II. Background
- First described in Uganda, 1947
- First large-scale human outbreak in 2007
III. Pathophysiology
- Genus: Flavivirus
- Single-stranded RNA Virus
- Similar to Dengue, Yellow Fever, West Nile
- Regions involved (CDC)
- Transmission
- Mosquito Bite by infected Aedes albopictus Mosquito (breeds in water containers)
- Primates are natural virus reservoir
- During epidemics, human to Mosquito to human transmission
- Other transmission
- In-utero and perinatal transmission
- Transfusion (blood, Platelets)
- Sexually transmitted
- Zika Virus may be transmitted in semen for up to 2-6 months
- Peterson (2016) MMWR Morb Mortal Wkly Rep 65(39):1077-81 [PubMed]
- Mosquito Bite by infected Aedes albopictus Mosquito (breeds in water containers)
IV. Symptoms
- Asymptomatic in >80% of cases
- Median Incubation Period: 6 days
- Duration: Typically mild symptoms for up to 1 week
- Common symptomatic presentation (similar in adults and children)
- Maculopapular rash (most common)
- Fever
- Nonpurulent Conjunctivitis
- Arthralgia
- Associated symptoms
V. Differential Diagnosis
VI. Labs: General
VII. Labs: Diagnosis (esp. pregnancy)
- Preferred testing protocols for pregnant women are evolving and dependent on multiple factors
- Timing from symptoms or exposure less than 2 weeks?
- Symptomatic?
- Endemic region for Zika Virus infection?
- CDC Zika Diagnostics
- Primary tests
- Real-time reverse transcriptase PCR (RNA NAT serum and urine)
- Preferred test in first 2 weeks
- Sources
- Zika RNA is expected in serum from before symptoms to 1 week after (up to 10 weeks rarely)
- Zika RNA may be present in urine for up to 2 weeks after symptom onset
- Samples may also be obtained from cerebrospinal fluid and amniotic fluid
- Positive RNA test confirms Zika, but negative test does not exclude Zika
- Serum Zika IgM
- Preferred test at 2-12 weeks after symptom onset
- False Negatives in first 2 weeks
- False Positives with other Flavivirus Infection (esp. previously exposed or vaccinated)
- Real-time reverse transcriptase PCR (RNA NAT serum and urine)
- Other testing in unclear cases when primary tests are non-diagnostic
- DengueVirus IgM
- Serum Plaque Reduction Neutralization Testing (serum PRNT)
- Indicated in positive or equivocal Zika Virus IgM
- False Positives due to cross reactivity with DengueVirus (avoid in Puerto Rico)
VIII. Management
- Exclude serious causes in differential (e.g. Dengue Fever)
- Supportive Care
- Hydration
-
Analgesics (e.g. NSAIDs, Acetaminophen)
- Avoid NSAIDs until Dengue Fever is excluded
- Avoid Aspirin (due to Thrombocytopenia risk in Zika, Hemorrhage risk in Dengue Fever)
- Reduce transmission to others
- Prevent further Mosquito Bites during acute Zika Virus infection
- Prevent sexual transmission
IX. Complications
- Congenital Zika Syndrome (with severe Microcephaly and associated neurologic complications)
-
Guillain-Barre Syndrome (also occurs with West Nile Virus)
- Risk following Zika Infection: 0.24 per 1000
- Median onset of neurologic findings after Zika Infection: 5-6 days
-
Thrombocytopenia
- May be severe, life threatening (rare)
- Zika Virus Encephalitis
X. Prevention
- See Prevention of Vector-borne Infection
- Pregnant women in Zika active regions
- Pregnant women in Zika active regions should use Condoms or abstinence throughout pregnancy
- Guidance for pregnant women with Zika Exposure (CDC)
- Nonpregnant women in Zika active regions
- Strongly consider effective Contraception if not desiring pregnancy
- Sexual transmission prevention
XI. References
- CDC Zika Virus
- WHO Zika Virus
- ACOG Zika Virus