Zika Virus

Zika virus is a mosquito-borne flavivirus that gained global attention due to its association with severe birth defects. While most infections are mild or asymptomatic, Zika poses significant risks during pregnancy, potentially causing congenital Zika syndrome including microcephaly and other brain abnormalities in developing fetuses.

⚠️ Pregnancy Warning

Pregnant women should avoid travel to areas with Zika virus transmission. If exposed, seek immediate prenatal care. Zika can cause severe birth defects including microcephaly.

Medical Disclaimer: This information is for educational purposes only and should not replace professional medical advice. Always consult with a qualified healthcare provider for diagnosis and treatment of any medical condition.

Understanding Zika Virus

Zika virus was first identified in Uganda in 1947 and remained relatively obscure until large outbreaks occurred in the Pacific islands (2013-2014) and the Americas (2015-2016). The virus is primarily transmitted by Aedes mosquitoes, the same species that spread dengue and chikungunya.

Global Impact

  • 2015-2016: Major outbreak in Brazil and Americas
  • WHO declared Public Health Emergency (2016)
  • 87 countries have reported mosquito transmission
  • Ongoing endemic transmission in many tropical areas
  • Periodic outbreaks continue worldwide

Transmission

Primary Transmission Routes

1. Mosquito Bites (Most Common)

  • Aedes aegypti (primary vector)
  • Aedes albopictus (secondary vector)
  • Mosquitoes bite during day and night
  • Peak biting times: early morning and late afternoon

2. Mother to Child

  • During pregnancy: Crosses placenta
  • During delivery: Rare but possible
  • Not through breastfeeding: Safe to breastfeed

3. Sexual Transmission

  • Can be transmitted through semen, vaginal fluids, and possibly saliva
  • Virus remains in semen longer than blood
  • Transmission possible before, during, and after symptoms
  • Can occur from asymptomatic partners

4. Blood Transfusion

  • Theoretical risk
  • Blood screening implemented in affected areas

Transmission Timeline

  • In blood: Few days to 1 week
  • In urine: Up to 2 weeks
  • In semen: Up to 3 months or longer
  • In vaginal fluids: Up to 2 weeks

Symptoms

Most Zika infections (60-80%) are asymptomatic. When symptoms occur, they are generally mild:

Common Symptoms

  • Fever: Low-grade (rarely exceeds 38.5°C/101.3°F)
  • Rash: Maculopapular, starting on face and spreading
  • Joint pain: Especially small joints of hands and feet
  • Conjunctivitis: Red eyes without discharge
  • Muscle pain: Myalgia
  • Headache: Behind the eyes
  • Fatigue: General malaise

Symptom Timeline

  • Incubation: 3-14 days after mosquito bite
  • Duration: 2-7 days
  • Recovery: Usually complete

Complications

Rare but serious complications include:

  • Guillain-Barré Syndrome: Muscle weakness and paralysis
  • Meningoencephalitis: Brain inflammation
  • Myelitis: Spinal cord inflammation
  • Thrombocytopenia: Low platelet count

Pregnancy and Congenital Risks

Congenital Zika Syndrome

Zika infection during pregnancy can cause a pattern of birth defects:

  • Microcephaly: Abnormally small head size
  • Brain abnormalities: Decreased brain tissue, damage to back of eye
  • Eye defects: Including vision problems
  • Hearing loss: Sensorineural deafness
  • Limb contractures: Joint movement problems
  • High muscle tone: Restricting body movement

Risk by Trimester

  • First trimester: Highest risk for severe defects
  • Second trimester: Continued risk
  • Third trimester: Lower but still present risk

Pregnancy Monitoring

For pregnant women with possible Zika exposure:

  • Immediate testing recommended
  • Serial ultrasounds every 3-4 weeks
  • Amniocentesis may be considered
  • Referral to maternal-fetal medicine specialist
  • Postnatal evaluation of infant

Diagnosis

Testing Indications

  • Symptomatic individuals with travel to endemic areas
  • Pregnant women with possible exposure
  • Sexual partners of travelers from endemic areas
  • Infants with microcephaly or mothers with exposure

Diagnostic Tests

  • RT-PCR:
    • Detects viral RNA
    • Most accurate in first week
    • Can test blood, urine, saliva, semen
  • Serology (IgM antibodies):
    • After first week of illness
    • Cross-reacts with dengue
    • Requires confirmation
  • Plaque Reduction Neutralization Test:
    • Confirms positive serology
    • Differentiates from other flaviviruses

Treatment

No specific antiviral treatment exists for Zika virus. Management is supportive:

Symptomatic Treatment

  • Rest: Adequate sleep and reduced activity
  • Hydration: Plenty of fluids to prevent dehydration
  • Fever/Pain: Acetaminophen (paracetamol)
    • Avoid aspirin and NSAIDs until dengue ruled out
    • Risk of bleeding complications
  • Rash: Antihistamines for itching if needed

Monitoring

  • Watch for warning signs of complications
  • Neurological symptoms require immediate evaluation
  • Pregnant women need specialized follow-up

Prevention

Mosquito Bite Prevention

  • Insect Repellent:
    • DEET (20-30%)
    • Picaridin
    • IR3535
    • Oil of lemon eucalyptus
  • Protective Clothing:
    • Long sleeves and pants
    • Light-colored clothing
    • Permethrin-treated clothing
  • Environmental Control:
    • Window and door screens
    • Air conditioning when possible
    • Mosquito netting over beds
    • Eliminate standing water

Sexual Transmission Prevention

  • For travelers returning from endemic areas:
    • Men: Use condoms or abstain for 3 months
    • Women: Use protection or abstain for 2 months
  • Couples planning pregnancy:
    • Wait recommended time after travel
    • Consider pre-conception counseling

Travel Recommendations

  • Check CDC travel advisories
  • Pregnant women should avoid endemic areas
  • Take mosquito precautions seriously
  • Consider postponing non-essential travel

Vaccine Development

No vaccine is currently available, though several candidates are in development and clinical trials.

Public Health Measures

  • Vector control programs
  • Surveillance and reporting
  • Blood supply screening
  • Public education campaigns
  • Research into vaccines and treatments
  • International coordination