus human brain cells reduced their size and viability in vitro and caused programmed cell death
    compared with dengue virus infection.
    Rating: Important

  25. Gourinat AC et al: Detection of Zika virus in urine. Emerg Infect Dis 21:84, 2015  [PMID:25530324]

    Comment: This brief report provides evidence of ongoing detection of ZIKV amplicons in urine testing by RT-PCR >10 days after illness onset compared with detectable RT-PCR products in serum for < 5 days. As cultures were not obtained concomitantly, it is not know if replicating virus was present. However, this finding has potential implication for infection control practitioners and others designing prevention strategies.
    Rating: Important

  26. Grard G et al: Zika virus in Gabon (Central Africa)--2007: a new threat from Aedes albopictus? PLoS Negl Trop Dis 8:, 2014  [PMID:24516683]

    Comment: This is more of an ecological study than one that definitively proves that Ae. albopictus is an important vector for Zika virus infection. This vector which can competently transmit dengue viruses and some lineages of chikungunya virus was shown to competently replicate Zika virus. And, as this vector has become increasingly important as a arboviral disease vector in Gabon in Central Africa, it is likely to play some role there in virus transmission. However, this does not answer whether it would also be an important vector for the Asian lineage virus currently circulating in the Americas and the Caribbean. As its distribution includes temperate as well as tropical/semitropical areas in the Western Hemisphere, a distribution similar to West Nile Virus could occur should Ae. albopictus become the predominant competent vector.

  27. Haddow AD et al: Genetic characterization of Zika virus strains: geographic expansion of the Asian lineage. PLoS Negl Trop Dis 6:, 2012  [PMID:22389730]

    Comment: Prior to the publication of this paper in 2012, only 2 ZIKV strains had been genetically characterized in detail. This reported analysis added 5 new strains and thereby led to the identification of 2 distinct lineages: African and Asian. The latter also includes strains isolated from Yap in Oceania are in this lineage which supported epidemiological data that the Yap strain had oriniated in Asia, not surprising given the geographic proximity of Malaysia and Cambodia, the origin of 2 of the other collected strains. Importantly, several of the strains showed deletions in a potential glycosylation site of the envelope gene (a 4 codon/12 amino acid deletion). The question of the meaning of these difference remains given that prior phylogenetic analysis of envelope/NS5 sequences of several African lineage strains suggested that such changes may be related to virus activity in the vector. This highlights the need for additional combined epidemiological and phylogenetic research of newly identified epidemic strains in the Western Hemisphere
    Rating: Important

  28. Hamel R et al: Biology of Zika Virus Infection in Human Skin Cells. J Virol 89:8880, 2015  [PMID:26085147]

    Comment: This study highlights the importance of identifying cellular tropisms in ZIKV infection which may help to guide interventions for prevention and control. Using skin biopsy specimens collected from healthy volunteers, the authors infected cells with 10^6 plaque forming units of ZIKV-containing supernatants and then studied for growth and response. Human skin cells including dermal fibroblasts, epidermal keratinocytes and immature dendritic cells were found to be permissive for virus growth, localized in the dermis and epidermis. Fibroblasts appeared to form autophagosomes associated with enhanced viral replication, which is seen in some other arboviruses.

  29. Hayes EB: Zika virus outside Africa. Emerg Infect Dis 15:1347, 2009  [PMID:19788800]

    Comment: This is an outstanding review if Zika virus infections and outbreaks occurring after the virus was identified outside of Sub-Saharan Africa up through the time of the outbreak on Yap Island. In addition, it provides an excellent discussion of the virus epidemiology, known pathogenesis until that time, clinical findings and diagnosis.
    Rating: Important

  30. Ioos S et al: Current Zika virus epidemiology and recent epidemics. Med Mal Infect 44:302, 2014  [PMID:25001879]

    Comment: This is an excellent summary of both sporadic case reports, disease clusters and epidemics from the first reported human case in 1964 through the epidemic in the French Polynesia islands from 2013-2014. The article provides the general epidemiology and clinical features including a summary and graphic display of the 73 neurological complications (Guilain-Barre syndrome, immune throbocytopenic purpura, meningo-encephalitis seen during the epidemic in French Polynesia). GBS appeared to be the predominant neurological complication. Vectors thought to be associated with transmission in each geogrphic location is discussed, when known
    Rating: Important

  31. Jacobs BC et al: The spectrum of antecedent infections in Guillain-Barré syndrome: a case-control study. Neurology 51:1110, 1998  [PMID:9781538]

    Comment: This case-control study from 1998 highlights the importance of multivariate analyses when seeking associations. Here, several pathogens found, on univariate analysis, to be associated with GBS were no longer significant when more rigorous multivariate techniques were applied. Hence, Campylobacter, CMV, EBV and M. pneumoniae are statistically assocated with GBS in this sudy of 16 infectious agents and 154 age and sex matched controls. Studies looking more closely at the reported association of ZiKV with GBS are needed.

