Wednesday, July 12, 2017

EID Journal: Zika Virus Infection in Patient with No Known Risk Factors, Utah, USA, 2016


Almost exactly a year ago, during our first `summer of Zika', word emerged from Utah of a unique infection of a caregiver of a Zika patient - a family member - who had no known risk factors; no travel to Zika endemic areas, no sexual contact with an infected person, and living in an area without a known competant mosquito vector.
First, on July 18th, we saw a Utah Dept Health Statement On Investigation Of `Unique' Case Of Zika Transmission followed later in the day by a CDC Statement On Utah's Local ZIka Transmission where they disclosed that the deceased imported case had a viral load 100,000 times greater than ever seen before, but were at a loss to explain how the caregiver might have caught the virus.
The `index case', an elderly family member with serious comorbidities and recent travel history to a Zika endemic area, died of organ failure on June 25th, while the caregiver (who recovered) developed symptoms on July 1st. 
All of this occurred weeks before Miami reported their first locally acquired Zika case, and as you can imagine, having  the first locally acquired case in North American coming from Utah made quite a stir. 
In September, the CDC followed up with an MMWR: Investigation Into the `Unique' Utah Zika Case, that included a lot more about the circumstances surrounding this case, but exactly how this caregiver contracted the virus remained unclear. 
The CDC did warn : . . .  family contacts should be aware that blood and body fluids of severely ill patients might be infectious.
Fast forward to today and we have an extremely detailed EID Journal Synopsis of this incident, and while the exact mode of transmission remains a mystery, it concludes that person-to-person transmission was `likely'.

Follow the link to read the entire report, as I've only included a few excerpts. 

Volume 23, Number 8—August 2017

Zika Virus Infection in Patient with No Known Risk Factors, Utah, USA, 2016

Elisabeth R. Krow-Lucal, Shannon A. Novosad, Angela C. Dunn, Carolyn R. Brent, Harry M. Savage, Ary Faraji, Dallin Peterson, Andrew Dibbs, Brook Vietor, Kimberly Christensen, Janeen J. Laven, Marvin S. Godsey, Bryan Christensen, Brigette Beyer, Margaret M. Cortese, Nina C. Johnson, Amanda J. Panella, Brad J. Biggerstaff, Michael Rubin, Scott K. Fridkin, J. Erin StaplesComments to Author , and Allyn K. Nakashima

Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (E.R. Krow-Lucal, S.A. Novosad, C.R. Brent, B. Christensen, M.M. Cortese, N.C. Johnson, S.K. Fridkin); Centers for Disease Control and Prevention, Fort Collins, Colorado, USA (E.R. Krow-Lucal, H.M. Savage, J.J. Laven, M.S. Godsey, Jr., A.J. Panella, B.J. Biggerstaff, J.E. Staples); Utah Department of Health, Salt Lake City, Utah, USA (A.C. Dunn, D. Peterson. K. Christensen, A.K. Nakashima); Salt Lake County Health Department, Salt Lake City (C.R. Brent, A. Dibbs); Salt Lake City Mosquito Abatement District, Salt Lake City (A. Faraji); University of Utah, Salt Lake City (B. Vietor, B. Beyer, M. Rubin)

In 2016, Zika virus disease developed in a man (patient A) who had no known risk factors beyond caring for a relative who died of this disease (index patient). We investigated the source of infection for patient A by surveying other family contacts, healthcare personnel, and community members, and testing samples for Zika virus.
We identified 19 family contacts who had similar exposures to the index patient; 86 healthcare personnel had contact with the index patient, including 57 (66%) who had contact with body fluids. Of 218 community members interviewed, 28 (13%) reported signs/symptoms and 132 (61%) provided a sample. Except for patient A, no other persons tested had laboratory evidence of recent Zika virus infection. Of 5,875 mosquitoes collected, none were known vectors of Zika virus and all were negative for Zika virus.
The mechanism of transmission to patient A remains unknown but was likely person-to-person contact with the index patient.
Currently, Zika virus is known to be transmitted by the bite of an infected mosquito, congenitally from an infected mother to her fetus, sexually, through blood transfusion, and by laboratory exposure (16). Healthcare providers and public health officials should be aware that person-to-person transmission beyond sexual transmission might occur, albeit rarely, and should be investigated to determine the potential source of infection by obtaining various body fluids from persons suspected of transmitting the virus to another person through an undetermined route. Additional investigation is needed to determine the infectious risk various body fluids represent for person-to-person transmission and to determine host factors that might increase susceptibility for infection.
Dr. Krow-Lucal is an Epidemic Intelligence Service Officer in the Arboviral Diseases Branch, Division of Vector-Borne Diseases, National Center for Zoonotic and Emerging Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO. Her primary research interests are immunology and infectious diseases.
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