Weeks before we learned of the first locally acquired Zika cases in Miami-Dade, Florida the Utah Dept announced a `Unique' Case Of Zika Transmission of a `family contact' - who acted as a caregiver - of an elderly person with travel history to a Zika endemic region.
The elderly family member - who had serious comorbidities - died of organ failure on June 25th, while the caregiver developed symptoms on July 1st.
That same day (July 18th) we saw a CDC press conference (see 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 caught the virus.
Today an early release of the MMWR describes the detailed epidemiological investigation undertaken by local, state and CDC officials.
While we now know a lot more about the circumstances surrounding this case, exactly how this caregiver contracted the virus remains unclear.
The CDC does warn : . . . family contacts should be aware that blood and body fluids of severely ill patients might be infectious.
Follow the link below to read the full report.
Preliminary Findings from an Investigation of Zika Virus Infection in a Patient with No Known Risk Factors — Utah, 2016
Early Release / September 13, 2016 / 65
Carolyn Brent1,2; Angela Dunn, MD3; Harry Savage, PhD4; Ary Faraji, PhD5; Mike Rubin, MD6; Ilene Risk, MPA1; Wendy Garcia7; Margaret Cortese, MD8; Shannon Novosad, MD9; Elisabeth Raquel Krow-Lucal, PhD4; Jacqueline Crain2,3; Mary Hill, MPH1; Annette Atkinson, MS10; Dallin Peterson3; Kimberly Christensen10; Melissa Dimond, MPH3; J. Erin Staples, MD4; Allyn Nakashima, MD3
On July 12, 2016, the Utah Department of Health (UDOH) was notified by a clinician caring for an adult (patient A) who was evaluated for fever, rash, and conjunctivitis that began on July 1. Patient A had not traveled to an area with ongoing Zika virus transmission; had not had sexual contact with a person who recently traveled; and had not received a blood transfusion, organ transplant, or mosquito bites (1).
Patient A provided care over several days to an elderly male family contact (the index patient) who contracted Zika virus abroad. The index patient developed septic shock with multiple organ failure and died in the hospital on June 25, 2016. The index patient’s blood specimen obtained 2 days before his death had a level of viremia approximately 100,000 times higher than the average level reported in persons infected with Zika virus (2).
Zika virus infection was diagnosed in patient A by real-time reverse transcription–polymerase chain reaction (rRT-PCR) testing on a urine specimen collected 7 days after symptom onset. In addition, a serum specimen collected 11 days after symptom onset, after patient A’s symptoms had resolved, was positive for antibodies to Zika virus by Zika immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (MAC-ELISA) and had neutralizing antibodies detected by plaque-reduction neutralization testing (PRNT). Working with Salt Lake and Davis County Health Departments, UDOH requested assistance from CDC with an investigation to determine patient A’s exposures and determine a probable source of infection.
The investigation consisted of four components: 1) an epidemiologic evaluation of family contacts of the index patient, 2) a serosurvey of health care workers who provided direct care to the index patient before his death, 3) a community serosurvey around the locations where the index patient had resided, and 4) active vector surveillance near the residences of the index patient and patient A.
For the purpose of this investigation, a family contact was defined as a person who resided in the same household as the index patient or had direct contact with his body fluids (i.e., tears, conjunctival discharge, saliva, vomitus, urine, or stool) during the period when he was most likely viremic, including a few days before his illness onset and until his death.
Nineteen family contacts, including patient A, were identified and interviewed, and provided blood or urine specimens for testing. Thirteen family contacts reported hugging and kissing the index patient’s face. Five family contacts reported being present while the index patient’s stool, urine, or vomitus was being cleaned. Patient A reported hugging and kissing the index patient, in a similar fashion to other family contacts, and assisted hospital personnel in holding the index patient while his stool was being cleaned, but did not have direct contact with stool.
Other than patient A, all family contacts were negative for Zika virus infection by rRT-PCR or MAC-ELISA on specimens obtained roughly 2–3 weeks after last exposure.
It remains unclear how patient A was infected; however patient A was known to have had close contact (i.e. kissing and hugging) with the index patient while the index patient's viral load was found to be very high.
Although it is not certain that these types of close contact were the source of transmission, family contacts should be aware that blood and body fluids of severely ill patients might be infectious. Given recognition of high levels of viremia during illness, it is essential that health care workers continue to apply standard precautions while caring for all patients, including those who might have Zika virus disease (3).