  32. Lanciotti RS et al: Genetic and serologic properties of Zika virus associated with an epidemic, Yap State, Micronesia, 2007. Emerg Infect Dis 14:1232, 2008  [PMID:18680646]

    Comment: This is the first very large outbreak of ZIKV reported with well characterized serological and phylogenetic data. Serological testing for evidence of immunity and/or cross-reactivity to ZIKV and 9 other flaviviruses is reported (dengue 1, 2, 3 and 4; Japanese encephalitis, yellow fever virus, West Nile virus, Murray Valley encephalitis virus and St Louis encephaltis virus). Importantly the paper demonstrates the the ease with which a primary flavirus infection which is ZIKV can be diagnosed serologically but the problem with cross reactivity when previous flavivirus immunity is present at the time of a ZIKV infection, even when the plaque reduction neutralization test (PRNT) is used after the IgM and IgG ELISA. A real-time RT PCR test was developed for use using newly derived sequence data from several ZIKV infected patients from the outbreak; 17 of 157 samples tests were postivie, 10 equivocal and 130 negative using this diagnostic modality. These 178 samples were then used to sequence the amino acid sequences adjacent to the envelope’s 154-glycosylation site and compare with other ZIKV strains in this area reported in GenBank. Notably, a 12 nucleotide (4 amino acid) insertion in the envelope gene gylcosylation site. Changes at this site have been noted in other strains and other flavivirus. It is unclear if this is a marker for evolutionary diversity, virulence or both.
    Rating: Important

  33. Meaney-Delman D et al: Zika Virus Infection Among U.S. Pregnant Travelers - August 2015-February 2016. MMWR Morb Mortal Wkly Rep 65:211, 2016  [PMID:26938703]

    Comment: This is a report of 4 case of Zika virus infection in pregnant women (Patients A-D). One of the 4 had an apparently normal infant delivered at 40 weeks gestation with exposure at 15 weeks; 1 spontaneous abortion occurred; 1 elective abortion with a highly affected fetus with absent corpus collosum and brain atropy. One patient, who had resided in Brazil until 12 weeks gestation delivered a child with chorioretinitis and hypertonia, difficulty swallowing and hyptonoia.
    Rating: Important

  34. Musso D et al: Potential for Zika virus transmission through blood transfusion demonstrated during an outbreak in French Polynesia, November 2013 to February 2014. Euro Surveill 19:, 2014  [PMID:24739982]

    Comment: Virus isolation from blood has been noted for up to at least 11 days after the onset of symptoms. Therefore, the potential for transfusion-associated ZiKV must be considered. However, our knowledge of the natural history of asymptomatic infection will need closer study to determine if viremia is present and for how long after exposure. This would have important implication for blood donation deferral policies in person who have traveled to endemic areas.

  35. Musso D et al: Potential sexual transmission of Zika virus. Emerg Infect Dis 21:359, 2015  [PMID:25625872]

    Comment: Isolation of virus or a positive RT PCR of seman could indicate the potential for sexual transmission. This may be more likely if hematospermia is present but this has not yet been determined. This has implications for advising patients re: safer sex or abstinence until completely recovered from illness.

  36. Musso D, Cao-Lormeau VM, Gubler DJ: Zika virus: following the path of dengue and chikungunya? Lancet 386:243, 2015  [PMID:26194519]

    Comment: This brief letter, appearing in response to the Pan American Health Organization’s alert issued on 7 May 2015 re: Zika virus transmission in northern Brazil provides informative maps which highlight the similarities in the spread of chikungunya viris and Zika virus outside of its usual Africa-Asia confined distribution before 2005.

  37. Oehler E et al: Zika virus infection complicated by Guillain-Barre syndrome--case report, French Polynesia, December 2013. Euro Surveill 19:, 2014  [PMID:24626205]

    Comment: This case report provides an excellent case summary and brief discussion of this neurological adverse outcome follwoing ZIKV infection. This case is notable for only antecedent arthralgia the day before the onset of initital neurological symptoms. This same outbreak in French Polynesia was ultimately associated with 74 adverse neurological outcomes, the majority of which were due to GBS.

