Epidemiology

History

• Zika Virus is Named After the Ugandan Forest Where it was First Isolated from a Rhesus Monkey
  • Virus was First Isolated in 1947
  • First Human Cases of Zika Virus Infection were in 1952 in Uganda and Tanzania
  • Zika Virus Subsequently Spread Across Africa

Modern Geographic Foci of Zika Virus Infection

• Outbreak in the Yap Islands of Micronesia in 2007
• Outbreak in French Polynesia in 2013-2014
  • Affected Approximately 66% of the Population: 32k infections
• Chilean Easter Island Cases Reported in 2014: Zika virus was first found in the Western hemisphere
• Brazilian Cases Reported in May, 2015
• Florida and Texas Cases/Traveler-Associated Cases in 2015-2016
  • First US Case of Zika Virus-Associated Microcephaly was Reported in Hawaii in 2016: mother had resided in Brazil during her pregnancy
  • First US Case of Sexually-Transmitted Zika Virus Infection in Texas in 2016

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Virology/Transmission

• Zika Virus is an Arbovirus (Arthropod-Borne Virus) (see Arboviruses)
  • Family Flaviviridae
  • Genus Flavivirus: “flavus” means yellow in Latin (originated from Yellow Fever Virus, so named because of its propensity to cause jaundice)
• Routes of Transmission
  • Bite from an Infected Mosquito (see Mosquito Bite): primary mode of transmission
    • Aedes Aegypti Mosquito: in most cases
      • Note: Aedes Mosquitoes Can Also Transmit Dengue Virus and Chikungunya Virus (see Dengue Virus and Chikungunya Fever)
    • Aedes Albopictus Mosquito (Asian Tiger Mosquito): also known to harbor Zika virus
  • Blood Product Transfusion
  • Human to Human Transmission (Apart from Sexual Transmission): has also been reported (although mechanism of transmission is unclear)
  • Laboratory Exposure
  • Maternal-Fetal Transmission
  • Organ Transplant
  • Sex (Vaginal, Anal, and Oral)

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Diagnosis

Real-Time Reverse Transcriptase Polymerase Chain Reaction (rRT-PCR) for Zika Virus

• Diagnostic
  • Testing for Dengue Virus and Chikungunya Virus Should Also Be Simultaneously Performed (see Dengue Virus and Chikungunya Fever): a single PCR test for all 3 infections is available from the CDC and other laboratories
• Samples
  • Serum: primary specimen
  • Urine: primary specimen
  • Whole Blood: sometimes used

Zika Virus Serology

• May Be Diagnostic

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Clinical Manifestations

General Comments

• Incubation Period: 2-14 days
• Disease Course
  • Clinical Manifestations Occurs in 20-25% of Patients Who Become Infected (MMWR Morb Mortal Wkly Rep, 2016) [MEDLINE]
  • Illness is Usually Mild and Self-Limited: resolving within 2-7 days after onset
• Distinction Between the Clinical Presentations of Zika Virus, Dengue Virus, and Chikungunya Virus (see Dengue Virus and Chikungunya Fever) (Centers for Disease Control and Prevention, “Zika Virus-What Clinicians Need to Know?” Clinician Outreach and Communication Activity Call 1/26/16) [LINK]

Cardiovascular Manifestations

• Myocarditis (see Myocarditis)
  • Epidemiology: rare case reports

Dermatologic Manifestations

• Pruritic Maculopapular Rash (see Papules)
  • Epidemiology: common
  • Clinical: usually begins on the face and spreads to trunk, extremities, palms, and soles

Gastrointestinal Manifestations

• Abdominal Pain (see Abdominal Pain)
  • Epidemiology: less common
• Diarrhea (see Diarrhea)
  • Epidemiology: less common
• Mucositis/Mucous Membrane Ulcerations (see Mucocutaneous Ulcers)
  • Epidemiology: less common
• Nausea (see Nausea and Vomiting)
  • Epidemiology: less common
• Palatal Petechiae
  • Epidemiology: rare case reports

