An Update on the Zika Virus

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Collaboration and information sharing leads to better diagnostics and helps limit the spread of the Zika Virus

The Zika virus (ZIKV) is not new—it was originally identified in Uganda’s Zika Forest region in 1947—but it was not until its pesky insect carriers took up “frequent flyer” status on this side of the ocean that the World Health Organization (WHO) declared ZIKV a “public health emergency of international concern” in February 2016.

According to FEMS Microbiology Letters, “Phylogenetic analysis has shown a close genetic similarity … with dengue virus… The virus is predominantly transmitted between humans through the bite of an infected mosquito, mostly of the species Aedes aegypti, but other modes of transmission have been identified, including trans-placental transmission between expectant mothers and their babies. Prolonged shedding of infectious virus in semen and in vaginal fluids and efficient viral replication in vaginal mucosa explain the ability of ZIKV to be transmitted sexually…”1

In the year since the WHO declaration, what has been learned to inform healthcare and safeguard public health? The virus is associated with brain-related birth defects, such as fetal microcephaly, hence it is particularly concerning to pregnant women. And there is now sufficient evidence to believe that ZIKV triggers Guillain-Barre Syndrome (GBS), according to a January 2017 literature review published in PLOS Medicine.2

So intense is the push for medical understanding, diagnostic improvements and vaccine development0 that ZIKV has dominated headlines, blog content and conference sessions for 12 months.

In an effort to pull the most salient findings into one resource, the College of American Pathologists (CAP) published a comprehensive review of the Zika virus in its January 2017 issue of Archives of Pathology & Laboratory Medicine. Comprised of 10 articles written by experts in the investigation of the emerging global pathogen, the series aims to provide pathologists and other healthcare professionals with critical insight to the history of Zika virus from its aforementioned 70-year-old discovery to its WHO designation as a public health emergency.

Further, the series represents the first special issue focused on Zika virus in a peer-reviewed medical journal. “This issue highlights up-to-date knowledge regarding the anatomic pathology and laboratory medicine aspects of this newly-emergent virus, so that everyone in the medical arena can know more about, and most importantly, protect patients from, the Zika virus,” David A. Schwartz, MD, MS Hyg, FCAP, who selected and edited the articles included in the series, crediting unprecedented cooperation and collaboration among physicians as well as biomedical, public health and social scientists during the Zika virus pandemic for the dissemination of information. “Their collective voices represent the collaboration that is the hallmark of the effective delivery of healthcare.”

Dx of Zika

One of the articles, Laboratory Diagnosis of Zika Virus Infection by Marie Louise Landry, MD, and Kirsten St. George, PhD, reviews the current status of methods for the laboratory diagnosis of Zika virus infection.3 The authors underscore the prioritization of rapid and accurate diagnosis of Zika virus infection, and review current recommendations, delving fully into various testing methods for Zika virus and their limitation.

They explained, “Until recently, the laboratory diagnosis of Zika infection was confined to public health or research laboratories that prepared their own reagents, and test capacity has been limited. Furthermore, Zika cross-reacts serologically with other flaviviruses, such as dengue, West Nile and yellow fever. Current or past infection, or even vaccination with another flavivirus, will often cause false positive or uninterpretable Zika serology results.”

Detection of viral RNA during acute infection using nucleic acid amplification tests provides more specific results, said the investigators, “… and a number of commercial nucleic acid amplification tests have received emergency use authorization. In addition to serum, testing of whole blood and urine is recommended because of the higher vial loads and longer duration of shedding. However, nucleic acid amplification testing has limited utility because many patients are asymptomatic or present for testing after the brief period of Zika shedding has passed.”

In conclusion the authors wrote, “The greatest need and most difficult challenge is development of accurate antibody tests for the diagnosis of recent Zika infection. Research is urgently needed to identify Zika virus epitopes that do not crossreact with other flavivirus antigens. New information is emerging at a rapid pace and, with ongoing public-private and international collaborations and government support, it is hoped that rapid progress will be made in developing robust and widely applicable diagnostic tools.”3

Still Making News

As we wend our collective way into 2017, Zika Virus discovery, discussion and debate continues on a daily basis. On Jan. 16, the New York Times reported on a “failed response” to Zika.

The conclusions drawn in the Times’ assessment of a year of Zika Virus activism are sobering: “The positives were counterbalanced by many negatives, experts said. They harshly criticized the partisan bickering that delayed a Zika-funding bill in Congress for months, and they decried the failure of every city in the hemisphere—other than Miami—to control mosquitoes … But the greatest failure, all agreed, was that while tourists were warned away from epidemic areas, tens of millions of women living in them—many of them poor slum dwellers—were left unprotected. As a result, a wave of brain-damaged babies is now being born. Their families are already suffering, and their medical care will eventually cost hundreds of millions of dollars. The failure to advise women to postpone pregnancy, if they could, until the epidemic passed ‘was the single greatest travesty of the epidemic,’ said Amir Attaran, a professor of law and medicine at the University of Ottawa. It was ‘hideously racist hypocrisy.’”4

In late January, Jamaica reported its first probable case of Zika-induced microcephaly in the Jamaica Observer.5 And according to the CDC, as of Jan. 25, there have been a total of 4,711 cases of Zika reported in the US, with 213 locally acquired cases in Florida and six locally acquired cases in Texas.6

The year holds ongoing questions and hopes for answers surrounding ZIKV. In her Oxford University Press blog, Luisa Barzon, MD, associate professor in the department of molecular medicine of the University of Padova, Italy, and an author of “Zika virus: from pathogenesis to disease control,” published in FEMS Microbiology Letters, pinpoints the most pressing questions at hand. Offering a map for forward-facing inquiry, Barzon wrote, “Several questions still remain open, such as how the virus infects and interacts with mosquito and human cells; which are the key genetic and molecular determinants of pathogenesis; how long the virus persists in human blood and tissues and its transmissibility; and how the innate and adaptive immune responses can counteract the virus and protect from reinfection. The responses to these questions are crucial, in this New Year and the future, to developing new antiviral medicines and improved protocols for ZIKV control.”1


References

  1. FEMS Microbiology Letters. Zika Virus: A New Year Update.
  2. PLoS Med. Zika Virus Infection as a Cause of Congenital Brain Abnormalities and Guillain–Barré Syndrome: Systematic Review. 2017;14(1): e1002203. doi:10.1371/journal.pmed.1002203 http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002203
  3. Arch Pathol Lab Med. Special Issue—The Zika Virus Global Pandemic: The Latest Emerging Infection. 2017;141:60-67; doi:10.5858/arpa.2016-0406-SA
  4. NY Times. How the Response to Zika Failed Millions.
  5. Jamaica Observer. Baby born with Zika-related microcephaly? 2017. 
  6. Centers for Disease Control. Zika Virus: Case Counts in the U.S. Updated Jan. 25, 2017. 

 

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Valerie Neff Newitt
Valerie Neff Newitt

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