On April 7, 2017, DSHS modified Zika Testing Criteria for Residents of the Lower Rio Grande Valley:
- Testing is recommended for pregnant residents of Cameron, Hidalgo, Starr, Webb, Willacy, and Zapata counties at their first prenatal care visit and again in the second trimester. If a pregnant woman is exhibiting symptoms in any stage of her pregnancy, she should be tested for Zika.
- Testing is recommended for other residents of those counties who exhibit a rash and at least one other common Zika symptom, either fever, joint pain, or conjunctivitis (red eyes).
- Testing is available through many commercial labs and through public health laboratories in the state.
Read the DSHS Health Alert for more information. Visit the Health Care Professionals page for information about caring for pregnant women and patients exposed to Zika.
Laboratory testing for Zika virus infection is available at the U.S. Centers for Disease Control and Prevention (CDC). The DSHS Austin Laboratory is performing reverse transcriptase polymerase chain reaction (RT-PCR) for Zika. Please review the Chikungunya, Dengue, and Zika PCR and Serology Specimen Criteria guidance document (75 kb, PDF) (updated Dec. 16, 2016) to facilitate laboratory testing of individuals meeting the testing criteria. Specimens submitted to the DSHS Austin Laboratory must be accompanied by a completed Chikungunya, Dengue, and Zika Testing Supplemental Information Form (65 kb, PDF) (updated Sept. 12, 2016)
On May 31, the CDC released interim guidance on Zika virus antibody testing and interpretation of results. Because of the differences in recommended clinical management of Zika and dengue virus infections, and the risk of adverse pregnancy outcomes in women infected with Zika virus during pregnancy, a conservative approach to the interpretation of antibody test results is necessary to reduce the possibility of a missed diagnosis of either infections. The timing of IgM antibody testing and the thresholds of plaque reduction neutralization test (PRNT) have changed.
- Serum IgM antibody test should be performed if real-time reverse transcription polymerase chain reaction (rRT-PCR) results are negative regardless of the day the specimen was collected.
- Based on earlier flavivirus research and limited preliminary data specific to Zika virus, the historical use of a 4-fold higher titer by PRNT might not discriminate between anti-Zika virus antibodies and cross-reacting antibodies in all persons who have been previously infected with or vaccinated against a related flavivirus (i.e., secondary flavivirus infection).
- Together with a positive or equivocal IgM to Zika or dengue virus:
- A PRNT titer >10 will be interpreted as a evidence of infection with that specific flavivirus infection when the PRNT to the other flavivirus(es) tested is <10.
- A PRNT titer <10 to a specific flavivirus will be interpreted as a no evidence of infection with that virus.
- If PRNTs are positive i.e., >10 to multiple flaviviruses, this will be interpreted as evidence of recent infection with a flavivirus.
CDC will continue to update this guidance as these data are preliminary and as additional rRT-PCR data becomes available. For more information about this guidance, visit Interim Guidance for Interpretation of Zika Virus Antibody Test Results.
Additional guidelines for health care providers are on the Health Care Professionals page.
See a comprehensive listing of contact information by county for local and regional health departments in Texas.
More information for state and local public health laboratories is on the CDC website.