Travel Surveillance and Genomics Uncover a Hidden Zika Outbreak during the Waning Epidemic.

The Zika epidemic in the Americas has challenged surveillance and control. As the epidemic appears to be waning, it is unclear whether transmission is still ongoing, which is exacerbated by discrepancies in reporting. To uncover locations with lingering outbreaks, we investigated travel-associated Zika cases to identify transmission not captured by reporting. We uncovered an unreported outbreak in Cuba during 2017, a year after peak transmission in neighboring islands. By sequencing Zika virus, we show that the establishment of the virus was delayed by a year and that the ensuing outbreak was sparked by long-lived lineages of Zika virus from other Caribbean islands. Our data suggest that, although mosquito control in Cuba may initially have been effective at mitigating Zika virus transmission, such measures need to be maintained to be effective. Our study highlights how Zika virus may still be "silently" spreading and provides a framework for understanding outbreak dynamics. VIDEO ABSTRACT.

Zika Virus IgM Detection and Neutralizing Antibody Profiles 12-19 Months after Illness Onset.

Data on the duration of detectable Zika virus-specific IgM in infected persons are limited. Neutralizing antibody cross-reactivity occurs between Zika virus and related flaviviruses, but the degree to which this confounds diagnosis is uncertain. We tested serum specimens collected 12-19 months after illness onset from patients with confirmed Zika virus disease for Zika virus IgM and Zika virus and dengue virus neutralizing antibodies. Among 62 participants, 45 (73%) had detectable Zika virus IgM and 12 (19%) had an equivocal result. Although all patients tested had Zika virus neutralizing antibodies, 39 (63%) also had neutralizing antibodies against dengue virus; of those, 12 (19%) had <4-fold difference between Zika virus and dengue virus titers, and 5 (8%) had dengue virus titer >4-fold higher than Zika virus titer. Prolonged detection of IgM and neutralizing antibody cross-reactivity make it difficult to determine the timing of Zika virus infection and differentiate between related flaviviruses.

Zika Virus IgM 25 Months after Symptom Onset, Miami-Dade County, Florida, USA.

We assessed IgM detection in Zika patients from the 2016 outbreak in Miami-Dade County, Florida, USA. Of those with positive or equivocal IgM after 12-19 months, 87% (26/30) had IgM 6 months later. In a survival analysis, ≈76% had IgM at 25 months. Zika virus IgM persists for years, complicating serologic diagnosis.

Partnerships Involved in Public Health Testing for Zika Virus in Florida, 2016.

The emergence of Zika virus in the Americas in 2015 and its association with birth defects and other adverse health outcomes triggered an unprecedented public health response and a demand for testing. In 2016, when Florida exceeded state public health laboratory capacity for diagnostic testing, the state formed partnerships with federal and commercial laboratories. Eighty-two percent of the testing (n = 33 802 of 41 008 specimens) by the laboratory partners, including Florida's Bureau of Public Health Laboratories (BPHL; n = 13 074), a commercial laboratory (n = 19 214), and the Centers for Disease Control and Prevention (CDC; n = 1514), occurred from July through November 2016, encompassing the peak period of local transmission. These partnerships allowed BPHL to maintain acceptable test turnaround times of 1 to 4 days for nucleic acid testing and 3 to 7 days for serologic testing. Lessons learned from this response to inform future outbreaks included the need for early planning to establish outside partnerships, adding specimen triage strategies to surge plans, and integrating state and CDC information systems.

Epidemiology of Pediatric Zika Virus Infections.

BACKGROUND AND OBJECTIVE: In July 2016, local transmission of Zika virus (ZIKV) was announced in Miami-Dade County, Florida. In this report, we describe the epidemiology of pediatric ZIKV infections in locally acquired and travel-associated cases. METHODS: All children aged 1 to 17 years tested for ZIKV between October 1, 2015, and March 29, 2017, were included. SAS 9.4 was used to analyze age, sex, race and/or ethnicity, origin of exposure, onset date, affiliation with a household cluster, clinical symptoms, hospitalizations, viremia, viruria, and antibody detection in specimens. RESULTS: Among 478 confirmed ZIKV cases in Miami-Dade County, 33 (6.9%) occurred in children (1-17 years). Twenty-seven (82.3%) cases were travel-associated. The median age of a pediatric Zika case patient was 11 years. Seventeen (51.5%) case patients were boys, and 23 (69.9%) were Hispanic. Among 31 symptomatic cases, all reported having rash, 25 (80.6%) reported fever, 9 (29.0%) reported conjunctivitis, and 7 (22.6%) reported arthralgia. Sixteen (48.5%) cases reported 2 of 4 and 8 (24.2%) reported 3 of 4 main symptoms. CONCLUSIONS: This report found that the majority of children identified during the 2016 ZIKV outbreak only presented with 2 of the 4 main symptoms. In addition, pediatric ZIKV cases were frequently associated with symptomatic household members.