Hematologic Manifestations

• Thrombocytopenia (see Thrombocytopenia)
  • Epidemiology
    • Rare Case Reports
    • Case Series Zika Virus Infections in Patients with Renal/Liver Transplants (Am J Transplant., 2017) [MEDLINE]: these cases presented with thrombocytopenia, bacterial superinfection, and graft dysfunction (but without rash, conjunctivitis, or neurologic symptoms)

Neurologic Manifestations

• Asthenia (see xxxx)
  • Epidemiology: may occur
• Congenital Microcephaly
  • Epidemiology
    • Congenital Microcephaly Has Been Reported in Neonates Born to Women Who Were Infected with Zika Virus
• Dysesthesia (see Dysesthesia)
  • Epidemiology: may occur
• Guillain-Barre Syndrome (see Guillain-Barre Syndrome)
  • Epidemiology
    • Case Reports (Lancet, 2016) [MEDLINE]
    • Latency: ranging from 6 days to 5-9 wks after the acute episode
• Headache (see Headache)
  • Epidemiology: may occur
• Meningioencephalitis (see Meningitis and Encephalitis)
  • Epidemiology: has been reported
• Myelitis (see Transverse Myelitis)
  • Epidemiology: has been reported
• Neuropsychiatric/Cognitive Symptoms
  • Epidemiology: has been reported

Ophthalmologic Manifestations

• Nonpurulent Conjunctivitis (see Conjunctivitis)
• Retro-Orbital Pain (see xxxx)
  • Epidemiology: may occur
• Uveitis (see Uveitis)
  • Epidemiology: rare case reports

Otolaryngologic Manifestations

• Transient Hearing Loss (see Hearing Loss)
  • Epidemiology: rare case reports

Rheumatologic Manifestations

• Arthralgias (see Arthralgias)
  • Clinical: mostly involving the small joints of the hands and feet
• Myalgias (see Myalgias)
  • Epidemiology: may occur

Other Manifestations

• Fever (see Fever): usually low-grade (up to 38.5 degrees C)

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Prevention

Protection from Mosquito Bites

• Clothing
• Insect Repellant
• Mosquito Netting
• Staying Indoors

Mosquito Control

• Eliminate Standing Water Sources

Prevention of Sexual Transmission

• Avoid Unprotected Sexual Contact
• Barrier Protection

Blood/Organ/Tissue Donor Screening

• Blood Donor Screening
• US FDA Recommendations for Hematopoietic Stem Cells, Tissues, and Donor Gametes

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Treatment

Supportive Care

• Hydration
• Acetaminophen (Tylenol) (see Acetaminophen): as required for pain

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References

• Guillain-Barre syndrome outbreak associated with Zika virus infection in French Polynesia: a case-control study.  Lancet.  2016;387(10027):1531–1539 [MEDLINE]
• Zika virus-associated Guillain-Barre syndrome: a warning for critical care physicians.  Intensive Care Med.  2016 Sep;42(9):1485–1486. doi: 10.1007/s00134-016-4364-x [MEDLINE]
• Travel-Associated Zika Virus Disease Cases Among U.S. Residents–United States, January 2015-February 2016. MMWR Morb Mortal Wkly Rep. 2016;65(11):286 [MEDLINE]
• Zika Virus Infection Among U.S. Pregnant Travelers – August 2015-February 2016. MMWR Morb Mortal Wkly Rep. 2016;65(8):211-4 [MEDLINE]
• Patterns in Zika Virus Testing and Infection, by Report of Symptoms and Pregnancy Status – United States, January 3-March 5, 2016. MMWR Morb Mortal Wkly Rep. 2016;65(15):395 [MEDLINE]
• Centers for Disease Control and Prevention, “Zika Virus-What Clinicians Need to Know?” Clinician Outreach and Communication Activity (COCA) Call 1/26/16 (Accessed 7/17) [LINK]
• Travel-Associated Zika Virus Disease Acquired in the Americas Through February 2016: A GeoSentinel Analysis. Ann Intern Med. 2017;166(2):99 [MEDLINE]
• Zika Virus Infection and Solid Organ Transplantation: A New Challenge. Am J Transplant. 2017;17(3):791 [MEDLINE]