  38. Olson JG et al: Zika virus, a cause of fever in Central Java, Indonesia. Trans R Soc Trop Med Hyg 75:389, 1981  [PMID:6275577]

    Comment: This report of a clinical investigation of in-patients at a hospital in Indonesia between 1977 and 1978 for presence of alphaviruses and flaviviruses. A total of 219 patients with paired sera demonstrated evidence of flavivirus infection and alphavirus infection. Testing was performed at the US Naval Medical Research Unit No 2 (NAMRU-2) in Jakarta. Seven patients demonstrated diagnostic rises to ZIKV only; 10 others had a 4-fold rise in antibody titer in pair sera but also showed diagnostic rises in dengue-2 virus or other flavivirus. This provides evidence of the likely evidence of ZIKV in Indonesia almost 40 years ago.

  39. Prisant N et al: Zika virus in the female genital tract. Lancet Infect Dis Jul 11  [PMID:27427201]

    Comment: Demonstration of rRT-PCR positive cervical mucus and a collected endocervical swab of a 27 year-old woman with symptomatic Zika virus infection.

  40. SIMPSON DI: ZIKA VIRUS INFECTION IN MAN. Trans R Soc Trop Med Hyg 58:335, 1964  [PMID:14175744]

    Comment: This is the first reported human case of Zika virus infection.
    Rating: Important

  41. Tappe D et al: First case of laboratory-confirmed Zika virus infection imported into Europe, November 2013. Euro Surveill 19:, 2014  [PMID:24507467]

    Comment: Despite the previous 2007 outbreak in Yap Island and the known ciruclation of ZIKV in Asia before this outbreak in Micronesia, the 1st case of infection in a returning traveler was not diagnosed until 2013. The German traveler, in his 50s, returned from a 3-week beach vacation in Thailand and reported onset of illness after less than 2 weeks into his vacation with arthralgia, peripheral edema, rash, fever, chills and malaise in the setting of reported mosquito bites. Athough dengue IgM was identified on indirect IFA, IgG was negative as was NS-1 testing. Because of the elevated Dengue IgM with negative IgG further investigations were undertaken for other flaviviruses. Zika-specific RT PCR was postive as was ZIKV IgM and IgG. Testing for Japanese encephalitis, yellow fever, West Nile, and chikungunya viruses were all negative.

  42. Tappe D et al: Acute Zika virus infection after travel to Malaysian Borneo, September 2014. Emerg Infect Dis 21:911, 2015  [PMID:25898277]

    Comment: Ths letter to the editor provides an interesting case report in which a case of classic acute clinical ZIKV infection is reported in a 45 year old German female traveler to Borneo with onset of illness 6 days after return form a 3-week vacation in Malaysia who then went on to develop hearing problems (dull metallic sound follwed by decreased in hearing) which lasted about 10 days before full resolution. This is the first report of hearing loss associated with ZIKV infection.

  43. Turmel JM et al: Late sexual transmission of Zika virus related to persistence in the semen. Lancet 387:, 2016  [PMID:27287833]

    Comment: Sexual transmission from male to female with symptom onset 44 days after onset of symptoms in her partners corresponding to sexual transmission between 34 and 41 days after the male index case. The exposure location was Martinique, located in the Caribbean. The male had had a febrile illness with maculopapular rash, arthralgia, and conjunctival injection but no hematospermia or dyusuria.
    Rating: Important

  44. Zammarchi L et al: Zika virus infection in a traveller returning to Europe from Brazil, March 2015. Euro Surveill 20:, 2015  [PMID:26084316]

    Comment: This is a single case report of a presumptive case (serologically confirmed) of Zika virus infection in a male traveler in his early 60s who traveled from Italy to Salvador de Bahia, Brazil for 12 days and presented with illness 4 days after his return. What is notable in this case was that in addition to the slightly pruritic erythematous rash, conjuctivitis and fever he was noted to have painful edema of the hands and feet. This is a feature that has been reported in severe dengue infections where it is beleived to represent capillary leak due to the effect of released cytokines on the tight junction of capillary epithelial cells. Laboratory testing in this patient revealed a negative NS-1 for dengue as well as low antibody levels on paired sera to dengue, chikungunya, Japanese encephalitis, West Nile virus, and yellow fever virus.
    Rating: Important

  45. Zika virus outbreaks in the Americas. Wkly Epidemiol Rec 90:609, 2015  [PMID:26552108]

    Comment: Brief, activity report as of November 2015, of ZIKV activity in the Americas from the first detection on Easter Island, Chile (located in the south-eastern Pacific Ocean) in February 2014. Thereafter, it was not until May 2015 that reports from the mainland in the Americas emerged with the first documented outbreak in northeast Brazil where 14 states were affected including Alagoas, Bahia, Ceara, Maranhao, Mato Grosso, Para, Paraiba, Parna, Pernambuco, Piaui, Rio de Janiero, Rio Grande do Norte, and Sao Paulo. In October 2015, Columbia reported its first endemic case. Subsequent to this report, the virus has been identified in >14 countries in Latin America and the Carribean.
    Rating: Important

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Last updated: October 25, 2016